Social Design Engineering Series

SDES-2020-12

Does perspective-taking promote intergenerational sustainability?

Mostafa E. Shahen
School of Economics and Management, Kochi University of Technology

Koji Kotani
School of Economics and Management, Kochi University of Technology
Research Institute for Future Design, Kochi University of Technology

Tatsuyoshi Saijo
Research Institute for Humanity and Nature
Research Institute for Future Design, Kochi University of Technology

11th September, 2020

School of Economics and Management
Research Institute for Future Design
Kochi University of Technology
KUT-SDE working papers are preliminary research documents published by the School of Economics and Management jointly with the ResearchCenter for Social Design Engineering at Kochi University of Technology. To facilitate prompt distribution, they have not been formally reviewed
and edited. They are circulated in order to stimulate discussion and critical comment and may be revised. The views and interpretations expressedin these papers are those of the author(s). It is expected that most working papers will be published in some other form.

Does perspective-taking promote intergenerationalsustainability?
Mostafa E. Shahen*,† Koji Kotani*,†,‡,§,¶ Tatsuyoshi Saijo*,†,‡,||
September 11, 2020

Abstract
The intergenerational sustainability dilemma (ISD) is a situation of whether or not a person sacrifices herself for future sustainability. To examine the individual behaviors, one-person
ISD game (ISDG) is instituted with strategy method where a queue of individuals is organized
as a generational sequence. In ISDG, each individual chooses unsustainable (or sustainable)
option with her payoff of X (X − D) and an irreversible cost of D (zero cost) to future generations in 36 situations. Future ahead and back (FAB) mechanism is suggested as resolution
for ISD by taking the perspective of future generation whereby each individual is first asked
to take the next generation’s standpoint and request what she wants the current generation tochoose, and, second, to make the actual decision from the original position. Results show that
individuals choose unsustainable option as previous generations do so or X
D is low (i.e., sustainability is endangered). However, FAB prevents individuals from choosing unsustainableoption in such endangered situations. Overall, the results suggest that some new institutions,such as FAB mechanisms, which induce people to take the perspective of future generations,
may be necessary to avoid intergenerational unsustainability, especially when intergenerationalsustainability is highly endangered.

Keywords: Intergenerational sustainability dilemma; future ahead and back mechanism; intergenerational sustainability index* Research Institute for Future Design, Kochi University of Technology†

School of Economics and Management, Kochi University of Technology
Urban Institute, Kyusyu University§
College of Business, Rikkyo University¶
Corresponding author, e-mail: kojikotani757@gmail.com||
Research Institute for Humanity and Nature‡

1

Contents
Nomenclature

2

1

Introduction

3

2

Methods and materials

6

3

Results

14

4

Discussion

20

5Conclusion

22

Nomenclature
DG

Dictator game

FAB Future ahead and back
IS

Intergenerational sustainability

ISD

Intergenerational sustainability dilemma

ISDG Intergenerational sustainability dilemma gameSDStandard deviation

2

1

1

Introduction

2

A social dilemma refers to a situation where every individual in a group or society behaves ac-

3

cording to her self-interest without cooperating with one another, leading to a failure of maximiz-4

ing the social welfare (Dawes, 1980). The provisions of public goods and common pool resources5

are considered to be intra- and inter-generational social dilemmas, and literature finds that com-

6

munication enhances cooperation, leading to Pareto improvement and socially optimal outcomes

7(Ostrom, 1990, ping Chen and Komorita, 1994, Mason and Phillips, 1997, Mantilla, 2015, Ozono

8

et al., 2020). The long-run survival of humankind on Earth is claimed to depend on whether or

9

not we can resolve intergenerational dilemmas and maintain resources by making communication

10and cooperation across different generations, i.e., intergenerational sustainability (IS) problems

11(Ehrlich et al., 2012, Steffen et al., 2015, Shahrier et al., 2017b). However, some authors claim that12

it is quite challenging to make such communication and cooperation across different generations,13

when they are neither interacting nor overlapping (González-Ricoy and Gosseries, 2016, Krznaric,

142020). Therefore, IS problems have occurred reflecting the lack of such communication and co-

15

operation such as climate change, sea-level rise, accumulation of public debt and biodiversity loss

16

(Greenhalgh, 2005, Hansen and İmrohoroğlu, 2016, Steffen et al., 2018, Bamber et al., 2019). A

17

key question here is “does the growing threat of IS problems induce societies and individuals to18

take cooperative actions when communications among generations are difficult or impossible?”

19(Barkenbus, 2010, Lenton et al., 2019). Given this state of affairs, this paper addresses how indi-

20

viduals cooperatively behave for maintaining IS.

21

We consider intergenerational sustainability dilemma (ISD) to represent a typical situation

22

where the current generation chooses to maximize (sacrifice) its own benefits without (for) con-23

sidering future generations, compromising (maintaining) IS where communications among gener-

24

ations cannot be made (Kamijo et al., 2017, Shahrier et al., 2017b). One of the main features in

25

ISD is its unidirectional or irreversible nature, as the current generation affects future generations,26

but the opposite is not true. Thus, ISD can be considered to have a similar structure to a dictator

27

game (DG) in which a dictator unidirectionally affects a recipient. In the unidirectional setting, the3

28

current generation (or the dictator) can prioritize its own benefits without considering future gener-

29

ations (or receivers). The DG has been widely studied by social scientists for the last few decades

30(Bohnet and Frey, 1999, Dana et al., 2006, Bardsley, 2007, List, 2007, Ekeli, 2009, Thompson,

31

2010, Macro and Weesie, 2016, Koch et al., 2017). The stake represents the economic factor in the32

DG and is observed to be an influential factor in the allocations between the dictator and a receiver

33(Hoffman et al., 1996, Cherry et al., 2002, List and Cherry, 2008, Novakova and Flegr, 2013, Rai-

34

hani et al., 2013). Engel (2011) reviews 440 DG papers in a meta-study, identifying that the stake

35

usually falls between 0 $ and 130 $, and an increase in the stake reduces dictators’ willingness

36

to give. Other researchers have focused on how information on the allocations of other dictators

37

affects a dictator’s allocation in the DG (Hoffman et al., 1994, Cason and Mui, 1998, Fehr and38

Schmidt, 1999, Bolton and Ockenfels, 2000, Diekmann, 2004, Herne et al., 2013). Ben-Ner et al.

39(2004) find that information about the allocations of other dictators leads a dictator to divide the40allocation in a similar way to how other dictators make their allocations. In short, previous studies

41

have shown that the economic factor and information about other dictators’ allocation influence

42

allocations in the DG.

43Many scholars have applied an experimental approach in examining group behaviors regarding

44

IS. Fischer et al. (2004) implement a common pool resource experiment with university students to45

investigate individual decisions in a group, demonstrating that the existence of subsequent groups

46

motivates individuals to sustain resources. Hauser et al. (2014) conduct an online intergenerational

47

goods experiment under a voting mechanism using a general subject pool and find that voting

48

could reduce the exploitation of resources by restraining defectors when a majority of subjects

49

are prosocial. Sherstyuk et al. (2016) examine the efficiency of a dynamic externality game in50

the laboratory, identifying that resolving the dynamic externalities becomes more challenging in

51

intergenerational settings than in settings with infinitely lived decision makers. They also claim that

52

access to information on the history of previous generations’ decisions may improve the negative

53

externalities. Kamijo et al. (2017) design and implement an ISD game (ISDG) in the laboratory

54

with a student pool to understand group behaviors in the ISD. They find that, within a group of4

55

three individuals, the introduction of an individual who is asked to play the role of deputy for future

56

generations, called an imaginary future person, enhances IS. Shahrier et al. (2017b,a) conduct an

57

ISDG field experiment using a subject pool drawn from the general public in urban and rural areas

58

of Bangladesh, showing that rural groups choose sustainable options more often than do urban

59groups, as the majority of rural people are prosocial. Moreover, they find that inducing subjects

60

to take and understand the perspective of the next generation before making their decision, an

61

institution called the future ahead and back mechanism, improves IS. Shahrier et al. (2017b,a)62

note that introducing an imaginary future person in a group is not effective at maintaining IS

63with a general subject pool of Bangladeshi people in the ISDG field experiments. Therefore, they64

institute and design a future ahead and back mechanism. Overall, group behaviors in IS are mainly65

affected by social preferences, access to information about the decisions of previous generations

66(i.e., history) and institutions or environments for group decisions.

67

Past studies suggest that individual behaviors in the DG and group behaviors in the ISD are

68

influenced by not only people’s social preferences of prosociality but also information about the69

allocations of other dictators and the decisions of previous generations, respectively. We call such70

information the retrospective factor for decisions in the ISD. On the other hand, how the current

71

generation affects future generations also alters people’s behaviors in the ISD. We call this effect72of the current generation’s choice on future generations the prospective factor for decisions in the73

ISD. This study systematically examines how individuals behave in response to the retrospective74

and prospective factors in the ISD and derive some implications for designing our societies to75

be intergenerationally sustainable. To this end, we design and institute a one-person ISD game76

(ISDG) with a strategy method in which a queue of individuals is organized as a generational77

sequence. Each individual is asked to choose either (i) an unsustainable option that yields payoff

78

X, imposing an irreversible cost on future generations of D, or (ii) a sustainable option that yields

79

payoff (X − D), without imposing any cost on future generations, in 36 situations where the80histories of previous generations’ choices (the retrospective factor) and the payoff structures of

81

X(the prospective factor, i.e., the IS index) are varied.
D

5

As a potential resolution of the ISD, we82

introduce a future ahead and back (FAB) mechanism whereby first, each individual is asked to take83

the position of the next generation and to request what she wants the current generation to choose

84

and second, she makes the actual decision from the original position.

85

The economic factor and information about how other dictators make their allocations in the86

DG have been established to affect the allocations between a dictator and a receiver along with87

) and histories of previous genpeople’s social preferences. Likewise, the economic factor (i.e., XD88

erations’ decisions in the ISD are hypothesized to affect the allocations of the decisions made by89

the current generation between herself and the next generation, consequently influencing subse-

90

quent generations and IS. The ratio in ISD is interpreted to represent how many generations can

91

enjoy the positive amount of resources before reaching the “devastating consequence” of resource

92

extinction (i.e., X = 0), when all the current and subsequent generations keep choosing unsustain-

93

able options. Therefore, it is very important and can be considered similar to an idea of the “tipping

94

point” in the ecological system (Westley et al., 2011, Steffen et al., 2015, 2018). However, there95

is a distinction between the DG and the ISDG in that a dictator unidirectionally affects only one

96

receiver, while the current generation unidirectionally affects not only the next generation but also

97

all subsequent generations. To the best of our knowledge, no previous research has systematically98

addressed and examined individual behaviors under various situations of the ISD. Specifically, the99

novelties of this research lie in (i) characterizing how individuals with different social preferences100

behave to be sustainable or unsustainable in response to the economic (the prospective) factor

101

and history of previous generations’ decisions (the retrospective factor) under the ISD and (ii)102

evaluating how effective an FAB mechanism that induces people to take the standpoint of future

103

generations is at maintaining IS.

104

2

Methods and materials

105

We administered a one-person intergenerational sustainability dilemma game (ISDG), social

106

value orientation (SVO) game and questionnaires to collect data on individual behaviors, social

6

107

preferences and sociodemographic information from subjects.

108One-person intergenerational sustainability dilemma game (One-person ISDG)

109

We designed and implemented a one-person ISDG, which possesses similar structures to those110of the ISDG played by a group of three people in Kamijo et al. (2017) and Shahrier et al. (2017b).

111

A one-person ISDG is organized by queuing a sequence of consecutive generations, and each112

generation is represented by one person. A generation is asked to make a choice between an

113

unsustainable option A and a sustainable option B. If a generation chooses option A, she receives

114

a payoff of X tokens (hereafter, we skip mentioning “tokens”), and the next generation faces the115

decision environment where the payoffs associated with options A and B uniformly decrease by116

D. If a generation chooses option B, she receives a payoff of X − D, and the next generation

117

has the same decision environment as the current one, where the payoffs associated with options

118

A and B never decrease. An essential feature of the game is that the current generation affects

119subsequent generations, while the opposite is not true.

120

The 1st generation always starts a one-person ISDG with option A = 3600 and option B =1213600 − D in any situation. Suppose that a subject is the 1st generation and plays the game with122

D = 900 in a specific situation. The 1st generation receives 3600 if she chooses option A, and the123

2nd generation plays the game with options A = 2700 and B = 1800. When the 1st generation

124

chooses option B, she receives 2700 and the 2nd generation plays the game with options A = 3600

125

and B = 2700. Next, suppose that a subject is the 5th generation and plays the game with D = 300

126

in another situation, given a history that the 1st and 3rd (2nd and 4th) generations chose option A

127(B). In this case, the 5th generation faces the decision environment where the payoffs associated128with options A and B are 3000 (= 3600−2D = 3600−2×300) and 2700, respectively, noting that129

the two previous generations choose option A. Therefore, the 5th generation receives 3000 if she

130chooses option A, and the 6th generation plays the game with options A = 2700 and B = 2400.

131

If the 5th generation chooses option B, she receives 2700, and the 6th generation plays the game132

with options A = 3000 and B = 2700.

7

[Table 1 about here.]

133

134

A strategy method is applied to create 36 different one-person ISDG situations that each subject

135

goes through (Selten, 1967). Specifically, the strategy method applied in this research follows a136

conditional information lottery (CIL) method (Bardsley, 2000, Bardsley and Sausgruber, 2005).

137

The CIL method enables us to create some fictional situations and one real situation where subjects

138

can not distinguish between the fictional ones and real one. The 36 situations in this experiment139

consist of 35 fictional situations, which are uniformly applied for all the subjects, and one real

140

situation (i.e. binding situation), which is different for each subject. In the 35 situations, the history

141of previous generations’ choices, the payoff of X that a generation can receive, a payoff difference142) are parametrized under theof D between options A and B and the ratio between X and D (i.e., XD

143

assumptions that the 1st generation always starts the one-person ISDG with options A = 3600 and

144

B = 3600 − D and that the value of D remains the same in each situation. Table 1 summarizes

145

the 35 different situations in the one-person ISDG, listing the associated percentages of previous

146

generations that choose unsustainable option A in history, ranging from 0 to 1; the payoff X that147

a generation can receive, ranging from 0 to 3600; the difference D, ranging from 100 to 1800; and148

the ratio between X and D, ranging from 0 to 36. Although table 1 contains the percentage of149

previous generations in history for each situation that chose option A as a summary, a subject is150

shown a whole history of how each previous generation chose between options A or B, displayed151

by a sequence of human-shaped icons with different colors in each situation as shown in tables 2

152

and 3.

153[Table 2 about here.]154[Table 3 about here.]

155

Figure 1 displays a scatter plot for the distribution of the 35 situations over the percentage

156

of previous generations who choose option A and the ratio between X and D, where each plot157

corresponds to one situation in table 1. In this experimental design, the history of the sequence8

158

for each situation and the ratio between X and D for each situation can be interpreted as the159

retrospective and prospective factors because they represent what happened in the past as well as

160

what will happen to the subsequent generations in the sequence for each situation, respectively.

161

Specifically, the history of the sequence for each situation is interpreted as the retrospective factor,

162

is interpreted as the prospective factor, representing how many generations
while the ratio of X
D

163

in the sequence can receive a positive payoff of X for each situation when each generation keeps

164choosing option A. We call the ratio of X
the intergenerational sustainability index (i.e., IS index)
D165

in the one-person ISDG. The parametrization is made to widely vary the retrospective (history) and166

prospective ( X) factors as well as to minimize the correlation among the factors in the one-person
D

167

ISDG with a strategy method, reflecting figure 1 (r = 0.099, P = 0.56). For example, the 23rd

168

situation in table 1 consists of a history in which 70 % of previous generations chose option A,

169

X = 1500 and D = 300, implying that the current generation is 11th and there are 10 previous

170

generations. Concretely, the history consists of 7 previous generations (i.e., 1st, 2nd, 4th, 6th, 8th,171

9th and 10th) that chose option A and of 3 previous generations (i.e., 3rd, 5th, 7th) that chose172

option B, as shown in figure 2. In this case, the payoffs associated with options A and B that the173

11th generation faces are 1500 (= 3600 − 7D = 3600 − 7 × 300) and 1200, respectively.

174[Figure 1 about here.]

175

Figure 2 shows the screens of the game, which are designed following Strombach et al. (2015).

176

In each situation, a subject observes the screen of the game when she is asked to decide between

177

options A and B. Here, we take the 23rd situation as an example. The first screen in figure 2

178

notifies the subject of the situation number (i.e., the 23rd situation), and the second screen presents

179

the history, options and associated payoffs for the current and next generations. At the top of the180

second screen, human-shaped icons represent the generations in each situation, and the dotted and181

striped icons represent the current and subsequent generations, respectively. The gray and light182

gray icons represent the previous generations in history who chose options A and B, respectively,

183

while the black icons represent the subsequent generations to come after the next generation. In

9

184

the middle of the screen, the options for the current and next generations are presented next to the185

white and striped icons, respectively.

186[Figure 2 about here.]187

In addition to these 35 situations of the one-person ISDG, each subject plays one binding situa-

188

tion whose decision environments evolve over generations according to how previous generations

189

have chosen and how the current generation chooses, being passed to the subsequent generations

190

within the sequence to determine the real payment to subjects. In the binding situation, the 1st191

generation starts the game with option A = 3600, where one value of D is randomly picked from192

the four possible values of 300, 600, 900 and 1200. Once it is picked, the value of D remains

193

the same for the 1st, 2nd, . . . generations in the sequence for the binding situation. The binding

194

situation is continued as long as the value of X is strictly positive and ends when it becomes zero195

or negative for some generation in the sequence. Therefore, the payoff structures in the decision

196

environment faced by each generation in the sequence for the binding situation are different, while197

the 35 situations in table 1 are uniformly played by all subjects. We call a series of the benchmark

198

experimental procedures in which each subject plays the 36 situations “basic ISDG treatment.”

199

Building upon the basic ISDG treatment, we apply the future ahead and back (FAB) mechanism

200

for the one-person ISDG in 36 situations, which is hereafter called the “FAB treatment.” In the201

FAB treatment, we ask each subject to go through the following steps in each situation. As the 1st

202

step, each subject is asked to imagine that she is in the next generation. From the standpoint of203

the next generation, she is asked to make a request about the choice that she wants the previous

204

generation to choose between options A and B. As the 2nd step, the subject is asked to return to her205

original (actual) position in the sequence, and she makes her final and actual decision by choosing

206

one option, A or B, for that situation. For instance, if a subject is the 5th generation in the sequence207

for one situation, then she is asked to imagine herself in the position of the 6th generation in the

208

sequence and to make a request about the choice that she wants the 5th generation in the sequence209

to make. After that, she is asked to return to her original position in the sequence (i.e., the 5th210

generation) and make her final and actual choice for that situation.
10

211

Each subject was randomly assigned to either the basic ISDG treatment or the FAB treatment212

and played the one-person ISDG with a strategy method in 36 different situations, consisting of213

the 35 fictional situations and a single binding situation. The orders of the 36 situations that each214

subject went through in the one-person ISDG were randomly shuffled to avoid order effects. The

215

experimenters offered the following explanation to the subjects: “One situation out of the 36 sit-

216

uations shall be chosen for the actual experimental payment, following a certain rule. Because

217

you do not know in advance which situation shall be chosen for the payment, please be serious

218

and considerate about a choice in each situation that may affect the subsection subjects, because

219

they will play after you.” However, in reality, to simplify the experimental procedures, the experi-

220

menters predetermined that the choices and outcomes in the binding situation would only be used221

to determine the experimental payment of each subject and to affect the subsequent subjects. In the222

one-person ISDG, one experimental token was calculated and exchanged as 1.5 JPY, and subjects

223

were paid 3000 JPY (≈ 27.8 USD) on average.

224

Social value orientation

225

Subjects’ social preferences are proxied by their social value orientations (SVOs), which were226

identified using the triple dominance measure (Van Lange et al., 1997). This measure consists of227

9 items, each of which contains three choices. For each item, subjects must make one choice over228

how to divide an amount of money between herself and a stranger. For example, each subject faces229

the following three options: A: you get 500 and the other gets 100, B: you get 500 and the other230

gets 500 and C: you get 560 and the other gets 330. A competitive subject is likely to choose option

231

A, maximizing the gap between her own and the stranger’s points (500 − 100 = 400). A prosocial

232

subject has high chances of choosing option B, as it maximizes the joint benefit (500 + 500 =

2331000). An individualistic subject chooses option C by maximizing her payoff without considering234

the other (Van Lange et al., 2007). A subject’s type, i.e., individualistic, competitive or prosocial,

235

is identified by her choices in the SVO game. When a subject makes 6 consistent choice for the236same orientation (i.e., individualistic, competitive or prosocial) out of the 9 items, then she is

11

237

considered to have that orientation or otherwise is “unidentified.” Subjects were randomly paired

238

for the computation of their payoffs based on their performance, and they were paid on average

239

500 JPY (≈ 4.7 USD) in the SVO game.

240

Experimental procedures241

Our experiments were conducted at experimental laboratories at Kochi University of Tech-242

nology. The experiment comprised 27 sessions, each involving 4 ∼ 5 subjects, for a total of 104

243

subjects (55 females and 49 males; average age = 20.4). The observations of 6 subjects in the FAB

244

treatment and 1 subjects in the basic ISDG treatment were dropped because of missing responses

245

in the one-person ISDG, which made the number of subjects in the FAB treatment lower than that246

in the basic ISDG treatment. The subjects were volunteer undergraduate students in various fields

247such as engineering and social science; each subject participated in only one session and was paid

248

in total 4000 JPY (≈ 37 USD) on average. The time of each session varied between the basic

249

ISDG and FAB treatments. One session in the basic ISDG treatment consisted of two parts and250

took approximately 75 minutes. In the first part, subjects completed the one-person ISDG for 40

251

minutes. In the second part, they completed the SVO game and questionnaires for 35 minutes. One

252

session in the FAB treatment also consisted of two parts and took approximately 90 minutes. In

253

the first part, subjects completed the one-person ISDG for 55 minutes—a longer duration than that254of the basic ISDG treatment due to the additional procedures in the FAB (see the 1st and 2nd steps

255of the FAB treatment within the dashed-line box in figure 3). In the second part, they complete the256

SVO game and questionnaires for 35 minutes.

257

Figure 3 presents a flow chart for the procedures of the one-person ISDG, SVO game and258

questionnaire in one session for the basic ISDG and FAB treatments. Upon arriving to the meeting259

room, each subject picked a lottery number that determined her experimental ID. Then, the subjects

260

were taken to two different designated rooms based on their experimental IDs. In the basic ISDG

261

treatment, each subject read the experimental instructions and listened to an oral presentation made262

by an experimenter about the basic one-person ISDG. We use neutral terminologies in the explana-

12

263

tions and avoid using terms such as “generations,” “sustainable” and “unsustainable.” Then, each264

subject completed the 36 situations of the basic one-person ISDG treatment in a shuffled order.

265

Each subject made her decision by choosing between options A and B in each of the situations.

266

When a subject finished making the decisions in all 36 situations, she was informed of the situa-

267

tion number that corresponded to the binding situation, which determined her final payoff from the268

one-person ISDG. Then, subjects moved to a different room to complete the SVO game and fill269

out the questionnaires. After that, the subjects moved to a payment room, where the payment for

270

the SVO game was calculated by randomly pairing subjects together. In the FAB treatment, each271

subject follow the same steps of basic ISDG treatment in addition to a perspective-taking step as272

follows. In each situation, the subject was asked to imagine that she was in the position of the next

273

generation in the sequence. From that position, she made a request to the previous generation on

274

which choice she wanted the previous generation to make. After that, she returned to her original275

position in the sequence and made her final decision between options A and B.
[Figure 3 about here.]

276

277

Screen of one-person ISDG game

278

Figure 4(a) shows the screens that a subject observes while playing the basic ISDG and FAB

279

treatments. The screens for the basic ISDG treatment are displayed and two screens presented in280

each situation. The first screen presents the situation number and appears for 3 seconds. After

281

that, the second screen appears for 15 seconds and presents the history of the previous generations’282

choices at the top of the screen and the options available for the current and subsequent generations

283

in the middle. We call the second screen the “one-person ISDG screen.” During the time in which284

the second screen is displayed, each subject makes her decision by entering the character “A” or

285“B” in another computer display served as a response device. A subject has to go through the above

286

processes by observing the first and second screens in each situation, and the one-person ISDG is287

continued until she finishes making the decisions in all 36 situations.

288

Figure 4(b) presents a series of screens that a subject faces for each situation under the FAB
13

289

treatment in the one-person ISDG. The first screen presents the situation number for 3 seconds.

290

The second screen is the same screen as the second screen in the basic ISDG treatment (i.e., the291

one-person ISDG screen), which is displayed for 4 seconds to familiarize subjects with the decision292

environment. The third screen is displayed to notify the subject that she should imagine herself

293

in the position of the next generation in the sequence and make a request about which choice she

294

wants the previous generation to make between options A and B. Then, the one-person ISDG

295

screen is displayed again for 10 seconds. At that time, the subject must make a request of the296

previous generation by entering the character “A” or “B” in another computer display served as a297

response device. After that, another notice screen appears for 3 seconds to let the subject know that298

she must return to her original position. The one-person ISDG screen appears one more time for299

10 seconds to present the one-person ISDG choices to the subject, and she makes her final choice300

from her original position in the current generation. Subjects make their final choice by entering

301“A” or “B” in the response device, while the request they have made as the next generation kept

302

visible on the display of the response devise. As in the basic ISDG treatment, a subject has to go

303

through the above processes by observing a series of screens in each situation, and the one-person

304

ISDG is continued until she finishes making the decisions in all 36 situations.
[Figure 4 about here.]

305

306

3

Results

307

Table 4 presents the summary statistics of experimental results for the basic one-person ISDG

308

(basic ISDG) and the future ahead and back (FAB) treatments. The number of subjects who par-309

ticipated in the basic ISDG and FAB treatments is 55 and 42 subjects, among which the number

310

of prosocial subjects are 30 and 14, respectively. Each subject went through the 36 situations

311

of the one-person ISDG in both treatments, generating a total number of observations of 1980

312(= 55 × 36) and 1512 (= 42 × 36) in the basic ISDG and the FAB treatment, respectively. Approx-

313

imately 33.7 % and 44.5 % of the generational choices are option B in the basic ISDG and FAB
14

314

treatments, implying that the percentages choosing option A are 66.3 % and 55.5 %, respectively.

315

These results appear to suggest that the FAB treatment is effective at inducing subjects to choose316

the sustainable option. To statistically confirm the difference, we run a chi-square test with the null

317

hypothesis that the frequencies of the observations of subjects choosing options A and B between

318

the basic ISDG and the FAB treatments are the same, and the null hypothesis is rejected at the 1 %319

significance level (χ2 = 42.4, P < 0.01).

320[Table 4 about here.]

321

Figure 5(a) shows the frequency distributions of the percentage per subject of the choice of322

option B in the 36 situations under the basic ISDG and FAB treatments; the percentage represents323

the number of situations in which the subject chooses option B divided by 36 (one subject goes324

through 36 situations and is asked to choose between options A and B in each situation). Fig-325

ure 5(a) demonstrates that the distribution under the basic ISDG treatment is skewed to the left, as326

the peak of the distribution is around 0 % to 10 %, indicating that a considerable portion of subjects

327

do not choose option B at all or only around 10 % of the time. On the other hand, the distribu-

328

tion under the FAB treatment is flattened, with more concentration of around 50 % as well as a329

reduction in the peak’s height at 0 %. We also draw the corresponding boxplots in figure 5(b) for330

the same distributions under the basic ISDG and FAB treatments, corroborating that the location

331

parameters, such as medians and quantiles, for the percentage of choices of option B per subject in332

the FAB treatment are generally higher than those in the basic ISDG. We also run a Mann-Whitney333

test with the null hypothesis that the distributions of the percentage of choices of option B per sub-334

ject between the basic ISDG and FAB treatments are the same. The null hypothesis is rejected335

at the 10 % significance level (z = −1.79, P = 0.072), implying that subjects are more likely to336choose option B in the FAB treatment than in the basic ISDG treatment.

337[Figure 5 about here.]

338

Table 5 displays the percentages of choices of option B for prosocial and proself subjects in339

each of the basic ISDG and FAB treatments by pooling observations from subjects. The percent15

340

ages of choices of option B made by prosocial subjects under the basic ISDG and FAB treatments

341(44.72 % and 55.56 %) are higher than those made by proself subjects (20.44 % and 38.99 %). The

342

result suggests that prosocial subjects tend to choose option B more than proself subjects, which343

is consistent with the literature (Gintis et al., 2003, Camerer and Fehr, 2006). At the same time,344

the percentages of choices of option B made by prosocial and proself subjects under the FAB

345

treatments (55.56 % and 38.99 ) are higher than those under the basic ISDG treatment (44.72 %346

and 20.44 %). We run a chi-square test with the null hypothesis that the frequency distributions of347

choosing option B among prosocial and proself subjects are the same between the basic ISDG and348

FAB treatments. The result rejects the null hypothesis at the 1 % level (χ2 = 129.6, P < 0.01),

349

demonstrating that the FAB treatment appears to be effective at inducing subjects to choose option

350

B, irrespective of subjects’ value orientations.

351[Table 5 about here.]352

To quantitatively characterize the marginal impact of subjects’ SVO and the prospective and353

retrospective factors on subjects’ choices in the one-person ISDG, panel logit regressions are ap-

354

plied to our experimental data. In the regressions, a dummy variable capturing the subject’s binary

355

choice between options A and B in each situation is specified as the dependent variable, taking a356

choice for option A as the base group. On the other hand, the SVO, the percentage of option A

357) in each situation and the interactionin the sequence history, FAB treatment & the IS index ( XD358

terms of these variables are specified as the independent variables. Since one subject provides 36359

observations in our experiment, the data are considered to possess a panel-data structure, where a360

panel unit is a subject and a time unit is one situation out of the 36. Since a time-invariant indepen-

361

dent variable (the SVO) is included as one of the independent variables in the analysis, we apply a362

random-effects panel logit regression (Wooldridge, 2010, 2019). With these model specifications,363

we not only estimate the model but also calculate the marginal effect of an independent variable364

on the likelihood of a subject choosing option B (Wooldridge, 2010). Table 6 summarizes the365

estimation results and the associated marginal probabilities from the three panel logit regressions.

16

366

In model 1 of table 6, we consider the basic independent variables, consisting of the prosocial

367

dummy, the percentage of option A choices in the sequence history, the FAB treatment dummy368

and the IS index, finding that all the coefficients and marginal probabilities of these variables are369

statistically significant at 1 % level. All the independent variables have a positive relationship with370

the probability of choosing option B except the percentage of option A choices in the sequence371

history. More specifically, subjects in the FAB treatment (prosocial subjects) are 15.8 % (22.4 %)372

more likely to choose option B than those in the basic ISDG treatment (proself subjects), while373

an increase of one unit in the IS index leads subjects to choose option B more often by 0.2 %.

374

On the other hand, subjects are 0.97 % less likely to choose option B as the percentage of option

375

A choices in the sequence history increases by 10 %. These results indicate that prosociality and376

the FAB treatment are effective at maintaining IS, which is in line with previous studies on group377

behaviors. For example, Hauser et al. (2014) indicate that a group tends to be sustainable when a378

majority are prosocial individuals, while Kamijo et al. (2017), Shahrier et al. (2017b) and Timilsina379

et al. (2019) show that the introduction of some mechanisms can have positive effects on group380

behaviors for IS.

381

In models 2 and 3, we include interaction terms for the FAB treatment dummy & IS index and382

the FAB treatment dummy & the percentage of option A choices in the sequence history. The

383

estimation results remain qualitatively the same as those in model 1, while the interaction term of384

the FAB treatment dummy & IS index (FAB treatment dummy & percentage of option A choices385

in history) is statistically significant at the 1 % level (insignificant) with a negative sign in models

386

2 and 3 (in model 3). The results suggest that subjects behave differently under the basic ISDG

387

and FAB treatments in response to the IS index, while they do not respond to the percentage of388

option A choices in the sequence history. Specifically, subjects tend to choose option A as the IS

389

index decreases, reflecting the result of model 1 in table 6. However, the results associated with the390

interaction terms in models 2 and 3 suggest that the FAB treatment prevents subjects from choosing

391

option A in response to a decrease in the IS index, making the treatment effective as sustainability

392

becomes endangered. We apply several other models including different specifications and other

17

393

interaction terms as robustness checks, yielding qualitatively similar results to those in models 1, 2

394

and 3 of table 6.

395[Table 6 about here.]396

To quantitatively demonstrate how subjects behave differently under the basic ISDG and FAB

397

treatments, we calculate the predicted probabilities of a subject choosing option B over the IS index398

in each treatment based on the estimation result of model 2 in table 6. The predicted probabilities399

are calculated by changing the IS index, holding other independent variables fixed at the sample

400

means. Because the interaction term of the FAB treatment dummy & IS index is estimated to be

401

negative in model 2, the predicted probabilities under the FAB treatment should be larger than402

those under the basic ISDG treatment as the IS index decreases. Figure 6 displays the predicted403

probabilities over the IS index under basic ISDG and FAB treatments represented by the solid and404

dashed lines, respectively. As seen in figure 6, the trajectories over the IS index are clearly different

405

between the basic ISDG and FAB treatments. The predicted probability under the basic ISDG

406

(solid line) increases in the IS index ranging from 0.27 to 0.41, while that under FAB (dashed line)407

is almost flat or only slightly decreases in the IS index ranging from 0.47 to 0.44. These results in408

figure 6 confirm that subjects tend to choose option A under the basic ISDG when the IS index of a409

prospective factor is low. However, the introduction of the FAB can induce subjects to consistently

410

or stably choose option B irrespective of the values of the IS index.

411[Figure 6 about here.]412

Next, we characterize how subjects respond to the retrospective and prospective factors in the413

ISD within a single framework. To this end, two heat maps are drawn to present the predicted414

probabilities of choosing option B under the basic ISDG and FAB treatments on the domain of the415

percentage of option A choices in the sequence history and the IS index (figure 7). The predicted416

probabilities are calculated based on the estimation results in model 3 of table 6. The predicted417

probabilities are calculated in the same way as in figure 6 by holding other independent variables
18

418

fixed at the sample means. In addition, as a robustness check, they are calculated based on the419

estimation results in model 2. We confirm that they remain qualitatively the same as in figure 7.

420

The vertical (horizontal) axis represents the percentage of option A choice in the sequence history421(IS index), and it varies from 0 to 1 (from 0 to 36). The density of the black color in each location of422

the domain reflects the predicted probability of choosing option B; the darker the color, the higher

423

is the predicted probability. The scale, ranging from 23 % to 52 %, is shown on the right-hand side424

in figure 7.

425

The predicted probabilities under the basic ISDG in figure 7 corroborate that subjects are more426

likely to choose option A as the IS index (the percentage of option A in history) becomes lower

427(higher), consistent with the results in table 6 and figure 6. This is quite intuitive in the sense that428

people in the current generation tend to give up being sustainable when previous generations chose429

such unsustainable options that it may be too late or the situation faced by the current generation430

too grave for sustainability to be improved. However, the predicted probabilities under the FAB

431

treatment in figure 7 show that subjects tend to choose option B stably and consistently, being more

432

invariant against changes in either the IS index or the percentage of option A in history than the433

probabilities in the basic ISDG. In fact, the predicted probabilities under the FAB treatment range

434

from 40 % to 52 %, demonstrating that asking subjects to take the position of the next generation

435

fundamentally affects their choices between options A and B in response to the retrospective and436

prospective factors in the ISD. Overall, the regression results in table 6, figures 6 and 7 establish

437

that people react to the retrospective and prospective factors in an intuitive way under the basic

438

ISDG, implying that people in the current generation choose unsustainability if previous genera-

439

tions betray them and it seems too late for the current situation to be made sustainable. However,440

the FAB treatment is demonstrated to prevent people from making such choices.

441[Figure 7 about here.]

19

442

4

Discussion

443

Some behavioral scientists and economists have recently emphasized the importance of analyz-444

ing economic, cognitive and noncognitive factors to characterize human behaviors at the individual

445

and group levels in a single framework (Borghans et al., 2008, Izuma et al., 2010, Lindqvist and446

Vestman, 2011, Acharya et al., 2018, Chen et al., 2019). Our experiments are considered to system-

447

atically examine individual behaviors in response to these factors under the ISD in the sense that448

prospective and retrospective factors and social preferences are known to correspond to economic449

and noncognitive factors, respectively (Borghans et al., 2008). Overall, the results are interpreted450

to demonstrate that the economic factors of the IS index and the percentage of option A choices in451

the sequence history as well as social preferences have impacts on individual behaviors in the ISD

452

in an intuitive way, consistent with the literature on the dictator and other games. In particular, a453

social preference of prosociality is identified as one influential factor in subjects choosing the sus-454

tainable option in the ISDG, and a similar result is consistently confirmed in common pool resource455

and public goods games (Hauser et al., 2014, Kamijo et al., 2017, Shahrier et al., 2017b, Timilsina

456

et al., 2017). However, people’s social preferences are claimed to be determined at young ages457

by the culture and social norms of societies, remaining fixed when they become adults. There-

458

fore, these preferences are considered impossible to change with policy or external interventions

459(Ockenfels and Weimann, 1999, Koch et al., 2011, Carlsson et al., 2014).

460

An important question here is why and how the FAB mechanism affects individual behaviors

461

in the ISD. Although we admit that there are several possible explanations, we conjecture that the462

FAB mechanism affects a cognitive factor in human-decision processes (Konow, 2000). In partic-

463

ular, Cooper (2007) argues that some dissonance in human cognition, that is, cognitive dissonance,464

may influence human decisions when individuals experience two or more different psycholog-

465

ical and/or economic representations in a decision-making situation, such as a social dilemma466

where two representations conflict with one another regarding interests and payoffs. Since the467

FAB mechanism requires each individual to experience or role-play two representations of the468

current and future generations where each generation’s interest conflicts, we argue that cognitive
20

469

dissonance in subjects’ decision-making processes might have been triggered and augmented to470

enhance sustainable choices over the outcomes observed in the basic ISDG.

471

Another possible explanation is that the FAB mechanism might affect not only cognitive factors

472

but also noncognitive factors in human decision-making processes. Some economists, psycholo-

473

gists and neuroscientists demonstrate that empathy is a primary factor in characterizing prosocial

474

behaviors in several different games and settings and is known to play a part in cognitive and475

noncognitive factors (Batson et al., 1988, Snow, 2000, de Vignemont and Singer, 2006, Decety

476

and Ickes, 2009, Mathur et al., 2010, Tusche et al., 2016). In economics, Andreoni and Rao (2011)

477

and Andreoni et al. (2017) demonstrate that prosocial donations are increased in the DG by letting

478

one subject role-play both the dictator and the receiver. They argue that empathy from the dictator479

to the receiver is enhanced by such role-playing and is a key means of promoting prosocial be-480

haviors. Furthermore, psychologists argue that empathy can be a main factor in a person making

481

decisions to the benefit of others or engaging in prosocial behaviors even at a personal cost (Batson482

et al., 1988). In the ISDG, choosing the sustainable option is equivalent to benefiting others at a483

personal cost. Thus, the FAB mechanism may be considered to enhance the empathy of the current

484

generation through its role-playing of the next generation in the ISD.

485

Democracy and capitalism have become two major social institutions that have been adopted

486

by many countries in the world over the last few decades. However, some social scientists ar-487

gue that these institutions are not future-oriented but present-oriented in their nature (Wolf, 2008,

488

Saunders, 2014). The decision-making processes under democracy and capitalism rarely require489

people to take the standpoint of future generations, even for intergenerational problems such as

490

climate change and government debt, and the decisions end up being mostly made from the cur-491

rent generation’s standpoint (Milinski et al., 2006, Ekeli, 2009, Christiano, 2010, Mulgan, 2011,492

Steffen et al., 2015, Hansen and İmrohoroğlu, 2016, Steffen et al., 2018). Our findings imply that493

IS problems will worsen in the absence of a new mechanism to affect people’s cognitive and/or

494

noncognitive processes. They also suggest that the FAB mechanism is one approach to nudge the495current generation toward being more future-oriented by asking her to role-play future generations

21

496

and send a request to the current generation. We believe that institutionalization of the FAB mecha-

497

nism is one possible resolution of the ISD, affecting people’s cognitive and noncognitive factors by498

propagating an idea of “putting oneself in future generations’ shoes” at the individual, household

499

and society levels. Introducing the FAB mechanism will be more likely to lead to better outcomes500

for sustainability than introducing nothing.

501

5Conclusion

502

This paper has addressed the intergenerational sustainability dilemma (ISD) and how individu-

503

als behave under the ISD. We hypothesize that the economic factor (the prospective factor, i.e., the504

IS index) and histories of previous generations’ behaviors (i.e., the retrospective factor) affect the505

decisions made by the current generation that impact herself and future generations in the ISD. To

506

examine the hypothesis, a basic one-person ISD game (ISDG) treatment was designed and imple-

507

mented with a strategy method in a laboratory experiment. In addition, the future ahead and back

508(FAB) mechanism was instituted as a possible solution for the ISD. The experimental results in509

the basic ISDG treatment show that people are more likely to choose the unsustainable option as

510

sustainability is increasingly endangered (i.e., the IS index is low and/or the percentage of previous

511

generations that chose the unsustainable option is high). In other words, people are said to react to512retrospective and prospective factors in an intuitive way, in that no one chooses to be sustainable

513

after previous generations have betrayed the current generation or if it appears too late to do any-

514

thing about the current situation. On the other hand, the FAB mechanism is identified to positively

515

influence individual behaviors for maintaining sustainability even in such an endangered situation.

516

We argue that a possible explanation for the effectiveness of the FAB mechanism is an increase in

517

cognitive dissonance and/or the associated empathy toward future generations.

518

Finally, we note some limitations and future avenues of research. Our research does not address

519

the detailed processes and channels of how and why the FAB mechanism affects individual behav-

520

iors in the ISD. To address these issues, two approaches can be suggested: (i) a neuropsychological

22

521

approach and (ii) qualitative and deliberative interviews. The neuropsychological approach should522

allow the collection of various psychological scales and neuroimages to examine the possible pro-523

cesses and channels engaged when individuals make decisions under the FAB mechanism in the524

ISDG. In this way, a specific factor that influences individual behaviors may be identified (Vander-

525

wolf, 1998, Watkins and Goodwin, 2019). Qualitative interviews and deliberative approaches have526

already been used by some economists and psychologists (Corbin and Strauss, 2014, Schulz et al.,527

2014, Rand, 2016, Palfrey et al., 2017). Individual interviews or group deliberations are conducted528

to clarify how individuals and groups reach decisions. Specifically, qualitative content analyses

529

and text mining can be applied to untangle the detailed changes in individual behaviors that occur

530

under the FAB mechanism in the ISDG. These caveats notwithstanding, it is our belief that this531

paper is an important first step in understanding individual behaviors in the ISD and suggests a

532

possible mechanism to enhance sustainability.

23References
Acharya, A., Blackwell, M., and Sen, M. (2018). Explaining preferences from behavior: A cognitive dissonance approach. Journal of politics, 80:400–411.
Andreoni, J. and Rao, J. (2011). The power of asking: How communication affects selfishness,
empathy, and altruism. Journal of public economics, 95:513–520.
Andreoni, J., Rao, J., and Trachtman, H. (2017). Avoiding the ask: A field experiment on altruism,
empathy, and charitable giving. Journal of political economy, 125:625–653.
Bamber, J., Oppenheimer, M., Kopp, R., Aspinall, W., and Cooke, R. (2019). Ice sheet contributions to future sea-level rise from structured expert judgment. Proceedings of the National
Academy of Sciences of the United States of America, 116:11195–11200.
Bardsley, N. (2000). Control without deception: Individual behaviour in free-riding experiments
revisited. Experimental economics, 3:215–240.
Bardsley, N. (2007). Dictator game giving: Altruism or artefact?
11:122–133.

Experimental economics,

Bardsley, N. and Sausgruber, R. (2005). Conformity and reciprocity in public good provision.
Journal of economic psychology, 26:664–681.
Barkenbus, J. (2010). Eco-driving: An overlooked climate change initiative. Energy Policy,
38:762–769.
Batson, C., Dyck, J., Brandt, J., Batson, J., Powell, A., McMaster, M., and Griffitt, C. (1988).
Five studies testing two new egoistic alternatives to the empathy-altruism hypothesis. Journalof personality and social psychology, 55:52–77.
Ben-Ner, A., Putterman, L., Kong, F., and Magan, D. (2004). Reciprocity in a two-part dictator
game. Journal of economic behavior and organization, 53:333–352.
Bohnet, I. and Frey, B. (1999). The sound of silence in prisoner’s dilemma and dictator games.
Journal of economic behavior and organization, 38:43–57.
Bolton, G. and Ockenfels, A. (2000). ERC: A theory of equity, reciprocity, and competition.
American economic review, 90:166–193.
Borghans, L., Duckworth, A., Heckman, J., and ter Weel, B. (2008). The economics and psychology of personality traits. Journal of human resources, 43:972–1059.
Camerer, C. and Fehr, E. (2006). When does ”economic man” dominate social behavior? Science,
311:47–52.
Carlsson, F., Johansson-Stenman, O., and Nam, P. (2014). Social preferences are stable over long
periods of time. Journal of public economics, 117:104–114.

24

Cason, T. and Mui, V.-L. (1998). Social influence in the sequential dictator game. Journal ofmathematical psychology, 42:248–265.
Chen, Y., Feng, S., Heckman, J., and Kautz, T. (2019). Sensitivity of self-reported noncognitive
skills to survey administration conditions. Proceedings of the National Academy of Sciences of
the United States of America, 117:931–935.
Cherry, T., Frykblom, P., and Shogren, J. (2002). Hardnose the dictator. American economic
review, 92:1218–1221.
Christiano, T. (2010). The constitution of equality: Democratic authority and its limits. Oxford
University Press.
Cooper, J. (2007). Cognitive dissonance: Fifty years of a classic theory. SAGE Publications Ltd.
Corbin, J. and Strauss, A. (2014). Basics of qualitative research: Techniques and procedures fordeveloping grounded theory. Sage publications.
Dana, J., Cain, D., and Dawes, R. (2006). What you don’t know won’t hurt me: Costly (but quiet)
exit in dictator games. Organizational behavior and human decision processes, 100:193–201.
Dawes, R. (1980). Social dilemmas. Annual review of psychology, 31:169–193.
de Vignemont, F. and Singer, T. (2006). The empathic brain: How, when and why? Trends in
cognitive sciences, 10:435–441.
Decety, J. and Ickes, W., editors (2009). The social neuroscience of empathy. The MIT Press.
Diekmann, A. (2004). The power of reciprocity: Fairness, reciprocity, and stakes in variants of the
dictator game. Journal of conflict resolution, 48:487–505.
Ehrlich, P., Kareiva, P., and Daily, G. (2012). Securing natural capital and expanding equity torescale civilization. Nature, 486:68–73.
Ekeli, K. (2009). Constitutional experiments: Representing future generations through submajority
rules. Journal of political philosophy, 17:440–461.
Engel, C. (2011). Dictator games: A meta study. Experimental economics, 14:583–610.
Fehr, E. and Schmidt, K. (1999). A theory of fairness, competition, and cooperation. Quarterly
journal of economics, 114:817–868.
Fischer, M., Irlenbusch, B., and Sadrieh, A. (2004). An intergenerational common pool resource
experiment. Journal of environmental economics and management, 48:811–836.
Gintis, H., Bowles, S., Boyd, R., and Fehr, E. (2003). Explaining altruistic behavior in humans.
Evolution and human behavior, 24:153–172.
González-Ricoy, I. and Gosseries, A. (2016). Institutions for future generations. Oxford University
Press.
25

Greenhalgh, C. (2005). Why does market capitalism fail to deliver a sustainable environment andgreater equality of incomes? Cambridge journal of economics, 29:1091–1109.
Hansen, G. and İmrohoroğlu, S. (2016). Fiscal reform and government debt in Japan: A neoclassical perspective. Review of economic dynamics, 21:201–224.
Hauser, O., Rand, D., Peysakhovich, A., and Nowak, M. (2014). Cooperating with the future.
Nature, 511:220–223.
Herne, K., Lappalainen, O., and Kestila-Kekkonen, E. (2013). Experimental comparison of direct,
general, and indirect reciprocity. Journal of socio-economics, 45:38–46.
Hoffman, E., McCabe, K., Shachat, K., and Smith, V. (1994). Preferences, property rights, andanonymity in bargaining games. Games and economic behavior, 7:346–380.
Hoffman, E., McCabe, K., and Smith, V. (1996). Social distance and other-regarding behavior in
dictator games. American economic review, 86:653–660.
Izuma, K., Matsumoto, M., Murayama, K., Samejima, K., Sadato, N., and Matsumoto, K. (2010).
Neural correlates of cognitive dissonance and choice-induced preference change. Proceedingsof the National Academy of Sciences of the United States of America, 107:22014–22019.
Kamijo, Y., Komiya, A., Mifune, N., and Saijo, T. (2017). Negotiating with the future: Incorporating imaginary future generations into negotiations. Sustainability science, 12:409–420.
Koch, J., Helbach, C., Ockenfels, A., and Weimann, J. (2011). Still different after all these years:
Solidarity behavior in East and West Germany. Journal of public economics, 95:1373–1376.
Koch, J. B., Riechmann, T., and Weimann, J. (2017). The dynamics of behavior in modified
dictator games. PLoS ONE, 12:e0176199.
Konow, J. (2000). Fair shares: Accountability and cognitive dissonance in allocation decisions.
American economic review, 90:1072–1092.
Krznaric, R. (2020). The good ancestor. Ebury Publishing.
Lenton, T., Rockström, J., Gaffney, O., Rahmstorf, S., Richardson, K., Steffen, W., and Schellnhuber, H. J. (2019). Climate tipping points-too risky to bet against. Nature, 575:592–595.
Lindqvist, E. and Vestman, R. (2011). The labor market returns to cognitive and noncognitive
ability: Evidence from the swidish enlistment. American economic journal: Applied economics,
3:101–128.
List, J. (2007). On the interpretation of giving in dictator games. Journal of political economy,
115:482–493.
List, J. and Cherry, T. (2008). Examining the role of fairness in high stakes allocation decisions.
Journal of economic behavior and organization, 65:1–8.

26

Macro, D. and Weesie, J. (2016). Inequalities between others do matter: Evidence from multiplayer
dictator games. Games, 7:11.
Mantilla, C. (2015). Communication networks in common-pool resource games: Field experimental evidence. Journal of economic behavior and organization, 118:215–226.
Mason, C. and Phillips, O. (1997). Matigating the tragedy of the commons through cooperation:
An experimental evaluation. Journal of environmental economics and management, 34:148–
172.
Mathur, V., Harada, T., Lipke, T., and Chiao, J. (2010). Neural basis of extraordinary empathy andaltruistic motivation. NeuroImage, 51:1468–1475.
Milinski, M., Semmann, D., Krambeck, H., and Marotzke, J. (2006). Stabilizing the Earth’s climate
is not a losing game: Supporting evidence from public goods experiments. Proceedings of the
National Academy of Sciences of the United States of America, 103:3994–3998.
Mulgan, T. (2011). Ethics for a broken world: Imagining philosophy after catastrophe. McGill
Queens Univ.
Novakova, J. and Flegr, J. (2013). How much is our fairness worth? The effect of raising stakes
on offers by proposers and minimum acceptable offers in dictator and ultimatum games. PLoS
ONE, 8:e60966.
Ockenfels, A. and Weimann, J. (1999). Types and patterns: An experimental East-West-German
comparison of cooperation and solidarity. Journal of public economics, 71:275–287.
Ostrom, E. (1990). Governing the commons: The evolution of institutions for collective action.
Cambridge University Press.
Ozono, H., Kamijo, Y., and Shimizu, K. (2020). The role of peer reward and punishment for public
goods problems in a localized society. Scientific reports, 10.
Palfrey, T., Rosenthal, H., and Roy, N. (2017). How cheap talk enhances efficiency in thresholdpublic goods games. Games and economic behavior, 101:234–259.
ping Chen, X. and Komorita, S. (1994). The effects of communication and commitment in a public
goods social dilemma. Organizational Behavior and Human Decision Processes, 60:367–386.
Raihani, N., Mace, R., and Lamba, S. (2013). The effect of $1, $5 and $10 stakes in an online
dictator game. PLoS ONE, 8:e73131.
Rand, D. (2016). Cooperation, fast and slow: Meta-analytic evidence for a theory of social heuristics and self-interested deliberation. Psychological science, 27:1192–1206.
Saunders, B. (2014). Democracy and future generations. Philosophy and public issues, 4:11–28.
Schulz, J., Fischbacher, U., Thoni, C., and Utikal, V. (2014). Affect and fairness: Dictator games
under cognitive load. Journal of economic psychology, 41:77–87.
27Selten, R. (1967). Die strategiemethode zur erforschung des eingeschränkt rationalen verhaltens
imrahmen eines oligopolexperiments. In Sauermann, H., editor, Beiträge zur Experimentellen
Wirtschaftsforschung, pages 136–168. Tübingen: JCB Mohr (Paul Siebeck).
Shahrier, S., Kotani, K., and Saijo, T. (2017a). Intergenerational sustainability dilemma and apotential solution: Future ahead and back mechanism. Research Institute for Future Design,
Kochi University of Technology, Working paper SDES-2017-9.
Shahrier, S., Kotani, K., and Saijo, T. (2017b). Intergenerational sustainability dilemma and thedegree of capitalism in societies: A field experiment. Sustainability science, 12:957–967.
Sherstyuk, K., Tarui, N., Ravago, M., and Saijo, T. (2016). Intergenerational games with dynamic
externalities and climate change experiments. Journal of the association of environmental andresource economists, 3:247–281.
Snow, N. (2000). Empathy. American philosophical quarterly, 37:65–78.
Steffen, W., Richardson, K., Rockstrom, J., Cornell, S. E., Fetzer, I., Bennett, E. M., Biggs, R.,
Carpenter, S. R., de Vries, W., de Wit, C. A., Folke, C., Gerten, D., Heinke, J., Mace, G. M.,
Persson, L. M., Ramanathan, V., Reyers, B., and Sorlin, S. (2015). Planetary boundaries: Guiding human development on a changing planet. Science, 347:1–9.
Steffen, W., Rockström, J., Richardson, K., Lenton, T. M., Folke, C., Liverman, D., Summerhayes,
C. P., Barnosky, A. D., Cornell, S. E., Crucifix, M., Donges, J. F., Fetzer, I., Lade, S. J., Scheffer,
M., Winkelmann, R., and Schellnhuber, H. J. (2018). Trajectories of the Earth system in theanthropocene. Proceedings of the National Academy of Sciences of the United States of America,
115:8252–8259.
Strombach, T., Weber, B., Hangebrauk, Z., Kenning, P., Karipidis, I. I., Tobler, P. N., and Kalenscher, T. (2015). Social discounting involves modulation of neural value signals by temporoparietal junction. Proceedings of the National Academy of Sciences of the United States of America,
112:1619–1624.
Thompson, D. (2010). Representing future generations: Political presentism and democratic
trusteeship. Critical review of international social and political philosophy, 13:17–37.
Timilsina, R., Kotani, K., and Kamijo, Y. (2017). Sustainability of common pool resources. PLoS
ONE, 12:e0170981.
Timilsina, R., Kotani, K., Nakagawa, Y., and Saijo, T. (2019). Accountability as a resolution forintergenerational sustainability dilemma. Research Institute for Future Design, Kochi Universityof Technology, Working paper SDES-2019-2.
Tusche, A., Bockler, A., Kanske, P., Trautwein, F., and Singer, T. (2016). Decoding the charitablebrain: Empathy, perspective taking, and attention shifts differentially predict altruistic giving.
Journal of neuroscience, 36:4719–4732.

28

Van Lange, P., Bekkers, R., Schuyt, T., and Vugt, M. (2007). From games to giving: Social value
orientation predicts donations to noble causes. Basic and applied social psychology, 29:375–
384.
Van Lange, P., Bruin, E., Otten, W., and Joireman, J. (1997). Development of prosocial, individualistic, and competitive orientations: Theory and preliminary evidence. Journal of personality
and social psychology, 73:733–746.
Vanderwolf, C. (1998). Brain, behavior, and mind: What do we know and what can we know?
Neuroscience & biobehavioral reviews, 22:125–142.
Watkins, H. and Goodwin, G. (2019). Reflecting on sacrifices made by past generations increases
a sense of obligation towards future generations. Forthcoming in Personality and social psychology bulletin.
Westley, F., Olsson, P., Folke, C., Homer-Dixon, T., Vredenburg, H., Loorbach, D., Thompson, J.,
Nilsson, M., Lambin, E., Sendzimir, J., Banerjee, B., Galaz, V., and van der Leeuw, S. (2011).
Tipping toward sustainability: Emerging pathways of transformation. AMBIO, 40:762–780.
Wolf, C. (2008). Justice and intergenerational debt. Intergenerational justice review, 2:13–17.
Wooldridge, J. (2010). Econometric analysis of cross section and panel data. MIT Press, 2 edition.
Wooldridge, J. (2019). Introductory econometrics. South-Western College Publishing, 7 edition.

29

List of Tables
1
2
3

4
5
6

The 35 situations that each subject plays in one-person ISDG . . . . . . . . . . . .
Detailed descriptions with human-shaped icon displays in history from 1 to 21
situations within the 35 ones as seen by each subject . . . . . . . . . . . . . . . .
Detailed descriptions with human-shaped icon displays in history from 22 to 35
situations within the 35 ones as seen by each subject (continuum from where weleft off in table 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Summery statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The percentages of option B for prosocial subjects in the basic ISDG and FAB
treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Panel logit models with a dummy variable of the binary choice between options A
and B as the dependent variable, with the choice of option A is the base group . . .

30

31
32

33
34
35
36

Table 1: The 35 situations that each subject plays in one-person ISDG
Situations% ofoption A
in history

X

D

X
D

# of
generations
in history

Current generation
Position1 Option A

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
1

0
0
0
0
0
0.25
0.25
0.25
0.33
0.33
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.63
0.67
0.67
0.67
0.7
0.7
0.75
0.75
0.75
0.75
0.78
1
1
1
1
1
1

3600
3600
3600
3600
3600
2700
1800
3400
0
1200
0
0
1200
2400
2400
2400
3400
3200
2600
1200
3000
2600
1500
2200
0
900
1800
3300
0
1800
1800
2400
3300
3000
3500

1800
1200
900
300
100
900
300
200
1200
600
1800
900
1200
600
600
300
200
100
200
1200
300
100
300
100
300
900
600
100
200
1800
900
1200
300
200
100

2
3
4
12
36
3
6
17
0
2
0
0
1
4
4
8
17
32
13
1
10
26
5
22
0
1
3
33
0
1
2
2
11
15
35

0
5
7
0
9
4
8
4
9
12
4
8
4
4
4
8
2
8
8
3
3
15
10
20
16
4
4
4
23
1
2
1
1
3
1

1
6
8
1
10
5
9
5
10
13
5
9
5
5
5
9
3
9
9
4
4
16
11
21
17
5
5
5
24
2
3
2
2
4
2

3600
3600
3600
3300
3600
2700
1800
3400
0
1200
0
0
1200
2400
2400
2400
3400
3200
2600
1200
3000
2600
1500
2200
0
900
1800
3300
0
1800
1800
2400
3300
3000
3500

Option B
1800
2400
2700
3300
3500
1800
1500
3200
-1200
600
-1800
-900
0
1800
1800
2100
3200
3100
2400
0
2700
2500
1200
2100
-300
0
1200
3200
-200
0
900
1200
3000
2800
3400

This represents current generation position in a situation. For example, in situation number 23, the number of generations in history is
10, thus current generation position is the 11th generation.

31

Table 2: Detailed descriptions with human-shaped icon displays in history from 1 to 21 situations
within the 35 ones as seen by each subject

32

Table 3: Detailed descriptions with human-shaped icon displays in history from 22 to 35 situations
within the 35 ones as seen by each subject (continuum from where we left off in table 2)33

Table 4: Summery statistics
Basic ISDG treatment

FAB treatment55
30 (55 %)
25 (45 %)36
19801313 (66.3 %)667 (33.7 %)42
14 (33 %)
28 (67 %)361512
839 (55.5 %)
673 (44.5 %)Total No. of subjects
No. of prosocial subjects
No. of proself subjects
No. of situations per subject
Total number of observations
Observations of choosing option A
Observations of choosing option B

34

Table 5: The percentages of option B for prosocial subjects in the basic ISDG and FAB treatments
Percentages of option B choices
Basic ISDG treatment

FAB treatment

Overall

Prosocial483
44.72 % (≈ 1080)

280
55.56 % (≈ 504)

763
48.17 % (≈ 1584)

Proself

20.44 % (≈ 184
)
900

393
577
38.99 % (≈ 1008
) 30.24 % (≈ 1908)

Subtotal

667
33.69 % (≈ 1980)

673
44.51 % (≈ 1512
) 38.37 % (≈ 1340
)
3492

35

36



X 5
D

0.224∗∗∗(0.058)−0.097∗∗∗(0.021)0.158∗∗∗(0.059)0.002∗∗∗(0.0006)

3492
51.98∗∗∗

1.42∗∗∗(0.369)−0.615∗∗∗(0.131)1.001∗∗∗(0.370)0.014∗∗∗(0.003)0.225∗∗∗(0.058)−0.095∗∗∗(0.021)0.159∗∗∗(0.058)0.002∗∗∗(0.0006)-

Marginal effects

3492
68.43∗∗∗

1.431∗∗∗(0.371)−0.602∗∗∗(0.131)
1.337∗∗∗(0.381)0.028∗∗∗(0.005)−0.032∗∗∗(0.008)Marginal effects1 Coefficients

Model 20.225∗∗∗(0.058)−0.095∗∗∗(0.021)0.159∗∗∗(0.058)0.002∗∗∗(0.0006)-

Marginal effects

3492
68.44∗∗∗

1.431∗∗∗(0.371)−0.599∗∗∗(0.175)
1.341∗∗∗(0.405)0.028∗∗∗(0.005)−0.032∗∗∗(0.008)-0.007(0.265)

Coefficients

Model 3***, **, * significant at the 1 %, 5 % and 10 % levels, respectively.
Standard errors in parentheses.
1 Calculated at the same means of the independent variables.
2 Prosocial is a dummy variable for SVO, taking 1 if the subject is categorized as prosocial and 0 otherwise.
3 % of choice A in history is the percentage of option A choices in the sequence history, taking a value from 0 to 1 reflecting the ratio of the number of previous generations that chose
option A to the total number of previous generations in the sequence history for each situation.
4 FAB treatment is a dummy variable taking 1 if the subject is in the FAB treatment and 0 otherwise.
5 IS index is an ordered categorical variable for the ratio of X , taking a value from 0 to 36.
D

Observations
Wald χ2

FAB × % of option A in history

FAB × IS index

IS index

FAB treatment4% of option A in history3

Prosocial2

Coefficients

Model 1

Table 6: Panel logit models with a dummy variable of the binary choice between options A and B as the dependent variable, with the
choice of option A is the base group

List of Figures
1
2
3
4
5
6
7

Scatter plot for the distribution of the 35 situations in our game . . . . . . . . . . .
The 23rd situation of the one-person ISDG as seen by each subject . . . . . . . . .
Procedures of the one-person ISDG, SVO game and questionnaire in one session .
The screen of the ISDGs as seen by each subject in chronological order . . . . . .
The distribution of the percentage of choices of option B per subject in the basic
ISDG and FAB treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Predicted probability of choosing option B for subjects in the basic ISDG and FAB
treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heat map of the predicted probability of choosing sustainable option B on the. . . .
domain of the percentage of option A choices in the sequence history and X
D

37

38
39
40
41
42
43
44

Percentage of choice A in history

Figure 1: Scatter plot for the distribution of the 35 situations in our game
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0

6
12
18
24
30
Intergenerational sustainability index (X/D)

38

36

Figure 2: The 23rd situation of the one-person ISDG as seen by each subject(a) The first screen(b) The second screen

39Figure 3: Procedures of the one-person ISDG, SVO game and questionnaire in one session

Instruction for the one-person ISDG
4~5 subjects are gathered in a room.

Each subject picks a lottery to determine her ID

Subjects are divided into two groups and sent to two rooms based on their IDs

Basic one-person ISDG treatment

Future ahead and back treatment

 Each subject goes through 36 situations in a shuffledorder: In each situation, each subject makes her
decision by choosing between options A and B.

 Each subject goes through 36 situations in a shuffledorder: In each situation, each subject goes through thefollowing two steps:
1st step: each subject is asked to imagine that
she is in the next generation in the sequence andmakes a request about the choice she wants theprevious generation to choose between options
A and B from the standpoint of the next
generation.
2nd step: she returns to her original position in
the sequence and makes her final decision bychoosing between options A and B the same
way as the basic ISDG treatment.
 After finishing the game, each subject is informed
about the binding situation and her payoff.

 After finishing the game, each subject is informed
about the binding situation and her payoff.

SVO and questionnaire Play the SVO game Answer questionnaire

Payment
 Move to a payment room
 Two subjects are paired randomly for the paymentof SVO game Subject payment = initial endowment + oneperson ISDG payoff + SVO game payoff

40

Figure 4: The screen of the ISDGs as seen by each subject in chronological order(a) One-person ISDG situation for the basic ISDG treatment(b) One-person ISDG situation for the FAB treatment

41

Figure 5: The distribution of the percentage of choices of option B per subject in the basic ISDG
and FAB treatments(a) Frequency distribution of the percentage of choices of option B
per subject in the basic ISDG and FAB treatments
FAB treatment

1050Frequency

15

Basic ISDG treatment

0

.5

1

0

.5

1

Percentage of choices of option B per subject

Percentage of choices of option B per subject(b) Boxplot of the percentage of choices of option B per subject in
the basic ISDG and FAB treatments
Basic ISDG treatment

FAB treatment

1
.9
.8
.7
.6
.5
.4
.3
.2
.1
0

42

Predicted probability of option B
.25
.3
.35
.4
.45

Figure 6: Predicted probability of choosing option B for subjects in the basic ISDG and FAB
treatments

0

4

8
12
16
20
24
28
Intergenerational sustainability index
Basic ISDG

43

With FAB

32

36

Figure 7: Heat map of the predicted probability of choosing sustainable option B on the domainof the percentage of option A choices in the sequence history and X
D
FAB Treatment

Percentage of option A in history

Basic ISDG

23%

1.0
0.8
0.6
0.4
0.2
0

52%

0

6

12

18

24 30

36

0

6

12 18 24 30 36

Intergenerational sustainability index (DX)44