== D R A F T

July 29, 2017==

Journal: OPEN MIND

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So good it has to be true: Wishful thinking in theory of mind

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Daniel Hawthorne-Madell1 , Noah D. Goodman1

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Department of Psychology, Stanford University

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Keywords: wishful thinking, computational social cognition, theory of mind, desirability bias

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Abstract

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In standard decision theory, rational agents are objective, keeping their beliefs independent from their

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desires. Such agents are the basis for current computational models of Theory of Mind (ToM), but the8accuracy of these models are unknown. Do people really think that others do not let their desires color

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their beliefs? In two experiments we test whether people think that others engage in wishful thinking. We

10find that participants do think others believe that desirable events are more likely to happen, and that

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undesirable ones are less likely to happen. However, these beliefs are not well calibrated as people do not

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let their desires influence their beliefs in the task. Whether accurate or not, thinking that others wishfully

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think has consequences for reasoning about them. We find one such consequence—people learn more

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from an informant who thinks an event will happen despite wishing it was otherwise. People’s ToM

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therefore appears to be more nuanced than the current rational accounts in that it allows other’s desires to16

directly affect their subjective probability of an event.

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Whether thinking “I can change him/her” about a rocky relationship or the more benign “those clouds

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will blow over” when at a picnic, people’s desires seem to color their beliefs. However such an

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explanation presupposes a direct link between his desires and beliefs, a link that is currently absent in20

normative behavioral models and current Theory of Mind (ToM) models.

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Does a causal link between desires and beliefs actually exist?1 The evidence is mixed. There are a22

number of compelling studies that find “wishful thinking,” or a “desirability bias” in both carefully

Corresponding author: Daniel Hawthorne-Madell, d.j.hawthorne@alumni.stanford.edu
1 While the causal link between desires and beliefs may, in fact, be bi-directional, we will focus on the evidence for the a priori effect of desires on beliefs.

Copyright ©2017 The Author(s). Published by MIT Press. All Rights Reserved.

== D R A F T

Journal: OPEN MIND/

July 29, 2017==

Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

23

controlled laboratory studies (Mayraz, 2011) and real world settings, such as the behavior of sport fans24

(Babad, 1987; Babad & Katz, 1991), expert investors (Olsen, 1997), and voters (Redlawsk, 2002).

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However, other researchers have failed to observe the effect—for example, Bar-Hillel et al.’s The elusive

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wishful thinking effect (1995), have provided alternative accounts of previous experiments (Hahn &27

Harris, 2014), and have argued that there is insufficient evidence for a systematic wishful thinking bias

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(Hahn & Harris, 2014; Krizan & Windschitl, 2007).

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Whether or not there actually is a direct effect of desires on beliefs, people might think that there is and30

use this fact when reasoning about other people. That is to say, people’s ToM might incorporate the31

wishful thinking link seen in Figure 1b. The direct influence of desires on beliefs is a departure from32classic belief-desire “folk” psychology in which beliefs and desires are independent and jointly cause

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action (Figure 1a). Previous models of ToM formalize belief-desire psychology into probabilistic models

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of action and belief formation. They show that inferring others’ beliefs (Baker, Saxe, & Tenenbaum,

352011), preferences (Jern, Lucas, & Kemp, 2011), and desires (Baker, Saxe, & Tenenbaum, 2009) can be

36

understood as Bayesian reasoning over these generative models. A fundamental assumption of these37

models is that beliefs are formed on the basis of evidence, and a priori independent of desire. We will38

call models that make this assumption rational theories of mind (rToM). We can contrast this rationally39

motivated theory with one that incorporates the rose-colored lenses of a desire-belief link, an optimistic40

ToM (oToM).2 We use their qualitative predictions to motivate two experiments into the presence (and41

calibration) of wishful thinking in ToM and its impact on social reasoning.

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In Experiment 1 we explore wishful thinking in both ToM and behavior. In the 3rd person point-of-view

50(3-PoV) condition, we test whether people use a rToM or an oToM when reasoning about how others

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play a simple game—will manipulating an agent’s desire for an outcome affect people’s judgments about

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the agent’s belief in that outcome? In the first person point of view (1-PoV) condition we test whether

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people actually exhibit wishful thinking when playing the game themselves. We carefully match the54(3-PoV) and (1-PoV) conditions and run them concurrently to have a clear test of whether people’s ToM

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assumptions lead them to make appropriate inferences about people’s behavior in the game.3 Regardless56

of its appropriateness, people’s ToM should have consequences for both how they reason about others’
2 We formally describe Bayesian models of both rToM and oToM in the Supplement (citation of supplementary material here XXX.
3 Experiment 1 is a slightly modified replication of the two conditions previously run as separate experiments (see Supplement).

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== D R A F T

Journal: OPEN MIND/

July 29, 2017==

Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

Competing models of ToM. Causal models of (a) rational ToM 45

Figure 2.

Stimuli used in Experiment 1. (a) the wheel used to determine

42

Figure 1.

43based upon classic belief-desire psychology and (b) optimistic ToM that in- 46

the payout for the next outcome and (b) the Galton board used to decide the44

cludes a direct “wishful thinking” link between desires and beliefs.

47

outcome. The blue arrow at the top indicates where the marble will be dropped.

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The numbers indicate the four drop positions used in the experiment.

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actions and how they learn from them. If people do attribute wishful thinking to others, it would have a

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dramatic impact on their interpretation of others’ behavior. In Experiment 2 we therefore test for a social

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learning pattern that only reasoners using a oToM would exhibit, highlighting the impact ToM

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assumptions have on social reasoning.
EXPERIMENT 1: WISHFUL THINKING IN TOM (3-POV) AND ONLINE BEHAVIOR (1-POV)

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3-PoV condition62

To test for the presence of wishful thinking in people’s mental models of others we introduced Josh, a63

person playing a game with a transparent causal structure. The causal structure of the game was64

conveyed via the physical intuitions of the Galton board pictured in Figure 2b (in which a simulated ball65

bounces off pegs to land in one of two bins). The outcome of the game is binary (there are two bins) with66

different values associated with each outcome (money won or lost). We call the value of an outcome (i.e.,67

the amount that Josh stands to win or lose) the utility of that outcome, U (outcome). Participants were68

asked what they think about Josh’s belief in the likelihood of the outcome pj (outcome). By manipulating69

outcome values we are able to test for wishful thinking. If people incorporate wishful thinking into their70

ToM, we should find that increasing an outcome’s utility results in higher estimates of Josh’s belief in the71

outcome’s occurrence, pj (outcome).
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== D R A F T

Journal: OPEN MIND/

July 29, 2017==

Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

72

We first measured pj (outcome|evidence) without manipulating the desirability of the outcome in the73“baseline” block of trials. Then in the “utility” block of trials we assigned values to outcomes,

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manipulating Josh’s U (outcome).4 In the utility block of trials we used a spinning wheel (Figure 2a) to75

determine what Josh stood to win or lose based on the outcome of the marble drop. By comparing these76

two blocks of trials we test for the presence of wishful thinking in people’s ToM.

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1-PoV condition78

To test whether people’s desires directly influence their beliefs in the Galton board game, we simply had

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the participant directly play the game (replacing Josh) and asked them about their belief in the likelihood

80of the outcome (their “self” belief ps (outcome)).

81

Methods

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Participants

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80 participants were randomly assigned to either the 3-PoV or the 1-PoV condition such that there were84

40 in each.

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Design and Procedure86

3-PoV condition

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Participants were first introduced to Josh, who was playing a marble-drop game with a Galton board (as88seen in Figure 2b). Josh was personified as a stick figure and appeared on every screen. We then89

presented the causal structure (i.e., physics) of the game by dropping a marble from the center of the90

board two times, with one landing in the orange bin (Figure 2b left bin) and the one landing in the purple

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bin (Figure 2b right bin). After observing the two marble drops, participants began the baseline block of

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trials. In the four baseline trials, the marble’s drop position varied and participants were asked “What do93

you think Josh thinks is the chance that the marble lands in the bin with the purple/orange box?”

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Participants’ responses were recorded on a continuous slider with endpoints labeled “Certainly Will” and95“Certainly Won’t.” Color placement was randomized on each trial, and the color of the box in question

4 Crucially, Josh’s U (outcome) should not be chosen by him, e.g., “I bet $5 that it lands in the right bin,” as such an action would render U (outcome) andp(outcome) conditionally dependent and both rToM and oToM would predict influence of desire on belief judgments. To test pure wishful thinking, Josh’s
U (outcome) has to be assigned to him by a process independent of p(outcome)—in our case a spinner.

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Journal: OPEN MIND/

July 29, 2017==

Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

96

varied between participants. The marble drop position was indicated with a blue arrow at the top of the97

Galton board, and there were four drop positions used (marblex ; top of Figure 2b) that varied in how

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likely they were to deliver the marble into the bin in question. In the baseline and subsequent trials

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participants did not observe the marble drop and outcome; they only observed the position the marble

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would be dropped from.

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After the baseline trials, participants were introduced to the utility trials, which included a spinning wheel

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that determined “how much Josh can win or lose” labeled with $1 and -$1. At the beginning of each trial

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the wheel was spun and the selected payout was displayed, e.g., “Josh has a chance of winning $1,” along104

with the Galton board. The bins were labeled with a $ and ∅ symbol.5 If the marble landed in the $ bin

105then Josh won/lost the money. The location of the $ bin was randomized on each trial. After seeing the106

Galton board with marblex indicated with a blue arrow, participants were asked two questions

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sequentially. First they were asked “What do you think Josh believes is the chance that the marble will108

land on the {$/-$} and he’ll {win/lose} $1” with the response recorded on the same slider as the baseline

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trials with endpoints labeled “Certainly Will” and “Certainly Won’t.” They were then asked “How much110

does Josh care about the outcome?” with the response on a slider with endpoints labeled from “Not at

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All” to “To a Great Extent.” Participants saw every combination of the two outcomes ($1, -$1) and the112four drop positions (see Figure 2b) for a total of 8 utility trials.

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1-PoV condition

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The procedure mirrored the 3-PoV condition with the participant taking the place of Josh. All questions

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were therefore re-framed to ask the participant’s beliefs about the outcome. The participants were given a116$1 bonus initially and instructed that one trial at random would be selected to augment their current

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bonus, i.e. they could gain or lose $1.

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Results

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3-PoV condition

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In a rational theory of mind, beliefs and desires are a priori independent. Manipulating Josh’s desires

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therefore shouldn’t have an effect on his beliefs, and we would predict that the utility trials look like the126baseline trials. However, as seen in Figure 3a, the utility trials varied systematically from the baseline
5 $ when the payout was positive and -$ when it was negative, with ∅ representing no payout.

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== D R A F T

Journal: OPEN MIND/

July 29, 2017==

Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

Experiment 1 data. The effect of an agent’s desire for an outcome on the mean subjective pj (outcome) attributed to the agent (with 95% CIs). For

118

Figure 3.

119each participant, the mean effect of the positive utility ($1) and the negative utility (-$1) was determined by taking the difference between the pj (outcome) in120

each utility trial and the corresponding baseline trial. The effect is shown for the (a) 3-PoV and (b) 1-PoV condition (where ps (outcome) is displayed). These

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data are compared with the posterior predictives of the (c) optimistic and (d) rational ToM models (see Supplement).

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trials and, therefore, the predictions of an rToM. To quantify this deviation we fit a logistic mixed-effects

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model to participants’ pj (outcome) responses. The model used marblex and the categorically coded

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value of the outcome (negative, baseline, and positive) as fixed effects and included the random effect of130

marblex and intercept for each participant. The resulting model indicated that if an outcome was131

associated with a utility for Josh, participants thought that it would impact his beliefs about the132

probability of that outcome.

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Participants thought that Josh would believe that an outcome that lost him money was less likely than the134

corresponding baseline trial (β = −0.70, z = −2.10, p = .036).6 They also thought that Josh would

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believe an outcome that would net him money was more likely than the corresponding baseline trial

136(β = .96, z = 2.87, p = .004).7 Finally, marblex , the direct evidence, had a significant influence137(β = 10.37, z = 11.78, p < .001). There was no evidence that the effect of the outcome value was138

affected by marblex (the interactive model did not provide a superior fit (χ2 (2) = .68, p = .736).

139

1-PoV condition
6 All p values reported for Experiment 1 are based on the asymptotic Wald test
7 There was no evidence of loss aversion in the relative magnitude of the wishful thinking effect for positive and negative utilities. In fact, the magnitude of

the wishful thinking effect was slightly stronger for positive utilities.

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== D R A F T

Journal: OPEN MIND/

July 29, 2017==

Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

140

Unlike in the 3-PoV condition, as seen in Figure 3b, there was no effect of utility on participants’141

ps (outcome) responses compared with their baseline responses. Using the same logistic mixed-model

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employed in the 3-PoV condition, neither outcomes that would lose the participant money143(β = .09, z = .30, p = .760), nor outcomes that would win them money (β = −.09, z = .30, p = .760)

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influenced participants’ ps (outcome) responses. Similar to the 3-PoV condition, a strong effect of the145

marble’s position was observed (β = 8.88, z = 11.95, p < .001).

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Comparing conditions

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To formalize the discrepancy of the effect of utility across conditions we analyzed them together with a148

logistic mixed-model. We used the same model described previously except we continuously coded the149

effect of utility and added an interaction between this utility and condition. The resulting model had a150

significant interaction between PoV (condition) and the effect of utility on participants’ pj/s (outcome)151

responses (β = .43, z = 3.83, p < .001). This interactive model provided a better fit than the additive152

model (χ2 (1) = 15.11, p < .001).

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Discussion

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The results from the 3-PoV condition indicate that people’s ToM includes a direct “wishful thinking”

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link. This is consistent with the qualitative predictions of the oToM model (Supplement, Eq. 2), unlike

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rToM models where beliefs and desires are a priori independent.8 However, the 1-PoV condition did not

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find evidence that people are biased by their desires in the Galton board game. This disconnect suggests

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that people’s attribution of wishful thinking in this situation is miscalibrated. That is to say that

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Experiment 1 represents a situation where wishful thinking is present in ToM reasoning but absent in

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actual behavior—people think others will behave wishfully when, in fact, they do not.

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This miscalibration is consistent with an over-attribution of wishful thinking. However, the present study

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does not provide insights into why there is this miscalibration. Any number of incorrect assumptions

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could lead to the results. Perhaps people think that everyone wishfully thinks, but only they are clever164

enough to correct for it. Alternatively they could think that $1 or $5 is much more desirable for others
8 Interestingly, there was consistency in the magnitude of this effect when Josh stood to gain $1 (as in the present experiment) or $5 in Experiment 1b (seeSupplement). The extent to which people attributed wishful thinking to Josh was therefore not sensitive to the magnitude of Josh’s potential payout for thisrange (where payout is our operationalization of his desire).

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Journal: OPEN MIND/

July 29, 2017==

Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

165

than it is for themselves. There are a number of actor-observer asymmetries and self-enhancement biases

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that could plausibly underpin the observed inconsistency (Jones & Nisbett, 1971; Kunda, 1999). Further

167

study is necessary to determine the cause of the over-attribution.

168

Regardless of whether people actually engage in wishful thinking, if people assume others do, then it

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should affect how they interpret others’ actions and learn from them. In Experiment 2 we therefore

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expand our sights to social learning situations where oToM (but, crucially, not rToM) predicts that desires

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affect a social source’s influence.

P(Team Wins)

EXPERIMENT 2: LEARNING FROM OTHERS WITH AN OTOM

Does fan want team to win?

Experiment 2 data. Effect of a social sources’ desire on how others learn from them for (a) data with 95% CIs, which we compare to the posterior

172

Figure 4.

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predictives of (b) an optimistic ToM, (c) a rational ToM. Points represent the mean p(teamx ) response after hearing equally knowledgeable sources place a174

bet on teamx that is either consistent, unrelated, or inconsistent with their desires.

175

Do people consider a social source’s desires when learning from them? It would be important to do so if176they think that his desires have a direct influence on his beliefs. Consider a learner using an oToM to177reason about her uncle, a Cubs fan, who proudly proclaims that this is the year the Cubs will win it all.

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Though her uncle knows a lot about baseball, the oToM learner is unmoved from her (understandably)

179

skeptical stance. However, if her aunt, a lifelong White Sox fan (hometown rival to the Cubs), agrees that180

the Cubs do look better than the Sox this year, then an oToM learner considers this a much stronger

181

teaching signal. In fact, a learner with an oToM would consider her aunt’s testimony as more persuasive–8–

== D R A F T

Journal: OPEN MIND/

July 29, 2017==

Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

182

than an impartial source, see Figure 4b. A learner reasoning with an rToM wouldn’t distinguish between

183

these three social sources9 as seen in Figure 4c.

184

We investigated which ToM best describes learning from social sources in a controlled version of this185

biased opinion scenario. Participants were asked how likely a team (x) was to win an upcoming match,

186

p(teamx ), in a fictional college soccer tournament after seeing a knowledgeable student bet on the team.

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The student was either a fan of one of the teams facing off, or indifferent to the outcome. Participants

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therefore saw three trials—the consistent trial where the student bet on the team he wanted to win, the189

inconsistent trial where he bet on the team wished would lose, and the impartial trial where he didn’t

190

care which team won before he bet.

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Methods

192

Participants

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120 participants were randomly assigned into the consistent, inconsistent, or impartial conditions.

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Design and Procedure

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Participants were first introduced to a (fictional) annual British collegiate soccer tournament and told that

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they would see bets on these matches from a student who “Unbeknownst to his friends makes a £100 bet

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online on which team he thinks will win this year’s game.”10 The student would either be a fan of one of198

the teams (attending that college) or neither of the teams (attending a different college). The students

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were equally knowledgeable across conditions, being described as seeing the outcome of the last 10

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matches these teams played against each other.

201

After the introduction, participants were given a test trial appropriate for their (randomly assigned)

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condition in which the student bet consistently with his school, bet against his school, or was impartial

203(not a fan of either school). After observing the student’s bet and allegiance participants were asked

204“What do you think is the chance that teamx wins the match this year.”

9 Assuming that the three sources are equally knowledgeable and their statements have no causal influence on the game, e.g., if the uncle is an umpire, hisdesires may matter through more objective routes.
10 See Supplement for complete experimental materials–9–== D R A F T

Journal: OPEN MIND/

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Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

205

Results

206

As seen in Figure 4a, participants’ responses were sensitive to the student’s a priori desires, consistent207

with learners who reason with oToM (but not an rToM). Participants who saw an impartial student bet on

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teamx thought the team was more likely to win than when they saw a fan of teamx place an identical bet

209(d = .80, 95% CI [.33 1.27], z = 3.35, p < .00111 ). This is consistent with the learner thinking that the

210

fan’s desire to see his team win made him think it was objectively more likely. Additionally, participants

211

who saw a fan of the other team bet on teamx were more influenced than the same bet from the impartial

212

student (d = .67, 95% CI [.21 1.14], z = 2.87, p = .004). As predicted by the model of the oToM learner,213

someone who bets against their desires is more diagnostic of teamx being dominant than the independent214

source. The oToM learner thinks that teamx had to be clearly dominant to overcome the wishful thinking

215

of a fan rooting against them.

216

Discussion

217

Assuming that fans engage in wishful thinking allows oToM learners to make stronger inferences about218

the strength of the fans’ evidence in some cases. For an rToM learner, the fan would have to have seen219

teamx win a majority of the 10 observed matches in order to bet on them, regardless of their

220

predilections, resulting in the flat predictions seen in Figure 4c. Meanwhile, the oToM learner thinks that221

a fan of teamx could bet on them even if the fan only observed them win a few times12 . If, however, the222

fan bets against their team, the oToM learner assumes that the fan must have seen their team trounced in223

the 10 observed matches. Using these insights, an oToM learner using Bayesian inference to learn from224

the fan will exhibit the qualitative pattern seen in Figure 4b, which is consistent with participants’225

behavior (as seen in Figure 4a). The pattern of results is consistent with the predictions of a learner using

226

an oToM, but there are limitations and additional potential explanations discussed at length in the227

Supplement.

GENERAL DISCUSSION

11 calculated with Fisher-Pitman permutation test
12 In fact, if the oToM learner thinks that the fan is a completely wishful thinker then his bet is no longer diagnostic of his evidence (he could have seen

anything!)–10–

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Journal: OPEN MIND/

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Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

228

Current computational models of theory of mind are built upon the assumption that beliefs are a priori

229

independent of desires. Whether social reasoners use such a rational ToM (rToM) is an empirical230

question. In two experiments we tested the independence of beliefs and desires in ToM and found that231

people behave as if they think that others are wishful thinkers whose beliefs are colored by their desires.

232

In the 3-PoV condition of Experiment 1 we found that people believe that others inflate the probability of233

desirable outcomes and underestimate the probability of undesirable ones, as they would if they have an

234

optimistic ToM (oToM) with a direct link between desires and beliefs (Figure 3). If people broadly

235

attribute wishful thinking to others (as Experiment 1 suggests) it should be reflected in their social

236

reasoning. For example, social learners using an oToM to make sense of an agent’s beliefs would be237

sensitive to that agent’s relevant desires. This is exactly what we found in Experiment 2 (Figure 4)—how238

much people learned from an agent’s beliefs depended on his desires. Agents whose beliefs ran against

239

their desires were more influential than impartial agents, who in turn were more influential than agents240with consistent beliefs and desires.

241

The observed presence of wishful thinking in ToM has no necessary relation to its existence in people’s

242“online” belief formation. Indeed, the 1-PoV conditions of Experiment 1 indicates that people’s model of243

other’s wishful thinking is not perfectly calibrated. They over-attribute wishful thinking to others in

244

situations where they would actually form their beliefs independently of their desires. Charting the245

situations where wishful thinking is over-applied in this way may be a fruitful avenue for further

246

research. At the extreme we could imagine finding that everyone thinks one another wishfully thinks, but

247

in fact everyone forms their beliefs independent of their desires! This radical thesis is surely too strong,13248

but oToM may well overestimate the strength of wishful thinking and over-generalize it—amplifying a249

small online effect into a larger social cognition effect. Attention to whether a task engages (potentially

250

amplified) oToM representations could provide insight into the considerable heterogeneity of the wishful251

thinking effect as it has been studied. Specifically, it could help explain why first-person wishful thinking

252

is reliably found in some paradigms and not others.

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The paradigms in which wishful thinking is reliably found involve participants reasoning about

254

themselves or others, such as the 3-PoV condition of Experiment 1 where participants reasoned about

13 As seen in well controlled examples of desires influencing online belief formation e.g., (Mayraz, 2011).

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Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

255

Josh’s beliefs (for a review of many tasks that may engage social reasoning see [Shepperd, Klein, Waters,

256& Weinstein, 2013], e.g., [Weinstein, 1980] but see [Harris & Hahn, 2011] and [Hahn & Harris, 2014] for257

an alternative explanation). Whereas asocial paradigms involving direct estimation of probabilities

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usually do not find the effect, like the 1-PoV condition of Experiment 1 where participants directly

259

estimated the chance that the ball would fall into a particular bin (for other examples of wishful thinking

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paradigms that do not involve social reasoning see Study 1 of [Bar-Hillel & Budescu, 1995], and for a261

more general review of asocial bias experiments see the “bookbags” and “pokerchips” paradigms cited in

262[Hahn & Harris, 2014], but see Francis Irwin’s series of experiments for an example of asocial paradigms

263

that do find a wishful thinking effect—starting with [Irwin, 1953]).

264

Where people’s predictions of others’ behaviors (1-PoV Experiment 1) and their actual behavior (3-PoV

265

Experiment 1) diverge is also important to map because these disconnects inject a systematic bias in266

social reasoning. Taking the social learning of Experiment 2 as an example, oToM learners ignored the267

belief of the agent whose bet was consistent with his desires. However, if this agent actually formed his268

beliefs without bias, then the learner would be missing a valuable learning opportunity. Asserting that269

others let their desires cloud their beliefs allows people to “explain away” those beliefs without seriously270

considering the possible evidence on which they are based. Future work should explore the details of

271

these effects. For example, does a learner attribute bias equally to those who share his desires and those272

who hold competing ones?

273

The experiments presented here suggest that people think that others are wishful thinkers; this has broad274

consequences for social reasoning ranging from our inferences about heated scientific debates to275

pundit-posturing. Our findings highlight the importance of further research into the true structure of276

theory of mind. Do people think that others exhibit loss aversion or overweight low probabilities? Is the277connection between beliefs and desires bi-directional? Rigorous examination of questions like these may

278

buttress new, empirically motivated computational models of ToM that capture the nuance of human279

social cognition—an idea so good it has to be true.

REFERENCES
280

Babad, E. (1987). Wishful thinking and objectivity among sports fans. Social Behaviour, 2(23), 231–240.

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Babad, E., & Katz, Y. (1991). Wishful thinking—Against all odds. Journal of Applied Social Psychology, 21, 1921–1938.

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Title: So good it has to be true: Wishful thinking in theory of mind

Authors: Daniel Hawthorne-Madell and Noah D. Goodman

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