June 20-23, 2017
San Domenico Palace
Taormina

Organizing Committee
Winton Au, Daniel Balliet, Robert Boehm, Nancy Buchan, Tamar Kugler,
Laetitia Mulder, Paul van Lange, Toshio Yamagishi

https://amsterdamcooperationlab.com

CONTENTS
Program Overview

3

Keynote Speaker Bios*

9

Keynote Presentations*11

Symposium Presentations*

13

Demonstration Presentations*

48

Poster Presentations*

63

Participant List**97*In order of appearance**Alphabetical order by first name2

Program Overview
June 20thJune 21stJune 22ndJune 23rd

8:00-8:30

Registration

8:30-10:20

Session 1

Session 5

Session 9

Session 13

10:20-10:50

Coffee Break andPosters

Coffee Break andPosters

Coffee Break andPosters

Coffee Break andPosters

10:50-12:20

Session 2

Session 6

Session 10

Session 14 &Business Meeting

12:20-2:00

Own Lunch

Own Lunch

Own Lunch

Own Lunch

2:00-3:50

Session 3

Session 7

Session 11

3:50-4:20

Coffee Break andPosters

Coffee Break andPosters

Coffee Break andPosters

4:20-5:00

Session 4(demonstration)

Session 8(demonstration)

Session 12(demonstration)

5:15-6:15

Keynote 1

Keynote 2

Keynote 3

6:15-7:15

Cocktail Reception

7:15-11:30

Own Dinner

Own Dinner

Own Dinner

3

Excursion Including
Conference Dinner(2:00-11:30)

DAY 1: June 20th 20178:30 am - 10:20 am
8:30
8:48
9:06
9:24
9:42
10:00

Session 1: Social Preferences (Symposium)

Welcome (Daniel Balliet, Nancy Buchan)
Disentangling Prosocial and Parochial Preferences: Laboratory and Field Evidence(Robert Böhm)
Ignorance as a tool of self-interest? (Susan Fiedler)
The role of interdependence in promoting fair resource divisions in children (Sebastian
Grueneisen)
Other regarding preferences in humans: focus on utility or appreciation? (Alfred Zerres)
Promises and dice: Do people keep their word rather than their money? (Jan Kristian
Woike)

10:20 am - 10:50 am

Coffee Break & Posters

10:50 am – 12:20 pm

Session 2: Evolution of Cooperation (Symposium)

10:50
11:08
11:26
11:44
12:02

Merely Opting Out of a Public Good Is Moralized: An Error Management Approach to
Cooperation (Andrew Delton)
Greater love has no one than this: to lay down one's life for one's friends (John 15:13)(Hannes Rusch)
A minimum set of factors necessary for the punishment and cooperation to evolve
without the aid of cultural group selection (Shuhei Tsuchida)
Coordinating decisions for cooperation: A comparative look at chimpanzee andhuman coordination (Shona Duguid)
The Relative Importance of Direct and Indirect Reciprocity Strategies for theEmergence of Cooperation (Károly Takács)

2:00 pm - 3:50 pm
14:00
14:18
14:36

14:54
15:12
15:30

Session 3: Biological Markers of Cooperation (Symposium)

The challenges of cheater detection in large-scale cooperation: From human societies
to the evolution of multicellularity and cancer (Athena Aktipis)
Structural neural networks reveal prosocial and selfish economic motivations (Alan
Fermin)A functional MRI study on how oxytocin affects decision making in social dilemmas:
cooperate as long as it pays off, aggress only when you think you can win (Bruno
Lambert)Manipulation of Pro-Sociality and Rule Following with Non-invasive Brain Stimulation(Jörg Gross)
Dispositional Social Risk-Seeking Promotes Trusting Strangers: Evidence based on
Attitudinal, Behavioral and Brain Data (Yiming Jing)
Does your health trump the environment? Stimulating water conservation amonghotel guests (Anouk Griffioen)

3:50 pm - 4:20 pm

Coffee Break & Posters
44:20 pm - 5:00 pm
16:20
16:25
16:30
16:35
16:40
16:45
16:50
16:55

Session 4: Demonstration Talks

Who are my fellow members in the groups to which I belong? Effects of groupcomposition and fautlines on parochial cooperation (Arjaan Wit)
Many relationships tempt you to cheat: Decreased cooperation in multiple prisoner's
dilemma (Dirk Semmann)
The Effect of Experience on the Impact of Monetary Incentives in Social Networks (Efrat
Aharonov-Majar)
The role of social preferences and recommendations in a game of conflict (Frederic
Moisan)Extension of Game Riskiness Model in Prisoner's Dilemmas through Expected Utility
Perspective (Gary Ting Tat Ng)
Incentives, Truth, and Consequence (Timothy Shields)
Context Matters: Moving Towards an Understanding of Person-Situation Influences on
What I Do AND What I Want You to Do in Social Dilemmas (Poonam Arora)
Does trust beget trustworthiness?: The effect of trusting intention on trustworthinessof the partner (Nobuyuki Takahashi)

5:15 pm - 6:15 pm

Keynote 1: Social Dilemmas in the field (Bettina Rockenbach)

6:15 pm - 7:15 pm

Cocktail Reception

DAY 2: June 21st 20178:30 am - 10:20 am
8:30
8:48
9:06
9:24
9:42
10:00

Session 5: Punishment (Symposium)

Expropriating free-riders and outsiders: theory, history and an experiment (David
Hugh-Jones)
Third party punishment in social dilemmas with heterogeneous and homogeneous
populations (Welmer Molenmaker)
The social consequences of punishment: When third-party punishment signals
morality and irrationality (Diogo Ferreira)Selfish people don’t free ride on punishment (Ori Weisel)
Which type of sanctioning institution is the most attractive and effective? (Misato Inaba)
Cultural Universals and Cultural Differences in Meta-Norms about Peer Punishment(Kimmo Eriksson)

10:20 am - 10:50 am

Coffee Break & Posters

10:50 am - 12:20 pm

Session 6: Commons Dilemmas and Pro-Environmental Behavior (Symposium)

10:50
11:08

Humans choose representatives who enforce cooperation in the climate change gamethrough extortion (Manfred Milinski)
Who cares who intervenes how? A framed field experiment on climate protection(Hendrik Bruns)
511:2611:44
12:02

Social Dilemma and Provision of Public Good: The Case of the Mursi Tribe in SouthWest Ethiopia (Eitan Andres)
Common-pool magic water: an investigation into the social strategies of 6-year-old
children in a resource dilemma (Rebecca Koomen)
Pro-social and anti-social punishment in international collective risk social dilemmas(Gianluca Grimalda)

2:00 pm - 3:50 pm
14:00
14:18
14:36
14:54
15:12
15:30

Session 7: Interdependence and Experimental Games (Symposium)

Not all Prisoner’s Dilemma Games are Equal: Incentives, Social Preferences, andCooperation (Cleotilde Gonzalez)“My Way Only”-thinking in social dilemmas (Pontus Strimling)
Incentive-based decision synchrony may enhance voluntary cooperation in a one-shotsocial dilemma game but may not promote positive evaluation of other game players (Toko Kiyonari)
Why Four Player Types And How They Fare in a Massively Multiplayer Game of Life
Simulation (Susanne Lohmann)
How Scarcity and Abundance affect Appropriation from common Resources (Rob
Nelissen)Indexing Prisoner’s Dilemma games: Quantifying psychological factors underlingcooperative behavior (Adam Stivers)

3:50 pm - 4:20 pm

Coffee Break & Posters

4:20 pm - 5:00 pm

Session 8: Demonstration Talks

16:20
16:25
16:30
16:35
16:40
16:45
16:50
16:55

What explains donations at the doorstep, and norm violations, in the field?
Reputation trumps resources (Paul Van Lange)
Happy to help if it's not too sad: The effect of mood on helping identifiable andunidentifiable victims (Hagit Sabato)
Justification Dilemma in private observation and its solution (Isamu Okada)
The games economists play: Why economics students behave more selfishly thanother students (Philipp Gerlach)
The Effects of Case Framing on the Willingness to Commit to Organ Donation (Inbal
Harel)
Prosocial loss aversion (Nadira Faber)
Implicit social categorization during intergroup competition. (Victor Shiramizu)
Trust and social distance among Americans, Chinese and Japanese (Yang Li)

5:15 pm - 6:15 pm
Dreu)

Keynote 2: Out-group aggression and In-group defense in Intergroup conflict (Carsten De

6

DAY 3: June 22nd 20178:30 am - 10:20 am
8:30
8:48
9:06
9:24

9:42
10:00

Session 9: Intuitive Versus Deliberative Decision-Making (Symposium)

The Effect of Decision Timing on the Willingness to Costly Reward Cooperation andPunish Non-Cooperation (Erik de Kwaadsteniet)
Context and Individual Preferences Shape Cooperative Decision Making (Giulia
Andrighetto)
Does honesty require time? A Meta-analysis (Nils Köbis)From spontaneous cooperation to spontaneous punishment: Distinguishing theunderlying motives driving spontaneous behavior in first and second order public goods (Dorothee
Mischkowski)
Deliberate thinking versus intuitive cooperation: On the role of processing mode forsocial mindfulness (Isabel Thielmann)
Mapping Morality with a Compass: Testing the theory of ‘morality as cooperation’ witha new questionnaire (Oliver Curry)

10:20 am - 10:50 am

Coffee Break & Posters

10:50 am - 12:20 pm

Session 10: Group Processes and Intergroup Relations (Symposium)

10:50
11:08
11:26
11:44
12:02

Minority v. Majority - A Structural Goal/Expectation Theory of Intergroup Conflict (DoraSimunovic)
Understanding parochial cooperation: Testing two theories (Hillie Aaldering)
Using peer influence to solve the social dilemma of workplace segregation (Fredrik
Jansson)
Are individuals on the right side of the political spectrum always less prosocial than
individuals on the left? The role of the in- versus outgroup status of interaction partners (Axel Burger)
Altruistic behavior in cohesive social groups: The role of target identifiability (Tehila
Kogut)

2:00 pm - 3:50 pm
14:00
14:18
14:36
14:54
15:12
15:30

Session 11: Reputation and Indirect Reciprocity (Sympoisum)

Self-governance sustains group-level reputation (Aron Szekely)
Solving Social Dilemmas by Reputation Mechanisms (Andreas Diekmann)
The dynamics of group-specific social preferences in intergroup conflict. A nationwide
incentivized experiment before and after the 2016 Austrian presidential election (Jürgen Fleiß)
Order without law: Reputation promotes cooperation in a cryptomarket for illegal
goods (Wojtek Przepiorka)
Understanding the Degree and Direction of Gossipers' Lies: The Role of Incentive
Alignment (Kim Peters)
The Psychology of Intergroup Trust Across 17 Countries (Angelo Romano)

3:50 pm - 4:20 pm

Coffee Break & Posters

74:20 pm - 5:00 pm
16:20
16:25
16:30
16:35
16:40
16:45
16:50

Session 12: Demonstration Talks

Rules and personal gains (Laetitia Mulder)
Gossip Versus Punishment: The Efficiency of Reputation to Promote and Maintain
Cooperation (Junhui Wu)
Do the powerful enforce the rules? Studying the effects of power on cooperation,
altruistic punishment and emotion in a public goods game (Loren Pauwels)
Women cooperate less than men in one-shot social dilemmas: Evidence from 12
nations (Angela Dorrough)The Evolution of Cooperation via Democratic Punishment (Stefan Pfattheicher)
How do people think about thieir interdependence: A multidimensional model ofsubjective outcome interdependence (Daniel Balliet)
Choice of Partners, Trust, and Scale of Interactions (Cathleen Johnson)

5:15 pm - 6:15 pm
Keynote 3: Cultural Values, Institutions, and Voluntary Cooperation: A Cross-societal
perspective (Simon Gaechter)
DAY 4: June 23rd 20178:30 am - 10:20 am
8:30
8:48
9:06
9:24
9:42
10:00

Session 13: Trust, Expectations, and Emotional Processes (Symposium)

Emotional Deception in Ultimatum Games (Eric van Dijk)
Greed is (Not Always) Good (Tamar Kugler)
Subjective and objective expectations of reciprocity in trust dilemmas (Anthony Evans)
A face bias in trust decisions (Bastian Jaeger)
It's not you it's me: how antecedent social decision-making impacts subsequent social
behavior (Joseph Calabrisotto)
Mimicry, empathy and its relation to pro-social behavior (Axel Franzen)

10:20 am - 10:50 am

Coffee Break & Posters

10:50 am - 12:20 pm

Session 14: Economic and organisational challenges (Symposium)

10:50
11:08
11:26
11:44

When justice concerns do (not) matter – / How justice sensitivity predicts voter's
preferences for (un)equal wealth distributions within a simulated democratic system (Thomas Schlösser)
Negative Brokerage: Understanding When, Why, and How Third Parties Divide andConquer (Eliran Halali)
In My Backyard? Human Cooperativeness and the Causal Roles of Physical Proximityand Exposure (Leonie Fütterer)
Business Meeting

2:00 pm - 11:30 pm

Excursion: Winery Tour with Tasting & Dinner8Keynote Speakers
Dr. Bettina Rockenbach

Prof. Dr. Bettina Rockenbach holds a diploma in Mathematics from the Universityof Bonn. As an assistant of the Nobel laureate Prof. Dr. Reinhard Selten she
received her Ph.D. and her Habilitation in Economics from the University of Bonnwith contributions to game theory and experimental economics. From 2000 to2011 Bettina Rockenbach held the Chair in Microeconomics at the University of
Erfurt. She founded and directed the experimental economics laboratory (eLab)
and the Center for Empirical Research in Economics and Behavioral Sciences(CEREB). From 2006 to 2008 Prof. Rockenbach served as the Dean of the Facultyof Economics, Law, and Social Sciences and from 2008 to 2011 as the VicePresident for Research and Young Academics at the University of Erfurt. Since
July 2011, Bettina Rockenbach holds the Chair for Experimental and Behavioral
Economics at the University of Cologne. From October 2012 to March 2015 sheserved as the Vice Dean for Research and Young Academics of the WiSo-Faculty
and since April 2015 Prof. Rockenbach is a Vice Rector of the University of
Cologne.
In 2013, Bettina Rockenbach was appointed to the German National Academy of
Sciences Leopoldina and since 2014 she is a member of the Senate of theGerman Science Foundation DFG. A focus of Bettina Rockenbach’s often
interdisciplinary research is in the design of institutions fostering cooperation insocial dilemma situations and the frameworks promoting socially responsible
economic behavior. She publishes in leading economic journals as well as in
distinguished general interest journals such as Science and Nature.
9

Carsten De Dreu

Carsten De Dreu obtained his PhD (1993; cum laude) from the University ofGroningen, The Netherlands. As post-doctoral fellow supported by the Royal
Netherlands Academy of Sciences (1994 – 1999), he worked at the University of
Illinois at Champaign-Urbana, Yale University, and Carnegie Mellon University.
From 1998 – 2015, De Dreu was full professor of work and organizational
psychology at the University of Amsterdam.
Carsten De Dreu is fellow of the Society for Personality and Social Psychology,
the Society for Industrial and Organizational Psychology, the Association for
Psychological Science. In 2012 he was elected into the Royal Netherlands
Academy of Sciences. He is a former president of the International Association
for Conflict Management (2001), and the European Association for Social
Psychology (2008-2011).
His scientific research and teaching focuses on the neurobiological andpsychological underpinnings of creativity and innovation, cooperative decisionmaking, and the regulation of conflict within and between groups. For his work
he received several awards, including most influential article awards from theAcademy of Management (2009, 2010), the William Owens Scholarly
Achievement Award from the Society of Industrial and Organizational
Psychology (2014), the Kurt Lewin Medal from the European Association of Social
Psychology (2014), and the KNAW-Hendrik Muller Award (2015).

10

Simon Gaechter

Simon Gaechter is a Professor of the Psychology of Economic Decision Making
at the University of Nottingham, UK. His main research interests are in the fieldof experimental and behavioral economics. He has long been interested involuntary cooperation in social dilemmas. His research draws on insights frompsychology, sociology, anthropology and biology and uses methods fromexperimental economics to understand basic issues in the psychology of humancooperation.

Keynote Presentations
Dr. Bettina RockenbachSocial Dilemmas in the field
The talk highlights the role of controlled field experiments for understanding and overcomingsocial dilemmas. On the one hand, controlled field experiments can inform theory, inparticular by taking advantage of studying social dilemmas under their real costs and benefits
and in their natural environment. The presented studies on cooperation and punishment
among strangers in the field demonstrate severe limitations of punishment in the field. On theother hand, controlled field experiments can inform politics by using behavioral insights tomitigate the negative consequences of social dilemmas. Taking the example of a hugebehavioral intervention study in Namibia we show the power of behavioral interventions toincrease payments for water by a magnitude of 30 percent.
11

Carsten De Dreu

Out-group aggression and In-group defense in Intergroup conflict
Intergroup conflict and competition can motivate individuals to contribute to their group’s
fighting capacity at a personal cost and at sometimes high risk. Sometimes, such self-sacrifice
is motivated by the greedy desire to subordinate and exploit out-groups (out-groupaggression) and, by implication, it is motivated also by the fear-based need to defend the ingroup against the rival’s out-group aggression. Archival analyses of group-hunting animals,
firms attempting hostile take-overs, and inter-state warfare all suggest that out-groupaggression is typically less successful than in-group defense, suggesting that evolutionary andcultural pressures may have favored capacities for cooperation and coordination when thegroup goal is to defend, rather than to expand, dominate, and exploit. Here I examine thispossibility in light of the results from experiments in which we engaged (groups of) individuals
in predator-prey contests and tracked neural and neuroendocrine activity, behavioral
investment in aggression and defense, and group-level coordination. Implications forregulating conflict and achieving world peace will be discussed, and avenues for future
research will be highlighted.

Simon Gaechter

Cultural Values, Institutions, and Voluntary Cooperation: A Cross-societal perspective
In this talk, I will present the results of a large-scale project (joint with Christian Thoeni, U
Lausanne, and Jonathan Schulz, Yale U) with public good experiments run in 43 countries
around the globe. I will present evidence for the hypothesis that the quality of a country’s
institution has positive effects in terms of voluntary cooperation in public goods games withand without punishment. Good institutions are not only important for standard economic andpolitical reasons, but also because they foster cooperation in situations in which cooperation
cannot be enforced through formal mechanisms.

12

Symposium Presentations
Disentangling Prosocial and Parochial Preferences: Laboratory and Field
Robert Böhm Evidence
Day 1, Session 1
Why do humans frequently behave altruistically toward in-group members while reacting in hostile ways to outgroups? The theory of parochial altruism proposes that positive preferences toward the in-group (i.e., prosociality)and negative preferences toward out-groups (i.e., parochialism) may have evolved jointly. Empirical evidence ismixed, though, potentially because previous research failed to assess individual-level prosociality and parochialism
as independent social preferences and has mainly been conducted in Western societies with low levels ofintergroup conflict. To overcome these shortcomings, we conducted three quasi-experimental, incentivized studies
with more than 700 participants across different countries and cultures. Importantly, we used adaptions of the SVO
slider measure to assess prosociality and parochialism independently, allowing a 2x2 classification of low vs. highprosociality and low vs. high parochialism. Study 1 was conducted among supporters of the Democratic vs.
Republican party during the 2016 US primaries and caucuses. We found that parochial altruists (i.e., participants
high on prosociality and high on parochialism) contributed most to the between-group pool of an Intergroup
Prisoner’s Dilemma-Maximizing Difference game (IPD-MD), which benefits the in-group and harms the out-groupat personal cost. Strikingly, in contrast to the theory of parochial altruism, most of those participants that wereclassified as prosocial were low in parochialism. Study 2 aimed to replicate these findings with different naturalgroups (i.e., German soccer fans from two conflicting first-league teams) and a different intergroup conflict game(i.e., Intergroup Prisoner’s Dilemma game, IPD). We found that those participants who were classified as parochial
altruists contributed more in the IPD than other prosociality/parochialism preference types. Again, only a minorityof prosocial individuals also scored high on parochialism. Study 3 tested whether individuals are more likely to
become parochial altruists if they live in an environment with more intense intergroup conflicts. Participants weremale Nyangatom from Western Ethiopia, a group of nomadic pastoralists who regularly engage in cross-borderintergroup conflict. We found that among participants from the border area with more recent conflict experiences,
parochial altruism was indeed more frequent than among participants from interior areas with little conflict
exposure. Our results provide partial support for parochial altruism theory. On the one hand, we indeed find thatparochial altruists are most likely to engage in aggressive intergroup conflict. However, we also find that highparochialism is present only among a minority of prosocial individuals, implying that individual-level prosociality is
not as clearly associated with parochialism as theory supposes.
SusannFiedler
Ignorance as a tool of self-interest?
Day 1, Session 1
In previous work people reported to experience ethical dissonance when behaving dishonest or unfair. One
proposed explanation is that their self-interest maximizing behavior stands often in conflict with their self-image(Self-Maintenance theory) whereas another account suggests that people are cognitively limited and systematicallybiased in their moral judgments (Bounded Ethicality). Two eye-tracking studies test the validity of these two main
theoretical accounts in the context of unethical and unfair decisions. The results of this line of research show that
attentional biases occur in the information search phase suggesting that people aim to avoid increased tension bypreemptive biased information processing. Using ignorance to reduce tension resulting from self-interested
behavior appears to be a reliable effect in situations where individuals where faced with the decision to maximize
their self-interest at the expense of an institution as well as at the expense of an individual person. This pattern ofresults provides an interesting starting point for understanding the strategic function of ignorance and provides
insides on the underlying mechanism of fair and unfair behavior.

13

Sebastian
Grueneisen
The role of interdependence in promoting fair resource divisions in children
Day 1, Session 1
Humans constantly have to coordinate their decisions even in social dilemma situations in which their immediate
interests are conflicting. For instance, two spouses may have opposing motives as to who of them incurs the cost of
behaving cooperatively (e.g., by picking up the kids from school) but they are also interdependent in the sense thatthey share an incentive to align their decisions since coordination failure is worse for both than any other outcome(a situation commonly modeled as chicken or snowdrift games). In recurrent interactions with stable partners
people often manage to solve this problem by negotiating fair compromises. So far, little is known about thedevelopment of this ability. In a first study, we therefore presented dyads of 5-year-olds (N=40) with an iterated
chicken game. We found that children successfully coordinated their decisions over multiple rounds and many
dyads did so by taking turns at behaving cooperatively, thus creating relatively fair payoff divisions. This finding
demonstrates that the ability to coordinate decisions despite having conflicting motives emerges early indevelopment. An open question, however, is what mechanism can account for such fair payoff divisions. One
explanation is that children value other’s welfare and have personal preferences for fair outcomes. Alternatively, fair
payoff divisions may mainly result from the interdependence between partners. That is, children may expect
activities involving collaboration between interdependent partners to be mutually beneficial. To address this issue,
we presented children with another conflict of interest requiring coordination (battle of the sexes). In this game,children had to choose between two payoff divisions. In the test condition, both children had to converge on thesame payoff division to be rewarded but they had different incentives as to which one to choose: one division wasfair and provided each player with an equal number of rewards whereas the other division was unfair and put one
child at an advantage. In control conditions, players could choose a payoff division individually, thus assessing
children’s baseline preference for fair resource divisions in this situation. Preliminary results indicate that children
were much more likely to converge on fair payoff divisions when they were interdependent and had to coordinate
their decisions (test condition) than when players could choose a payoff division individually (control conditions).
The results are discussed in relation to theories emphasizing the role of interdependence between collaborative
partners in shaping human cooperative decision-making and in generating mutually beneficial outcomes.

14

Alfred Zerres Other regarding preferences in humans – focus on utility or appreciation?
Day 1, Session 1
The classic concept of social value orientation (SVO) focuses on a three-category typology of preferences foroutcomes for the self and others (Messick & McClintock, 1968): (a) cooperators maximize outcomes for the self andthe other; (b) individualists primarily maximize outcomes for the self with little or no regard to the other; and (c)competitors focus on the maximization of their relative advantage over the other. Our research builds on thisliterature by exploring the underlying motivation that drives peoples’ other regarding preferences. In particular, wetest the hypothesis that an individual’s concern for another person’s outcomes may be motivated by either: (a) aninterest in the (economic) utility of the other person; or (b) an interest in the genuine feeling of appreciation (andsocial inclusion) by the other person. In many social decisions, both of these other-regarding motivations may
appear aligned and lead to similar short-term behavioral outcomes, However, they may stem from different
evolutionary origins (for a discussion of evolutionary origins of human altruism see, Fehr & Fischbacher, 2003) and,
therefore, have different functions for human fitness and important social implications. We developed a set ofdecomposed games based on the triple-dominance measure for SVO (e.g., Van Lange, Otten, De Bruin, &Joireman, 1997) with information asymmetry that forces participants to choose between these two other-regarding
motivations. In each game (total 18), the decision-maker (participant) chose between 4 different distributions ofmoney between him/herself and an anonymous recipient. The decision-maker was informed that immediately after
the decision, the recipient would receive information about this decision, all available choices, and the respective
outcomes for the decision-maker and the recipient. However, only the decision-maker also received information
about a hidden multiplier for each choice. This multiplier influenced the respective outcomes for the recipient, if therespective game was selected for payment (about 3 out of 18 games). Each game, included a competitive choice(maximized difference between the self and the other), an individualistic choice (maximized outcome for the self), a“utilitarian prosocial” choice (maximizes joint gain and minimizes differences after considering the hidden
multiplier), and a “genuine appreciation” choice (maximizes joint gain and minimizes differences before considering
the hidden multiplier). Across multiple experiments we found that about 30% of the participants were primarily
driven by utilitarian considerations, whereas about 15% were motivated by genuine concerns for social
appreciation. Moderators and implications of these findings will be discussed.
Jan Kristian
Woike
Promises and dice: Do people keep their word rather than their money?
Day 1, Session 1
Promises can generate trust and scaffold cooperation. Yet, it has been claimed that words are cheap talk and easy
to be broken in the absence of punishment, and that most people tend to lie (at least a little), when it improves
their personal gain. We used a novel, integrative approach to study the effect of promises on cheating behavior(N=776): Participants first played a variant of the dice-rolling game in two conditions. In the control condition,
participants chose between a higher and a lower payment rate without further consequence. In the promise
condition, participants could only choose the higher payment rate when they promised to truthfully report theirdice rolling results. We show that over-reporting in the promise condition was lower than in the control condition
and further, that over-reporting correlates with demographic and personality variables. After the dice rolling gameparticipants played a novel two-dimensional sender-receiver game, where they played the role of sender, and had
the opportunity to add a voluntary promise, affirming the correctness of their message. A second group ofparticipants were randomly assigned to the receiver role and acted upon a sender’s message with consequences
for both players’ payoffs. We analyze the effect of the senders' promises on the receivers' behavior, the relation
between the sender's behavior in the sender-receiver game and the dice-rolling game, as well as correlations withpersonality measures and the PANAS scale. Findings are supported by qualitative data such as open explanations
given by participants.

15

Andrew
Merely Opting Out of a Public Good Is Moralized: An Error Management
DeltonApproach to Cooperation
Day 1, Session 2
People regularly free ride on collective benefits, consuming them without contributing to their creation. In
response, free riders are often moralized, becoming targets of negative moral judgments, anger, ostracism, or
punishment. Moralization can change free riders’ behavior (e.g., encouraging them to contribute or discouraging
them from taking future benefits) or it can motivate others, including moralizers, to avoid or exclude free riders;these effects of moralization are critical to sustaining human cooperation. Based on theories of error management
and fundamental social domains from evolutionary psychology, we propose that the decision to moralize is a cuedriven process. One cue investigated in past work is observing a person illicitly consume collective benefits. Here,
we test whether the mind uses a second cue: merely opting out of contributing. Use of this cue creates aphenomenon of preventive moralization: moralization of people who have not yet exploited collective benefits but
who might—or might not—in the future. We tested for preventive moralization across 4 studies using implicit andexplicit measures of moralization, a behavioral measure of costly punishment, and a nationally representative
sample of almost 1,000 U.S. adults. Results revealed that merely opting out of contributing to the creation of
exploitable collective benefits— despite not actually exploiting collective benefits— elicited moralization. Results
further showed that preventive moralization is not due to the moralization of selfishness or deviance but insteadfollows from the uncertainty inherent in moralization decisions. These results imply that even people who will never
exploit collective benefits can nonetheless be targets of moralization. We discuss implications for social and political
dynamics.
HannesGreater love has no one than this: to lay down one's life for one's friends.
Rusch(John 15:13)
Day 1, Session 2
Human high-stake altruism, i.e. behavior that benefits others at a substantial fitness cost to the helping individual, is
one of the most awe-inspiring behaviors we know and maybe as old as humankind. However, it cannot be studied
empirically in any controlled laboratory context for obvious reasons. Thus, although numerous theories exist thatcan potentially explain how high-stakes altruism may have been conserved or even promoted by natural selection,
we are currently short of suitable ways to test these theories against each other in an ecologically valid way. Overthe last four years, I have been collecting a large data set (N ≈ 10,000) on recipients of the ‘Carnegie Medal for Civil
Heroism’ and the US-military’s ‘Medal of Honor’. These men and women distinguished themselves through acts ofextraordinary bravery and selflessness by risking, and often losing, their lives for those of others in a range ofcontexts. In this talk I give an overview of the results obtained so far in the analysis of this data. These include
published results on Medal of Honor recipients (Rusch 2013, Evol Psychol; Rusch & Störmer 2015, Mil Spect; Rusch
et al. 2015, Evol Hum Behav) as well as yet unpublished results on both groups of ‘heroes’. For this talk, particularemphasis will be put on the geographic origins of the distinguished individuals, as a proxy for cultural factors
potentially affecting inclinations to act heroically, as well as on a comparison of their longevity with that of arandom sample of the US population, as a proxy for potentially underlying genetic differences. This research
project on documented historical cases of high-stakes altruism is work in progress. Yet, as I will demonstrate in thetalk, the current data set already allows for the investigation of numerous principle questions about instances of
irrefutably costly human prosociality in an ecologically valid way. In addition, I would love to use the opportunity ofthis meeting to discuss ideas about further analyses and potential extensions of the data set with interested
colleagues, and to invite collaborations.

16

ShuheiA minimum set of factors necessary for the punishment and cooperation to
Tsuchida
evolve without the aid of cultural group selection
Day 1, Session 2
In this presentation, we reanalyzed the model of coordinated punishment (Boyd, Gintis, & Bowles, 2010) whichsuggested that punishment and cooperation can evolve without relying on the cultural group selection. Comparedto the past models of punishment, their model is much more complicated, and it is not clear why cooperation andpunishment evolved in their model. By thoroughly examining their model, we attempted to extract a minimum setof the conditions that is necessary for the evolution of punishment. In the Boyd et al.’s model, a punisher sends a
costly signal to all the other group members at the beginning and coordinate their decisions in later rounds
whether to cooperate or defect, and whether to punish non-cooperators or not. If a punisher perceives there is notenough number of other punishers in a group, s/he behaves as a non-cooperator who do not engage incooperation and punishment in the all subsequent rounds. If there is enough number of punishers existing in agroup, punishers make a cooperation and punish non-cooperator. They also divide the cost of punishment so thateach punisher’s cost is kept small while non-cooperators receive a significant amount of damage from being
punished. Through careful examinations of Boyd, et al.’s mathematical model, we found that, for cooperation andpunishment to stabilize, only the two factors are needed. (1) The cost of punishing a non-cooperator must be smalland (2) non-cooperators must be sensitive to the punishment so that they change their action and keepcooperating once punished. In the past studies of the evolution of cooperation, it was often argued that noncooperators need to be incurred a large amount of cost of being punished. In contrast, we found that it is much
more important to keep the cost of punishment small than maintaining the amount of punishment incurred by anon-cooperator large. In the presentation, we argue that our results are best interpreted in the context of symbolic
punishment (Masclet, et al., 2003). Both laboratory experiments and anthropological research showed that those
who failed to cooperate and received the mere verbal accusations from others change their behavior. The
conditions we found match the features of symbolic punishment. We argue that the most important puzzle of theevolution of the punishment is not about why people punish but about why symbolic punishment is so prevalent in
the human society.
Shona
Coordinating decisions for cooperation: A comparative look at chimpanzee
Duguidand human coordination
Day 1, Session 2
One of the challenges of cooperation is to coordinate decisions with others. Even when interests are aligned, thismay not be a trivial task. Recent theoretical accounts have proposed that humans have evolved unique skills for
coordinating decisions and actions with others in the pursuit of common interests. We tested this hypothesis using
a comparative approach; comparing the coordination skills of humans to our closest living relatives, chimpanzees.
Chimpanzees, like humans, coordinate their actions in a variety of contexts including group hunting, territory
defence, and joint travel. However, coordination may not be achieved in the same way. Across several experiments,
we presented dyads of each species (in this case children and captive chimpanzees) with different coordination
problems, including stag hunt games and pure coordination problems. Each of these problems is instantiated as aforaging task that requires coordination of decisions but also of actions in time and space to be more similar to thecoordination problems that chimpanzees would face in the wild. Combining the findings across tasks, a picture
emerges of the relative coordination skills of these two species. While chimpanzees are able to coordinate
successfully to a certain extent in all tasks, the way they do so differs markedly from humans. By 4 years of age
children have a greater range of coordination strategies available to them that allow them to coordinate flexibly
and efficiently across various types of coordination problems. This is particularly apparent when comparing theways both species use communication to solve these problems and points to potential limitations of coordinationand thus cooperation in chimpanzees.

17

The Relative Importance of Direct and Indirect Reciprocity Strategies for the
Károly Takács Emergence of Cooperation
Day 1, Session 2
Both direct and indirect reciprocity are good candidates to explain the evolution of cooperation in structured
societies. The relative importance of different forms of reciprocity might be differentiated and one form could
potentially drive out the feasibility of others. In the Prisoner’s Dilemma played in random networks we show thatwhen present, direct reciprocity gains dominance over network-based indirect reciprocity as well as over networkindependent generalized reciprocity. When direct reciprocity is absent, indirect reciprocity strategies are able tobecome dominant in the population and to supply a higher cooperation rate than that is attainable by direct
reciprocity. Forgiveness is a characteristic that improves the performance of all reciprocal strategies in the long run.
Population size and network density seem to improve the chances of generalized reciprocity, but these results are
purely due to an increased likelihood of non-convergence. Our results are robust to a wide range of conditions,
including noise.
AthenaThe challenges of cheater detection in large-scale cooperation: From humanAktipissocieties to the evolution of multicellularity and cancer
Day 1, Session 3
Detecting and responding to cheating is important in any large-scale social system. Work on human sociality has
found that people detect cheating in social rules like “If you take the benefit, you must pay the cost” or “You should
not ask unless you are in need.” A similar cheater detection problem exists in cellular sociality. Multicellularity is an
example of extremely high levels of cooperation and coordination, and one that is possible largely because of theclose relatedness of constituent cells. However, mutations can give rise to cellular cheaters that signal for moreresources than they should, proliferate when they should not and shirk their cellular duties. If unchecked, thesecells grow in frequency in the population, accumulate more mutations and eventually can lead to cancer. How has
multicellularity solved this problem of detecting pre-cancerous cheaters? In this talk I discuss the cheater detection
and response systems that our multicellular bodies use to protect us from would-be cancer cells. Multicellularbodies are equipped with an arsenal of cheater suppression mechanisms, many of which employ the principles ofcheater detection. One of these is the cancer suppression gene TP53. TP53 is a central node in a complex cellular
information processing system that integrates diverse signals to ‘decide’ whether a cell can continue its cell cycle,
requires DNA repair or should undergo programmed cell death (apoptosis). The costs and benefits of thesedifferent alternatives differ for organisms with different sizes, life spans and reproductive strategies. By applying
cheater detection and signal detection theory to the problem of cancer suppression, we can better understand thefunction of complex gene regulatory networks that protect multicellular bodies from cancer.

18Structural neural networks reveal prosocial and selfish economic
Alan Ferminmotivations
Day 1, Session 3
Social value orientations (SVO) are individual economic motivations to maximize own payoff or to achieve
egalitarian outcomes. Individuals with selfish motivations are less cooperative and make more unfair reward
distributions that benefit themselves than prosocial individuals. The neural substrates of SVO have recently been
associated with the structure and function of disparate brain regions involved in emotion and deliberation. Given
that human behavior results from the interaction among multiple brain regions, the current work investigatedwhether SVO is better explained by the role of single brain regions or by the anatomical interaction of large-scaleneural networks. Graph theoretical analysis was used to investigate differences in topological patterns of structuralbrain connectivity based on covariance of gray matter volume of 90 brain regions in individuals classified as
prosocials (n = 114) and proselfs (n = 130). Global measures of structural network connectivity included clustering(local interconnectivity) and path length (global integration). Permutation and area under the curve (AUC)
procedures were used to investigate group differences in hubs based on betweenness (node’s fraction of shortpath connections), modular structure, and regional network measures of degree (node connections), clustering andbetweenness. Main structural connectivity differences based on SVO were found in modularity organization andbrain hub regions. The analysis revealed a larger number of modules in prosocials (m = 13) than in proselfs (m = 8).
Detailed modularity analysis revealed that both left and right amygdala, a region involved in emotional Pavlovian
value association, formed an independent module in prosocials, whereas in proselfs the amygdala formed modules
with memory (parahippocampus) and reward processing (basal-ganglia) regions. A module comprised ofprefrontal regions involved in deliberation was found in both groups, but this prefrontal module also included
temporal cortical regions in proselfs. Hubs integrating information from multiple brain areas were found in proselfs
in prefrontal brain regions (e.g. middle frontal gyrus), while prosocials’ hubs were found in posterior cortical brain
regions involved in social cognition (e.g. precuneus and superior temporal gyrus). This study revealed that theoverall structural connectivity features of prosocials’ and proselfs’ brains follow regular properties of biologicalneural networks. However, the hub and modularity analyses revealed important neuroanatomical connectivity
patterns encompassing regions involved in value computation, social cognition, and deliberation that distinguishedprosocials and proselfs. This is the first report on differences in structural neural network connectivity based on
individual economic preferences and sheds light on the neurobiological mechanisms associated with SVO.
A functional MRI study on how oxytocin affects decision making in social
Bruno
dilemmas: cooperate as long as it pays off, aggress only when you think you
Lambertcan win.
Day 1, Session 3
We investigate if the neuropeptide oxytocin (OT) known to moderate social behaviour, influences strategic decision
making in social dilemmas by facilitating the integration of incentives and social cues. Participants (N = 30) played
two economic games with different incentive structures in the fMRI scanner after receiving OT or placebo (following
a double blind, within-subject design). Pictures of angry or neutral faces (suggesting a threatening or safe decisionenvironment) were displayed alongside the game matrices. Results show that, in a coordination (or assurance)
game, OT facilitates cooperation for risk averse individuals. The nucleus accumbens becomes significantly more
activated than in an anti-coordination (or chicken) game. In the latter, aggression is incentivized but fatal if thepartner also aggresses. Here OT significantly downregulates the amygdala and steers decisions in accordance withthe valence of the facial cue: aggress when neutral; retreat otherwise. These results are compatible with recent
theories that OT facilitates heuristic decision making by modulating brain regions in the mesolimbic dopaminergic
system. Through its combined influence on amygdala and nucleus accumbens, cooperative or aggressive decisions
are selected in function of the best match between incentives and social cues present in the decision environment.

19

Manipulation of Pro-Sociality and Rule Following with Non-invasive Brain
Jörg Gross
Stimulation
Day 1, Session 3
Decisions are often governed by implicit or explicit rules about adequate social behavior. Recent research suggeststhat the right lateral prefrontal cortex (rLPFC) is causally involved in the implementation of internal fairness rules(norms), by controlling the impulse to act selfishly. A drawback of these studies is that norms have to be deduced
from behavior and that norm-following and pro-sociality are indistinguishable. Here, we made implicit rules explicit
and directly confronted participants with a rule that demanded to make advantageous or disadvantageousmonetary allocations for themselves or another person. To disentangle the role of rLPFC in rule following and prosociality, we applied non-invasive brain stimulation (transcranial direct current stimulation) to divergently
manipulate its neural excitability. Changing brain activity within the rLPFC did not simply increase or decrease
selfishness, as previously thought. Instead, depending on the direction, brain stimulation over the rLPFC caused
participants to either 'blindly' follow rules (even those resulting in self-disadvantage) or to adaptively break rules
when they were in conflict with internal social goals. Our results therefore demonstrate a causal role of the rLPFC in
adaptively weighing the costs and benefits of rules with social consequences.
Dispositional Social Risk-Seeking Promotes Trusting Strangers: Evidence
Yiming Jing
based on Attitudinal, Behavioral and Brain Data
Day 1, Session 3
Trust by definition is an intention or action to accept vulnerability. However, previous research has foundinconsistent results regarding whether one’s risk-taking propensity facilitates the decision to trust unknown people.
The problem in these studies may lie with how risk tolerance has been measured; most studies have only assessed
participants’ risk-taking preferences in financial gambling. The risk associated with trusting strangers is inherently
social, however, and so may not be captured by purely economic tasks. In two correlational studies, based on
exceptionally large datasets (N = 117,458) across 74 countries, we first demonstrate that, in addition to expectationsof stranger benevolence and pro-social preferences, social risk-taking preferences (as measured by theendorsement of stimulation values) was a unique, pan-cultural predictors of trusting strangers (attitudinal trust). We
also found that risk-taking preferences were a stronger predictor of stranger trust in more collectivistic-oriented
countries. In a subsequent brain potentials study, 20 high social risk-seekers (HSR) and 20 low social risk-seekers(LSR) made trusting/distrusting decisions regarding unknown trustees while their EEG activity were recorded in
one-shot trust games. At the decision-making stage, HSR participants exhibited a larger N2 and increased β power
following distrusting decisions than trusting decisions, suggesting greater cognitive control exerted to distrust. By
contrast, no such N2 and β differences were found for LSR participants. At the outcome evaluation stage, LSR
participants exhibited a more negative going dFRN and increased θ power (following losses compared to gains)
than did HSR participants, indicating enhanced risk sensitivity of LSR people. Importantly, high and low social riskseekers in this study did not differ on their average levels of financial risk-seeking and pro-social orientation. Thesebehavioral and brain data further reveal how dispositional social risk-seeking facilitates stranger trust and civic
cooperation.

20

AnoukDoes your health trump the environment? Stimulating water conservation
Griffioen
among hotel guests
Day 1, Session 3
One difficulty with pro-environmental behavior is that the associated environmental benefits will only materialize
later in time, whereas the associated individual costs usually occur right now. A popular way of overcoming thisissue is by appealing to benefits of pro-environmental behavior that are immediate and concrete (e.g., financial or
health benefits). Moreover, as people differ in what they value in life (some do not highly value the environment
but do care for money, and vice versa), the effectiveness of various appeals may depend on those values. In an
attempt to reach a broader audience, different motivations are often targeted at the same time. Based on earlier
findings and literature on combining interventions (Griffioen et al., 2016), we expect that appeals that highlightenvironmental and immediate benefits at the same time are not more effective than having one appeal separately.
In two studies we tested how people respond to messages that appeal to concrete, immediate benefits (healthbenefits), to more abstract, distant benefits (environmental benefits), and to both benefits at the same time. In
Study 1, 127 participants were randomly assigned to a 2(Environmental message: yes/no) × 2(Health message:
yes/no) between-subjects design targeted at taking colder and shorter showers. Compared to the control group,
all experimental messages led to an increased willingness to change behavior. The message which combined two
appeals was thus not more effective than the single appeal messages in terms of self-reported willingness tochange. In Study 2, a field study at a hotel in The Netherlands (n = 113), we tested the effectiveness of these samemessages on objectively measured behavior. We equipped hotel rooms with detailed measurement equipment onwarm water and electricity use. In line with previous research, we find that participants in the control condition use
less warm water when they score high on biospheric values (i.e., how much they value the environment).
Interestingly, participants who received a health message (alone or in combination with an environmental message)
only used less warm water when they scored low on biospheric values. Again, a message which combined healthand environmental information was not more effective than a health message by itself. These findings indicate thatpeople who score low on biospheric values can be motivated by other immediate, concrete benefits of proenvironmental behavior. We discuss theoretical and practical implications of this research, and link these findings
to construal level theory.
David HughJones
Expropriating free-riders and outsiders: theory, history and an experimentDay 2, Session 5
Current literature sees the punishment of free-riders as an under-supplied public good. We disagree. Often, freeriders can be expropriated by a coordinated group. This power makes punishment profitable, but it can also be
abused. Both individual free-riding and arbitrary expropriation reduce social welfare. We show that making
coordination more difficult can contain abuses and focus punishment on free-riders. Our theory also suggests whyheterogenous communities may fail to provide public goods: because expropriation targets minorities instead offree-riders. We support this argument with historical evidence from the California gold rush. Lastly, we run alaboratory public goods experiment with expropriation. Outcomes were more efficient when expropriation was
harder; in some circumstances, outgroup members were expropriated more than ingroup members, and reacted
differently to this punishment.

21

Welmer E.
Third party punishment in social dilemmas with heterogeneous andMolenmakerhomogeneous populations
Day 2, Session 5
The welfare of future generations depends on the sacrifices we make today. Yet, more and more common
resources are facing exhaustion because they are overexploited by the present generation. For example, energy
conservation, overfishing, and water scarcity are all contemporary social dilemmas arising from excessive
consumption. As rivalry over common resources often takes place between groups, social dilemmas typically haveheterogeneous populations, i.e., members from distinct social groups. Therefore, social dilemmas often posechallenges that transcend the within-group boundaries. To solve these social dilemmas, people should not only
constrain their own consumption, they should also be willing to incur the costs of punishing those who feel lessinclined to constrain their consumption, irrespective of the norm violators’ group affiliations. Here we present two
experiments on the willingness to enforce social norms – through third party punishment – in social dilemmas withheterogeneous or homogeneous populations. We show that third party observers punish norm violationscommitted by members of their real social group (ingroup) more lenient than similar norm violations committed bymembers of another real social group (outgroup), not only in social dilemmas with heterogeneous populations(Exp. 1 and Exp. 2), but also in social dilemmas with homogeneous populations (Exp. 2). Experiment 1 (N = 276) also
shows that third party observers punish ingroup members even more lenient when they are outnumbered byoutgroup members, while the composition of heterogeneous populations has no influence on how they punish
outgroup members. Furthermore, Experiment 2 (N = 179) shows that third party observers punish outgroupmembers – but not ingroup members – more harshly in social dilemmas with heterogeneous populations than insocial dilemmas with homogeneous populations. Experiment 2 also shows no relationship between intragroupcooperation (in social dilemmas with homogeneous populations) and intergroup punishment of norm violators (insocial dilemmas with heterogeneous populations). Taken together, our results thus reveal a general intergroup bias
in third party punishment of norm violators, even when the norm violations are not committed against ingroupmembers and only outgroup members are harmed directly. This sheds new light on people’s willingness to enforce
social norms. However, these findings are puzzling for existing evolutionary theories of human cooperation,
especially those based on group selection; and emphasize the importance of considering the natural ecology – ourancestral environment – that prevailed during human evolution.
Diogo
The social consequences of punishment: When third-party punishment
Ferreirasignals morality and irrationality
Day 2, Session 5
When social norms are violated, people sometimes engage in acts of costly third-party punishment, spending
money to reduce the outcomes of those who act selfishly. The present research investigates how people perceive
punishers, and under what conditions punishment can function as a signal of prosociality by conveying long-term
reputational benefits. Across four studies, we find that punishers are preferred over nonpunishers as interaction
partners, and are seen as more moral and more likely to cooperate in the future. However, punishment is only
viewed positively under certain conditions. Punishment is seen as irrational when it involves withholding a reward
instead of taking away earnings, if the degree of punishment is too severe, or if the act of punishment does notoccur in response to an intentional transgression. Third-party punishment has the potential to convey long-term
reputational benefits, but there are many situations where punishing others leads to a negative social evaluation.

22Ori Weisel
Selfish people don’t free ride on punishment
Day 2, Session 5
Overall, humans are an exceptionally cooperative species, but they are also heterogeneous in their dispositions
towards cooperation. Conditional Cooperators (CC’s) positively reciprocate others’ cooperation; their willingness tocooperate increases with their expectations about, or experience of, the cooperation of others. Self-regarding
people (SR’s) do not cooperate regardless of their beliefs or experience regarding others’ behaviour. Even a small
proportion of SR’s in a mixed population can lead to the breakdown of cooperation over time, but cooperation canbe enforced by individuals’ willingness to negatively reciprocate non-cooperation by use of punishment, even at apersonal cost. Sustained cooperation requires both positive and negative reciprocity. A prevalent assumption in theliterature is that positive and negative reciprocity go hand in hand in the form of strong reciprocity. In other words,
this assumption postulates that mainly CC’s bear the cost of punishment, and that SR’s do not punish others’ noncooperative behaviour. This ‘strong reciprocity’ assumption is indeed a compelling one, especially when
considering that punishment can reasonably be considered a form of second-order cooperation; after all, why
would individuals who are never willing to engage in first-order cooperation (i.e., SR’s) be willing to engage insecond-order cooperation in the form of punishment? The assumption, however, has never been explicitly tested.
The present paper reports on an experiment that was specifically designed to compare the punishment behaviourof CC’s and SR’s. The main result is that CC’s and SR’s are very similar in both their punishment behaviour and in
the way punishment is related to anger, the main relevant emotion.
Misato Inaba Which type of sanctioning institution is the most attractive and effective?
Day 2, Session 5
Sanctioning institutions are effective means for maintaining cooperation, and are present in most human societies.
However, the provision of a sanctioning institution must address two problems: How do people agree on forming asanctioning institution, and how is the institution maintained? Regarding the former question, previous studies haveshown that humans voluntarily form sanctioning institutions, consisting of punishments and/or rewards (e.g.,Rockenbach & Milinski, 2006; Gürerk, et al. 2006; 2014). However, these studies did not compare different types ofsanctioning institutions directly. Therefore, it remains unclear which sanctioning system is most favorable. In thecurrent study, we conducted an experiment to answer this question. We added the option of group choice to theordinary repeated social dilemma setting. There were 20 periods, each of which consisted of three stages. In thefirst stage, participants chose between a group with or without a sanctioning institution. In the second stage,
participants played a social dilemma game within the group they chose in the first stage. In the third stage, in thegroup with a sanctioning institution, participants engaged in sanctioning. Types of sanctioning institutions weremanipulated such that there was either punishments only, rewards only, or both punishments and rewards. Results
showed that participants favored groups with a reward-only or a reward-punishment institution over the nosanction group. However, the number of participants who chose the punishment-only group increased gradually
over time. During the second-half period of the punishment-only condition, the number of times participants chose
the group with a punishment institution was positively correlated with desire to achieve mutual cooperation, thedesire to punish others, and the expectation that others would cooperate. The cooperation level in the group witha sanctioning institution was the highest in the reward-punishment group in the reward-punishment condition.
There was no difference between cooperation levels in the reward-only group and the punishment-only group.
These results suggest that it is easy to implement reward-only and reward-punishment based institutions because
people are attracted these institutions. In terms of the cooperation rate, however, there was no difference between
the reward-only and punishment-only institutions. The most effective institution to promote cooperation was the
combination of both punishment and reward. Combining these results, consistent with Gürerk, et al. (2006), theinstitution which carries out both punishment and reward appears to be most favorable.

23

KimmoCultural Universals and Cultural Differences in Meta-Norms about Peer
ErikssonPunishment
Day 2, Session 5
Norms can be enforced by individuals sanctioning norm violators without having any formal authority to do so.
Such peer punishment could be approved of by others as a legitimate service to the group, but it could also be
condemned as aggression. The fact that norm enforcement is morally judged can be conceived of as meta-norms.
In order to examine whether meta-norms vary between cultures we collected judgments of peer punishment
animations in three individualistic countries (Netherlands, Sweden, and United States) and five collectivistic
countries (China, Japan, Pakistan, Russia, and United Arab Emirates). The animations showed an agent overharvesting a common resource and another agent who punished this behavior, acting either alone or backed by agroup of peers. In all countries, the individual punisher was less approved of than the group-backed punisher.
Compared to a non-punisher, both punishers were disapproved of in individualistic countries, whereas they wereclose to neutral or even approved of in collectivistic countries. This cultural difference in meta-norms was mainly
driven by women. Our study constitutes a first step in mapping how meta-norms vary around the globe.
ManfredHumans choose representatives who enforce cooperation in the climate
Milinskichange game through extortion
Day 2, Session 6
Social dilemmas force players to balance between personal and collective gain. In some social dilemmas, such as
elected climate summits negotiating climate-change mitigation measures, the decisions are made not by individual
players from all countries involved but by their representatives. Inspired by the negotiations for greenhouse-gas
emissions reductions, we experimentally studied a collective-risk social dilemma that involved representatives
deciding on behalf of their fellow group members. From a total of 630 undergraduate students we assembled 15
groups of 18 players each where the groups are sub-divided into 6 ‘countries’ of 3 players each who elect, re-elector vote out their representative for the 6 representatives’ ‘summit’. For control, we assembled 15 groups of 6
players each and 15 groups of 18 players each. Each group played 3 consecutive collective-risk social dilemma
games. Selfish players were preferentially elected and were hence found most frequently in the ‘representatives’
treatment. Across all treatments, we identify the selfish players as extortioners, cf. Press & Dyson, PNAS 2012. As
predicted by our mathematical model, their steadfast strategies enforce cooperation from fair players who finallycompensate almost completely the deficit caused by the extortionate co-players. Our identification of extortionate
behavior in the collective risk social dilemma suggests two counteracting major effects when, with all due caution,
we try to interpret the social dynamics of climate summits with our results in mind. On the one hand, thecompetitive advantage of selfish players in getting elected or re-elected appears to work against reaching acollective target such as preventing dangerous climate change—there might not be enough fair representatives
around to support the target. On the other hand, selfish players, who are ubiquitous and show up in all but 1 of the
135 individual collective-risk games, consistently act as extortioners. Their steadfast strategies enhance the alreadyexisting willingness of our fair players to contribute towards reaching the collective target. If we compare
extortionate to hypothetical non-extortionate selfish players, we conclude—with more than just a hint of
Machiavellian thinking—that extortion benefits the prevention of dangerous climate change. Everybody gains, but
the extortionate representatives and their groups gain the most.

24Hendrik
Who cares who intervenes how? A framed field experiment on climate
Bruns
protection
Day 2, Session 6
Governmental and private actors increasingly prefer nudges to, e.g., information provision, financial incentives, or
restrictions of choice options. Nudges are defined as a strategy to alter behavior without significantly changing
economic incentives or limiting options. How-ever, being often very subtle and covert, nudges are also criticized as
unethical, and as limit-ing to behavioral autonomy. We investigate how a default (the nudge) affects individual
contributions to climate protection relative to a recommendation, which is designed to be less, and a mandatory
minimum contribution, which is designed to be more intrusive. We also test their interaction with available
information on the source of the intervention. The source is either not specified, a political person, or an expert in
the field of environmental protection. Additionally, we test the influence of decision makers' valuations of
behavioral autonomy, which we measure with a questionnaire on psychological trait reactance. Psycho-logicalreactance is defined as motivation occurring when behavioral freedom is eliminated or threatened with elimination.
Trait reactance, specifically, measures a person's proneness to experience such a motivation. Conceptually, wehypothesize that decision makers react to the treatments based on their attributions of ulterior motivations to theintervening actor. We argue that this attribution depends on the treatment factors, as well as on trait reactance. We
conduct a real-stakes online framed field experiment. The experiment is distinctive in two ways: First, contributions
to the public good are real insofar as real carbon emission licenses from the European Union Emission Trading
Scheme (EUETS) are bought. Second, the actor responsible for the implementation of the respective intervention isa real member of the German Government, who we asked to specify the amount prior to the experiment. With thisexperiment we will assess whether nudges differ from other interventions in their impact on pro-environmental
behavior, whether some actors benefit more from using either intervention, and whether certain interventions are
more suitable for influencing decision makers that highly value behavioral freedom. Findings will be essential forpolicy makers that need to choose the best option from a canon of interventions for an appropriate target group.
Additionally, by evaluating default effects relative to recommendations and choice restrictions, as well as by testing
how their relative influence is moderated by trait reac-tance, we significantly contribute to the discussion of nudges
and behavioral autonomy. This experiment is registered at the American Economic Association's registry for
randomized controlled trials with a unique RCT ID: AEARCTR-0001661.
Social Dilemma and Provision of Public Good: The Case of the Mursi Tribe
Eitan Adresin South West Ethiopia
Day 2, Session 6
The Mursi that are considered as one of the rare and unique tribal existence, may be found in the southwestern
corner of Ethiopia, in the valley of the River Omo, about 100 km. north of Lake Turkana and the border with Kenya.
The population of about 7,500 Mursi are living in their very small villages in their dome-shaped houses, covered
with grass that can be erected in a few hours. They maintain the traditional mix of subsistence activities of floodretreat and rain-fed cultivation of sorghum and maize, and cattle herding. In recent years, the Mursi became world
famous because of the women wearing large pottery or wooden discs or ‘plates’ in their lower lips. A new “line ofbusiness” has emerged, that is the supply of tourists’ demand for photographs of the Mursi women. The number offoreign tourists is still limited but the Mursi appreciate the lucrative exchange. A woman hopes to be paid 10 ETB(about 50 $ cents) for each photograph taken of her, but she usually has to settle for a lot less. The more attractive
women utilize their “merchandise” (the private good) which may yield higher income, while the less attractive andolder women are left aside. Our public good experiment applied with a group of 23 Mursi women. They wereasked to agree to replace personal photographs compensation with a “group pot” (the public good), so that eachwoman in the entire group will receive an equal fix amount of 40 ETB (about $2), no matter how many times she
personally was photographed by a group of 18 tourists. The process of settling the social dilemma is discussed,
along with comparison to a similar experiment with the Dassanetch tribe.

25Rebecca
Common-pool magic water: an investigation into the social strategies of 6Koomen
year-old children in a resource dilemma
Day 2, Session 6
Competition over limited resources is a ubiquitous challenge for humans and all social animals. When naturally
renewable resources are publically accessible they are often vulnerable to over-exploitation and subsequentcollapse. Such resource systems result in common-pool resource (CPR) dilemmas to the extent that the goals of theindividual in the short-term are pitted directly against the collective long-term goals of the group. Experimental
research with human adults shows that, although very difficult, CPR dilemmas can be managed successfully when
individuals can communicate directly (Sally, 1995), especially when groups can collectively decide on management
rules (e.g. how much to extract or when) rather than when rules are externally imposed upon them (Ostrom, 2006).
The development of CPR management skills, such as collective inhibitory control and communicative strategy
agreement, remain unexplored in children. We therefore presented dyads of 6-year-olds with a CPR dilemma
involving a quantity dependent (i.e. collapsible) but renewable resource, “magic water”, which children used tocollect individual rewards (floating eggs). In the collective condition (24 dyads), the magic water system was sharedand collectively managed. In the parallel condition (24 dyads), each child had access to her own resource systemapparatus and could manage its functioning and egg collection independently. The results show that, as withadults, CPR dilemmas are challenging but solvable for 6-year-olds: 54% of dyads in the collective condition wereable to prevent immediate resource collapse in at least 1 out of 3 trials. By contrast, however, 92% of dyads in theparallel condition were able to prevent immediate collapse on both the second and third trials, indicating that thechallenge of the CPR dilemma was mitigated once the element of social interdependence was removed. We
discuss variations in success between the two conditions and between dyads within the collective condition as aresult of their communicative strategies. Specifically, we explore the effects of individualistic strategies versus more
inclusive cooperative verbal strategies, as well as the role of self-imposed distraction to help mitigate the collective
inhibitory control challenge of maximizing resource collection within trials.

26Gianluca
Pro-social and anti-social punishment in international collective risk social
Grimalda
dilemmas
Day 2, Session 6
The effectiveness of punishment in sustaining cooperation has been questioned because of the endemic presenceof anti-social punishment in some cultural areas (Hermman et al., Science 2008, Gächter et al., PTRSB 2010). In thisstudy we involve German and Russian individuals in “collective risk social dilemma” (CRSD) (Milinski et al, PNAS
2006, PNAS 2008) games. This game captures the incentives faced by individuals faced with collective risks alike toclimate change. In a CRSD, groups of individuals have to invest in a public fund to avoid the possibility of“catastrophic” losses, equal to 75% of their savings, at the end of a 10-round interaction. In a standard CRSD, theexistence of a “safety threshold” is common knowledge. If the total amount of contributions to the fund is at least
equal to the threshold, no loss will occur. If total contributions fall short of the threshold, then the “catastrophe” will
happen with certainty. In real life the threshold is however not certain. We therefore follow Barrett and Dannenberg(PNAS, 2012) and introduce uncertainty over the safety threshold. The loss is avoided with a probability
proportional to the total amount of money that the group invests in the public fund. Theoretically, uncertainty inthe threshold has the effect of shifting the game equilibria from a coordination game to a Public Goods Game (i.e.
defection dominates cooperation). Germany is a country where typically punishment works efficiently to increasecooperation. On the contrary, in Russia punishment is typically detrimental (Gächter et al., PTRSB 2010; Gächter &Herrmann, EER 2011). In this way we can study the effectiveness of punishment when “virtuous” cooperators meet“failing” cooperators. Each CRSD is played by six individuals under six different conditions: (1)+(2): Intra-nationalwith and without punishment; (3)+(4): Inter-national with and without punishment hiding the group members’
nationality; (5)+(6): Inter-national with and without punishment revealing group members’ nationality. Initial
sessions reveal that punishment is highly effective in increasing cooperation in both inter-national contexts and innational contexts within Germany. We do not find appreciable differences from revealing nationality or not
revealing nationality. Average cooperation by individuals belonging to the two national groups quickly converge
after a few rounds, in spite of initial differences (with Germans typically contributing more in early rounds). We alsofind that individuals appear to be willing to pay a certainty premium to completely avoid uncertainty.
Cleotilde
Not all Prisoner’s Dilemma Games are Equal: Incentives, Social Preferences,
Gonzalezand Cooperation
Day 2, Session 7
The Prisoner's Dilemma (PD) is a classic conundrum representing many decision problems between two players:
they decide whether to cooperate with each other or to act in their own interest. The PD has been used to explain
many naturally occurring dilemmas, at the personal, organizational and social levels, in which there exists a tension
between individual self-interest and the common good. Two factors may influence cooperative behavior in the PD:
the incentive structure of the game and the intrinsic social preferences of each of the two players. We present aframework that integrates these two factors to identify patterns of high or low cooperation from repeatedinteractions. In an experiment using a collection of PD games and a measure of individual social preferences we
identify regions of PD games in which: (1) cooperation is insensitive to social preferences; (2) where nice people canbe exploited; and (3) where being nice is consistently rewarding. We discuss the theoretical and practical
implications of these findings.

27

Pontus
Strimling“My Way Only”-thinking in social dilemmas.
Day 2, Session 7
When extrapolating results from theoretical and experimental research on social dilemmas to real world behaviour,
it is commonly assumed that people have a clear idea about the structure of the strategic situations they are in (i.e.,that they know when they are acting in a social dilemma type situation). Lab researchers often test that subjects
have understood the strategic structure of the game, but little is known about lay people’s ideas of the strategic
structure of real-life situations. Here we present survey-based investigations of people’s understanding of thestrategic structure of a range of everyday situations. We find that people tend to be remarkably insensitive to thestrategic differences between situations. People have the same view of many different situations, namely: They havea behaviour that they prefer; this preference is independent of what others do; they would prefer others to act thesame way they do. We refer to this view of a situation as “My Way Only”-thinking. Across a range of situations in
our survey, “My Way Only” was the dominant response to all situations except those for which the strategic
implications of others’ behaviour are extremely clear (as in what side of the road to drive on). I will present three
aspects of this finding. First, what are the psychological mechanisms behind “My Way Only”-thinking? Second, inwhich situations does “My Way Only”-thinking arise (e.g., how does it depend on any objective payoff structure andhow easy these payoffs are to observe)? Third, how should these findings inform our understanding of how people
behave in real life social dilemmas?
Incentive-based decision synchrony may enhance voluntary cooperation ina one-shot social dilemma game but may not promote positive evaluation
Toko Kiyonari of other game players.
Day 2, Session 7
Synchronous activity, such as walking in step with others or singing together, help solving the free-rider problem ina subsequent collective action (Wiltermuth & Heath, 2009). We investigated whether decision synchrony ineconomic games in the absence of physical synchrony can boost trust and cooperation in a social dilemma game.
Participants were randomly assigned to one of four initial game conditions: Two types of coordination, both
involving two equilibria: (1) Stag Hunt Game (SHG) in which one equilibrium is better than the other for both, andyet choosing the option that leads to better equilibrium involves a risk of less than partner’s outcome. (2) Driving
Game (DrvG) where both equilibria are equally desirable. Two other games are: (3) No-Independent Game (NIG)
where two players’ decisions are simply synchronized based on their own benefit without being affected by theother player’s decision. (4) Prisoner’s Dilemma Game (PDG). In the first stage, participants played one of thosegames for ten trials each time with a randomly matched member of about twenty-person group. In the second
stage, they played a one-shot social dilemma game involving all group members. Equally desirable outcomes wereachieved in the first three games than in the PDG in the first stage. The cooperation rate in the subsequent social
dilemma game was higher in the two coordination game (52%, SHG; 48%, DrvG) compare to NIG (32%) and PDG(14%). Although participants in the two coordination games expected equally high rate of cooperation from theirgroup members, they were different in the evaluation of their group members. The participants in the SHG
evaluated their group members more positively (e.g., trustfulness, cooperative, intelligent, generous, friendly, andlikable) than did in the rest of three game conditions. These results suggest that the simple synchrony of decisions
is not enough to induce higher level of group cooperation (i.e., NIG). Experience of coordinated decisions in the
DrvG promote cooperation in the immediately following social dilemma game, but are not enough to induce
positive evaluations of group members, which may create the foundation of longer-run cooperation. Because the
SHG involves possible risk of facing a spiteful partner, coordinated decisions in the SHG implies the lack of spitefulmembers in the game, leading to the better evaluation of group members.

28

Susanne
Why Four Player Types?—And How They Fare in a Massively Multiplayer
Lohmann
Game of Life Simulation
Day 2, Session 7
Starting in 2012, every year 150 UCLA students are embedded in a massively multiplayer game of life simulation.
Their grades depend on the game points they cumulate over the course of 10 weeks as a function of their own
decisions, the decisions made by other students, and luck. The number 150 is not an accident. It is Dunbar’s
Number, named after the anthropologist Robin Dunbar, and it corresponds to the number of people you can havea personal relationship with and keep track of reputationally. Cloaked by pen names, students’ identities areprotected, but their game play is hardly anonymous. In the course of their online game play, they get to know
quite a bit about each other: birth order, gender, race or ethnicity, and parental income; religion, religiosity, andreligious practice; political orientation and party identification; and much else besides. Along the way, they build a
reputation: a student will say or do something in one class session only to have their message or action come tohaunt them, or salve them, in a subsequent class session. The effect is to recreate the ancestral village where
humans encountered one another over and over again as they play countless games of collective action. In thestandard social science laboratory, each game is executed anonymously and in isolation. In this fully online course,
about 100 mini games are embedded in a larger game of life and played under conditions of non-anonymity. It isin the latter setting that four player types emerge, corresponding to typologies posited by anthropologist Mary
Douglas (fatalist, individualist, egalitarian, hierarchical), game developer Richard Bartle (explorer, killer, achiever,socializer), and many others. Why four? There are four kinds of collective action: cooperation, competition,
coordination, and collaboration. Each kind comes with a variety of games. A given player type does well in certain
kinds of games and poorly in other kinds. In a given kind of game, the bright side of one type offsets the dark sideof another type. Across the four kinds of games, the four player types, by virtue of their coexistence, save one
another from ruin. They perform about equally well—after all, if one or the other player type performed relatively
poorly in the simulation setting, this would suggest that the corresponding real-world type would have suffered asurvival disadvantage in the ancestral environment and hence died out.
Rob Nelissen How Scarcity and Abundance affect Appropriation from common Resources Day 2, Session 7
Economic theory proposes that scarcity makes people greedy. Still, economic models focus on conditions in which
the collective needs exceed the availability of the resource, such that appropriation directly affects vital outcomes toindividual actors. Fortunately, the experience that resources are insufficiently available to meet their desires is much
more common to people than the experience that resources fall short of their needs. Therefore, we believe thatscarcity is better understood as a limited rather than a deficient supply of resources. It is rather unlikely that limited
resources make people more selfish. As a social species, humans are accustomed to the recurrent problem ofcollectively rationing limited resources. Therefore, humans have evolved behavioral means for mitigating the riskthat the competition for limited resources would become too costly. Unlike scarcity, abundance is an alienexperience in human history that our evolved psyche never learnt to deal with it. So, the other regarding
preferences only emerge and thrive in conditions of scarcity, whereas they will evaporate under conditions ofabundance. Based on this reasoning, we predicted that participants would be more self-interested (take more)when confronted with a shared resource that is abundant, and take less when they are confronted with a sharedresource that is scarce. To investigate this, we compared appropriation levels of a shared, limited resource (M&Ms)
in three resource-availability conditions. In the low resource availability condition, participants took M&Ms from adispenser that was almost empty. In the high resource availability condition, the dispenser was filled to the top. In
the Blind condition, participants could not see the contents of the dispenser. Consistent with our predictions, wefound that people take more from a common resource when it is more abundantly available. This seems to bemainly the result of high levels of resource availability instigating- rather than low levels of resource availability
inhibiting appropriation. Participants in the high resource availability condition took more- but participants in the
low resource availability condition did not take less than participants who did not know the level of the available
resource. In a subsequent study, we replicated these effects using money as a resource.
29

Indexing Prisoner’s Dilemma games: Quantifying psychological factors
Adam Stivers underling cooperative behavior
Day 2, Session 7
Since Rapoport and Chammah’s (1965) seminal work on the K-index of cooperation, many different indexes havebeen proposed to quantify the Prisoner’s Dilemma Game (PDG) in terms of incentives for psychological motives
such as cooperation, control, fear, greed, risk, and similarity. Many of these indexes have been generated byindependent lines of research. Until now, there has been no systematic effort to establish a unifying framework forthese indices. We sought to determine how many PDG indexes have been identified and whether they can beorganized in a meaningful arrangement that can help to understand the psychology of PDG behavior. To addressthese questions, we first collected and catalogued the literature on 38 PDG indexes from a search. Then, we
considered the full range of possible different PDG by varying payoffs. For each of the 38 indexes, each of thepossible PD games has a score (for example, the game T = 10, R = 8, P = 3, S = 0 has a score of 0.5 on the Kindex). We then computed the rank-order correlations among the different PD indexes across the full range of PD
games. There were many perfect or near perfect correlations between indices, suggesting that they are functionallyequivalent and yield the same rank-ordering of possible PD games. The correlation matrix was submitted to aprinciple components analysis that suggested two factors accounting for 99.912% of the variance. Next, a k-meanscluster analysis of the 38 indices based on the two factors revealed six clearly distinct “families” of PD indexes. Eachfamily corresponds to theoretical constructs in the history of research on the PDG. Specifically, we show theappropriate labels are: 1= Cooperation, 2= Greed, 3= Fear, 4= Risk, 5= Cooperation/Greed hybrid, and 6=
Cooperation/Fear hybrid. Since its inception, the PDG has been the centerpiece of social dilemma research. The
PDG presents a fundamental choice problem both because of mixed motivations in the PDG, and because it
captures the essence of many real world interpersonal, organizational, and geo-political conflicts. The current
research provides a catalogue of the many indexes in the PDG and establishes an organizational framework
intended for future research. Behavioral work can subsequently address questions of which index is most consistent
with people’s choices. And perhaps of central interest, this framework can be used to assess the correspondence
between PDG indexes and individual differences in prosociality, greed, fear, and risk.

30Erik W. de
The Effect of Decision Timing on the Willingness to Costly Reward
Kwaadsteniet Cooperation and Punish Non-Cooperation
Day 3, Session 9
Numerous empirical studies have demonstrated that both positive sanctions (rewards) and negative sanctions(punishments) can promote cooperation. However, it is not only important to know that sanctions can increasecooperation once they are installed, it is also important to know under what conditions people are actually willingto administer them. Sanctioning either involves a decision before or a decision after others’ choice behavior. For
instance, a manager can promise bonuses to employees who will reach a certain target, thereby essentiallyinstalling a sanction before the desired behavior has occurred. However, a manager can also decide about giving abonus after an employee has reached a target, thereby deciding about a sanction after the desired behavior has
occurred. Although both types of sanctioning decisions (beforehand and afterwards) occur quite frequently in thereal world, the effect of decision timing has rarely been studied. The present research tries to fill this gap in theliterature. Based on research about non-consequential reasoning, we predict that people are less willing to install
sanctions for choice behavior that might occur in the future (i.e., beforehand) than for choice behavior that has
already occurred in the past (i.e., afterwards). We tested this reasoning in two experimental social dilemma studies.
Method / Experiment 1 had a 2 (sanction type: reward vs punishment) x 2(decision timing: before versus after)
between-subjects design. Third-parties either had the opportunity to reward the group members or theopportunity to punish the group members playing a public good dilemma (sanction type manipulation). Thesesanctioning decisions either had to be made before or right after the group members had made their choices(decision timing manipulation). Experiment 2 was similar to Experiment 1, but this time we also added a condition inwhich the sanction decision was made after some time delay. So, this experiment had a 2 (sanction type: reward vspunishment) x 3 (decision timing: before versus directly afterwards vs afterwards with some delay) betweensubjects design. Conclusion / In both experiments, we found that people sanction less often and to a lesser extent
when sanctioning decisions are made beforehand (as compared to immediately afterwards or after some delay).
This effect was similar for rewards and punishments. These findings corroborate our reasoning that decision timing
has an impact on the willingness to employ costly rewards for cooperation and punishments for non-cooperation.
We will discuss how this can be explained by non-consequential reasoning.
GiuliaAndrighettoContext and Individual Preferences Shape Cooperative Decision Making
Day 3, Session 9
Are people intuitively cooperative or does cooperation only emerge after deliberation? We argue that the answer
depends both on peoples’ social preferences and the normative context in which they make their decisions. Basedon results from two experiments involving 1092 subjects, we show that when cooperative norms are salient, selfish
subjects deciding quickly contribute little while those who are slow contribute more, while contributions fromprosocial subjects remain high and stable over time. By contrast, when norms are neutral, contributions do notchange over time. To explain our results, we propose an extension of the Social Heuristic Hypothesis that takes into
account the interaction between social preferences and decision context. This theoretical framework allows us tomake more granular predictions about the circumstances under which cooperation is likely to emerge, and helps toreconcile previously contradictory results. We apply this framework to illustrate how public policies can incorporate
the influence of both decision contexts and social preferences to increase cooperation in everyday settings.

31

Nils Köbis
Does honesty require time? A Meta-analysis
Day 3, Session 9
Does the truth come out naturally? Or, is it our intuitive inclination to lie and cheat? Given the relevance of thisancient-old question, it is not surprising that multiple attempts to answer it experimentally exist. However,
Economics and Psychology have put forth radically different answers: the empirical evidence obtained bybehavioral economics (and social psychology) suggest that people’s intuitive tendency is to serve their self-interest,
even by lying, and only with deliberation adhere to social norms and be honest. Cognitive psychology in contrast,
suggests that lying requires suppressing the truth, making deception effortful. Two lines of literature exist therefore
in parallel: one suggesting that human’s natural inclination is to self-benefit also by lying and cheating, anothersuggesting that the truth is intuitive. We report two meta-analyses on the role of intuition vs. deliberation inhonesty. Specifically, we investigate how manipulation of cognitive processing affects dishonesty in (1) incentivized
behavioral economic tasks in which lying is self-serving and (2) cognitive psychological tasks in which people are
instructed to lie or respond truthfully, and their reaction time for doing both is measured, and compared. Our
survey of the (published and un-published) literature suggests that 97 studies have tackled those questions, ofwhich we have by now obtained data for 84.6%. At ICSD, we will discuss initial results shedding light on (1) whether
a main effect of intuition vs. deliberation exists, and (2) which (if any) variables moderate the effect. These results
will allow determining whether honesty is intuitive or does require time.
From spontaneous cooperation to spontaneous punishment –Dorothee
Distinguishing the underlying motives driving spontaneous behavior in first
Mischkowski
and second order public goods
Day 3, Session 9
Rand, Greene and Nowak (2012) presented findings supporting their hypothesis concerning the spontaneous
nature of cooperation by showing that cooperative behavior is related to shorter decision times. Elaborating on
their work, we tested the generality of their findings by investigating the relation between response time andpunishment behavior. In two lab studies (N total = 277) participants played a public goods game (PGG) in groupsof four. After each round, a punishment option was given to each player (second-party punishment) with a cost-toimpact ratio of 1 to 4. We measured dispositional social preferences (i.e., Social Value Orientation) up to 24 hours
before the lab session and captured the affective responses towards the cooperation behavior of the other players
after the PGG via the PANAS. Similar to a spontaneous cooperation effect, we find that the invested resources topunish decrease over decision time. The underlying motives of spontaneous punishment, however, differ fromthose driving spontaneous cooperation. The latter is moderated by Social Value Orientation (SVO) in that it is only
valid for prosocials, who gain positive utility from increasing other persons’ welfare. The effect of spontaneous
punishment, though, is independent of SVO. Rather, we find a significant three-way interaction in that spontaneous
punishment is only valid for above-average contributors that are highly upset about the lower cooperation
behavior of their group members. Our results point out the different motivations underlying the effects of
spontaneous cooperation vs. spontaneous punishment, even though the mere behavior follows a similar patternover the course of decision time. Spontaneous cooperation is conditional on dispositional prosociality whereas
spontaneous punishment is rather driven by the recent group interaction and used in an affect regulative mannerof situational high contributors to compensate subjectively perceived injustice.

32

IsabelDeliberate thinking versus intuitive cooperation: On the role of processing
Thielmannmode for social mindfulness
Day 3, Session 9
Social mindfulness has recently been introduced as a type of prosocial behavior that does not only involve a will to
act prosocially, but also a skill to initially see others’ needs and preferences in situations of interdependence. As
such, social mindfulness particularly captures aspects of empathy and perspective taking beyond the willingness tobehave in a cooperative fashion. Correspondingly, social mindfulness has been proposed to involve processes ofexecutive functioning and deliberate thinking and, in turn, to require cognitive resources. However, given that
empirical tests of this conjecture are currently missing, testing the influence of processing mode on social
mindfulness is a vital step in validating and more thoroughly understanding this new construct. Moreover,investigating social mindfulness as a function of processing mode provides a critical test on whether – contrary to
its theoretical conceptualization – social mindfulness might alternatively follow the logic of intuitive cooperation (asobserved in more classical social dilemmas). In this regard, we considered it important to additionally test forpotential person-situation interactions between processing mode and prosocial traits (i.e., Honesty-Humility andSocial Value Orientation). Overall, we conducted three studies using different experimental manipulations to test
whether social mindfulness indeed increases under deliberate compared to intuitive cognitive processing. In Studies
1 and 2, participants (N = 422 and N = 107, respectively) were either asked to thoroughly think about theirdecisions (deliberate thinking condition) in a social mindfulness task or to decide as fast as possible, based on theirgut feelings (intuitive thinking condition). In Study 3 (N = 178), we finally used a cognitive load manipulation to
trigger either deliberate (no cognitive load) or intuitive thinking (high cognitive load). Contrary to the idea thatsocial mindfulness requires cognitive resources – and also ruling out that it follows intuitive cooperation – in all
three studies, we only found a negligible (close to zero) effect of processing mode on socially mindful choices. By
contrast, prosocial personality traits (Honesty-Humility and Social Value Orientation) revealed a main effect onsocial mindfulness, irrespective of processing mode. Our findings thus suggest that social mindfulness does not
require deliberate processing, but rather that it constitutes a general social preference which is influenced by stablepersonality traits capturing prosocial tendencies. By implication, social mindfulness thus seems to be distinctivefrom other types of pro-social behavior as measured in social dilemmas.
Mapping Morality with a Compass: Testing the theory of ‘morality as
Oliver Curry
cooperation’ with a new questionnaire
Day 3, Session 9
What is morality? What explains its content and structure? And how is it best measured? The theory of morality-ascooperation (MAC) argues that morality is a collection of biological and cultural solutions to the problems ofcooperation recurrent in human social life. MAC uses evolutionary biology and nonzerosum game theory to
identify seven distinct types of cooperation: helping kin, helping group, reciprocating, hawkish signals of prowess(such as bravery), dove-ish signals of deference, dividing disputed resources, and respecting prior possession. And
MAC predicts that a) each of these types of cooperation will be considered morally good; b) each type of morality
will constitute a distinct domain or factor; and c) an instrument that measures each of these factors will provide a
better, more comprehensive measure of morality than an instrument that does not. The present study tests MAC’s
predictions by developing a new self-report measure of moral values (MAC-Q; Study 1: N=1,392; Study 3: N=469),
and comparing its psychometric properties with those of the Moral Foundations Questionnaire (MFQ; Study 2:
N=1,042; Study 3). The results of these studies support MAC’s seven-factor model of morality. As predicted, factor
analysis identifies distinct domains relating to family values, group loyalty, reciprocity, bravery, respect, fairness andproperty rights. And, consistent with previous research, the present studies do not support MFT’s five-factor model.
These results provide a new and more extensive map of the moral domain, a new tool for investigating it further,and a new theory to guide future exploration.

33

Dora
Minority v. Majority - A Structural Goal/Expectation Theory of Intergroup
Simunovic
Conflict
Day 3, Session 10
The current project investigates intergroup bias between minorities and majorities from an evolutionary
perspective, utilizing the Structural Goal/Expectation theory (sGET; Yamagishi, 1986a; Kimmel & Puitt, 1977). The
author defines minorities and majorities as distinct groups of unequal size which are nevertheless areinterdependent. This definition highlights two structural characteristics, namely relative group size, and group-levelinterdependence, which the author predicted would impact intergroup bias. Group-level interdependence is a newconcept, here defined as the influence actors have on the common resource. A mathematical analysis of acommon resource dilemma as described by the Public Good game (PGG; Ledyard, 1995) reveals skewed incentives
for cooperation the minority and majority playing the PGG together. The minority has a vested interest to defect.
From this, the author predicted majority members would discriminate against the minority to a greater extent thanthe other way around. I furthermore predicted that the level of discrimination would be explained by expectationsof contributions to the common resource. In Study 1, the author conducted a pretest to determine whether outgroup hate would occur if the participants are merely categorized into a minimal minority and majority. To avoid
confounding effects of self-interested ingroup love and outgroup hate, the participants were independent from theingroup network of reciprocity, which has previously been shown as a mechanism of intergroup bias (Bounded
Generalized Reciprocity (BGR); Yamagishi, Jin, & Kiyonari, 1999). The participants' contributions in an allocation
game showed no bias across conditions, indicating that mere categorization into minority and majority is notenough to elicit out-group hate. In Study 2, participants from the general population were categorized into aminimal minority and majority, and then took part in an online allocation game. In it, they acted as supervisors of areal PGG between minority/majority students in a laboratory study. Thus, the consciousness of group-levelinterdependence was experimentally manipulated. As predicted, majority participants exhibited out-group hate bygiving less to minority members. Minority participants allocated funds equally. The bias was explained by
expectations of contribution to the PGG. The results are discussed from the evolutionary perspective, suggestingthat minority discrimination could be a default strategy in certain structural contexts.

34

Hillie
Aaldering
Understanding parochial cooperation: Testing two theories
Day 3, Session 10
Individuals are inclined to parochial cooperation: Making self-costly contributions to the own group, which may or
may not directly harm the other group. Parochial cooperation is especially observed among pro-social individuals(Aaldering et al., 2013; Abbink et al., 2010; De Dreu, 2010). This is remarkable, given much literature suggesting thatpro-socials are willing to make self-costly contributions to a larger collective of people (Au & Kwon, 2004; Balliet,
Parks, & Joireman, 2009). To solve this paradox, we propose that parochial cooperation should be studied in anintergroup game which simultaneously allows for (a) parochial cooperation with, or (b) without direct harm to theout-group and (c) universal cooperation: benefitting both groups. Initial findings using this game suggest that prosocials are particularly likely to invest in parochial cooperation, as long as it does not directly harm the other group.
Why then are individuals, and especially pro-socials, inclined to show parochial cooperation? Using this game, we
test two theories that propose different mechanisms underlying parochial cooperation: The Social Identity
Approach (SIA) and the Theory of Bounded Generalized Reciprocity (BGR). According to the SIA, individuals invest
in their own group when they identify strongly with their group (Brewer, 1999; Dovidio & Gaertner, 2010; Hornsey,2008). According to BGR, individuals cooperate with others from whom they expect indirect reciprocation ofcooperation. Thus, reputation concerns should determine reciprocity expectations and behavior (Yamagishi, Jin, &Kiyonari, 1999; Yamagishi & Mifune, 2008). We investigate which of the two mechanisms predicts parochialcooperation and whether social value orientation modulates such cooperation. In a first laboratory experiment (N =221) we created three conditions: increased in-group identification versus increased in-group reputation concerns
versus a control condition. Results showed more parochial cooperation in the reputation compared to both otherconditions- but only among pro-socials. Thus, especially pro-socials are receptive to reputation concerns, which
drive their parochial cooperation more than identification does. We will present this work and new studies, which
aim to replicate these findings as well as investigate how universal cooperation can be enhanced. Will extending
reputation concerns beyond the in-group increase universal cooperation? Results will shed more light on theunderlying mechanism of intergroup cooperation, specifically parochial cooperation, and suggest how universal
cooperation can be increased. Moreover, we show how social value orientation modulates intergroup cooperation
and when pro-socials are more or less willing to serve the own group versus the collective of two groups
combined.

35

Fredrik
JanssonUsing peer influence to solve the social dilemma of workplace segregation
Day 3, Session 10
Segregation (by race/gender etc.) in society is not only a social problem, but it is also potentially a social dilemma.
For example, it was illustrated in a famous theoretical model by Schelling that even if people prefer to live in mixedsocieties, society will still end up being segregated if the preference for having at least a few group peers aroundyou is stronger. A potential solution to this dilemma would be to influence people’s utilities such that they would
accept even higher levels of diversity, with even fewer ingroup members around them. The aim of this study is tomeasure preferences to see whether segregation is indeed a social dilemma, and to test whether utilities can bealtered to solve it. Our study looks at the specific situation of workplace segregation, and employees’ preferences
for colleagues, with respect to race and gender, through surveys, simulations and an experiment. First, we do findmoderate preferences for homogeneity, where respondents prefer diverse workplaces to completely
homogeneous ones. However, since the respondents are also unwilling to be in the minority, the prediction is that,in the long run, workplaces become more segregated, suggesting that this is indeed a social dilemma. Second, we
try to alter people’s utilities in an experiment such that they will choose hypothetical workplaces with more
outgroup members. From experiments in social psychology, we know that prejudice can be reduced by social
consensus information on lack of prejudice among peers. Also, our survey data indicate that, apart from
homophily, a reason to avoid vastly diverse workplaces is that these may be perceived as having lower status. Fromthese observations, we hypothesise that people’s utilities are malleable to social consensus information promoting
diverse workplaces. As predicted, respondents update their preferences to be more in line with those of their peers,when presented with information on their responses. This effect remains unaltered in a follow-up survey a week
later, even when social consensus information is no longer present. By presenting respondents with diversity-prone
information, they can accept having fewer ingroup colleagues. Simulations suggest that, over time and through afeedback process, this may considerably decrease segregation, and, since the new outcome is more in line withindividual preferences, give a potential solution to the social dilemma.

36Are individuals on the right side of the political spectrum always lessprosocial than individuals on the left? The role of the in- versus outgroup
Axel Burger
status of interaction partners
Day 3, Session 10
How is social value orientation (SVO) linked to political ideological orientations? Prior research found that prosocial
individuals (compared to individualistic and competitive individuals) tend to place themselves further left on a leftright continuum and are more likely to vote for left-wing political parties (van Lange, Bekkers, Chirumbolo, &Leone, 2012). In addition, different dimensions of political ideological orientations – right-wing authoritarianism(RWA) and social dominance orientation (SDO) – have been reported to both be negatively correlated withprosocial orientation (Chirumbolo, Leone, & Desimoni, 2016). This presentation, however, aims at demonstratingthat under some circumstances individuals on the right can be even more prosocial than individuals on the left. In
particular, it is argued that (1) the cooperativeness of individuals on the right depends strongly on whether theinteraction partner is perceived as an ingroup member or an outgroup member (while this aspect is less relevant
for individuals on the left) and that (2) conservatism can be positively correlated with cooperativeness when theinteraction partner is an ingroup member. In the studies that were conducted to test these hypotheses, ideologicalorientation was conceptualized two-dimensionally in terms of SDO and RWA in addition to assessing left-right selfplacements. This allowed for specific investigations of the importance of different dimensions of political ideologicalorientations for cooperative behavior. Cooperativeness was measured using the Slider Measure of Social Value
Orientation (Murphy, Ackermann, & Handgraaf, 2011). This instrument yields a continuous estimate of the weight aperson assigns to the outcomes of others relative to their own in interdependent situations instead of a nominal
categorization of individuals into prosocial, individualistic, or competitive. In Study 1 no information at all waspresented about the interaction partner. It revealed a negative correlation of cooperativeness with SDO but nosignificant association with RWA or with the left-right self-placement. In Study 2 the in- versus outgroup status of
the interaction partner was manipulated experimentally. It revealed that SDO was negatively associated withcooperativeness irrespective whether the interaction partner was an in- or outgroup member. However, RWA(controlling for SDO) was negatively associated with cooperativeness when the interaction partner was an outgroupmember, but positively associated with cooperativeness when the interaction partner was an ingroup member.
Study 3 measured cooperation in the context a solidarity game and found that the association of conservatism (interms of a left-right self-placement) with cooperation was similarly moderated by the in- versus outgroup status of
the interaction partner.
Tehila Kogut
Altruistic behavior in cohesive social groups: The role of target identifiability
Day 3, Session 10
People’s tendency to be more generous towards identifiable victims than towards unidentifiable or statistical victims
is known as the Identifiable Victim Effect. Recent research called the generality of the effect into question, showingthat in cross-national contexts, identifiability affects mostly willingness to help victims belonging to one's “in-group”.
Furthermore, in inter-group conflict situations identifiability increased generosity towards a member of theadversary group, but it decreased generosity towards a member of one's own group. In the present research we
examine the role of group-cohesiveness as an underlying factor accounting for the discrepant findings regarding
identifiability. We examined novel groups generated in the lab, using the minimal group paradigm as well as
natural groups of students in their regular exercise sections. Allocation decisions in dictator games revealed
opposite patterns particularly in giving to in-group members: in cohesive groups identifying the recipient
decreased, rather than increased generosity.

37

Aron Szekely Self-governance sustains group-level reputation
Day 3, Session 11
To what extent does trust among strangers depend on expectations of reciprocity? Theories of trust based on
expectations suggest that trusting behavior can be encouraged facilitating positive expectations. Yet, recent
research suggests that people underutilize expectations in trust decisions. We examine the processes underlying
the tendency to discount expectations: Our central premise is that people strategically discount expectations
because they are ambiguous and do not come to mind easily. We manipulate the ambiguity and salience oftrustors’ expectations, comparing trust decisions based on subjective and objective expectations of reciprocity.
Study 1 compared the effects of expectations in the trust game across three conditions: In the subjective condition,
players had to form expectations of trustees’ behavior after decisions were made. In the salient condition, players
estimated the likelihood of reciprocity immediately before each decision (thereby bringing them to mind). Finally, inthe objective condition, players received explicit information about the probability of reciprocity before eachdecision. When participants were instructed to form expectations prior to their choices, making them salient, theyrelied on them more in their final decisions. The ambiguity of self-generated expectations also influenced trust:
expectations had the strongest effect on decisions when they were objectively provided. Study 2 manipulated theambiguity of objective expectations: In the low-ambiguity conditions, participants learned about the precise
probability of reciprocity (e.g., 20%). In the high-ambiguity conditions, participants received an imprecise estimateof the same probability (e.g., participants were told that the probability of reciprocity was between 10 and 30%). We
also compared the effects of ambiguity on trust and individual risk-taking decisions. Ambiguous expectations had aweaker effect on behavior than precise expectations. Moreover, the effects of ambiguity were comparable for trustand individual risk-taking decisions. We observed two key findings related to the difference between trust and risktaking decisions: 1) trust decisions based on objective probabilities were more sensitive to changes in expectations
than individual risk-taking decisions and 2) participants were more willing to trust strangers than take individual
risks. The present studies suggest that people discount subjective expectations of reciprocity because they areambiguous and do not come to mind easily at the moment of decision-making. This pattern of behavior does notconform to fully rational models of trust, can be understood in terms of boundedly rational decision-making.
Trustors rely on information to the extent that it is reliable and easily processed.

38

Andreas
Diekmann
Solving Social Dilemmas by Reputation Mechanisms
Day 3, Session 11
Reputation, image scoring (Nowak and Sigmund 1998) and signaling are related and effective mechanisms topromote cooperative behaviour. Provided the “shadow of the future” is large enough, cooperation may emerge inrepeated dilemmas (Axelrod 1984). However, reputation mechanisms inform about actors’ past behaviour, andcooperation may be sustained when the “shadow of the past” is sufficiently large. Particularly, economictransactions and social exchange may fail because actors do not trust each other. Trust problems are aggravatedby time-lagged exchange and uncertainty about the quality of goods or services exchanged (Kollock 1994), andthese problems are often solved by reputation mechanisms. Research from anthropology, economic history (Greif1989) and game theory (Milgrom, North, Weingast 1990) shows that reputation mechanisms, based on available
technologies of their time, have contributed to the solution of trust problems in economic transactions throughout
history. Today, reputation is a powerful mechanism to ensure cooperative behaviour in digital markets (Diekmann
et al. 2014) and even the illegal markets in the “dark net”. Also, there is a dark side of reputation if reputational
information is unreliable or even faked or an actor’s reputation is destroyed by his opponents. Moreover, there isan incentive problem to provide the collective good of reliable Information mitigated by "strong reciprocity". / I will
discuss these and other problems of decentralized and self-organized reputational systems using large data setsfrom eBay auctions and second-hand car sales on the internet platform “Autoscout”. Statistical analysis sheds alight on the functioning and problems of reputational systems. The Autoscout data were collected by automatic
web crawling in 2015. During data collection, information on faked emission reports gained widespread attention.
As a by-product of the analysis I will report an estimate of the impact of “Dieselgate” on the market.

39

The dynamics of group-specific social preferences in intergroup conflict. A
nationwide incentivized experiment before and after the 2016 Austrian
Jürgen Fleiß
presidential election.
Day 3, Session 11
Social Value Orientation (SVO), a distributive social preference, has received much attention as a factor predicting
general cooperation behavior, but less is known about the role of SVO in predicting intergroup conflict behavior. It
is an open question whether an individual’s prosocial preferences are independent of others’ group membership(i.e., universalism), in-group bounded or even go together with a hostile attitude towards the out-group (i.e.,
parochialism). Moreover, it is also not known whether, and if so how, group-specific social preferences change overtime after winning vs. losing an intergroup conflict. Our study contributes to this line of research by, first, measuring
incentivized social preferences by means of the SVO Slider measure, varying within-subjects whether the recipientis an anonymous other, an in-group or an out-group member. Second, the participants of our study constitute a
representative sample of the Austrian population (N = 660) and data was collected during the Austrian presidential
elections, a time of heated conflict between the competing political groups. Third, we apply a panel design bymeasuring participants’ SVOs repeatedly: within the week directly before vs. after the presidential elections on
December 4th 2016. We find differences in SVOs when participants are matched with in-group vs. outgroup
recipients in the week before the election. Both left- and right-wing voters are more prosocial towards in-groupthan out-group recipients (Cohen’s d = .81 and .94). In addition, we find a notable share of SVO values indicatingcompetitive preferences towards out-group recipients for both left- and right-wing voters (27% and 18%).
Comparable effects are found at the second measurement after the election. Regarding parochialism, we find thatboth in-group prosociality and strong in-group identification lead to stronger differences in SVOs between ingroup and out-group recipients. This indicates that highly-identified group members and group members with awillingness to benefit in-group members at personal cost are also more likely to discriminate between in-groupand out-group members. For changes in social preferences before vs. after the election, we find that for right-wing
voters, whose candidate lost, prosociality towards in-group recipients increases (Cohen’s d = .12), whereas rightwing voters’ social preferences towards out-group recipients and left-wing voters’ social preferences towards ingroup and out-group recipients remain stable. Overall, results demonstrate that social preferences are groupspecific. Moreover, prosociality towards the in-group is associated with parochialism. Lastly, group-specific social
preferences are largely stable but may also change due to group identity threat (i.e., losing an election).
WojtekOrder without law: Reputation promotes cooperation in a cryptomarket forPrzepiorka
illegal goods
Day 3, Session 11
The emergence of large-scale cooperation in humans poses a major puzzle for the social and behavioral sciences.
Reputation formation – individuals’ ability to share information about others’ deeds and misdeeds – has beenfound to promote cooperation. Individuals with a reputation to lose have a strong incentive to behave
cooperatively and are therefore attractive partners in social and economic exchange. However, these findings aremostly based on small scale laboratory and field experiments or on data gathered from online markets embedded
in functioning legal systems. Using process data from a cryptomarket for illegal drugs, we show how buyers rating
sellers after completed transactions create reputational incentives for sellers to cooperate. Sellers with a better
rating history charge higher prices and sell their merchandise faster than sellers with no or a bad rating history. Our
results show how reputation creates incentives for cooperative behavior at a large scale, in the absence of law
enforcement and among anonymous actors with doubtful intentions. Cryptomarkets are online marketplaces in theso-called Dark Web, which can only be accessed by means of encryption software that conceals users’ identities
and locations. The encryption technology makes it virtually impossible for law enforcement to intervene. Moreover,given the nature of the traded goods, traders’ good intentions are highly uncertain at best. This creates severe trust
problems between buyers and sellers as it makes buyers vulnerable to sellers’ fraudulent transactions. At the sametime, cryptomarkets constitute an ideal setting to study how the reputation mechanism brings about order withoutlaw.
40

Understanding the Degree and Direction of Gossipers’ Lies: The Role of
Kim Peters
Incentive Alignment
Day 3, Session 11
Gossip is considered to be an important vehicle for reputational information that can build cooperation in large,
mobile societies characterized by frequent, one-shot interactions with strangers. However, some cast doubt on thecapacity for gossip to perform this beneficial social function, pointing to the ease with which gossipers canpurposely or inadvertently spread inaccurate reputational information. Indeed, a growing body of simulation work
has shown that introducing inaccuracy into gossip can quickly undermine its cooperative potential. To date,however, there is very little behavioural research that can speak to the conditions under which people share moreor less accurate gossip and the subsequent impact of this on cooperation. This project sheds light on these issues
by exploring the impact of incentive alignment on gossip accuracy and people’s levels of trust and trustworthiness
when interacting in repeated social dilemmas. Participants (N=288) who were randomly allocated to a role (Investor
or Agent) and colour (Red or Blue) played 20 rounds of a two-player trust game in anonymous 16-person
networks. Investors were permitted to exchange gossip about Agents between rounds. Alignment between
Investor’s incentives was varied across networks. In the Care about Audience (CA) treatment, Investors received abonus if the total payoff of same colour Investors exceeded that of other colour Investors. In the Care about Target(CT) treatment, Investors received a bonus if the total payoff of same colour Agents exceeded that of other colour
Agents. In the Control treatment, the bonus was not linked to performance. Incentive alignment did influence thedegree and direction of gossip inaccuracy. In particular, levels of inaccuracy were higher in the two experimental
treatments than in the control. However, the direction of this inaccuracy differed. In the CA treatment, Investors
sent accurate gossip to same colour Investors and inaccurate gossip to different colour Investors. In the CT
treatment, Investors sent overly positive gossip about same colour Agents and overly negative gossip about
different colour Agents. Participants were sensitive to the potential for inaccuracy in gossip: the heightened
inaccuracy in the Experimental treatments was associated with lower levels of trust and trustworthiness. Therefore,
this project shows that when it is in their own interests to do so, gossipers will spread inaccurate information, andthat over time this reduces the capacity for gossip to shore up cooperation.
AngeloRomanoThe Psychology of Intergroup Trust Across 17 Countries
Day 3, Session 11
Intergroup relations are becoming increasingly important in a globalized world. Thus, cross-national investigations
are needed to understand the dynamics that make people more willing to cooperate with ingroup, compared tooutgroup members. The goal of the present work is to test contrasting hypotheses from the most prominent
theories on ingroup favoritism across 17 nations. We focus on both general psychological mechanisms andindividual differences (SVO and gender) that may explain intergroup trust and trustworthy behavior among
humans. In particular, we test the hypothesis that (a) individuals tend to favor ingroup members in situations wheregroup membership is mutually known by the interaction partners (bounded generalized reciprocity perspective,
Yamagishi, Jin & Kiyonari, 1999), (b) that prosocials are more parochial altruists than proselfs (De Dreu, 2010), and(c) that men, compared to women, discriminate more between ingroup and outgroup members (male warrior
hypothesis, Van Vugt, De Cremer, & Janssen, 2007). We present results from a comprehensive investigation ofcross-societal cooperation (N = 3236) in trust and trustworthy decisions involving samples from 17 countries (i.e.
Argentina, Brazil, China, Estonia, Germany, Indonesia, Italy, Japan, New Zealand, Poland, Russia, South Korea,
Spain, Taiwan, Turkey, United Kingdom, and United States). The study was a 2 (partner membership knowledge:
Common vs Unilateral) × 5 (group membership: Ingroup, Outgroup, Stranger, China, United States) within-subjects
experimental design. Overall, results show that people trusted more ingroup members compared to outgroupmembers. Moreover, people tended to trust more their partners in situations involving mutual knowledge about
the other partners’ nationalities, regardless of group membership. Then, contradicting the view that pro-socials
trust more ingroup members, we found that they cooperated more with others in general, irrespective of others’
group membership. Finally, women tended to trust less others, and men discriminated more between ingroup andoutgroup members, a result that support the male warrior hypothesis.
41Eric van Dijk
Emotional Deception in Ultimatum GamesDay 4, Session 13
That bargainers may obtain better deals by communicating emotions like anger and disappointment, (e.g. Lelieveld
et al., 2008) implies that they may strategically misrepresent their emotions (Andrade & Ho, 2009). We developed a
new paradigm and analytical strategy to study emotional deception in ultimatum bargaining (Güth et al., 1982).
After receiving a low (80-20) offer, participants (recipients) first privately indicated their disappointment and anger(100-point rating scales; experienced emotions). Subsequently, they could (mis)inform the allocator how
disappointed/angry they were (100-point rating scales; communicated emotions), before the allocator would makethe final offer. By co-analyzing the absolute AND nonabsolute differences between experienced andcommunicated emotions, we identified both the extent of misrepresentation, and the specific strategy(exaggeration vs. downplaying of emotions). Experiment 1: Design: Report (experienced versus communicated) andEmotion (anger versus disappointment) as within-measures. Results: The absolute difference measure indicatedthat participants misrepresented disappointment and anger to a similar extent. The co-analysis of nonabsolutedifferences indicated uniform exaggeration of disappointment (participants communicated higher levels than they
had experienced), but a more differentiated pattern for anger (some exaggerated, others downplayed anger),which fits the idea that communicating anger may be considered risky: it may work if people concede to anger, but
could backfire by inviting retaliation (e.g., Van Dijk et al., 2008). Experiment 2: We investigated whether
communication is dependent on whether one can only communicate one emotion (either disappointment oranger), or both emotions (as in Experiment 1). Design: Between-participant’s conditions: disappointment-only
condition, anger-only condition, and anger+disappointment condition. Report (experienced versus communicated)
and Emotion (anger versus disappointment) as within-measures. Results: For participants who could only
communicate anger or only disappointment, we see uniform exaggeration. We only see the differentiated patternwhen they can communicate both emotions (as revealed in Experiment 1). Experiment 3: Design: Two betweenparticipants conditions: Low Power versus High Power. Report (experienced versus communicated) and Emotion(anger versus disappointment) as within- measures. Power was manipulated by the consequences of rejection for
the allocator (Fellner & Güth, 2003; high consequences put the participant in a high power position). Results: We
observed uniform exaggeration for disappointment, but a differentiated pattern for anger: exaggeration by highpower participants and downplaying by low power participants. Conclusion: With a new methodology andanalytical strategy we demonstrated that (a) bargainers strategically misrepresent their emotions(anger/disappointment), but (b) the type of misrepresentation depends on the availability of options tocommunicate (single vs. multiple), and one’s power position. Results are related to the social functional approach toemotions.

42

Tamar Kugler Greed is (Not Always) GoodDay 4, Session 13
The purpose of this paper is to systematically investigate how perceptions of greed affect cooperative behavior. We
define greed as a selfish motivation to acquire an unfairly excessive amount of a resource, at the expense of others.
Little is known on how negative perceptions of greed affect future behavior in social dilemmas. We ask whether
people become greedier when interacting with greedy others, whether people become less greedy when others
perceive them as greedy, and whether there are negative consequences to garnering a greedy reputation. We
conduct a series of studies utilizing a 2-person common-pool-resource dilemma. In study 1, participants play the
CPR game, rank the greed level of their opponents, and then play an unexpected second round of the game. The
results show a positive relationship between the other’s extraction level and the reported greed perceptions, as well
as a positive relationship between perceived greediness of the other in the first round, and own levels of extractionin the second round. So, greed fosters more greed. Study 2 explores whether people become less greedy whenaware that others perceive them as such. Participants played one round of the CPR game. Then, they rated how
greedy the other participant was. Finally, they played a second, unexpected round of the game against the same
opponent. Before the second round, they received information about how greedy their opponent rated them. If
people care whether others perceive them as greedy, higher levels of conveyed perceived greed would be
associated with lower second round extraction levels. The results confirm this hypothesis. Furthermore, conveying
information about one’s level of greed acts to moderate the effect of the other’s perceived greediness on
subsequent behavior. Study 3 explores reputational effects of greedy behavior. Are people less likely to cooperate
when interacting with others who have a greedy reputation? Do people attempt to strategically managing theirreputation? Half of the study participants played a CPR game and rated their counterpart’s level of greed. The
remaining participants were then matched with the previous participants, and received the greed ratings of theirpartners. We compared a baseline condition where the second round of the game was unexpected, to a managed
reputation condition, where the second round was known in advance. The results show that reputation matters,
and that people anticipated the negative consequences of a greedy reputation, and strategically attempted tobehave in a less greedy manner.

43

Anthony
Evans
Subjective and objective expectations of reciprocity in trust dilemmas
Day 4, Session 13
Suppose I am the proud owner of a ticket for the sold-out Whisky Weekend Amsterdam, but I realise that I can nolonger make it. I decide to give the ticket to one of my close friends – the question is to which one? I compare howmuch each of my friends would enjoy the whisky weekend and finally settle on the biggest whisky-lover amongst
them. In economics, the dominant - although not unchallenged - view has been that such interpersonal
comparisons of utility (ICU) are hopelessly intractable and as such impossible. Proposals made in defence of ICU
converge towards the argument that people would perform intuitive ICU by inferring others’ mental states; in turn,
ICU’s reliability would depend on those mentalizing processes’ accuracy and as such be an empirical question.
Research from social neuroscience has provided important insights on how people reason about others’
preferences and wellbeing. However, it remains unknown how this reasoning figures in comparing several others’
wellbeing (i.e., ICU). Meanwhile, research from social psychology suggests that people have a tendency to assume
others do perceive the outside world similar to themselves and as such have similar preferences. Here, what
remains empirically unknown is whether these insights translate to ICU, in which decision-makers do not have a
direct self-interest. My PhD project (started in Oxford in October 2016 under the supervision of Nadira Faber and
Molly Crockett) aims to close these gaps and to provide an empirical approach to ICU. In my first experiment, thatserves as a first step in this direction, I find that when people are asked to choose between a safe payment and alottery for someone else – without any self-interest being involved – their choices are predicted by their own
preferences, as social psychology would predict. Notably, this is only the case when participants believe their own
risk preferences are typical, which raises the question what criteria other than their own preferences people may
use to infer others’ desires when in cases they believe their own preferences being untypical. Instead of accepting
ICU as a hopelessly intractable or impossible social dilemma, we need to learn more about the way people perform
such comparisons at the common-sense level.
BastianJaeger
A face bias in trust decisions
Day 4, Session 13
Social dilemmas are characterized by the potential for mutual gain but also by uncertainty about the other person’s
trustworthiness. People try to alleviate this uncertainty by using available cues. One cue which influences trust
decisions – both inside and outside the lab – is the interaction partner’s perceived facial trustworthiness. People relyon these face judgments even when decisions are extremely consequential, when other cues are available, andwhen it is explicitly proscribed. This is particularly puzzling given the limited accuracy of facial trustworthinessjudgments. We suggest that, much like other biases (e.g., stereotypes or anchors), the widespread effects of facial
trustworthiness judgments are caused by their automatic accessibility due to spontaneous, fast, and efficient
processing. In three experiments, we investigate a potential face bias by studying participants’ use of facial cues
(i.e., a photo of the trustee) and payoff cues (i.e., the trustees’ incentive to betray). In the first study (n = 125), we
elicited the perceived validity of the two cues. Participants chose to see either a photo of their partner or the
payoffs of their partner while making a decision in a trust game. The wide majority (79%) chose to see the payoffs
which suggests that participants perceive payoffs to be a more valid cue than faces. In study 2 (n = 361), both cues
were provided simultaneously. We tested whether facial cues would influence participants’ decisions even thoughmore valid payoff cues were available. Trust decisions were influenced by facial cues in the presence of payoff cuesand the influence of payoff cues even diminished in the presence (vs. absence) of facial cues (study 2a). On theother hand, the influence of facial cues did not diminish in the presence (vs. absence) of payoff cues (study 2b).
Together, these results demonstrate a divergence between the perceived validity of facial cues and the extent towhich they influence participants’ trust decisions. Much like other decision biases that are characterized byirrational, unconscious, or seemingly unwanted influence of certain cues, we argue that the automatic processing offacial trustworthiness has a biasing effect on peoples’ trust decisions.

44JosephIt's not you it's me: how antecedent social decision-making impacts
Calabrisotto
subsequent social behavior.
Day 4, Session 13
A wealth of multidisciplinary research has aimed to understand the motives behind peoples’ willingness to risk theirown health and prosperity for the benefit of others. However, one factor that has not been systematically includedin the past research on cooperation is how social dilemmas influence subsequent social decision-making. We positthat people are motivated to cooperate, at least in part, as a result of how previous intrarelational moral
interactions are emotionally experienced and appraised. We conducted a series of three studies exploring therelationship between making a social decision within a prisoner’s dilemma paradigm and its influence on
subsequent prosocial decision-making. In study 1 we found that college students (N=197) who had taken part in a
prisoner’s dilemma paradigm, where money was at stake, were more than twice as likely (compared to the control
group) to make a selfish choice about an amount of money in a follow-up decision (χ2 (2, 197) = 26.98, p < .001).
What was noteworthy about this finding is that the primary difference between the control group and those in thetwo conditions who played the prisoner’s dilemma game was participation in the game itself. This suggests thatexperiencing a social dilemma where money was at stake led to more selfish subsequent decision-making. In study
2 we replicated our prisoner’s dilemma paradigm online via Amazon’s Mturk worker portal. Interestingly, when
conducted online we found that participants in the control group and the prisoner’s dilemma condition groups
were extremely selfish in the subsequent monetary decision-making task. Additionally, we found that acting
prosocially in the prisoner’s dilemma was predictive of acting prosocially in the subsequent monetary decisionmaking task, and that acting selfishly in the prisoner’s dilemma was predictive of making a selfish choice in thesubsequent monetary decision-making task. In study 3 we replicated our PD paradigm from study 1 using time,
instead of money, as the factor at stake in the social dilemma. This time we found no significant differences insubsequent prosociality between those who first took part in the social dilemma and those who did not, suggestingthat money being at stake has distinct and particular effects on prosociality in subsequent social decision-making.
Taken together, these results indicate that under certain conditions, such as having an in-person interaction withsomeone as opposed to an online-only interaction, experiencing a social dilemma can lead to more selfish
decision-making in follow-up decisions.
Axel Franzen Mimicry, empathy and its relation to pro-social behavior
Day 4, Session 13
Humans have a tendency of facial mimicry. Particularly, yawning can be contagious. Prior studies suggest that thesusceptibility of contagious yawning varies among individuals and is related to empathy. However, the existing
evidence is sparse. We present results from two laboratory studies conducted with 171 (study 1) and 333 (study 2)
student volunteers. Subjects were video-recorded while watching mute videos of yawning, scratching, or laughing
individuals. Empathy was measured using the Interpersonal Reactivity Index. While subjects imitated all facial
expressions to large extents, only contagious yawning was related to empathy. Subjects who yawned in response toobserving others yawn exhibited higher empathy values. However, we found no evidence that the susceptibility tocontagious yawning is directly related to pro-social behavior.

45

When justice concerns do (not) matter – How justice sensitivity predicts
Thomasvoter's preferences for (un)equal wealth distributions within a simulated
Schlösser
democratic system
Day 4, Session 14
This research examines whether a person’s individual sensitivity towards justice (i.e., justice sensitivity, measured
one week in advance) predicts distributional preferences in experimentally simulated democratic systems (N=324).
Based on the notion that unequal distributions are likely to be perceived as unjust, we hypothesized that persons
who are truly concerned about the just treatment of others (i.e., other-sensitive persons) hold a genuine preference
for equal distributions and low inequality. Persons who show the tendency to only care about a just treatment forthem self (i.e. victim-sensitive persons) were instead assumed to hold no genuine distributional preferences, butprefer the degree of inequality that serves their self-interest. With a so-called “welfare state game” we measured
distributional preferences in a democratic decision-making process and found our hypotheses to be supported:
Other-sensitive persons displayed a general preference for low inequality irrespective of whether they financiallygained or lost from a democratically chosen simulated equal or unequal society (using Gini-coefficients close to
those of Finland and the US, respectively). In contrast, victim-sensitive persons preferred a low inequality or highinequality distribution of income depending on whether the one or the other served their financial self-interest. This
study suggests, again and in a new context, that justice sensitivity shapes behavioral reactions to situations where
justice is at stake; especially that voting for a more or less unequal society not only depends on the actual individual
position in a society (lower, middle, or upper class) but – beyond this – is differentially contingent on victim
sensitivity. Some political implications will be discussed.
Negative Brokerage: Understanding When, Why, and How Third Parties
Eliran Halali
Divide and Conquer
Day 4, Session 14
Third parties fill a range of important functions in groups, acting as catalysts of social and economic exchange(Stovel & Shaw, 2012) and as conduits of social information (gossip: Wu, Balliet, & Van Lange, 2015), serving as
conflict managers (mediators or arbitrators; Boehm, 2012; Rubin, 1980) and as enforcers of group norms (Balliet,
Mulder, & Van Lange, 2011). Although early work in sociology has highlighted also negative forms of brokerage(Simmel, 1950), relatively little is known about the factors that propel third parties to instigate conflict among others(Burt & Knez, 1995; Case & Maner, 2014; De Waal, 2007). The current research explores antecedents andconsequences of negative brokerage in groups. We propose that third parties engage in divide-and-conquer
behavior by incentivizing competition and punishing cooperation. To explore this social process, we introduce theWar-maker Game, an interactive decision making task in which two individuals choose whether to cooperate orcompete and a third-party chooses whether or not to intervene in their interaction. Intervention introduces side
payments that transform the game individuals are playing from a highly cooperative game (Maximizing Difference,in which cooperation is the dominant strategy) to a highly competitive game (Prisoner’s Dilemma, in which
competition is the dominant strategy). Whereas avoiding intervention constitutes a safe strategy that results in fixed
payoff to the third party, intervention makes the third party vulnerable to others’ choices. Specifically, relative to
non-intervention, the third party gains when others compete but loses when others cooperate. Four studies
investigated when, why, and how third parties act as dividers. Specifically, in the first three studies using the Warmaker game we find that: (i) The mere possibility of negative brokerage significantly decreases cooperation in the
War-maker Game; (ii) A substantial proportion (roughly a quarter) of third-parties choose to engage in this form ofnegative brokerage despite the risk involved; (iii) Eliminating the risk to third-parties dramatically increases
intervention rates and further suppresses cooperation rates; and (iv) Third parties are significantly more likely tointervene in the Peacemaker Game (Halevy & Halali, 2015; Nakashima, Halali, & Halevy, 2017) as compared with the
War-maker Game. Further, using a different research paradigm in the fourth study we find that positive andnegative brokerage behaviors by third parties follow from distinct values and traits. Overall, these findings shed
new light on the psychology of divide-and-conquer behavior by third parties.

46

Leonie
In My Backyard? Human Cooperativeness and the Causal Roles of PhysicalFütterer
Proximity and Exposure
Day 4, Session 14
Cooperativeness among genetically unrelated humans remains a major puzzle in the social as well as in the naturalsciences. Physical distance has been discussed as an important factor in reducing feelings of responsibility. In
contrast, physical proximity may prevent moral transgression, and increase cooperativeness. Effects could further
depend on whether there is a direct exposure to the people in need or not. So far, to the best of our knowledge,
causal evidence from real environments does not exist. Yet in light of the recent refugee crisis, as a concrete,
morally relevant context, evidence may be more important than ever. This paper is the first to identify causal effectsof physical proximity and direct exposure on cooperative behavior towards non-kins in a real life field study. We
focus on the willingness to monetarily support refugees in Germany. We vary how physically close refugees arelocated, and whether there is a direct exposure to them or not. All these contexts are relevant: The decision to
support refugees and welcome them in a society may hinge on whether refugees are close, or physically far away.
Also, it may matter whether people are directly confronted with refugees or not. Our data demonstrate thatphysical proximity significantly increases cooperativeness. Direct exposure, however, has counteractive effects.
While the latter effect may be gender-dependent, overall, willingness to support is highest when refugees are close,
yet remaining an abstract entity in the sense that they are not seen. Statement of Significance: Far more than one
million refugees and migrants have fled into Europe since 2015. They have encountered welcoming attitudes, butalso skeptical and outright hostile reactions. It may now be more important than ever to understand what causessuch attitudes. The decision to support and welcome refugees in a society, may hinge on whether they arephysically close, e.g. right at the border, or physically far away. Also, it may matter whether people are directly
confronted with refugees, e.g. seeing them, or not. This paper is the first to isolate effects of physical distanceversus proximity as well as direct exposure in a real situation. We find that physical proximity increases willingness
to support. Yet direct exposure has counteractive effects.

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Demonstration Presentations
Who are my fellow members in the groups to which I belong?
Effects of group composition and fautlines on parochial
Arjaan Wit
cooperation
Day 1, Session 4
After a merger of organisations or a restructuring of prior separated units within the organisation, an
individual may find him or herself participating in newly formed groups which are composed of members
originating from his or her own former ingroup and outgroup. How do members of such heterogeneousgroup weigh private interests, the interests of their former ingroup and outgroup members who now
constitute subgroups in the newly formed group, and the interests of the newly formed groups as awhole? The results of an experimental Prisoner’s Dilemma vignette study show that participants are
sensitive to the composition of two newly formed groups to which they belong (Within-Ss factor):
Participants show more cooperative choice behavior in a newly formed 10-p group in which they
themselves and six other members of their former ingroup (i) are in the majority (schematically: iiiiiiiooo)
than in a newly formed 10-p group in which seven members of their former outgroup (o) are in the
majority (iiiooooooo). The observed tendency of participants towards parochial cooperation is enhanced
under the activation of faultlines within the 10-p groups (Between-Ss factor): Participants who anticipate acomparison between members of the former ingroup (i) and members of the former outgroup (o) display
stronger parochial cooperation than participants who anticipate a comparison between all 10-p groups inthe study. Interestingly, additional data suggest that participants´ cooperative choice behavior is lessaffected by the number of co-operators that they expect among their nine fellow members than by theformer affiliation of these co-operators: In the 10-p group in which former outgroup members are in the
majority (iiiooooooo), participants do not go along with the high number of co-operators that they
expect among the former outgroup members. In terms of the Goal Expectation Theory (Pruitt & Kimmel,
1977) these participants hold cooperative expectations but do not share former outgroup members´ goal
to cooperate in their common interest. The discussion elaborates on the potential of the present crossedgroups social dilemma paradigm (see also De Pauw, 2013) to study cooperation and competition inheterogeneously composed groups in labs as well as applied settings.

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Many relationships tempt you to cheat: Decreased cooperation
Dirk Semmann
in multiple prisoner’s dilemma
Day 1, Session 4
Humans are an extraordinarily social species. Throughout our day-to-day lives we interact with a varietyof counterparts, in much differentiated relationships. Humans distinguish between kin, friends orcolleagues and also relationships in non-human animals are hallmarked by qualitative differences. Overall,natural selection seems to have favored individuals who rather affiliate and cooperate with a smaller
subset of all feasible partners. In an experiment with human participants, we investigated how the numberof interaction partners impacts cooperative behavior in the iterated prisoner’s dilemma (IPD) with an
unknown endpoint. Half of the participants played a single IPD, which is the common set-up. As a novel
feature, the other participants interacted in three, independent IPDs at a time. We find that overall
cooperation is lower in the multiple-partners setting. In fact, these participants established only one
cooperative relationship similar to the relationship of the single-partner setting, where cooperation levels
increased over time. Moreover, in one of the two remaining relationships, cooperation could not gain afoothold, although cooperative behavior is expected when direct reciprocity can operate. Hence, ourparticipants formed selective and differentiated cooperative relationships when multiple interactions were
offered. Furthermore, we show that in regard to fitness participants with highly differentiated relationships
behaved risk-averse and receive intermediate, but safe, payoffs - a beneficial strategy in ecologically
predictable environments. Additionally, we provide results on strategic behavior of participants.
Contradictory to previous findings, participants used conditional strategies close to generous tit-for-tat.

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The Effect of Experience on the Impact of Monetary Incentives in
Efrat Aharonov-Majar Social Networks
Day 1, Session 4
Research on the effect of economic incentives on human behavior has tended to use the rationality
assumption to predict individual behavior and/or to develop and compare models that capture deviationsof human behavior from the rational model. However, generalizing these results to predict the effect of
incentives in complex, multi-agent social networks is not straightforward. In such environments, thepredictive ability of the rationality assumption is limited. One example is difficulties in adopting newtechnologies. In this problem, the prospect of adopting a new technology is risky, and the outcome of
adopting depends on the decisions of others in the network. Specifically, adopting yields a positive
outcome only when a sufficient number of network members also adopt the technology. In the current
research, we suggest that the main long term effects of incentives can be captured with simple andrelatively general learning models. Such models provide clear predictions that do not depend on therationality benchmark or on specific assumptions about the decision maker's beliefs. Building onparadigms from the literature decisions from experience, we conducted two experiments in which
participants were faced with repeated choices between a Safe and a Risky (Adoption) option. In Study 1,
participants were assigned to two conditions: In the low variability condition, the risky choice yielded apositive outcome only if the majority of group members chose it in a given trial. In the High variability
condition, a risky choice yielded a positive or negative outcome with equal probability if the majority ofgroup members chose it. For both conditions, if the risky choice was chosen by the minority ofparticipants, it yielded a negative outcome. After participants made their choice, they received feedbackon their outcome, and on the number of other participants who made the same choice. We found thatthe ability of a group to successfully maximize social welfare is lower for environments characterized byhigh outcome variability compared to environments with low variability. In Study 2, we demonstrated how
different types of incentive can improve the group performance under high outcome variability. The
research makes two important contributions: first, it demonstrates how phenomena that were previously
described in individual contexts are manifested in groups; second, it demonstrates that the effect of
incentives on behavior in complex situations is not always straightforward.
The role of social preferences and recommendations in a game
Frederic Moisanof conflict
Day 1, Session 4
In this experimental study, we investigate the role of two distinct social features in resolving conflict
between two individuals repeatedly interacting in a chicken game: (1) individual differences through otherregarding preferences, and (2) recommendations as public signals. Our findings indicate that, althoughbiased recommendations (favoring one player over the other) can significantly improve efficiency, themost effective mechanism consists in constantly alternating signals pointing to the two pure equilibria. In
addition, while this type of recommendation significantly reduces inequality, it also removes any effect ofsocial preferences that is common otherwise (e.g., nice people no longer get exploited by individualistic
people). Finally, our study suggests that the recommendation mechanism has to be selected with care as
it may otherwise induce significant negative reciprocity between players beyond the context of thecurrent game.

50

Extension of Game Riskiness Model in Prisoner’s Dilemmas
Gary Ting Tat Ng
through Expected Utility Perspective
Day 1, Session 4
Game riskiness model is a way to conceptualize risk in prisoner’s dilemmas (PDs) such that the riskiness ofcooperation is defined by the variance of outcomes of cooperation relative to the variance of outcomesof defection. PDs with variance of cooperation outcomes greater (less) than that of defection outcomes
are termed as more risky games (less risky games). Past studies found that risk-seeking individuals
cooperated more in more risky games while risk-averse individuals cooperated more in less risky games,
and the positive effect of expectation of cooperation (EC) on cooperation was larger among more risky
games than among less risky games (Au et al., 2012; Ng & Au, 2016). The present paper extends thegame riskiness model through expected utility perspective and hypothesized that the positive effect of EC
on cooperation would be larger among risk-averse individuals than among risk-seeking individuals. The
hypotheses were tested using a field study such that university students who were taking psychology
courses that had group projects were invited to participate in the study. They were asked their estimatedcourse score in four hypothetical situations in which the four hypothetical situations correspond to thefour possible outcomes in PDs. In this way, we were able to capture their perceived conflict template of
the group project. They were also asked their expectation of contribution of themselves and other groupmembers. Their risk attitude was measured by a set of ten risk gambles. Consistent with our hypotheses,
for those who perceived the group projects as PDs, the positive effect of EC of other group members on
their contribution was larger among more risky games than among less risky games. We also found thatthe positive effect of EC on their contribution was larger among risk-averse individuals than among riskseeking individuals. The present study demonstrated that the game riskiness model can be generalized
beyond laboratory settings to real-life settings and beyond monetary payoffs to other domains.
Timothy Shields
Incentives, Truth, and Consequence
Day 1, Session 4
We experimentally examine how disclosure and framing of payoffs affect behavior in an intracompany
setting where there are known conflicts of interest between parties. Our experimental manipulations
illuminate the consequences of altering the information environment germane to cooperation within thesetting. Information sharing has been cited as key determinant of a company’s success that includes, but
is not limited to, employee commitment, inter-divisional coordination and cooperation, and effective
incentives. These are scenarios where complete contracting may not be obtained due to lack orunverifiable of information, and/or the prohibitively high cost of formal contracting, and thus economic
and personal interactions rely on trust and honesty. Reliance often works well, but sometimes it can break
down, especially in light of conflicts of interest caused by monetary incentives. Intracompany interactions
are subject to other complexities not typical in other social dilemmas. Unlike actors in the competitive
economy who choose their exchange partners, employees are generally “exogenously” brought together.
Furthermore, formal social rules and measures designed to promote trust and honesty are not typicallyapplicable to intracompany settings. Additionally, managers of divisions are often autonomous within thecompany. As such, we look to manipulations feasible to the company in light of the complexities. In thiswork, we ask if framing the economic payoffs and/or providing history of past transactions affects
cooperation. If so, are these manipulations substitutes or compliments? Last, whose behavior is changed?
We find while framing payoffs improves behavior in the short term, providing history promotes
cooperative behavior in the long-term. Male participants and those scored relatively higher as
Machiavellians appear more sensitive to treatment effects.
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Context Matters: Moving Towards an Understanding of PersonSituation Influences on What I Do AND What I Want You to Do
Poonam Arora
in Social Dilemmas
Day 1, Session 4
Social dilemmas in lab studies are frequently framed as tradeoffs between relative economic gains thus
highlighting their interdependent nature. SVO and communication with others influence choices in theselab dilemmas. In real world dilemmas, context can vary between gain, break-even, and loss, andinterdependence may not be obvious. This research examines the influence of economic context and
SVO in real world dilemmas where communication is not certain; proposes underlying psychologicalmechanisms; and, explores implications for real world dilemmas. An exploratory field study with 15 CEOsof agribusinesses found under conditions of certain loss, cooperation was lower (p<.05) andaccompanied by a greater “me-focus” (p<.05). A follow-up MTurk study (N = 375) that measured SVO(Murphy et al, 2011), randomly assigned participants to one of three economic contexts (loss, neutral,gain) before having them read the dilemma, respond to statements about whether the dilemma was anindividual or interdependent choice, and make their choice, replicated field study findings. In a binary
regression model, both economic context (p<.05) and SVO (p<.05) were significant predictors ofcooperation. SVO was mediated by perception of the dilemma as an individual, not interdependent
decision (p<.05). Further analysis of SVO and economic context revealed that an individualisticallyoriented participant, was more likely to perceive the dilemma as an individual decision, and was more
likely to do so in the loss compared with breakeven or gain conditions. In a third study (MTurk, N= 382)
that randomly assigned participants to three economic contexts (loss, neutral, gain), participants wereasked for their decision in the dilemma, whether they would like to communicate with the other person in
the dilemma, and what they would discuss during the communication. This study replicated choicepatterns from previous studies, and found that all participants would choose to communicate with theother person in the dilemma independent of economic context or SVO. Economic context however, wasa significant predictor (p<.05) of what participants would choose to discuss, and thus what they want theother to do in the dilemma. In the loss condition, despite their high level of defection (66%), they would
discuss the other person not defecting. In the gain condition (62% cooperated), they would discuss
ensuring mutual cooperation. In the neutral condition (70% cooperated), they would discuss coordination
on any mutually beneficial outcome. Taken together, these findings shed light on decision processes inreal world social dilemmas and the contexts that constrain them.

52

Does trust beget trustworthiness?: The effect of trusting intention
Nobuyuki Takahashi
on trustworthiness of the partner
Day 1, Session 4
Trust is considered a lubricant for social life. Yamagishi (1998, 2011) distinguishes trust, which is acharacteristic of a truster representing the expectation of another’s benign behavior when exploitation ispossible, from trustworthiness, which refers to a characteristic of a trustee, which represents their altruistic
disposition. Including Yamagishi (1998, 2011), most previous studies have regarded trust andtrustworthiness as personality traits which are stable over time. However, they may be situation
dependent. The current study focuses on the possibility that trustworthiness is influenced by whether thetrustee was trusted or not. Previous studies that examined whether being trusted has a positive effect on
the trustworthiness of the trustee report mixed results. For example, Kiyonari et al. (2006) showed thattrustworthiness was not higher when the trustee knew that he was trusted vs. when not trusted, while
Hayashi et al. (1999) provided counter evidence. Thus, the current study sought to provide clear evidence
that trust begets trustworthiness by making two improvements on previous studies. First, we manipulated
the extent to which the trustee was trusted as a within-subject factor so that we could reveal whether thetrustee’s behavior would change depending on the degree of being trusted. Second, we manipulated theintention of truster as a between-subject factor to examine whether a truster’s intention plays a major role
when the trustee makes the decision to reciprocate a truster. We used the Investment Game in which thetruster’s and trustee’s decisions are continuous (Berg, et al., 1995). We used a 3 x 2 design. The first factor
is the degree of being trusted. In the experiment, the truster was actually a computer and wasprogrammed to invest low/middle/high amount to participants. The second factor is the intention of thetruster. Participants were told that the truster made their own decisions in the intention conditions, butwere told that the decisions were made by lottery in the no-intention conditions. The results revealed thatthe amount participants returned was higher in the middle and high investment conditions, but only in
the intention conditions. In the no-intention conditions, the amount of investment had no effect. These
results indicate that trust begets trustworthiness only when the trustee knows that the truster had an
intention to trust him. Thus, trusting behavior and trustworthy behavior can be mutually reinforcing toachieve a more profitable relationship.

53

What explains donations at the doorstep, and norm violations, inPaul Van Lange
the field? Reputation trumps resources
Day 2, Session 8
One interesting case of prosocial behavior is when volunteers knock on your front door and invite
donations for a noble cause, often to help improve circumstances of people unknown to the giver or thecollector or even a mere category of people or threats (e.g., victims of a tsunami, people fighting Cancer).
What is it that makes people give in these face-to-face situations? The present study examines therelative ability of six variables to predict donations at the doorstep. We examine the relative ability of age,sex, education, net income, religiosity, and population density to predict donations at the doorstep of 403
districts or counties in the Netherlands. Findings uncovered that, by far, the most powerful predictor ispopulation density. Donations at the doorstep are higher in districts characterized by low density (fewer
individuals per square kilometer). This finding is perfectly consistent with the notion that direct andespecially indirect forms of reciprocity guide prosocial behavior, in particular, through reputational
concerns. In communities with less density, people are more likely to know the person, or be connectedwith the collector in an extended sense (e.g., friends of friends). The other variables predicted donations
less powerfully, if at all. For example, income was one of the weakest predictors of donations at the door
step. Next, we examined norm violations as a function of several characteristics. At the county level, we
examined norm violations such as receiving a ticket for parking at illegal spots, and found once again that
population density matters. Various norm violations are more prevalent with increasing density. Generally,
the findings provide field data that complement two decades of experimental research on the power of
reputation in promoting generosity and norm-compliance. Or as the title conveys: Reputation trumps
resources.
Happy to help—if it’s not too sad: The effect of mood on helping
Hagit Sabato
identifiable and unidentifiable victims
Day 2, Session 8
We examine the role of mood in donation decisions. In an attempt to reconcile inconsistencies in theexisting literature, we suggest that the effect of mood on donation decisions may be dependent on thenature of the intended help recipient—be it a specific identified individual, or a more general need. The
findings of three studies consistently show a significant interaction between mood and identifiability. In
Study 1, individual differences in people’s moods interacted with the identifiability of the recipient,demonstrating that the identifiability effect was attenuated by a good mood. Study 2 and Study 3 provide
more causal relationships between mood and the identifiability effect, by replicating the same pattern
while using different manipulations to induce moods. In both studies, donations to identified single
victims exceeded donations to unidentified people with the same need—under the sad moodmanipulations and under the control conditions—while participants in the Happy Mood conditions
tended to donate more to address the general cause, rather than to specific identified recipients. We
discuss possible mechanisms behind this donation pattern.

54

Isamu Okada
Justification Dilemma in private observation and its solution
Day 2, Session 8
Indirect reciprocity is one of the key mechanisms for resolving social dilemmas. Intensive studies overdecades have been exploring several types of assessment rules that are evolutionarily stable for keeping
cooperation regimes. Despite their efforts, however, little is known about effects of private(heterogeneous) information on social systems. Most studies on indirect reciprocity assume publicobservation in which individuals can only equally share a unique assessment for each individual. Just, thesociety is dominated over by a surveillance system that observes all the behaviors and broadcasts its
judgments and the residents are not permitted their personal assessments for the others. Here we
consider a private observing system that loosens such the unnatural assumption and explore theevolutionarily stable norms in the system. In the system, the justification dilemma emerges. This isbecause the justified defection is not necessarily justified in the system. We employ methods of individualbased simulations by which all of the major norms: Image-scoring, Simple-standing, Stern-judging,
Shunning, and Staying, can be dealt with and private assessment can be implemented without any
approximation. Our simulation shows that 1) narrower road to cooperation: the evolutionarily stablenorms in the private monitoring are more restricted to tolerant norms Simple-standing and Staying thanthose in the public monitoring, 2) stable coexistence of discriminators and unconditional cooperators:
unconditional cooperation can play a role for keeping a high level of cooperation in mixtures with thetolerant norms in the private monitoring, 3) Pareto improvement: the private monitoring can achieve
higher cooperation rate than the public monitoring does. Our model reevaluates the role ofunconditional cooperation, a naive strategy. So far, unconditional cooperators have often been assessed
as detrimental under the Image-scoring norm because they are the so-called second-order free-riders
who shirk paying the cost for excluding defectors through withholding help. In most studies on theevolution of cooperation by indirect reciprocity with the public observation, the key point is how to
exclude such the naive cooperators. In contrast with this, indirect reciprocity with the private observation
offers the unconditional cooperators a part of a solution. Tolerant reciprocity Staying and Simplestanding can maintain a cooperative regime in concert with unconditional cooperators. Furthermore, theaverage payoff at the evolutionarily stable point with the private observation is higher than that with the
public observation if the cost-benefit ratio of the giving game exceeds a threshold and no mutation isassumed.

55

The games economists play: Why economics students behave
Philipp Gerlach
more selfishly than other students
Day 2, Session 8
Do economics students behave more selfishly than other students? Experiments involving monetary
allocations suggest so. This article investigates the underlying motives for economic students’ more selfish
behavior by separating three potential explanatory mechanisms: economics students (1) are lessconcerned with fairness when making monetary allocation decisions; (2) have a different notion of what isfair in the monetary allocation; or (3) are more skeptical about other people’s generosity, which in turnmakes them less willing to comply with a shared fairness norm. These mechanisms were tested by inviting
students from various disciplines to play a relatively novel experimental game and asking all participants
to give reasons for their choices. Compared with students of other disciplines, economics students wereabout equally likely to mention fairness in their comments and had a similar notion of what was fair in thesituation. However, they expected lower offers, made lower offers, and were less willing to enforce
compliance with a fair allocation at a cost to themselves. The economics students’ lower expectations
mediated their allocation decisions, suggesting that they behaved more selfishly because they expected
others not to comply with the shared fairness norm.
The Effects of Case Framing on the Willingness to Commit toInbal Harel
Organ Donation
Day 2, Session 8
We often come across stories of cases involving organ-donations in the media. Sometimes the story ispresented anonymously, without any identifying information. In many cases the identity of the donor isgiven. In some cases, the identity of the recipient is known. In the current research we examine how suchpresentations of organ donation cases may affect people's willingness to sign organ donationcommitment cards (study 1) to donate the organs of a deceased relative (study 2) and to support thetransition to "opt-out" policy (study 3). In all studies participants first read a scenario about a young man
who was killed in a car accident. The man had signed an organ-donation card in the past, therefore, his
parents decided to donate his organs. His kidney was implanted in the body of another young man who
urgently required it. Participants were randomly assigned to one of three conditions: In the identified
donor condition the name and the picture of the man who was killed and who donated the kidney wereadded. In the identified recipient condition, the same name and picture were added to the information
about the recipient. In the control condition no identifying information was added. Results show thatsignificantly more people signed an organ donation commitment after reading the case with theidentified recipient, as compared with the two other conditions. Similarly, willingness to donate the organsof a deceased relative (study 2) and to support for the transition to "opt-out" policy (study 3) were greaterin the identified recipient condition than in the two other conditions. Asking people about the extent towhich they thought about death vs. saving lives under the three experimental conditions we find thatwhen the receiver is identified, greater attention is given to the possibility for saving life. Contrary, when
the donor is identified, the salience of death is greater. In that case, reading the story (even when resulted
in saving life) is likely to enhance the salience of one's own death and may distance people fromwillingness to support organ donations.

56

Nadira Faber
Prosocial loss aversion
Day 2, Session 8
It is a general human tendency to try to avoid losses when making decisions concerning own outcomes.
Would people also show loss aversion when making decisions that affect the welfare of others? Wedemonstrate what we call prosocial loss aversion: the tendency to invest more own resources to help
others avoid losses than to help them acquire equivalent gains. We found that participants helped
another person more to avoid losing money than to win money. Our findings further suggest thatprosocial loss aversion is a deliberate process people apply their moral heuristics to. Participants were
economically rational in their decisions. Prosocial loss aversion seems largely driven by reputational
concerns, as we found it only when decisions were visible to the other person.
Victor Shiramizu
Implicit social categorization during intergroup competition
Day 2, Session 8
Group bias is a well-explored phenomenon in social psychology: studies report that it promotes trust,generosity, and positive emotions to in-group members, while avoidance, derogation, and hostility are
directed to outgroup members. The economic games are broadly used to understand variables
underlying group bias, but few studies have developed a paradigm to study group competition based on
game theory. Most studies have also used explicit measures to assess favoritism to in-group. To
investigate the occurrence of implicit negatively skewed perception pattern to rival competitors, we havedeveloped an economic game based on “minimal group” paradigm, where two groups compete tomaximize the profits without depleting a public resource. The winner group received two chocolate boxes
as a prize. The sample was composed of 97 individuals, 39 men and 58 women, ranging from 17 to 41
years. After the game, participants were submitted to Implicit Association Test (IAT) to measure thereaction time (latency) between a stimulus appearance representing the groups and the categorization.
Participants in control condition responded to the IAT without participating in the game. Generalized
Estimating Equations (GEE) were applied to build two models to better show the game outcomes. Model
1 showed that participants in experimental condition indicated a stronger association of pleasant words totheir own group and of unpleasant words to the opposing group when compared to control condition.
Model 2 showed an interaction effect, in which loser participants performed social categorization faster inthe compatible associations compared to incompatible ones when the out-group members celebrated
and did not share the prize. Our study reinforces previous studies about social categorization using agroup competition paradigm and an implicit measure of ingroup favoritism, showing that evolved
psychological mechanisms might be activated in low hostility level situations. Interestingly, the strength ofsocial categorization was intensified or mitigated according to outgroup members behavior.

57

Trust and social distance among Americans, Chinese andYang Li
Japanese
Day 2, Session 8
In this study, we investigate behavioural and attitudinal trust within different social relationships among
American (N=142), Chinese (N=126) and Japanese (N=139) participants. Participants reported theirattitudinal trust and behavioural trust (using the Trust Game), as well as their relationship closeness withrespect to three relational partners at different levels of social distance: a Close Other, an Acquaintanceand a Distant Other. We found that social distance moderated cross-national differences in both
attitudinal trust (F (3.84, 775.50) = 5.04, p = .001, partial η2 = .02) and behavioural trust (F (3.83, 773.27) =11.83, p < .001, partial η2 = .05). Trust of distant others is higher among Americans and Chineseparticipants than among Japanese participants. However, the magnitude of this cross-national difference
got reduced when social distance became closer. We further revealed that emotional closeness andstrength of communal sharing fully mediated the moderating effect of social distance on cross-national
differences in attitudinal trust. However, these two facets of relationship closeness did not mediate social
distance’s moderating effect on national differences in behavioural trust. Last, Chinese participants seemto be more trusting and less sensitive to social distance than Japanese participants. This indicates somevariabilities between East Asian countries with respect to their citizens’ interpersonal trust. Taken together,
our results indicate that social distance is an important moderator in cross-cultural comparisons ofinterpersonal trust. Future research should investigate how interpersonal trust is developed in different
relationship contexts and in different cultures.
Laetitia Mulder
Rules and personal gains
Day 3, Session 12
Unethical behavior may be reduced by the use of specifically or generally formulated rules. For example,
corrupt behavior may be countered by the rule that one should not engage in conflicts of interest(general formulation) or that one should not accept gifts from clients (specific formulation). Specific rules
steer behavior more effectively because they reduce moral rationalizations (Mulder, Jordan, & Rink, 2015).
However, as general rules are still often preferred as they are more encompassing and communicate
moral values (e.g., Weaver & Treviño, 1999), there is a need to test the circumstances determining theeffectiveness of both general and specific rules. We tested the moderating role of personal gains. We
argue that, when there is much to gain from an unethical act, people are more tempted to morally
rationalize their acts. A general rule, more than a specific rule, allows for moral rationalization. Thus, wehypothesize that personal gain increases lying when there is a general rule, but not when there is a
specific rule. We tested this in a 2 (personal gain: low versus high) × 3 (rule: no, specific or general) lab
experiment in which participants could tell a self-interested lie at the cost of another person (the dicegame, Gneezy, Rockenbach, & Serra-Garcia, 2013). The rule in the specific rule condition was “Tell thetruth” and the rule in the general rule condition was “Do what is morally right”. Personal gain was
manipulated by varying the outcome of the die role: this was either 1 (which made the personal gain ofreporting a higher number, high) or 5 (which made the personal gain of reporting a higher number, low).
The results showed that both rules reduced lying. Also, people were more likely to lie when personal gain
was high rather than low. However, a specific rule restrained the influence of personal gain. That is, when
there was a specific rule, people did not lie more when personal gain of lying increased. A general rulealso restrained the influence of personal gain, but to a lesser extent. That is, when there was a generalrule, people lied more when personal gain of lying increased. The results suggest that, especially insituations where there is much to gain from unethical behavior, it pays to introduce rules to restrain
people from engaging in the behavior, and it pays to choose for specific rather than general rules.
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Gossip Versus Punishment: The Efficiency of Reputation to
Junhui Wu
Promote and Maintain Cooperation
Day 3, Session 12
Prior theory suggests that reputation spreading (e.g., gossip) and punishment are two key mechanisms topromote cooperation in groups, but no behavioral research has yet examined their relative effectivenessand efficiency in promoting and maintaining cooperation. To examine these issues, we observed
participants interacting in a four-round public goods game (PGG) with or without gossip and punishment
options, and a subsequent two-round trust game (TG). We manipulated gossip as the option to sendnotes about other group members to these members’ future partners, and punishment as the option toassign deduction points to reduce other group members’ outcomes with a fee-to-fine ratio of 1:3.
Findings revealed that in the four-round PGG, the option to gossip increased both cooperation andindividual earnings, whereas the option to punish had no overall effect on cooperation (but a positiveeffect on cooperation in the last two rounds of the PGG) and significantly decreased individual earnings.
Importantly, the initial option to gossip made people more trusting and trustworthy in the subsequent TG
when gossip was no longer possible, compared to the no-gossip condition. Thus, we provide some initialevidence that gossip may be more effective and efficient than punishment to promote and maintaincooperation.
Do the powerful enforce the rules? Studying the effects of power
on cooperation, altruistic punishment and emotion in a public
Loren Pauwels
goods gameDay 3, Session 12
Power asymmetry is inherent in many social relationships, and a number of recent studies suggest thathaving high power or social status negatively affects generosity, reciprocity and trust. This study further
explores the power’s role in steering the outcome of social interactions, by investigating how priming
power (in a separate experimental task) affects cooperation and punishment in an incentivized public
goods game (n=146) with stranger matching. Punishment of those who violate cooperative norms isthought of as one of the central drivers of humans’ puzzlingly high levels of cooperation, and occurs even
if that punishment brings along immediate costs and no future benefits for the punisher. In line with
Akerlof and Kranton’s economic theory of identity (2000) and Magee and Smith's social distance theory of
power (2013), we posit that what is ‘fair’ to those experiencing power (relative to those lacking power) willbe less about dividing resources equally and more about ‘taking (or holding onto) what they consider tobe theirs’. Having power generates approach behavior, but only in a way that perpetuates one’s
advantageous position, leading to seemingly more deliberated, economically rational behavior. To
distinguish between several motives for cooperation and punishment, we include three experimental
conditions: a no punishment, monetary punishment, or nonmonetary punishment condition. We
hypothesize that those in power will contribute less, but only when there is no threat of monetary
punishment. In addition, we expect the powerful to engage less in the punishment of norm violators - but
only when punishment is costly. While the behavioral data does not confirm our first hypothesis
concerning cooperation, it does confirm our second hypothesis: that the powerful punish significantly lesswhen punishment is costly. A second major aim of this study is to shed light on the affective processes bywhich power affects social behavior. To this end, subjects are videotaped during the experimental session,and their facial expressions are analyzed with FaceReader software to yield objective measurements of six
basic emotions and a neutral state. Since anger was found to motivate sanctioning behavior in previous
studies, we specifically investigate whether those in power experience relatively less anger in response tonorm violations, and additionally explore other differences in emotional state.
59

Women cooperate less than men in one-shot social dilemmas:
Angela DorroughEvidence from 12 nations
Day 3, Session 12
Women are commonly stereotyped as being more communal, caring, emotionally expressive, and warm
than men. Indeed, there is substantial empirical evidence that women act more prosocially in many
contexts. In a comprehensive study involving population-representative samples from 12 different
countries (N = 2,429) we find that - contrary to the stereotype - women cooperate significantly less thanmen in fully incentivized one-shot prisoner's dilemma games. This difference in cooperation is driven by
the fact that women hold lower expectations regarding the cooperativeness of their anonymousinteraction partners than men.
Stefan Pfattheicher
The Evolution of Cooperation via Democratic Punishment
Day 3, Session 12
In social dilemma situations, individuals benefit from uncooperative behavior while exploiting resources of
the collective. One prominent solution to prevent uncooperative behavior and to increase cooperation isto establish a system of costly peer punishment, that is, the option to invest private resources to punish
interaction partners. However, recent research revealed that a peer punishment is inefficient andmaladaptive in the sense that the total payoff is reduced and punishment of cooperative individuals is
possible. In the present work, we propose that a system of democratic punishment, that is, direct andequal participation of each individual in the punishment decision making process with punishment only
executed when a majority has voted for its execution, can address the shortcomings of a peer
punishment system. Using a public goods game, we show higher cooperation level, higher total payoffand reduced executed punishment in the democratic compared to a peer punishment system. Beyond,
we document that fairness perceptions of and satisfaction with the system as well as interpersonal trust
are increased in the democratic punishment system. Implications for how cooperation and punishment
systems evolve are discussed.

60

How do people think about thier interdependence: A
Daniel Balliet
multidimensional model of subjective outcome interdependence
Day 3, Session 12
Interdependence is a fundamental characteristic of social interactions. Interdependence Theory states that
6 dimensions describe differences between social situations. Here we examine if these 6 dimensions
describe how people think about their interdependence with others in a situation. We find that people(insitu and exsitu) can reliably differentiate situations according to 5, but not 6, dimensions ofinterdependence: (1) mutual dependence, (2) power, (3) conflict, (4) future interdependence, and (5)information certainty. This model complements an existing model of situation construal (DIAMONDS) andoffers a unique framework for understanding how people think about social situations. Furthermore, we
examine factors that are theorized to shape perceptions of interdependence, such as situational cues(e.g., partner nonverbal behavior) and personality (e.g., HEXACO and Social Value Orientation).
Furthermore, we study the implications of subjective interdependence for emotion and cooperative
behavior during social interactions. This model of subjective interdependence explains substantial
variation in the emotions people experience in situations (e.g., happiness, sadness, anger, and disgust),
and explains 24% of the variance in cooperation, above and beyond the DIAMONDS model. Throughout
these studies, we develop and validate a multidimensional measure of subjective outcome
interdependence that can be used in diverse situations and relationships – the Situational
Interdependence Scale (SIS). We discuss how this model of interdependence can be used to better
understand how people think about social situations encountered in close relationships, organizations,and society.
Cathleen Johnson
Choice of Partners, Trust, and Scale of Interactions
Day 3, Session 12
This paper reports the results of a finite prisoner’s dilemma experiment with endogenous choice ofpartners and scale of interaction. Prior to each round of decisions, players decide whether to interact or
break the link. For active links, players can select a preferred scale of interaction, and the minimum of thetwo scale decisions in each pair determines the actual scale. A doubling of the scale, for example,
doubles all payoffs, including the gains from cooperation and unilateral defection, and the losses frommutual defection. In some treatments, each person can maintain up to three active links with others, but
no more, so adding a partner requires one to break off from another. Links that are discontinued can bereactivated at a later point. This flexibility to choose partners and the scale of interaction results insustained levels of cooperation at high interaction scales for active links, despite the known finite numberof rounds and the inability of future partners to see prior decisions made by third parties. In the choiceof-partners treatment, more than half of the decisions involve cooperation in the final round. Links thatare deactivated by one or both players are almost never reactivated, and subsequent defection iscommon if they are. In contrast, mutual cooperation typically results in increases in the scale.

61

Poster Presentations
Adiel Moyal
Relative Monetary Outcomes as Affecting Envy and Generosity
Day 1
In three studies we examine allocation decisions in which the allocators’ choices concern solely theoutcome of their counterparts, as their own outcomes are fixed. We ask whether the relative outcomes of
the allocators – higher/lower than the counterparts’ outcomes – affect their willingness to afford thecounterparts the highest possible outcome. The findings show that the direction of relative outcomes,
inducing upward/downward social comparison, affects the choice of allocation, reflecting envy in theformer case. The effect of this social comparison spills over to a subsequent, ostensibly unrelated decision
in a standard dictator game, yielding less or more generous choices.
Do Future-Oriented Persons Use Less Energy? A Study Combining
Andreas Diekmann
Survey and Metered Electricity Usage Data
Day 1
Household’s energy reduction is a cooperative and environmentally responsible behavior in the social
dilemma of climate change. Theory suggests that future orientation should foster pro-environmental
behavior since most such behavior only leads to conservation in the long run. However, previous research
has led to mixed results: Studies assessing future orientation in terms of subjective discount rates do notprovide any support (e.g. Bruderer Enzler, Diekmann & Meyer, 2013) while studies based on multi-item
scales of future orientation repeatedly have lent support to the hypothesis (see Milfont, Wilson & Diniz,
2012, for a review, or Bruderer Enzler, 2015, for a recent example). However, a major limitation of previous
research has been the fact that these studies either rely on self-reported or stated behavior. The present
study therefore combines survey data of 1,095 persons with metered data on electricity use provided by autility company. Future orientation was measured by both a short version of the Consideration of Future
Consequences scale (CFC; Strathman, Boninger, Gleicher & Edwards, 1994) and a binary choice task toassess discount rates (incentivized by a lottery). Contrary to expectations, we do not find any correlations
between energy use and discount rates. The CFC scale, however, is related to energy use. This isparticularly true for the future orientation subscale and less so for the concern with immediate
consequences subscale. In sum, our results based on metered energy use replicate the results of studies
based on self-reported behavior. This is surprising as we expected the behavioral measure to perform as
well as (or better as) the psychological measure of future orientation once behavior was not assessed by
self-reports. Future research is needed to look into why this could be the case.

62

Andrew HafenbrackMindfulness and Financial Altruism
Day 1
Mindfulness originally came from Buddhism, which, like all religions, encourages altruism. However, theforms that mindfulness teachings have taken in the workplace are usually disconnected from moral or
altruistic considerations (Purser & Milillo, 2015) due to the need to separate sacred and secular institutionsin Western societies (Kucinskas, 2014). The present research sought to answer the question of what therelationship is between the secular form of mindfulness – on the trait and state levels – and financial
altruism towards present and future others. Specifically, we investigated whether people who are high intrait mindfulness (using the Philadelphia mindfulness scale: Cardaciotto et al., 2008), not necessarily due
to training, are more inclined to be altruistic with money and, if so, to whom. We also investigatedwhether manipulated state mindfulness, induced by 15 minutes of a focused breathing meditation (using
the recording from Hafenbrack, Kinias, & Barsade, 2014), influences financial altruism. In addition, we not
only investigated prosocial behaviors that benefit others in the present, as most current research does,
but we also investigated prosocial behaviors that have beneficial consequences for others in the future,similar to intergenerational decision making. Across two studies using a behavioral measure of financial
altruism (from Tost, Wade-Benzoni, & Johnson, 2015), we found converging evidence that links both trait
and state mindfulness with increased altruism to present others but not to future others. Interestingly, thepresent moment awareness factor of the trait mindfulness scale was significantly positively correlated with
altruism towards present others, but the acceptance factor of the trait mindfulness scale was marginallynegatively related to altruism towards present others. We interpret these findings to suggest that eventhough secular mindfulness does not specifically encourage altruism, the psychological state ofmindfulness is related to and can increase financial altruism. That the effect was only observed towards
present others but not towards future others and that the present moment awareness factor was morestrongly correlated with altruism than the acceptance factor suggests present moment temporal focus is a
key mechanism of these findings. This also may tentatively suggest that manipulated state mindfulness
more easily induces present moment awareness than it does nonjudgmental acceptance. I will alsomention another project I have with Isabelle Solal which finds that these results change when individuals
are in a state of guilt such that mindfulness can reduce reparative behavior (generosity towards people
one has harmed) because it reduces guilt.

63Angelo Romano
Reciprocity Outperforms Conformity to Promote Cooperation
Day 1
Evolutionary psychologists have proposed two processes that could give rise to the pervasive amounts ofhuman cooperation observed among non-genetically related individuals: reciprocity and conformity. Eachevolutionary process results in distinct psychological mechanisms and it may be that humans possesseach set of psychological mechanisms that can compete for influence over behavior. We test whether
reciprocity outperforms conformity in promoting cooperation, especially in a situation when these
psychological processes would promote a different (non)cooperative response. To do so, across threestudies, we employ a variant of the Asch conformity paradigm whereby participants make decisions in acooperative decision task with a partner after learning (a) that their partner has behaved cooperatively (ornot) on several previous trials (Reciprocity-to-Cooperate) and (b) that their group members have
behaved cooperatively (or not) on several previous trials with that same partner (Conformity-toCooperate). Although we find support that both mechanisms can influence cooperation, we found thatreciprocity had a stronger influence on cooperation. Moreover, we find that conformity can be partly
explained by a concern about one’s reputation – a finding that supports a reciprocity approach. Thus, ourfindings suggest that people more strongly adjust their behavior to acquire direct and indirect benefits ofsocial exchange, compared to imitating others to conform to social norms.
Anne-Marie NeiseAn empirical approach to interpersonal comparisons of utlility
Day 1
Suppose I am the proud owner of a ticket for the sold-out Whisky Weekend Amsterdam, but I realise that
I can no longer make it. I decide to give the ticket to one of my close friends – the question is to whichone? I compare how much each of my friends would enjoy the whisky weekend and finally settle on the
biggest whisky-lover amongst them. In economics, the dominant - although not unchallenged - view has
been that such interpersonal comparisons of utility (ICU) are hopelessly intractable and as such
impossible. Proposals made in defence of ICU converge towards the argument that people would
perform intuitive ICU by inferring others’ mental states; in turn, ICU’s reliability would depend on thosementalizing processes’ accuracy and as such be an empirical question. Research from social neurosciencehas provided important insights on how people reason about others’ preferences and wellbeing.
However, it remains unknown how this reasoning figures in comparing several others’ wellbeing (i.e., ICU).
Meanwhile, research from social psychology suggests that people have a tendency to assume others do
perceive the outside world similar to themselves and as such have similar preferences. Here, what remains
empirically unknown is whether these insights translate to ICU, in which decision-makers do not have a
direct self-interest. My PhD project (started in Oxford in October 2016 under the supervision of Nadira
Faber and Molly Crockett) aims to close these gaps and to provide an empirical approach to ICU. In myfirst experiment, that serves as a first step in this direction, I find that when people are asked to choose
between a safe payment and a lottery for someone else – without any self-interest being involved – theirchoices are predicted by their own preferences, as social psychology would predict. Notably, this is only
the case when participants believe their own risk preferences are typical, which raises the question whatcriteria other than their own preferences people may use to infer others’ desires when in cases they
believe their own preferences being untypical. Instead of accepting ICU as a hopelessly intractable or
impossible social dilemma, we need to learn more about the way people perform such comparisons at
the common-sense level.

64

The Roles of Personality Features and Perceived Threat in theAvi Besser
Attitudes of Israelis Toward Peace with the Palestinians
Day 1
The purpose of the present study was to examine the associations between personality features and theattitudes of Israelis toward peace with the Palestinians. Further, we were interested in the possibility thatthe associations between personality features and attitudes toward peace with the Palestinians would be
moderated by the extent to which Israelis viewed the Palestinians as a potential threat to their safety andsecurity. We examined this possibility in a sample of 2,631 Israeli community members. Our results
revealed that the perceived threat posed by the Palestinians moderated the associations that certain
personality features (i.e., openness, psychopathy, agreeableness, and Machiavellianism) have withnegative attitudes of Israelis toward peace with the Palestinians. For example, low levels of openness andhigh levels of psychopathy were associated with relatively negative attitudes toward peace with thePalestinians when the perceived threat posed by the Palestinians was believed to be relatively low. These
results are consistent with the broader perspective that personality features tend to have stronger
associations with outcomes when situational forces are relatively weak.
Interdependence perceptions in daily life: How does subjective
Catherine Molhointerdependence influence emotions and cooperative behavior?
Day 1
Previous research has used experimental games that vary in their objective interdependence to study
cooperative behavior, as well as the emotions that facilitate or impede it. However, in everyday life,
people rarely have objective knowledge regarding the consequences of their own and others’ behavior.
Thus, more research is needed to examine how people form subjective perceptions of interdependence
when such information is not explicitly provided to them. Here, we report results from three studies thattest a theoretical model of interdependence perceptions organized along five dimensions: degree ofinterdependence, conflict, power, future interdependence, and information certainty. In Study 1 (N = 407),
we find that situations encountered within different relationship types (Fiske, 1992) are associated withdiffering perceptions of interdependence, power, and information certainty. In Study 2 (N = 331), we
further observe that perceptions of daily life situations in terms of different interdependence dimensions
meaningfully relate to emotional responses (i.e., happiness, sadness, anger, and disgust), and to the selfreported benefits of one’s own behavior for others. Finally, in Study 3 (targeted N = 300), we use an
experience-sampling methodology to replicate these findings in the context of daily life interactions overthe course of one week.

65Supervisors’ psychological contract, informal mentoring andChih-Ting Shihsubordinates’ job performance: a multilevel analysis
Day 1
Informal mentorship presents supervisors with a social dilemma involving both a social conflict (individual
vs. collective interests) and a temporal conflict (short-term vs. long-term interests) as costs to producing
the collectively beneficial goods resulting from mentorship. This study adopted a psychological contract
theory to examine the relationships among three types of psychological contract fulfillment, informal
mentoring, and subordinate job performance. We propose that three types of psychological contract—balanced, relational, and transactional—determine the extent to which supervisors perceive social
dilemmas, which then impacts those supervisors’ willingness to devote themselves to informal
mentorship. Using a sample of 225 sale managers and 594 sale representatives insurance industry acrossTaiwan, our findings, as we predicted, showed that fulfillment of three types of psychological contractaffected the degree of mentoring provided. Balanced psychological contract across the three types has
the largest effect on more mentoring benefit-cost balance, and through informal mentoring provided,
affecting subordinate job performance. These findings suggest that organization may provide long-term
and incentive employment relationship to encourage supervisors involving mentoring subordinate, thenultimately beneficial for both subordinate performance and organizations.
The Impact of Employment Practices on Society: The Significance ofCindy Schipani
Worker VoiceDay 1
This paper argues that employers should adopt practices that provide employees with opportunities toexercise voice. Time and time again, we see corporate scandals that could have been avoided if
employees were encouraged to speak up when they saw problems in the workplace. Recent scandals
include Volkswagen cheating on emissions tests and requirements and the Wells Fargo performance
incentive scandal – scandals that may have been prevented if employees felt safe reporting issues to theirsupervisors and if the supervisors were receptive to the information. Moreover, employee voice
opportunities have been linked to numerous positive psychological, relational and health-related
outcomes, including improved justice perceptions, better attitudes, increased satisfaction at work, andimproved performance ratings. On the other hand, suppression of voice can lead to stress, and loss ofthe senses of control and self-efficacy. Unfortunately, the current legal environment together with various
provisions in employment contracts may negatively impact an employee’s willingness to exercise voice inthe workplace. Our paper discusses the importance and role of employee voice as well as some of thenegative consequences associated with stifling voice. It then discusses the legal environment of
employment-at-will in the United States, which may play a large part in stifling employee voice. Next, thesignificance, benefits and perils of whistleblowing as an aspect of voice are discussed and analyzed, andrecent efforts to restrict whistleblowing are critiqued. We then offer proposals for positive businesspractices to encourage worker voice. The exercise of employee voice is important despite the restrictive
legal environment in which employees work – for the good of the firm, the employees and society.

66How do people think about interdependence? A multidimensional
Daniel Balliet
model of subjective outcome interdependence
Day 1
Interdependence is a fundamental characteristic of social interactions. Interdependence Theory states that
6 dimensions describe differences between social situations. Here we examine if these 6 dimensions
describe how people think about their interdependence with others in a situation. We find that people(insitu and exsitu) can reliably differentiate situations according to 5, but not 6, dimensions ofinterdependence: (1) mutual dependence, (2) power, (3) conflict, (4) future interdependence, and (5)information certainty. This model complements an existing model of situation construal (DIAMONDS) andoffers a unique framework for understanding how people think about social situations. Furthermore, we
examine factors that are theorized to shape perceptions of interdependence, such as situational cues(e.g., partner nonverbal behavior) and personality (e.g., HEXACO and Social Value Orientation).
Furthermore, we study the implications of subjective interdependence for emotion and cooperative
behavior during social interactions. This model of subjective interdependence explains substantial
variation in the emotions people experience in situations (e.g., happiness, sadness, anger, and disgust),
and explains 24% of the variance in cooperation, above and beyond the DIAMONDS model. Throughout
these studies, we develop and validate a multidimensional measure of subjective outcome
interdependence that can be used in diverse situations and relationships – the Situational
Interdependence Scale (SIS). We discuss how this model of interdependence can be used to better
understand how people think about social situations encountered in close relationships, organizations,and society.
Dorota Markiewicz
A cooperator in conflict: The A-Contextual Dual Concern Measure
Day 1
The A-Context Dual-Concern measure (ACDC) was designed to mirror contextual variation of real-world
scenarios involving conflict, accounting for five conflict strategies: avoiding, accommodating, cooperating,competing, and compromising (Pruitt & Rubin, 1986). Participants were engaged in multiple scenariobased resource-allocation decomposed game tasks. To further investigate context effects on behavior, we
introduced two conditions where participants were asked to respond assuming the other party is a ‘friend’or ‘stranger’. Social Value Orientation was included to identify prosocial participants as an individual
difference control. An American sample of 72 participants aged 17 to 73 (M=27.59, SD= 9.57) wascollected. Repeated measures ANOVA indicated main effects for three out of five conflict handling styles
for both stranger and friend conditions: Competing, Accommodating and Compromising. Regression
analysis revealed that among pro-socials, those with a stronger concern for self use a competitive
approach against strangers while those with a higher concern for others use an accommodating
approach towards strangers. These findings question the extent to which individual differences impact
behavior in conflict. Furthermore, they highlight the need for thorough research on contextual influenceswith measurable behavior in the design. Conclusions for further research are discussed.

67GOTS Dilemma with Sequential Protocols and AsymmetricEfrat Aharonov-Majar Endowments
Day 1
We explore behavior in the Give-Some-or-Take-Some (GOTS) dilemma. This paradigm reflects real-lifesituations in which individuals or organizations can contribute to a common pool, make requests fromthat pool or refrain from action (“pass”). This paradigm combines the properties of a Commons Pool
Dilemma (Take-Some) and Public-Goods Dilemma (Give-Some) with uncertain thresholds, but all theuncertainty is social. Previous research with simultaneous decisions revealed that when the initialendowments are unequal, players’ decisions were consistent with an “appropriateness” heuristic: playerswith higher endowments were more likely to contribute to the common pool while players with lower
endowment were more likely to make requests. In the present research, we extend this line of work andexamine behavior in the GOTS dilemma under a sequential protocol. More specifically, we explore how
players’ initial wealth, position in the decision order and the information about the position affect theirdecisions. Participants played in groups of 5 members with different endowments (20,40,60,80,100 points)
that were replenished before every game. In study 1, participants were told that the order of decision is afunction of their endowment – ascending (from the needy to the rich) or descending (from the rich to theneedy) – or random (determined by computer). Before making their decision, participants were given
feedback on the decisions made by the players who preceded them in the sequence. Thus, participants
could be in the same position in the order of decisions, but receive different information. In Study 2, weremoved the feedback on other players’ decisions, so participants were only provided with information on
the order of the decisions, the way it was determined (endowment-based, or random) and on theirposition in the sequence. This allowed us to directly explore how participants’ expectations, shaped by theinteraction between their position and the information about the order, affected their decisions. The
results replicate previous findings on the effect of initial wealth on decisions. However, in the absence of
feedback on previous decisions, the order of decisions did not have significant effect. The findings
improve our understanding of this new type of dilemma and demonstrate the importance on feedback
for cooperative behavior under a sequential protocol.

68

A Cross-Cultural Understanding of the Role of Trust, SVO and
Eric Scalone
Context in Predicting Cooperation in Social Dilemmas
Day 1
Past research suggests Social Value Orientation or SVO (Murphy & Ackermann, 2013) predicts choice insocial dilemmas, as does economic and group context (Arora et al, 2012; Dufwenberg et al, 2006). In
addition, trust in the other may be a contextual moderator: Joireman et al (1997) found that the level oftrust in the other moderates cooperative behavior of pro-socials. Thus, SVO (an individual variable),
context (situational variable), and trust of the other (individual and/or contextual variable) all influence thedecision to cooperate; in part by changing how much decision-makers are concerned with mutual
outcomes of all impacted by the decision. What is less well understood however, is how these variables(SVO, context and trust) collectively influence choices in social dilemmas. Trust, however, shows
systematic variation across cultures (Gunia et al, 2011). Thus its interaction with SVO and context may vary
cross-culturally. In two MTurk studies – one each in the U.S. (high-trust culture) and India (low-trust
culture), we examined (i) how SVO, economic context, and trust in the other together predict anindividual’s concern for mutual outcomes, (ii) whether the concern for mutual outcomes translates into
cooperative action, and (iii) whether these findings vary across high- and low-trust cultures. Our studies
measured SVO (Murphy et al, 2011), cultural tightness as a control for cultural influence of social norms(Gelfand et al, 2011), before randomly assigning participants to one of three economic contexts (loss,
neutral, gain). Participants read the scenario, told us whether they could trust the other, their concern formutual outcomes, and choice in the dilemma. Although SVO was a significant predictor of concern formutual outcomes, independent of culture (p<.05), its effect was moderated by trust in the other in theUS, and trust in the other and tightness of cultural norms in India, suggesting that SVO may not just be anindividual difference variable. Economic context was a significant predictor of concern for mutual
outcomes (p<.05), but only in the US. Thus, trust in the other predicts concern for mutual outcomes,
which in turn predicts cooperation in the US. In India, however, participant reported concern for mutual
outcomes does not determine cooperation as this stated concern may just be cultural norm driven cheap
talk: it is only trust in the other that determines cooperative action in a social dilemma. These findings
have ramifications for local and global social dilemmas and negotiations.
Eva Maria Krockow
Far but Finite Horizons Promote Cooperation in the Centipede game Day 1
Cooperation is a fundamental form of social interaction, and turn-taking reciprocity one of its mostfamiliar manifestations. The Centipede game provides a formal model of such alternating reciprocal
cooperation, but a backward induction (BI) argument appears to prove logically that instrumentally
rational players would never cooperate in this way. In an attempt to increase the game’s applicability toreal-life decision contexts, we investigated the effects of game length and termination rules oncooperation in the Centipede game. We found that increasing the game length from 8 to 20 decisionnodes increased cooperation, but only if the game’s end was known to participants. Games with unknown
ends manifested lower cooperation levels without an endgame effect (increased defection immediately
before a known end). Random game termination by the computer appeared to increase the percentage
of games adhering to the Nash equilibrium outcome mandated by game theory, and generally lowered
cooperation levels. Our results suggest that far but finite horizons, which are common to many real-life
relationships, may improve cooperation in the Centipede-type decision contexts.

69Effects of Collective Identity on Individuals’ Decisions to Delay
Sherry K. Schneider
Treatment to Prevent Antibiotic ResistanceDay 1
Current overuse of antibiotics contributes to antibiotic resistance of future generations. Such self-interest
at odds with the collective good creates a social dilemma. Since antibiotic consumption is the main driverof the development of antibiotic resistance, behavior change is urgently needed (Hollis & Maybarduk,2015). Research has found priming collective identity increases cooperation in social dilemmas (e.g. Van
Lange, Joireman, Parks, & Van Dijk, 2013). We will present the results of a study conducted to compare
the effects of interdependent and intergenerational primes of identity to a neutral prime on thewillingness to delay antibiotic treatment. The study uses a between-subjects experimental design withhypothetical vignettes (Ronnerstrand & Andersson Sundell, 2015). To prime identity, the participants readparagraphs discussing global warming (an environmental social dilemma) from different points of view. A
third prime served as a control. Next, participants read a scenario in which a doctor prescribed
antibiotics, but recommended postponing antibiotic treatment to see if the disease will resolve itself.
Participants then decided if and how long to delay treatment. Finally, they completed a questionnaire that
included demographic questions and a measure of consideration of future consequences (CFC). We
hypothesize participants primed with either collective identity will agree to delay antibiotic treatment
longer compared to those receiving a neutral prime, with the intergenerational prime having greatest
impact. Age, parenthood, perceptions of health, and CFO are predicted to positively correlate with thedecision to delay treatment, and may moderate the effects of the primes.
Tadeusz Płatkowski
On Axiomatization and a Classification of Social Dilemmas
Day 1
We consider multiperson social dilemmas played in large populations. The members of the population
form coalitions, which generate a social welfare, identified with the value of the coalition, and equal to thesum of the payoffs of its all members from a social dilemma game. The total welfare is distributed among
the coalition members. The evolution of the populations is governed by the replicator equations. We
show that the egalitarian distribution of the welfare fosters the long run cooperation in such populations.

70

The Social Expectation to Be Ethical: A Role Definition Perspective of
Ted Paterson
Ethical Leadership and Unethical Behavior
Day 1
Many ethical dilemmas are social in nature, with the self-interest of the actor in contrast to the broader
interests of a collective. In fact, mounting evidence demonstrates that unethical behavior exacts
numerous costs to the organizations that participate in it. For example, Cialdini, Petrova, and Goldstein(2004) propose that the costs of unethical behavior in organizations include increased absenteeism, lower
job satisfaction, and higher turnover due to the mismatch between employees’ and organizational values
and increased health problems, diminished trust, and undermining of positive behavior as a result of theincreased surveillance which often results from unethical behavior. Accordingly, any efforts thatorganizations can make to avoid ethical lapses are warranted from both philosophical and pragmatic
perspectives. One such effort is ethical leadership, defined as “the demonstration of normatively
appropriate conduct through personal actions and interpersonal relationships, and the promotion of suchconduct to followers through two-way communication, reinforcement, and decision-making” (Brown,
Treviño & Harrison, 2005, p. 120). A growing literature suggests that organizations that promote ethicalleadership are more likely to avoid unethical behavior (Mayer, Aquino, Greenbaum, & Kuenzi, 2012;
Schaubroeck et al., 2012). Whereas some research has suggested a direct link between ethical leadershipand unethical behavior (e.g., Mayer et al, 2012), others have introduced mediating mechanisms such as
ethical culture (Schaubroeck et al., 2012) and ethical climate (Mayer, Kuenzi, & Greenbaum, 2010) that
help explain how this effect occurs. While these studies have advanced our understanding of the social
mechanisms at work in the ethical leadership -unethical behavior relationship, they have largely ignored
the fact that a primary purpose of leaders is to define roles for organizational members and that saidroles dictate behavior for their inhabitants (Graen, 1976; Klieman, Quinn, & Harris, 2000). To further
explicate the relationship between ethical leadership and unethical employee behavior, we adopted arole-based perspective and introduced the concept of perceived ethical role breadth. That is, we exploredthe impact that leaders’ actions and voice behaviors have on in-role versus extra-role perceptions of
employees as they relate to ethical behavior and the impact, in turn, on unethical behavior. In a fieldstudy involving 394 employees and 68 supervisors and a randomized experiment conducted with 121
working professionals we find that, as predicted, leaders’ behaviors and voice have a significant influenceon perceived ethical role breadth and that these role breadth perceptions impact unethical behavior.

71

Punishment in the Second-party Punishment Game, Players'
Yoshie Matsumoto
Testosterone Levels, and Their Body Sizes
Day 1
The role that the punishment of norm violators plays has been one of the central issues in recent
theoretical and empirical research on the evolution of human cooperation. The punishment of norm
violators is a form of second-order cooperation, which provides incentives for otherwise norm-violating
individuals to change their behavior to abide by the norm. At the same time, punishment is a form of
aggression by definition of which the goal is to inflict harm on the target; it may sometimes lead thepunished to an enhanced level of cooperation, but this may be a rather unintended consequence of theaggressive response to a challenge to the respondent’s relative standing. To examine if the punishmentof norm violators is a form of aggression, we examined the body size and testosterone levels of 96 maleplayers (under 40 years old) of a second-party punishment game (SPPG). A high level of testosterone is
known to be related to aggression, particularly aggressive responses when challenged, in both nonhuman animals and humans. Furthermore, the positive relationship between body size and aggressive
behavior is well documented in non-human and human animals. In the SPPG, participants first played aone-shot prisoner’s dilemma game (PDG) knowing that there would be a later chance to inflict a cost toeach other. We first found a positive relationship between punishment and body size (weight and bodymass index). At the same time, we found that the same body size index, BMI, was not related toparticipants’ cooperation levels in the PDG. The testosterone levels of the players in this game did notcorrelate with punishment of norm violators. However, a positive effect of testosterone levels was foundon punishment of cooperators; both testosterone levels and body size significantly predicted punishmentof cooperators. These findings were obtained only among those whose concern for relative standing ininterpersonal relations was high. Body size or testosterone levels did not predict either types ofpunishment among those whose concern for relative standing was low. Our finding that body size
increased punishment behavior, particularly among participants who were highly concerned with theirrelative standings, adds further evidence for the interpretation of punishment in the SPPG as anaggressive response to a challenge to their relative standing. Facing such a challenge, larger-bodied men
who have possibly experienced more success when they have acted in aggressive ways are likely torespond by acting aggressively.

72

Psynteract: A Flexible, Cross-Platform, Open Framework for Research
Felix Henninger
in Strategic Interaction
Day 2
We introduce a novel platform for strategic interaction research in the laboratory, or more generally any
form of study in which participants' experiences depend not only on their own responses, but also on
those of other participants who complete the same study in parallel. The software thus particularly serves
the rapidly growing field of strategic interaction research within psychology and behavioral economics byenabling real-time, consequential versions of paradigms such as the prisoner’s dilemma or the ultimatum
game. Our platform extends existing experimental software to incorporate interactive functionality,
combining currently available modes of stimulus display and response collection with a network-based
communication protocol. This approach allows us to draw upon the capabilities already available, such as
accuracy of temporal measurement, integration with auxiliary hardware such as eye-trackers or (neuro-)physiological apparatus, and recent advances in experimental software, for example capturing response
dynamics through mouse-tracking. Through integration with OpenSesame, an open-source graphicalexperiment builder, studies can be assembled via a drag-and-drop interface, requiring little or no further
programming skills. In addition, by using the same communication mechanism across software packages,
we also enable interoperability between systems. Our source code, which provides support for all major
operating systems and several popular experimental packages, can be freely used and is distributed
under an open source license. The communication protocols underlying its functionality are also well
documented and can be easily adapted to further platforms. Code and documentation, as well as several
examples, are available at https://github.com/psynteract/ .

73

Francisco Javier
Integrating Teams with Skill Distribution Differentials: Adversely
Santos Arteaga
Selecting the Merging Partners
Day 2
We present a formal model illustrating how differences in the distribution of skills across different teams
of workers that must be coordinated to undertake a given project may either trigger or eliminate themerging incentives of the more skilled/developed team. Two types of equal-sized teams will beconsidered, a developed host one, and a developing external one. The development level of a team isdetermined by the relative distribution of skills across its workers. Thus, the proportion of unskilled toskilled workers will be higher in the developing teams when compared to the developed host one.
External teams choose to either cooperate with the host one, by sending an agreed upon proportion ofskilled and unskilled workers, or defect, by increasing the proportion of unskilled workers sent toundertake the project. In this regard, the equilibrium strategies of the host developed team consist ofeither rejecting the workers from a less developed external team or merging with them to undertake aproject. An immediate implication from our strategic framework is that external teams provide a lower
payoff from merging to the host developed one as their relative proportions of unskilled workers sent tocoordinate the development of the project increase: • Cooperation by the external team increases the
incentives of the host team to merge. • However, external teams which are farther away from thedevelopment level of the host will face a higher probability of ending up in a reject equilibrium even if
their incentives to cooperate are the same as or higher than those of a more developed external team.
Assume that two external teams announce the same percentages of skilled and unskilled workers being
sent to integrate with the host team. Then, the less developed external team, would provide a lower
payoff to the host developed team in any merging equilibrium. As a result, less developed teams will haveto cooperate with higher probability in the mixed strategy equilibria of the resulting games. Moreover, we
will illustrate how external teams composed by a relatively larger proportion of skilled workers will be
more prone to end up in a merging equilibrium with the host team than those composed by a lower
amount of skilled workers but more in need of merging. Indeed, the latter teams may face a reject
equilibrium when cooperating, while, at the same time, the former more developed ones end up in amerge equilibrium when defecting.
The core concepts of simulation models of ingroup bias: A criticalFredrik Jansson
review
Day 2
In this experimental study, we investigate the role of two distinct social features in resolving conflict
between two individuals repeatedly interacting in a chicken game: (1) individual differences through otherregarding preferences, and (2) recommendations as public signals. Our findings indicate that, althoughbiased recommendations (favoring one player over the other) can significantly improve efficiency, themost effective mechanism consists in constantly alternating signals pointing to the two pure equilibria. In
addition, while this type of recommendation significantly reduces inequality, it also removes any effect ofsocial preferences that is common otherwise (e.g., nice people no longer get exploited by individualistic
people). Finally, our study suggests that the recommendation mechanism has to be selected with care as
it may otherwise induce significant negative reciprocity between players beyond the context of thecurrent game.

74

The institutional roots of interpersonal trust: multi-national evidence
Giuliana Spadaro
across European countries
Day 2
Promoting interpersonal trust at the collective level is key to lay the foundation for the development ofcooperation and the enhancement of economic and social growth. The issue of how to generate trust ininterpersonal exchanges amongst strangers, the so-called generalized trust, constitutes a primary goal
given its several implications to solve social dilemmas. Indeed, amongst strangers it becomes unlikely toestablish trusting relationships based on reputational cues such as interaction history and partners’ trust
signals. The current work presents data from the European Social Survey (ESS), a major comparative andrepresentative survey of (mostly) European countries. We propose meta-analytic evidence across thewaves of ESS collected data between 2004 and 2014, with the primary focus of expanding current
research on the relationship between trust in national political institutions and interpersonal trust. Then,
we tested this relationship considering its indirect effects, exploring the possible influence of politicalinstitutions’ ability to fuel individuals’ perceived protection and to reduce the perceived exposure toinsecurity. Through the meta-analysis of direct effects, our findings confirm that the extent of institutional
trust predicts the degree of interpersonal trust across all countries. Moreover, we found a significant
indirect effect of self-protection in the relation between institutions and interpersonal trust. The results ofthis investigation are in line with other collected experimental findings that manipulated the effect oftrustworthy institutions on interpersonal trust in the context of experimental games. Our analysis calls into
question the possible psychological mechanisms involved in the relationship between institutional andinterpersonal trust, suggesting that an approach that is capable of considering how institutions can
reduce individuals’ exposure to insecurity is required.
Greg Leo
Complainer's Dilemma
Day 2Should administrators require complainers to fill out lengthy forms or make it easy to complain but
require many complaints before addressing a problem? In order to analyze the outcomes of thesepolicies, it is important to take into account the strategic environment they impose. I model the strategic
incentives facing complainers in a game called the m-volunteer's dilemma. Any who complain pay cost c;
if at least m complain, all receive benefit b. The equilibria of this game have interesting implications forcomplaint policy. Even when the administrator cannot directly observe the value of fixing problems,complaints that are not worth addressing can be avoided (in equilibrium) by carefully choosing therequired number of complaints and the cost of complaining. Further, policies that require many
complaints at a small cost dominate (in terms of efficiency) policies that require few complaints at a highcost. In addition to complaint policy, I discuss other applications and properties of the m-volunteer's
dilemma and compare it to the familiar volunteer's dilemma from Diekmann (1985), which is the special
case of m=1.

75

Underestimating of reward and overestimating of punishment in
Hitoshi Yamamoto
public good game
Day 2
Theoretical approaches have clarified that sanction systems (i.e. punishment or reward) could not
maintain the cooperation in order to invasion of the high-order free riders. However, in experimental
studies, it is widely reported that cooperation is sustainable by the first-order sanction. Although it ispointed out that the divergence between this theory and reality is caused by excess estimates for
sanction, it is not clarified whether there is a similar effect on punishment and reward. From loss aversion
in the prospect theory, it is expected that human evaluates more losses due to punishment than profit
due to reward. Here we conduct a subjective experiment with one-shot public good game. The results ofthe experiment revealed that the cooperation rate was increased by introduction of sanction system, andmoreover, punishment increased the cooperation rate more than reward. Further, when the amount of
which others exercise sanction was estimated to explore the cause of differences in the cooperation rateoccurred, it was elucidated that sanction exercise amount of others was overestimated in the punishment
condition. It is considered that this result occurs because inclination of human loss aversion overestimates
loss due to punishment.
Engaging in Business Impairs Trustworthiness Judgment on Novel
Hongchuan Zhang
Faces
Day 2
Trust is the foundation of business. Previous studies repeatedly showed that the level of interpersonal
trust is decreasing rapidly across different countries and cultures. Many researchers linked this trend withthe business culture immerged by people living in the modern society. Here we designed four studies to
examine whether engaging in business, either by learning an economics-related major or by working in abusiness field would impair one's judgment about the trustworthiness on a novel face. In study 1, we
directly compared undergraduate students who major in economics (accounting, finance, etc.) with thosefrom in other majors (mathematics, literature, etc.). The two groups were not different from each other in
judging the faces with low trustworthiness values (untrustworthy faces), but the former made significantly
lower judgments on faces with high trustworthiness values (trustworthy faces). In study 2, we comparedbank employees with people working in other fields (social workers and administrative staff). The same
pattern again merges that bank employees significantly underestimated the trustworthiness values ofnovel faces that are trustworthy per se. To make a causal conclusion, in study 3 we asked undergraduate
students from non-economic majors to imagine they are engaging in business (as a bank employee) or inother career (as an administrative staff) and write about their experience before making similar judgments
as above. The manipulation led to results that were similar to study 1 and 2: After the priming of
engaging in business imagination, participants turned to underestimate the trustworthy faces' values. In
study 4, we reversed the manipulation by asking undergraduate students from economics-related majors
to imagine that they are not engaging in business (as an administrative staff). After this manipulation,compared to those still imagine that they are engaging in business, participants' trustworthinessjudgments on novel faces were "restored" to a significantly higher level. We discussed the above resultsfrom an angle of "embodied culture" to show that business culture plays a role of mindset in our daily
encountering with people and its function depends how salient a cue we get from the identity ofourselves.

76

Jaap Schaveling
Voice & Silence: Hire the ‘right’ people
Day 2
Research questions
1. Does Psychological Capital (confidence, hope, optimism, courage) influence silence and voice?
2. Is this influence mediated by Fear?
3. Is this influence moderated by respectively Supervisor attitude in respect to voice, friendly supervisor,
voice opportunities, Perceived Organizational Support (POS), organizational courage.
Method - cross sectional with validated questionnaires. The analyses have been performed using SPSS v.
22, PROCESS v2.16 and AMOS v. 22.
Sample• The sample was composed by 175 participants. Five participants were removed from the dataset after
exploring for unengaged responses and outliers.
• Of this sample of 170 participants 77% was male, 81 % Dutch, 87% have a high educational level, meanof age is 47 years, and 32% is from the technology branch, 36% Manufacturing and 8% from theprofessional services branch.
Results
1. PsyCap was good second order construct (Hair et al, 2010) for confidence, hope, optimism and courage(Χ2=(126) = 186.800, Ratio = 1.48; NFI=.85; IFI=.95; TLI=.94; CFI=.95; RMR=.07; SRMR=.06; RMSEA=.053).
2. The total effect of PsyCap on Silence was significant and negative. This effect was totally mediated by
Fear; higher PsyCap was related to less fear which in turn was related to less Silence.
3. The total effect of PsyCap on Voice was significant and positive. This effect was not mediated by Fear.
4. None of the expected moderators is functioning as moderator nor for silence neither for voice. Thismeans that silence and voice are influenced by an individual determinant (PsyCap). Fear is functioning asa full mediator for silence.
Recommendation
Seen from a management point of view: you cannot stimulate voice by managerial or organizational
characteristics. So you have to hire the ‘right’ people. It looks like silence and voice are in the hands of HR
people (Psychologists!) and not managers.
Social Value Orientation, Expectations and Cooperation in Social
Jan Pletzer
Dilemmas: A Meta-Analysis
Day 2Interdependent situations are pervasive in human life. In these situations, it is essential to form
expectations about the other’s behavior to adapt one’s own behavior to increase mutual outcomes andavoid exploitation. Social value orientation, which describes the weights individuals attach to their own
and to the other’s outcome in such interdependent situations, predicts these expectations of cooperation
in social dilemmas. Yet, scientific evidence is inconclusive about the exact differences in expectations
between prosocials, individualists, and competitors. The meta-analytic results here show that prosocials
expect most cooperation from others in social dilemmas, whereas individualists and competitors do notsignificantly differ in their expectations. The importance of these expectations in the decision process isfurther highlighted by our finding that they partially mediate the well-established relationship betweensocial value orientation and cooperative behavior in social dilemmas.

77

Jefferson Marlon
Monticelli
An institutional perspective on coopetition
Day 2
Coopetition is recognized as a multifaceted, multilevel and paradoxical phenomenon that shares adivergent use of definitions lack of generalizability, and a limited contextual focus. Few studies haveaddressed coopetition from the perspective of the institutional environment since most studies focus ondeveloped countries that enjoy stronger institutions. Moreover, rarely international business has beenviewed through coopetitive relations. Therefore, the purpose of my research is to study firms in aparticular industry that manifest coopetition strategies in their home country in the internationalization
process. I also aim to improve the understanding of how formal institutions influence international
performance through coopetitive strategies. More robust institutions have a greater influence to promote
coopetition strategies. Thus, strategies are being conducted in more complex levels, involvingorganizational strategies and institutional influences. Thus, two contributions are expected to be seen: a)
as a research about coopetition associated with the performance in the internationalization of firms, there
will be an examination whether coopetition matters for internationalization and how it matters; and b) a
stress on the institution-based view in the discussion about coopetition in an industry from an emerging
country. As the research question is: how does coopetition influence the performance in theinternationalization of firms from emerging markets taking into account the role of institutions in thisenvironment? I will focus on coopetition between competitors that cooperate simultaneously in the same
industry. Institutions are considered formal structures responsible for guiding or restricting the choices of
agents, affecting positively, negatively, or even indifferently, their strategic decisions with the aim toincrease the competitiveness of local businesses by developing learning and relationship networks,
reducing transaction costs, and promoting the internationalization of firms. In industries with highcompetition and cooperation, institutions stimulate coopetition between rival firms, so that they create
barriers to new entrants. Cases of multiple industries will be used: information technology, footwear, andwines because of the accessibility criterion and for having different internationalization levels and learning
curves. The starting point will be analyzing each industry entity. A multifaceted survey will be applied tointernationalized firms in a multi-industry. In order to analyze the results, the quantitative stage ofinvestigation aims to adopt multiple regression analysis tests and/or Structural Equation Modeling (SEM),
depending on the constructs defined in the final version of the measurement instrument. My purpose
relates formal institutions and international performance, considering coopetition as a mediator.
Jessica Federman
Leadership and Financial Incentives
Day 2
I report evidence that thoughts of money increased the acceptability of using passive leader behaviors
versus active leader behaviors toward personnel exhibiting work performance problems. However, thechoice of passive leadership versus active leadership was more deliberative for those primed withthoughts of money.

78

Correlates of social sanctioning in laboratory games and real world
Jessica Nolansocial dilemmas
Day 2
Two studies were conducted to explore the psychological correlates of individuals’ willingness to imposesocial sanctions in laboratory and real world social dilemmas. In Study 1 participants (N = 68) were led tobelieve that they were playing an N-person public goods dilemma with three other players. Following
round 3 they received false feedback indicating that Player J had defected. They were then asked toanswer several questions about their perception of Player J’s behavior and to decide if they wanted tocommunicate with Player J. The majority of participants (72.1%) chose to send an emoticon to Player J,
but only 23.5% of participants chose to send a message. Consistent with Schwartz’s (1968) moral norm
activation theory and Latane and Darley’s (1970) bystander intervention model, results showed that thosewho “helped” or “intervened” by sending a message to the defector reported greater feelings of personal
responsibility to communicate to them that their behavior was unacceptable, and perceived that theywould “personally suffer the consequences” of Player J’s defection. Those who chose to sanction thedefecting player were also more likely to perceive that there were both positive and negative
consequences associated with imposing these social sanctions. In Study 2 (N = 53) participants
completed a survey that asked them how willing they would be to sanction someone committing 24
different environmental transgressions (e.g., dumping used motor oil down a storm drain), and then to
answer questions about their perceptions of the transgressor’s behavior. Data was aggregated across the
24 transgressions for each variable. Consistent with the results of Study 1, the results of Study 2 showedthat there was a correlation between participants’ willingness to sanction environmental transgressors
and: the extent to which they felt that it was their responsibility to communicate to the transgressor that
their behavior was not acceptable (r = .75, p < .001), and the extent to which they perceived that theywould personally suffer the consequences of the transgressors’ actions (r = .30, p < .001). Willingness tosanction was also significantly positively correlated with the perception that communicating with thetransgressors would have both positive and negative consequences. Suggestions are made for exploringthese variables further in future research on social sanctioning in social dilemmas.
Mututally advantageous play: going beyond best-response
Jurgis Karpus
reasoning in games
Day 2
The game theoretic notion of best-response reasoning is sometimes criticised when its application
produces multiple solutions of games, some of which seem less compelling than others. The recent
development of the theory of team reasoning addresses this by suggesting that interacting players ingames may sometimes reason as members of a team - a group of individuals who act together in theattainment of some common goal. A number of properties have been suggested for team-reasoning
decision-makers' goals to satisfy, but a few formal representations have been discussed. In this paper wesuggest a possible representation of these goals based on the notion of mutual advantage. We propose
a method for measuring extents of individual and mutual advantage to the interacting decision-makers,
and define team interests as the attainment of outcomes associated with maximal mutual advantage in
the games they play. Following the presentation of our notion of maximal mutual advantage in games I
will propose a reasons-based explanation of playing strictly dominated strategies in games.

79From interactive to coordinated decision-making: A theory ofLuca Tummolini
collaborative interaction in conditional games
Day 2
From prehistoric collective hunting to contemporary international research networks, a collaborative
group is one in which individuals are prepared to make a concerted effort to achieve an outcome. How
should we understand such willingness to make a concerted effort or, in other words, to purposefully
engage in coordinated action? Drawing on philosophical and empirical research, we argue thatcollaborative interaction relies on agents who are responsive to the intentions of others and who alsocare about group behavior as a whole. While game-theoretic models of reciprocity focus on the former
type of agents (“reciprocal” players), models of team-reasoning emphasize the latter one (“team” players).
Neither approach by itself provides an adequate theory of the “collaborative” type. Using the frameworkof conditional game theory (Stirling 2012, 2016), we will present a dynamic model of joint decision-making
between collaborative types that integrates essential features of reciprocity and of team reasoning
approaches. In particular, conditional preference orderings are used to model responsiveness to theintentions of others, influence cycles capture reciprocity, and new solution concepts based on
coordination utility describe the choices that collaborative types make when they take systematic group
behavior into account. An emergent notion of preference for coordinated action at the group-level
naturally follows. The theory is applied to the Snowdrift game (also known as Chicken in Economics or
Hawk-Dove in Biology). By comparing the classical analysis to that afforded by conditional game theory,
we identify the conditions in which agents jointly decide to act in coordination with others, ie when they
engage in coordinated decision-making. Finally, we discuss how conditional game theory also provides
the conceptual tools to compute a measure of the “social cohesion” of a group, an important construct insocial psychology and sociology that has, so far, eluded rigorous treatment.

80

Maik Theelen
External attacks and cooperation in social dilemmas
Day 2
Although violent inter-group conflict has declined throughout the ages, it still plays a pivotal role inhuman life. Conflict may result in detrimental outcomes for the participating individuals as well as for thecollective. At the same time, it can also foster intra-group cooperation through the increased necessity tounite in times of conflict. Field research and experimental research indeed suggests that conflict can leadto enhanced cooperation within the conflicting groups, also known as inter-group conflict–intra-groupcooperation effect. However, the underlying structural and psychological processes are not clear yet. In
this paper, we devise a novel and flexible experimental paradigm to examine the effect of an enemy
attack (i.e., harm to the decision-maker and/or her interaction partner by a third party) on cooperation
between interaction partners. We use a modified version of the prisoner’s dilemma game (PDG) in which
we add a third player who will take points away from the interacting players when they fail to mutually
cooperate. We use this game in two incentivized online experiments. In Experiment 1, we show that an
enemy attack can indeed increase cooperation compared to the standard PDG, even though there is no
economic incentive to do so (i.e., defection remains the dominant individual strategy). This effect,
however, only exists when a group identity is present (i.e., political identity), suggesting that an enemy
attack increases intra-group but not inter-personal cooperation. One aspect of conflict that has received
relatively little attention is the intentionality behind an attack. Related research, however, shows thatpeople react more forgiving towards people who inflict harm intentionally compared to unintentionally. In
Experiment 2, we experimentally manipulate the intention of the attacking player to see whether thisinfluences the inter-group conflict–intra-group effect we found in Experiment 1. In doing so, we replicate
the inter-group conflict–intra-group cooperation effect and further show that the intention behind an
attack (i.e., whether the enemy is forced to attack or attacks intentionally) does not seem to influence theeffect of an enemy attack on cooperation. Finally, we show that in both experiments the inter-groupconflict–intra-group cooperation effect is mediated by the closeness participants experience towards theirinteraction partner.

81

Overcoming the social dilemma in knowledge work: Team member
Meike Wiemannstrategies to deal with colleagues' free riding
Day 2
Organizations increasingly rely on teams as their fundamental organizing unit (e.g. McGrath and Argote,2008). These teams are especially employed for knowledge-intensive and creative work and composed ofdiversely-skilled experts (North and Güldenberg, 2008). Thus, they can respond to the growing pressure
to quickly come up with new ideas and solutions implied by international competition and technologicalprogress (Kozlowski and Bell, 2003). This development brings about new challenges for organizations.
One of the most striking issues is that knowledge-intensive teams are likely to develop collaboration
problems referred to as a social dilemma, i.e., a situation in which the actions of self-interested teammembers lead to collective irrationality that makes everyone worse off (Dawes, 1980). In knowledge
teams, the risk of free riding is particularly high and not easy to manage. Knowledge-intensive teamwork
is characterized by complex collaborative activities that are to locate, create, apply, and share knowledge
among a group of co-workers (Jackson et al., 2006; Chuang et al., 2013). This complexity makes the mostcommonly used instrument to curb free riding in teams – formal managerial control – difficult to apply(e.g. Kirsch et al., 2010; Henderson and Lee, 1992; Kirsch, 1996). Especially, the contributions of experts,
who typically form those teams, to the overall team outcome are hard or even impossible for supervisors
to define, monitor, measure or enforce (Frost et al., 2010). This is why in knowledge-intensive teamworkcontexts, the monitoring and enforcement responsibility to control free riding strongly relies on the teammembers themselves. They have closer and more frequent contact to other group members andtherefore possess more accurate information concerning team member performance than supervisors(Barclay and Harland, 1995). In this paper, we empirically develop a typology of team members’ informal
control behaviors to manage free riding of colleagues. First, a free-listing study is conducted, which
identifies salient peer behaviors that are exerted in response to other team members’ free riding in acontext that is typical for knowledge work. In a second study, we apply card sorting and multidimensional
scaling methods to categorize these behaviors. Our findings suggest that informal team-based control offree riding differs along two dimensions: full pressure versus no pressure, and team-orientation versus
self-orientation. Based on these two dimensions, our analyses reveal four distinct control approaches:‘bring it into the light’, ‘solve it around the table’, ‘fight it behind the back’, and ‘adjust it yourself’.

82Giving fish to the innocent, and rods to the guilty: the effect ofTehila Kogut
targets' perceived responsibility on helping decisions
Day 2
Research in the past decades highlighted the role of empathy in people's decisions to help others (e.g.
Batson 1991). While some victims tend to raise spontaneous empathic emotions in the perceiver, leading
to an immediate willingness to help, other targets may be less recruiting and may even raise negative
emotions, turning people away from helping. Specifically, targets that are perceived responsible for theirplight tend to raise anger and the potential donor may turn away from helping them, using the target's
responsibility for the situation to justify their decision (Brickman et al. 1982; Kogut, 2011). We suggest thatthe responsibility of the target interacts with the method of helping, such that people may be willing tohelp a "responsible" target if the method of help is indirect, and provides a long-term solution. We
conducted three studies to examine our hypothesis, according to which when the needy person isperceived innocent people are willing to help by providing an immediate relief (e.g. money), as well as byhelping to found a more comprehensive, long-term solution. However, when the needy person isperceived responsible, willingness to help is dependent on the method of helping and people are
reluctant to fund an easy, immediate, direct help. Yet, they are willing to help in an indirect manner, by
supporting the ability of the needy to solve their own hardship. In Study 1 and Study 2 we employed a
2X2 between subject design, manipulating the target's responsibility (innocent vs. responsible) and themethod of help (direct-immediate vs. a long term solution), using two different helping contexts. In study
3 we used a within subject design, asking the same participants for their willingness to provide directimmediate help and a long term solution to help a needy person, while manipulating the target's
perceived responsibility. In all three studies we found the same pattern of results suggesting that people
are more likely to help an innocent needy, especially when the method of help is direct and immediate.
However, when the method of help includes a more indirect, long term solution, levels of help are similar
when the target is perceived responsible or innocent. We examine different mechanisms behind thiseffect.

83

Institutions, Principles of Ethics, and Neuro-Psychological Adaptation
Toshio Yamagishi
Systems
Day 2
This paper is not a standard presentation paper focused on a single or few empirical studies. Rather, it is asynopsis of a book I am hoping to write in a few years. It is about the roles of three types of institutions
that have been the source of selection for three relatively distinct neuro-psychological systems controlling
contemporary humans’ behavior in social dilemmas. Pecking-order institution. Homo-sapience share with
their gregorian mammalian species the institution of pecking-order in which social order is maintained byestablishing a system of dominance. The drive for social dominance, or competitive SVO, and winningcoalition formation, constitute the core the adaptive system. Collectivistic institution. The need forextended care of babies born with immature brain made homo-sapience establish cooperative breeding
in a small group of extended families, that is, the collectivistic institution. The collectivistic institution wasmade possible by controlling the drive of its members’ drive for social dominance and their attempts forfree-riding. Social dilemma researchers have traditionally focused on the control of free-riders, but thecontrol of social dominance has played more important role in establishing collectivistic institutions
throughout most of the evolutionary history of our species. What cultural psychologists call collectivistic
or interdependent self-construal (the belief that individuals are meaningless and cannot function without
being embedded in a collectivity) represents neuro-psychological adaptation to this type of institution
and its accompanying parochial moral system promoting within-group mutual help and cooperation, of
which activation is carried out mostly by emotional neuro-psychological systems. Individualistic institution.
Long-distance trading and the universalistic rule of law made individuals’ pursuit of opportunities andself-interest (social dominance) under the legal, not collectivist, protection; protection which comes with
control by the group is less critical under the rule of law. The individualistic (legal) institution isaccompanies by universalistic moral system controlled heavily by cognitive neuro-psychological systems,
and promotes what cultural psychologists call independent or individualistic self-construal according towhich individuals give priority to detect immediate and long-term incentives for behavior. / Implications
for the social dilemma research. Human neuro-psychological systems are adaptive under a particularinstitution (gene-institution co-evolution), but the moral systems do not see this institutional-fitness of
their systems, resulting in mutual disdain of the emotionally-based and cognitively-based moral
principles. Participants in economic games differ in their identification of the game situation as a particularinstitution, and react accordingly.

84

The Effect of Second-order Rewards and Punishment in Public Goods
Eizo Akiyama
Game --- An Experiment
Day 3
Provision and maintenance of public goods in social groups has played an important role in thedevelopment of human society. In the provision of public goods, however, there usually exists temptation
to free-ride on the others’ contribution (temptation to betrayal/defection) without contributing(cooperating) to public goods. This kind of problem is called social dilemma, and has been an important
issue in human society. In order to formulate and address the problems in social dilemma, researchers invarious field have often used "public goods game" and have tried to find out effective ways to prevent
freeriding behaviors and to promote cooperation. In experimental studies on social dilemma,"punishment" for defection and "reward" for cooperation are drawing attention as systems to enhancecooperation in public goods games. For example, Fehr and Gachter (2002) investigated the effect ofvoluntary punishments on the formation of a cooperative society in public goods games. Sefton et al.
(2007) found that coexistence of reward and punishment systems can facilitate contribution by subjects.
On the other hand, it has been pointed out since Axelrod (1986) that the existence of cost for punishment
and for reward might bring about another level of free-riding problem; that is, there can be a temptation
to free ride on others’ voluntary punishment for defectors (others’ voluntary reward for cooperators). This
problem is called "second-order free-rider problem". In our study, based on and extending theframework of Fehr and Gachter (2002) and of Sefton et al. (2007), we investigated the effects of secondorder punishment (reward), where those who did not punish free-riders might be punished by others(those who gave reward to contributors might be given reward by others). Note that execution of
second-order punishment (reward) requires some cost, which might cause another level of free-rider
problem. / Our main results are the followings. Firstly, the possibility of second-order punishment has
significant effect to increase participants’ contribution to the public goods, while that of second-orderreward does not. Secondly, participants do not actually execute second-order punishment (reward) as
frequently as first-order punishment (reward).
Brief Update on Target Class and Prosocial Behavior: Replications
Niels J. Van Doesum and Mechanisms
Day 3
Literature on the psychological effects of social class keeps accumulating, especially regarding prosocial
behavior. It has been found – and challenged – that self social class can impact prosociality. But how
about those who may benefit; the targets in a social interaction? At the previous meeting in Hong Kong
we presented three US-based studies that showed how higher social class targets elicited lower
prosociality when operationalized using the SoMi (social mindfulness) paradigm (reported, with anadditional study, in Van Doesum, Tybur, & Van Lange, 2017). In the current presentation we confer datafrom two replication studies in the Netherlands (laboratory) and the UK (online). The basic pattern of theprevious research was replicated in both studies: Higher class targets elicited lower prosociality. In thesecond study (UK) we additionally found support for the fairness perspective as suggested by the earlier
studies, by uncovering mediation through feelings of deservedness and compassion. Specifically, lower
class targets were perceived as being more deserving of good things in life and elicited greatercompassion relative to higher class targets. However, perceptions of warmth, competence and prosocial
personality traits of honesty-humility and agreeableness (HEXACO) did not mediate the relationshipbetween target social class and prosociality. Similar to the previous studies, self social class did not
influence prosociality. These two replications confirm that social class is relevant for prosocial behavior
indeed, but more in terms of target social class than self social class.
85

Nikka Angela
Psychological Vulnerability of Bullied Young Adults in Their Prose
Bayaborda
and Poetry Compositions: An IPA
Day 3
Bullying is considered as one of the most widespread global phenomena. Previous studies examined links
between bullying victimization and negative outcomes on the victims’ mental health that arise in
adulthood. Scriptotherapy or writing therapy was found to alleviate or reduce tensions in patients withpsychological disorders and provide more insights to the therapist or counselor regarding the problems
the patients might have. This research examines, through their prose and poetry compositions, thevulnerability of young adults who were adolescent victims of bullying to acquiring psychological disorders.
The findings of the research revealed a unanimous pattern in the maladaptive psychological state ofbullied young adults, with particular concern in the manifestation of symptoms for internalizing disorders.
Dysfunctional behaviors and thought patterns were apparent across bullied young adults like depression,
self-harming, social withdrawal, poor self-esteem, feelings of guilt and anxiety, and fearfulness. The longterm effects of being bullied were found to significantly decrease mental health in adulthood, thus
making victims of bullying psychologically vulnerable to acquiring mental health disorders. The utilizationof scriptotherapy was found to be a contributor to their optimistic desire to unlearn the negative coping
behaviors resulting from their bullying trauma and act towards self-improvement through reaching out toothers and seeking professional help
Niklas Harring
The Large Scale Social Dilemma of Antibiotic ResistanceDay 3
Antibiotic resistance is a multilayer large-scale collective action dilemma. Individual patients may request
antibiotic therapy, but an overall reduction in antibiotic use is necessary to limit resistance. Likewise,
physicians may sometimes be tempted to circumvent guidelines regarding prescriptions of antibiotics, inorder to sustain trustful doctor-patient relationships. Thus, to limit unnecessary use of antibiotics, there isan urgent need for steering of antibiotic use, legitimate both in the eyes of patients and physicians.
Making use of a hypothetical scenario experimental approach, this paper explores antecedents of support
for steering among both patients and physicians. Since variation in antibiotic prescription patterns can be
attributed both to patients’ request of antibiotics and physicians’ willingness to prescribe, this study
investigate the influence of scenarios vignettes emphasizing 1) demand or 2) supply factors on theacceptability of regulatory/self-regulatory instruments. We will do this by using an experimental design on
respondents in the Citizens Panel provided by Laboratory of Opinion Research, University of Gothenburg.
Gender differences in the trust game and the gift-exchange game: A
Olmo van den Akker meta-analysis
Day 3
Do men and women differ in trusting behavior? This question is directly relevant to social, economic, andpolitical domains yet the answer remains elusive. In this thesis, I present a meta-analytic review of theliterature on gender differences in the experimental gift-exchange game (GEG) and trust game (TG) –economic games that are frequently used to measure trust and reciprocity of trust. The GEG metaanalysis consists of 33 studies and more than 1.300 participants. We found no difference between the twogenders with regard to trust (Hedges’ g = 0.057) and we found that men reciprocate trusting behavior
more than women (Hedges’ g = 0.247). We also considered several moderators, but none of these had
an influence on gender differences in trust and reciprocity. Preliminary results for the TG meta-analysis
indicate that men trust more, and women reciprocate trust more. At the time of the conference, all data
will be in and I will discuss important differences between the GEG results and the TG results.

86Development and testing a Diagnostic Capacity Tool for Improving
Patricia McKay
Socio-Ecological GovernanceDay 3
The capacity to sustainably govern complex socio-ecological systems (SES) has been identiﬁed as anecessary but daunting task by SES scholars, resource stewards and stakeholders. This research sought toinform the question: What are determinant capacities and functional linkages that can be incorporated
into diagnostic tools for analysts seeking to improve sustainable socioeconomic system SES governance?
Literature was used to identify and translate determinant capacities and functional linkages into aquantiﬁable metric of governance quality. The tool was developed from ecological, business, governanceand decision science literature. This tool recognizes the dynamic and systemic linkages between the
resources and the social systems that use and govern them for improving systems thinking and SES
outcomes. The tool was tested to determine its ability to capture perceived characteristics of governancequality and problem management using Michigan’s cleanup and redevelopment program. The results ofthis research indicated that the exploratory tool was reliable and valid. This research contributes to theevolving body of SES frameworks, speciﬁcally the study of individual and organizational capacities for
improved SES outcomes. The implications of this research suggest participatory network-based
governance with higher levels of resource exchange, in the form of interdependency, trust, diplomacy
and reciprocity, aligns with practitioners’ perceptions of improved program performance. Further, whilesome capacities and related ﬁndings of this research may be context speciﬁc, concepts associated withthe development and testing of this diagnostic tool, such as the use of systems thinking, participatory
network-based governance, and related competencies, may have more universal application.
Manufacturing Mis/Trust: How Media Framings of Great Power
Relations Today Contribute to War and Peace, An Experimental
Peter Gries
Analysis
Day 3This article explores the impact of media framings of great power relations today as positive or negative
sum on the prospects for war and peace. In an online experiment (N = 260) using real CNN news video
clips, we demonstrate that intergroup affect and trust mediate the causal relationship between exposure
to different media framings of US-China relations and the China policy preferences of American viewers.
Specifically, zero (vs. positive) sum media framings of US-China relations reduced Americans’ trust in the
Chinese people and government, and increased their anger about China’s possible rise; mistrust andanger in turn drove Americans to prefer a tougher China policy. These causal findings demonstrate thepsychological mechanisms through which Realist and Power Transitions theories, which popularize a viewof great power relations as inherently zero-sum, generate the psychological conditions of mistrust andanger that promote conflict, becoming self-fulfilling. Interventions to promote positive-sum perceptionsof mixed-motive social dilemmas and improve the prospects for peace in US-China relations are
discussed. This research is particularly timely given the election of Donald Trump as the next President of
the United States. Trump lives and champions a dog-eat-dog view of the world. Manhattan real estate isa zero-sum game of rent-seeking—not creating wealth and expanding the pie like most other industries,
but through crushing “enemies.” Trump’s “deals” are not about cooperation and expanding the pie, but
about extracting the biggest piece for himself. If this zero-sum mindset becomes a hallmark of Trump’s
foreign policy, our research should shed light on the psychological mechanisms through which a zerosum view of great power relations, which are actually often mixed-motive social dilemmas, becomes selffulfilling.
87

Philipp Gerlach
The Truth about Lies: A Meta-Analysis on Dishonest Behavior
Day 3
Philosophers have long been speculating about the conditions under which humans behave dishonestly.
In more recent times, researchers have begun to experimentally investigate these boundary conditions. In
this talk, I will meta review experimental paradigms that tempted participants to materially profit frommisreporting private information and then measured the degree as to which participants could not resist.
In die roll tasks, for example, participants earn more money from reporting higher outcomes of ananonymous die roll. The degree of dishonest behavior can be estimated by comparing the actual reports
to the expected distribution of fair die rolls. Meta analytical integration of more than 27,000 observations
from 93 die roll tasks, 131 coin flip tasks, 103 matrix tasks, and 162 cheap talk games revealed great variety
in the rates of dishonest behavior, from virtually 0% to 100% dishonest responses. We present the resultsof moderator analyses that assessed the boundary conditions of dishonest behavior, showing that bothexperimental aspects (e.g., the incentive to misreport) and participant characteristics (e.g., students vs.
non-students) play a major role.
Who educates a defecting partner?: The effect of opportunity cost on
Rie Mashima
the ability to control a partner’s behavior
Day 3
Engaging in social interactions with others entails the risk of exploitation. According to the emancipation
theory of trust (Yamagishi, 1998; Yamagishi, 2011), there are two solutions to problems of social
uncertainty. One is to form committed relationships, where strategies such as TFT can be employed.
However, commitment formation is costly when there are better opportunities outside of current
relationships. In such environments, general trust provides a springboard to a larger world ofopportunities. Because high-trusters experience many opportunities to initiate new relationships, they
can develop a higher social intelligence, such as skills to detect trustworthiness of others (Yamagishi,
1998). The above argument may lead us to believe that high-trusters possess many desirable
characteristics, while low-trusters do not. However, as maintaining low levels of trust is also an adaptive
strategy; low-trusters must perform better than high-trusters in some domains. We propose thatmanaging existing relations to achieve mutual cooperation is one skill that low-trusters acquire. In orderto maintain committed relationships, it is necessary for both parties to realize that one party’s defection
effectively leads to mutual defection. Thus, defection does not pay in the long run. However, individuals
must educate their partner to make them understand the incentive structure, thus players must pay thecost to educate their partners when defected upon. Contrary to those who live in low opportunity costsocieties, people who live in high opportunity cost societies do not need to educate their partners,
because high-trusters would quickly exit from current relationships at the first sign of defection. Thus,
high-trusters will therefore not develop the skill to manage relationships from which they cannot escape.
To examine this hypothesis, we conducted a vignette experiment assessing respondents’ behaviors
toward defecting partners in long-lasting relationships. Respondents were asked to read a scenario
describing an iterated PD and answered questions regarding their behaviors. The scenario described apartner who had initially cooperated but turned to a defector. After reading the scenario, respondents
reported their intention to defect on their partner (i.e., intention to play TFT) and their intention to pay
the cost to rectify their partner’s behavior (i.e., intention to educate). We also measured the level ofopportunity cost in the environment in which respondents were embedded. We predict that theintention to engage in TFT and educate a defecting partner will be negatively correlated with the level ofopportunity cost. We will report the detailed results at the conference.
88

A minimum set of factors necessary for the punishment andShuhei Tsuchidacooperation to evolve without the aid of cultural group selection
Day 3
In this presentation, we reanalyzed the model of coordinated punishment (Boyd, Gintis, & Bowles, 2010)
which suggested that punishment and cooperation can evolve without relying on the cultural group
selection. Compared to the past models of punishment, their model is much more complicated, and it is
not clear why cooperation and punishment evolved in their model. By thoroughly examining their model,
we attempted to extract a minimum set of the conditions that is necessary for the evolution ofpunishment. In the Boyd et al.’s model, a punisher sends a costly signal to all the other group members at
the beginning and coordinate their decisions in later rounds whether to cooperate or defect, and whether
to punish non-cooperators or not. If a punisher perceives there is not enough number of other punishers
in a group, s/he behaves as a non-cooperator who do not engage in cooperation and punishment in the
all subsequent rounds. If there is enough number of punishers existing in a group, punishers make acooperation and punish non-cooperator. They also divide the cost of punishment so that each punisher’s
cost is kept small while non-cooperators receive a significant amount of damage from being punished.
Through careful examinations of Boyd, et al.’s mathematical model, we found that, for cooperation andpunishment to stabilize, only the two factors are needed. (1) The cost of punishing a non-cooperator
must be small and (2) non-cooperators must be sensitive to the punishment so that they change theiraction and keep cooperating once punished. In the past studies of the evolution of cooperation, it wasoften argued that non-cooperators need to be incurred a large amount of cost of being punished. In
contrast, we found that it is much more important to keep the cost of punishment small than maintaining
the amount of punishment incurred by a non-cooperator large. In the presentation, we argue that our
results are best interpreted in the context of symbolic punishment (Masclet, et al., 2003). Both laboratory
experiments and anthropological research showed that those who failed to cooperate and received themere verbal accusations from others change their behavior. The conditions we found match the featuresof symbolic punishment. We argue that the most important puzzle of the evolution of the punishment is
not about why people punish but about why symbolic punishment is so prevalent in the human society.

89Intergroup conflict increases cooperation in defenders, but decreases
Simon Columbus
it in aggressors
Day 3
Intergroup conflict often increases intragroup cooperation towards the provision of public goods,
including contributions to the conflict itself. It has recently been proposed that the presence of athreshold for the provision of a public good, rather than competition with another group, is what leads tothis increase in cooperation during conflicts. Experimental results show that in symmetric intergrouppublic goods games, any threshold increases cooperation, including when it is set by an outgroup that is
not affected by the ingroup's level of cooperation, or even sampled randomly from a distribution. In real
life, however, intergroup conflict often is not a case of two sides pursuing the same, yet non-shareablegoal, but of one side looking for appropriation and expansion at the cost of another side seeking survival
and preservation of the status quo. Such asymmetric conflict describes small-scale and modern warfare,but also hostile take-overs in business. Here, we use a recently developed intergroup aggressordefender conflict game to test whether intergroup conflict affects intragroup cooperation during
asymmetric conflict. We find no overall effect of intergroup conflict on intragroup cooperation (relative toa game against ‘nature’). However, we find that intergroup conflict increases cooperation among
defenders, but decreases cooperation among aggressors. This indicates a unique contributionof intergroup conflict to intragroup cooperation, but with a crucial moderation by the motivation
underlying cooperation.

90

Public goods versus environment: A social dilemma to investigate theSina A. Klein
conflict between cooperation and pro-environmental behavior
Day 3Pro-environmental behavior often requires cooperation with other people, e.g. when carpooling to work.
However, pro-environmental behavior and cooperation can also be in conflict with or even harm eachother, e.g. when choosing between biological versus fair trade products. Previous research almost
exclusively focused on the former case, neglecting the importance of the latter. Hence, we developed asocial dilemma paradigm that provides a framework to investigate the conflict between these behaviors.
In this dilemma, all players receive a certain endowment and play in random groups of three. Then, eachplayer decides whether to keep the endowment for themselves, to contribute it to a public goods (PG)
account of their group, or to put it in an account for the environment. The money in both the public
goods and the environment account is doubled by the experimenter. The resulting sum in the public
goods account is equally redistributed to all group members and paid out together with the money
participants kept for themselves (if any). The resulting sum in the environment account is donated to an
environment conservation organization. Participants (N = 94) played four versions of this dilemma in
randomized order. The four versions varied with respect to different situational conditions: (1) the“baseline” version as described above, (2) the baseline version with the additional rule that eachcontribution to the PG account leads to a deduction from the environment account, (3) the baseline
version with the additional rule that each contribution to the environment account leads to a deduction
from the PG account, and (4) both additional rules from (2) and (3) combined. Overall, cooperation was
the most frequently chosen option. Furthermore, when cooperation harmed the environment (version 2),
cooperation decreased while pro-environmental behavior increased compared to the baseline. When
pro-environmental behavior harmed other people (version 3), pro-environmental behavior decreased
while cooperation increased. Finally, when cooperation and pro-environmental behavior harmed eachother (version 4), more people chose to keep the money to themselves. Participants’ decisions were inline with expectations, corroborating this paradigm as a valid instrument for the investigation of theconflict of cooperation and pro-environmental behavior.
Sky King
Product Recalls Conceptualized as a Social Dilemma
Day 3
I demonstrate that the product recall decision can be viewed as a social dilemma where short-term
individual interests and long-term collective interests are at odds. Additionally, I will present how theConsideration of Future Consequences (CFC), "the extent to which people consider the potential distantoutcomes of their current behaviors and the extent to which they are influenced by these potential
outcomes” (Strathman et al. 1994), effects the product recall decision. Specifically, CFC effects recall
intentions through ethical perceptions of the decision. When decision makers’ CFC is high and when thedecision is perceived as being an ethical decision, willingness to recall a product increases.

91

The Group Size Effect on Cooperation in Social Dilemmas: A MetaStijn Peperkoorn
Analysis
Day 3
While humans evolved in small-scale kin-based groups, modern societies tend to contain larger groups. It
is unclear, however, what group size elicits most cooperation. For over several decades, researchers haveproposed that group efficiency and cooperation would decrease as the size of the group increases. Yet,past research has showed somewhat inconsistent findings on how group size affects cooperation. To
provide a quantitative review of the group size effects on cooperation, we report a meta-analytic review
of over 45 papers that manipulated group size and measured cooperation in social dilemmas games(e.g., N-person prisoner’s dilemma, commons dilemma, volunteer’s dilemma, public goods dilemma).
Using meta-regression techniques, we also investigated whether this group size effect was moderated by
the K index of cooperation (i.e., the incentive to cooperate), the marginal per capita return (MPCR) (theprivate benefit for each unit contributed to the group project), the number of iterations in the game (oneshot, repeated one-shot, or repeated iterations) and the type of social dilemmas (e.g., resource dilemmas,
step-level public goods, and continuous public goods dilemmas). Preliminary results indicated an overall
small negative effect of group size on cooperation. We discuss the broader implications for theory andresearch on group size and cooperation.
Tadeusz Płatkowski
Egalitarian Solutions of Social Dilemmas in Populations
Day 3
We propose an axiomatic derivation and a classification of social dilemmas, represented by multiperson
symmetric games. The popular games, such as for example the N-person Prisoner's Dilemma, the Public
Goods, the Tragedy of the Commons, the Volunteer's Dilemma, and the Assurance Game are included in
the proposed frame. For two--person games the axiomatization leads to three types of social dilemmas
only: the Prisoner's Dilemma, the Chicken and the Stag Hunt game. The proposed classification of social
dilemmas is based on the notion of greed and fear. We show that each dilemma has at least one of thesebuild in for general classes of social dilemmas.
Jessica Federman
Money Increases Passive Managerial Mindset Toward Others
Day 3
The current study investigated the effects of thoughts of money on managerial interventions of personnel
work performance. Participants completed decision making tasks that characterized their intentions andmethods for correcting personnel work performance that differed along the dimensions of autonomousinterventions (passive leadership) versus controlling interventions (active leadership). Participants primed
with thoughts of money were more likely to agree to using autonomous interventions than the control
group for correcting personnel work performance problems, whereas the control group predominantly
chose to use active leadership interventions compared to the treatment condition. The results show thatthoughts of money promoted the use of a passive leadership stance yet may be deliberative to conserve
future resources for the self.

92

Sharing compromising information: How crime begets trust andWojtek Przepiorka
cooperation among criminals
Day 3
We investigate in how far deviant acts are not only a manifestation of preferences, but also necessitatedby the lack of trust and commitment encountered in extra-legal contexts. When people have reasons to
distrust one another, as criminals do for instance, they could still cooperate by sharing compromisinginformation with which to blackmail each other and ensure compliance. The content of this information
would consist of deviant acts which once credibly revealed trigger punishment by a third party. We
pursue this conjecture experimentally, investigating whether even in a basic and artificial setting actors
use deviant acts to foster profitable cooperation with each other. In our experiment, subjects first acquirea label based on how cooperative they are in a series of dyadic interactions with trust at stake.
Cooperative subjects obtain the label “dove” and uncooperative subjects obtain the label “hawk.” In thereminder of the experiment, we vary whether subjects’ labels are revealed automatically or by their own
choosing. And we vary whether hawks who are made or make themselves known as such, respectively,
can be inflicted a monetary penalty. In the condition in which labels are automatically revealed andwithout the possibility to inflict a penalty on hawks, we find that doves cooperate with doves and avoid
hawks, whereas hawks seek to interact with both doves and hawks but, unlike doves, mostly defect. Thispattern hardly changes after subjects are given the choice to reveal their label before each interaction.
Although the majority of hawks chooses not to reveal their label and the large majority of doves reveals,
those who do not reveal behave like hawks and are treated as such by their interaction partners. Oncethe possibility to penalize hawks is introduced, doves become less reluctant to interact and cooperatewith hawks, but hawks meeting a dove fear the “stick” and prefer to stay out. However, the proportion ofhawks who interact and cooperate with each other increases. Although few in numbers, some hawks
understand the strategic advantage of exchanging compromising information by revealing their label,
and they do so to cooperate with each other. However, the majority of hawks are less strategic and follow
a rather blunt strategy: hide and defect. Our results corroborate Thomas Schelling’s initial idea thatcompromising information can be conceived as a “hostage” which, when mutually exchanged, makes
each party to the interaction vulnerable and therefore trustworthy in joint illicit endeavors.
The Rich Are Easily Offended by Unfairness: Wealth Triggers Spiteful
Yi Ding
Rejection of Unfair Offers in China
Day 3
What does it do to people when they are rich or poor? Do they differ in their response to unfair
treatment? These questions are pertinent to any society, especially contemporary China which faces atransition to greater wealth but also stronger wealth inequality. Here, we measured self-reported wealth(i.e., family income, Study 1) and manipulated wealth using a “lucky draw” game (Studies 2 to 4) toexamine among Chinese participants how wealth affects responses to unfairness in an ultimatum game.
Across four studies, we found that wealthy people rejected an unfair offer (i.e., being offered ¥2 while theother kept ¥8) more frequently than the less wealthy, and that this tendency to reject unfairness wasmediated by their increased feelings of entitlement. This suggests that the wealthy, or even people who
temporarily perceive themselves to be wealthy, are more easily offended by unfairness than the lesswealthy.

93

Experimental evidence of full cooperation among Japanese ruralvillagers in a Prisoner’s dilemma game: A field and laboratorycomparison of the impact of social group membership on
Yohei Mitani
cooperation
Day 3
Local norms and shared beliefs in cohesive social groups regulate individual behavior in everyday
economic life. We conduct a door-to-door field experiment where over a hundred villagers recruitedfrom twenty-three communities in a Japanese rural mountainous village play a simultaneous prisoner’s
dilemma game. To see whether a set of beliefs shared through interactions among community members
affect experimental behavior, we compare villager’s behavior under in-community and out-community
random matching protocols. We also report a counterpart laboratory experiment with seventy-two
university student subjects to address the external validity of laboratory experiments. Our findings are
three-fold. First, almost full cooperation is achieved when villagers play a prisoner’s dilemma game with
their anonymous community members. Second, cooperation is significantly higher in the in-groupcompared to the out-group treatment in both laboratory and field. Third, although a significant
treatment effect of social group membership is preserved, a big difference in the average cooperation
rates is observed between laboratory and field.

94

Participant List
Name
Adam Stivers
Adiel Moyal
Alan Fermin
Alfred Zerres
Andreas
DiekmannAndreas Gloeckner
Andrew Delton
Andrew
Hafenbrack
Angela DorroughAngelo Romano
Anne-Marie Neise
Anouk Griffioen
Anthony Evans
Arjaan Wit
Aron Szekely
Athena Aktipis
Axel Burger
Axel Franzen
Barry Goldman
Bastian Jaeger
Bettina
Rochenback
Bibb Latané
Biljana Gjoneska
Brent Simpson
Bruno LambertInstitution (Email)Gonzaga University (adam.stivers@gmail.com)
The Hebrew University of Jerusalem (Adielmoyal@gmail.com)
Tamagawa University (ferminalan@gmail.com)
University of Amsterdam (a.zerres@uva.nl)
ETH Zurich (diekmann@soz.gess.ethz.ch)
University of Hagen (andreas.gloeckner@fernuni-hagen.de)
Stony Brook University (andydelton@gmail.com)
UCP Católica Lisbon School of Business & Economics (hafenbrack@ucp.pt)
University of Hagen (angela.dorrough@fernuni-hagen.de)
VU Amsterdam (a.r.romano@vu.nl)
University of Oxford (anne-marie.neise@psy.ox.ac.uk)
Wageningen University (anouk.griffioen@wur.nl)
Tilburg University (tony.m.evans@gmail.com)
Leiden University (wit@fsw.leidenuniv.nl)
Institute of Cognitive Sciences and Technologies (aszeke81@gmail.com)
Arizona State University (aktipis@asu.edu)
University of Mannheim (aburger@mail.uni-mannheim.de)
University of Bern (franzen@soz.unibe.ch)
University of Arizona (bgoldman@eller.arizona.edu)
Tilburg University (bxjaeger@gmail.com)
University of Cologne (bettina.rockenbach@uni-koeln.de)Center for Human Science (latane@humanscience.org)
La Sapienza (biljana.gjoneska@uniroma1.it)

Carolyn Declerck
Carsten De Dreu
Catherine Molho
Cathleen Johnson

University of South Carolina (bts@sc.edu)
University of Antwerp (bruno.lambert@uantwerp.be)
University of Antwerp, Faculty of Economic Sciences(Carolyn.declerck@uantwerpen.be)
Leiden University (c.k.w.de.dreu@fsw.leidenuniv.nl)
VU Amsterdam (c.molho@vu.nl)
University of Arizona (cathleen.a.johnson@gmail.com)

Chih-Ting Shih
Cindy Schipani

National Pingtung University (sctings@mail.nptu.edu.tw)
University of Michigan (schipani@umich.edu)
95

Cleotilde (Coty)
Gonzalez
Daniel BallietDavid Hugh-Jones
Diogo Ferreira
Dirk Semmann
Dora Simunovic
Dorothee
Mischkowski
Efrat Aharonov
Eitan Adres
Eizo Akiyama
Eliran Halali
Eric Scalone
Eric van Dijk
Erik W. de
Kwaadsteniet
Eva Maria Krockow
Flore Bridoux
Fredrik Jansson
Fujio Toriumi
Gary Ting Tat Ng
Gianluca Grimalda
Giulia Andrighetto
Giuliana Spadaro
Hagit Sabato
Hannes Rusch
Heike HennigSchmidt
Hendrik Bruns
Hillie Aaldering
Hitoshi Yamamoto
Hongchuan Zhang
Ilja van Beest
Inbal Harel
Isabel Thielmann
Isabela Maria
Rinderu
Isamu Okada

Carnegie Mellon University (coty@cmu.edu)
VU Amsterdam (d.p.balliet@vu.nl)
University of East Anglia (D.Hugh-Jones@uea.ac.uk)
Universidade Federal de Sergipe (diogoseco@ufs.br)
Max Planck Institute for Evolutionary Biology (dirk.semmann@evolbio.mpg.de)
Jacobs University (saveusmilkboy@gmail.com)
University of Hagen (dorothee.mischkowski@fernuni-hagen.de)
Carnegie Mellon University (eaharono@andrew.cmu.edu)
Technion, Israel Institute of Technology (adres@netvision.net.il)
University of Tsukuba (eizo@sk.tsukuba.ac.jp)
Bar-Ilan University (halalie@biu.ac.il)
Manhattan College (escalone01@manhattan.edu)
Leiden University (dijk@fsw.leidenuniv.nl)
Leiden University (kwaadsteniet@fsw.leidenuniv.nl)
University of Leicester (emk12@le.ac.uk)
University of Amsterdam (fbridoux@hotmail.com)
Stockholm University (fredrik.jansson@su.se)
The University of Tokyo (tori@sys.t.u-tokyo.ac.jp)
The Chinese University of Hong Kong (ttng@link.cuhk.edu.hk)
Institute for the World Economy (gianluca.grimalda@ifw-kiel.de)European University Institute; Institute of Cognitive Science and Technology, CNR(giulia.andrighetto@gmail.com)
University of Turin (gspadaro@unito.it)
Ben Gurion University (hagit.s10@gmail.com)
Philipps University Marburg (hannes.rusch@wiwi.uni-marburg.de)Bonn University (hschmidt@uni-bonn.de)
University of Hamburg (ithinkimdead@web.de)
University of Amsterdam (H.Aaldering@uva.nl)
Rissho University (hitoshi@ris.ac.jp)
Central University of Finance and Economics (Hongchuan.zhang@cufe.edu.cn)
Tilburg University (i.vanbeest@uvt.nl)
Ben Gurion University (inbalh86@gmail.com)
University of Koblenz-Landau (thielmann@uni-landau.de)
VU Amsterdam (m.i.rinderu@student.vu.nl)
Soka University (okada@soka.ac.jp)
96Jaap Schaveling
Jan Kristian Woike
Jan Luca Pletzer
Jeff Joireman
Jessica Federman
Jessica Nolan
Jörg Gross
JosephCalabrisotto
Junhui Wu
Jürgen Fleiß
Jurgis Karpus
Károly Takács
Kim Peters
Kimmo Eriksson
Laetitia Mulder
LeonardPeperkoorn
Leonie Fuetterer
Loren Pauwels
Luca Tummolini
Maik Theelen
Manfred Milinski
Marilynn Brewer
Masamichi
Sakagami
Masanori
Takezawa
Meike Wiemann
Misato Inaba
Nadira Faber
Nancy Buchan
Nichola Raihani
Niels van Doesum
Niklas Harring
Nils Köbis
Nir Halevy
Nobuyuki
Takahashi

Nyenrode Business Universiteit (jaapschaveling@me.com)
Max Planck Institute for Human Development (Woike@mpib-berlin.mpg.de)
VU Amsterdam (j.pletzer@jacobs-university.de)
Washington State University (joireman@wsu.edu)
CSU Dominguez Hills (jef236@cornell.edu)
University of Scranton (jessica.nolan@scranton.edu)
Leiden University (mail@joerg-gross.net)
University of Michigan, Ann Arbor (joecala@umich.edu)
Beijing Normal University (junhui.wu@hotmail.com)
University of Graz (juergen.fleiss@uni-graz.at)King's College London (jurgis.karpus@kcl.ac.uk)
MTA TK, Hungarian Academy of Sciences (takacs.karoly@tk.mta.hu)
University of Queensland (k.peters@uq.edu.au)Stockholm University and Mälardalen University (kimmoe@gmail.com)
University of Groningen (l.b.mulder@rug.nl)
Vrije Universiteit Amsterdam (l.s.peperkoorn@vu.nl)
Karlsruhe Institute of Technology (KIT) (leonie.fuetterer@kit.edu)
Universiteit Antwerpen (Loren.Pauwels@uantwerpen.be)
Italian National Research Council (luca.tummolini@istc.cnr.it)
RWTH Aachen University (maik.theelen@rwth-aachen.de)
Max Planck Institute for Evolutionary Biology (milinski@evolbio.mpg.de)Ohio State University (brewer.64@osu.edu)
Tamagawa University (sakagami@lab.tamagawa.ac.jp)

Hokkaido University (m.takezawa@let.hokudai.ac.jp)
University of St. Gallen (meike.wiemann@unisg.ch)Kansai University (shangrileaf@gmail.com)
University of Oxford (nadira.faber@psy.ox.ac.uk)
Darla Moore School of Business, University of South Carolina(nancy.buchan@moore.sc.edu)
UCL (nicholaraihani@gmail.com)
Leiden University (n.j.van.doesum@fsw.leidenuniv.nl)
University of Gothenburg (niklas.harring@pol.gu.se)
University of Amsterdam (n.c.kobis@uva.nl)
Stanford University (nhalevy@stanford.edu)
Hokkaido University (ntakahas@let.hokudai.ac.jp)97Oliver Scott Curry
Olmo van den
Akker
Ori Weisel
Patricia McKay
Paul van Lange
Peter Gries
Philipp Gerlach
Pontus Strimling
Poonam Arora
Rebecca Koomen
Rie Mashima
Rob Nelissen
Robert Böhm
Sebastian
Grueneisen
Sebastian Mader
Sherry Schneider
Shirli Kopelman
Shona Duguid
Shuhei Tsuchida
Simon Columbus
Simon Gaechter
Sky King
Stefan Pfattheicher
Susann Fiedler
Susanne Lohmann
Tadeusz
Platkowski
Tamar Kugler
Ted Paterson
Tehila Kogut
Terry Dworkin
Tess Robertson
Thomas Schlösser
Timothy Shields
Toko Kiyonari
Victor Shiramizu

University of Oxford (oliver.curry@anthro.ox.ac.uk)
University of Amsterdam (ovdakker@gmail.com)
Tel Aviv University (oriw@tauex.tau.ac.il)Michigan State University (mckaypa1@msu.edu)
VU Amsterdam (p.a.m.van.lange@vu.nl)
University of Oklahoma (gries@ou.edu)
Max Planck Institute for Human Development (pgerlach@mpib-berlin.mpg.de)Institute for Future Studies (pontusstrimling@gmail.com)
Manhattan College (poonam.arora@manhattan.edu)
Max Planck Institute for Evolutionary Anthropology (rebecca_koomen@eva.mpg.de)
Health Sciences University of Hokkaido (rmashima@hoku-iryo-u.ac.jp)
Tilburg University (r.m.a.nelissen@tilburguniversity.edu)
RWTH Aachen University (robert.boehm@rwth-aachen.de)
Max Planck Institute for Evolutionary Anthropology(sebastian_grueneisen@eva.mpg.de)
University of Bern (sebastian.mader@soz.unibe.ch)
University of West Florida (sschneider@uwf.edu)
University of Michigan (shirli@umich.edu)
Max Planck Institute for Evolutionary Anthropology (shona_duguid@eva.mpg.de)
Hokkaido University (shutsuchida@gmail.com)
Vrije Universiteit Amsterdam (simon@simoncolumbus.com)
University of Nottingham (simon.gaechter@nottingham.ac.uk)
Weber State University (skyking28@gmail.com)
Ulm University (stefan.pfattheicher@uni-ulm.de)
Max Planck Institute for Research on Collective Goods(susann.fiedler@googlemail.com)
University of California, Los Angeles (UCLA) (lohmann@ucla.edu)
Warsaw University (tplatk@mimuw.edu.pl)
University of Arizona (tkugler@eller.arizona.edu)
Oregon State University (ted.paterson@oregonstate.edu)
Ben-Gurion University (kogut@bgu.ac.il)
Seattle University School of Law (dworkint@indiana.edu)
Stony Brook University (theresa.robertson@stonybrook.edu)
University of Cologne, Germany (t.schloesser@uni-koeln.de)
Timothy Shields (shields@chapman.edu)
Aoyama Gakuin University (tokokiyonari@gmail.com)
Federal University of Rio Grande do Norte (victorshiramizu@gmail.com)
98

WelmerMolenmaker
Wojtek Przepiorka
Wynn Stirling
Yang LiYi Ding
Yiming Jing
Yoshie Matsumoto
Yves Hertig

Leiden University (w.e.molenmaker@fsw.leidenuniv.nl)
Utrecht University (w.przepiorka@uu.nl)
Brigham Young University (denise_gibbons@byu.edu)
The University of Melbourne (noahcatlee@gmail.com)
Vrije Universiteit Amsterdam (y.i.ding@vu.nl)
University of Oklahoma (yjing@ou.edu)
Tamagawa University (mtmtyoshie@gmail.com)
University of Fribourg (yves.hertig@unifr.ch)99