Theory of Mind Enhances Preference for Fairness
Haruto Takagishi 1,2, Shinya Kameshima 3, Joanna Schug 1,
Michiko Koizumi 1, Toshio Yamagishi 1
1
Hokkaido University, 2 JSPS, 3 Kansai University of Welfare Sciences
Cooperation and Punishment

Punishment of norm violators promotes cooperative
behavior (Yamagishi, 1986; Fehr & Gatcher, 2002)
Cooperation and Punishment

Punishment of norm violators promotes cooperative
behavior (Yamagishi, 1986; Fehr & Gatcher, 2002)
 Threat of peer punishment enhances proposer’s offers to the
responder in the ultimatum game (Spitzer et al., 2007)
 Anticipating that others may become angered by and punish
those who behave unfairly encourages us to follow social
norms
Cooperation and Punishment

Punishment of norm violators promotes cooperative
behavior (Yamagishi, 1986; Fehr & Gatcher, 2002)
 Threat of peer punishment enhances proposer’s offers to the
responder in the ultimatum game (Spitzer et al., 2007)
 Anticipating that others may become angered by and punish
those who behave unfairly encourages us to follow social
norms

We examine the effect of the ability to anticipate others’
social preferences on fairness-related behavior.
Developmental studies of Fairness

Developmental study of economic decision-making has
received considerable attention in recent years
Developmental studies of Fairness

Developmental study of economic decision-making has
received considerable attention in recent years
 A developmental study investigating fairness in children and
adolescents ranging from seven to eighteen years of age found
that the preference for fairness increases with age
(Harbaugh et al., 2003)
Developmental studies of Fairness

Developmental study of economic decision-making has
received considerable attention in recent years
 A developmental study investigating fairness in children and
adolescents ranging from seven to eighteen years of age found
that the preference for fairness increases with age
(Harbaugh et al., 2003)
 Fairness-related behavior toward in-group members, increases
with age among children age three to eight (Fehr et al., 2008)
Developmental studies of Fairness

Developmental study of economic decision-making has
received considerable attention in recent years
 A developmental study investigating fairness in children and
adolescents ranging from seven to eighteen years of age found
that the preference for fairness increases with age
(Harbaugh et al., 2003)
 Fairness-related behavior toward in-group members, increases
with age among children age three to eight (Fehr et al., 2008)

And many other studies have been conducted
(Sally & Hill, 2005; Benenson, Pascoe, & Radmore, 2007; Gummerum, Keller,
Takezawa, & Mata, 2008; Olson, & Spelke, 2008)
Theory of Mind and Economic Decision-making

Autistic Spectrum Disorder (ASD) had a substantial
negative effect on the amount of tokens allocated by the
proposer in the ultimatum game (Sally, & Hill, 2005)
Theory of Mind and Economic Decision-making

Autistic Spectrum Disorder (ASD) had a substantial
negative effect on the amount of tokens allocated by the
proposer in the ultimatum game (Sally, & Hill, 2005)

Chimpanzees, who do not have a well developed theory
of mind in the human sense made unfair offers and
accepted unfair offers in the ultimatum game
(Jensen, Call, & Tomasello, 2007)
Theory of Mind and Economic Decision-making

Autistic Spectrum Disorder (ASD) had a substantial
negative effect on the amount of tokens allocated by the
proposer in the ultimatum game (Sally, & Hill, 2005)

Chimpanzees, who do not have a well developed theory
of mind in the human sense made unfair offers and
accepted unfair offers in the ultimatum game
(Jensen, Call, & Tomasello, 2007)

However, to date no study has directly investigated the
role that theory of mind plays in fairness-related
behavior among normally developed children
Hypothesis

In this study, we examined the role of theory of mind in
the proposer’s behavior in the ultimatum game

We predicted that compared with proposers who had not
yet developed theory of mind, proposers who had
developed theory of mind would behave in a more fair
manner
Methods (participants)

Sixty-eight preschoolers (36 males and 32 females)
participated in the study
 The mean age in month was 65.76 (SD = 7.0)
 Fifty-six from an older class (6 years) and twelve from a
younger class (4 years)

All participants played the ultimatum game and the false
belief task
Methods (The Ultimatum Game)

The participants played a one-shot ultimatum game
 The proposer received 10 candies from the experimenter and
decided how to divide the amount of candies between two
players (the propose and the responder)
 Then, the responder accepted or rejected the proposer’s offer
 If the responder accepted the offer, then both received the
amount of candies according to the proposer’s offer
 If the responder rejected the offer, then both received nothing
Methods (The Ultimatum Game)
PROPOSER
tray
candies
lever
RESPONDER
PROPOSER
candies
candies
RESPONDER
black box
candies
candies
lever
Methods (False Belief Task)

Acquisition of theory of mind was determined by
whether or not participants successfully completed a
false-beliefs task (Sally-Anne task; Baron-Cohen et al., 1985).
Methods (False Belief Task)
bag
A girl stores a ball in a box and leaves the room.
box
Methods (False Belief Task)
bag
The boy moves the ball to a bag
Methods (False Belief Task)
?
When the girl returns, the participant is asked where the girl will look
for the ball.
Results (Amount offered by the proposer)

67.7 % of the proposers and 73.5 % of the responders
passed the false-beliefs task
Results (Amount offered by the proposer)

67.7 % of the proposers and 73.5 % of the responders
passed the false-beliefs task
*The mean offer to the responder
8
7
6
t (32) = 2.36, p < .05
5
4
3
2
1
0
passed (n = 23) failed (n = 11)
*Distribution of proposer’s offers
Results (Multiple Regression Analysis)
Table 1 Regression Analysis of the Amount Offered to the Responders
Independent Variables
β
Sex Dummy (Male = 0, Female = 1)
.24
Relationship Quality
.13
Age in month
Theory of Mind Dummy (Failed = 0, Passed = 1)
R2
* p < .05
- .03
.39 *
.22
The participants’ teachers evaluated the quality of the
relationship between all 34 pairs
(1= very bad relationship to 7= very good relationship)
Results (Multiple Regression Analysis)
Table 1 Regression Analysis of the Amount Offered to the Responders
Independent Variables
β
Sex Dummy (Male = 0, Female = 1)
.24
Relationship Quality
.13
Age in month
Theory of Mind Dummy (Failed = 0, Passed = 1)
R2
* p < .05
- .03
.39 *
.22
The participants’ teachers evaluated the quality of the
relationship between all 34 pairs
(1= very bad relationship to 7= very good relationship)
Results (Multiple Regression Analysis)
Table 1 Regression Analysis of the Amount Offered to the Responders
Independent Variables
β
Sex Dummy (Male = 0, Female = 1)
.24
Relationship Quality
.13
Age in month
Theory of Mind Dummy (Failed = 0, Passed = 1)
R2
* p < .05
- .03
.39 *
.22
The participants’ teachers evaluated the quality of the
relationship between all 34 pairs
(1= very bad relationship to 7= very good relationship)
Results (Multiple Regression Analysis)
Table 1 Regression Analysis of the Amount Offered to the Responders
Independent Variables
β
Sex Dummy (Male = 0, Female = 1)
.24
Relationship Quality
.13
Age in month
Theory of Mind Dummy (Failed = 0, Passed = 1)
R2
* p < .05
- .03
.39 *
.22
The participants’ teachers evaluated the quality of the
relationship between all 34 pairs
(1= very bad relationship to 7= very good relationship)
Results (Multiple Regression Analysis)
Table 1 Regression Analysis of the Amount Offered to the Responders
Independent Variables
β
Sex Dummy (Male = 0, Female = 1)
.24
Relationship Quality
.13
Age in month
Theory of Mind Dummy (Failed = 0, Passed = 1)
R2
* p < .05
- .03
.39 *
.22
The participants’ teachers evaluated the quality of the
relationship between all 34 pairs
(1= very bad relationship to 7= very good relationship)
Results (Rejection Rates)

63.6% of unfair offer were rejected by the responders,
while all 23 fair or hyper fair offers were accepted
*Rejection rates of unfair offer
100
80
%
ns.
60
40
20
0
passed (n = 7)
failed (n = 4)
Results (Rejection Rates)

63.6% of unfair offer were rejected by the responders,
while all 23 fair or hyper fair offers were accepted
* Rejection rates of each offer
Summary & Discussion

Our results showed that theory of mind had a major
effect on fairness-related behavior of the proposer
 Preschoolers who acquired theory of mind proposed a fairer
division of the candies
Summary & Discussion

Our results showed that theory of mind had a major
effect on fairness-related behavior of the proposer
 Preschoolers who acquired theory of mind proposed a fairer
division of the candies

Our study also showed that theory of mind do not affect
rejection behavior
 The unfair outcome itself (e.g., inequity aversion; Fehr &
Schmidt, 1999) may play a more important role in rejection
behavior among preschoolers than among adults
Thank you for your attention !!
The Ultimatum Game Machine.
Appendix 1: The Effect of Age
Table 1 Regression Analysis of the Amount Offered to the Responders
Independent Variables
Model 1
Model 2
Model 3
β
β
β
Sex Dummy (Male = 0, Female = 1)
.17
.14
.24
Relationship Quality
.21
.21
.13
.10
- .03
Age
Theory of Mind Dummy (Failed = 0, Passed = 1)
R2
* p < .05
Fifty-six from an older class (6 years) and
twelve from a younger class (4 years).
.39 *
.08
.09
.22
Appendix 2: Relationship Quality
The post experimental questionnaire

The participants’ teachers evaluated the quality of the
relationship between all 34 pairs
(1= very bad relationship to 7= very good relationship)
Appendix 2: Emotion ? Belief ?
We conducted the second experiment.
Ultimatum Game
+ False belief Task
+ Emotion Understanding Task (Denham, 1986)
Patticipants (N = 146)
Forty eight 6 years old children
Fifty two 5 years old children
Forty six 4 years old children
Table 1 Regression Analysis of the Amount Offered to the Responders
Independent Variables
Sex Dummy (Female = 0, Male = 1)
Class (younger = 0, middle = 1, older = 2)
Model 1
Model 2
Model 3
-0.14
-0.16
- 0.10
0.36**
Affective perspective-taking
0.38**
0.24
0.02
0.02
Theory of Mind Dummy (Failed = 0, Passed = 1)
R2
* p < .05, ** p < .01
0.27*
0.15
0.18
0.23