13th International Conference on Social Dilemmas Kyoto, JAPAN, August 20-24, Your peers are watching you: Reputation sensitivity and in-group favoritism Hirofumi Hashimoto Nobuhiro Mifune Toshio Yamagishi (Hokkaido University)

In-group Favoritism in Minimal Groups In-group favoritism: Cooperation or altruism more toward in-group members rather than out-group members In-group favoritism is ubiquitous in social life (e.g., nations, races, firms, schools, etc.) Ps showed in-group favoritism even in artificially created minimal groups. (e.g., Tajfel et al., 1971; Billig and Tajfel 1973)

In-group Favoritism in Minimal Groups Ps showed in-group favoritism even when divided into Minimal Groups, in a laboratory setting. (e.g., Tajfel et al., 1971; Billig and Tajfel 1973) In-group favoritism in Minimal Groups emerges only when Ps mutually know each others’ group memberships (e.g., Jin & Yamagishi, 1997; Yamagishi, Mifune, Liu & Pauling, 2008; Foddy et al., 2006; Suzuki et al., 2007; Yamagishi & Mifune, 2008)  Simply sharing a social category is NOT sufficient for in-group favoritism in Minimal Groups to occur.

■ Method – One-shot Dictator Game – Ps ： 155 (M=84, F=71) – Ps were categorized into two minimal groups, and allocated money to a (in-group or out-group) recipient out of an endowment of \900. ■ Independent variables (between-participant factors) – Recipient’s group membership (in-group or out-group) – Knowledge of group membership (common or private) Yamagishi & Mifune (2008)

Common knowledge condition: Both the dictator and the recipient know each other’s group membership. Dictator (Participant) Recipient (a purported participant) He is a member of my group Yamagishi & Mifune (2008)

Private knowledge condition: While the dictator knows the recipient’s group, the recipient does not know which group the dictator is from. He is a member of my group, But… I don’t know which group he belongs to Dictator (Participant) Recipient (a purported participant) Yamagishi & Mifune (2008)

Result (Yamagishi & Mifune, 2008) Percentage of dictators who gave the recipient at least half of the endowment.  In-group Favoring resource allocation emerged only in the common knowledge condition …..WHY?

Common Knowledge He is a member of my group The dictator believed that recipient also knew he was an in-group member. ➔ Dictator would feel that his behavior was being monitored by the recipient. ➔ He should avoid any unfair behavior that might contribute to his negative reputation.

Private Knowledge He is a member of my group I don’t know which group he belongs to Even if Ps behaved in an unfair manner, their own reputation within the group would NOT be affected. Thus, Ps didn’t need to avoid unfair behavior.

Being monitored and concern for reputation are important factors in understanding in-group favoritism.  To obtain more supporting evidence, we attempted to replicate the results of Yamagishi & Mifune’s (2008) by focusing more on monitoring and reputation. The present study

Since 60’s social psychologists conducted a number of studies and have demonstrated that when Ps feel that they are being monitored, they tend to exhibit more pro- social behavior in economic games. – Cooperate more in a two- or n-person dilemma game (e.g., Bixenstine et al., 1966; Fox & Guyer, 1978; Dawes, McTavish & Shaklee, 1977; Kurzban, 2001) – Allocate more in a dictator game (Burnham, 2003; Haley & Fessler, 2005; Piazza & Bering, 2008) – Show more moralistic punishment in a third party punishment game (Kurzban, DeScioli & O’Brien, 2007)  Even though Ps were told that their behaviors are anonymous, they still showed concern about being monitored and showed pro-social behavior. Monitoring & Reputation

Since 60’s social psychologists conducted a number of studies and have demonstrated that when Ps feel that they are being monitored, they tend to exhibit more pro- social behavior in economic games. – Cooperate more in a two- or n-person dilemma game (e.g., Bixenstine et al., 1966; Fox & Guyer, 1978; Dawes, McTavish & Shaklee, 1977; Kurzban, 2001) – Allocate more in a dictator game (Burnham, 2003; Haley & Fessler, 2005; Piazza & Bering, 2008) – Show more moralistic punishment in a third party punishment game (Kurzban, DeScioli & O’Brien, 2007)  Even though Ps were told that their behaviors are anonymous, they still showed concern about being monitored and showed pro-social behavior. Monitoring & Reputation

One way to make Ps feel that they are being monitored is to present a pair of eyes as a subtle cue of monitoring

Eyes (“subtle cues”) shown on the computer display With eye $3.14 / $ More than $0: 79% Without eye $2.38 / $ More than $0: 53% Haley & Fessler (2005)

 Using Haley & Fessler’s experimental paradigm, we attempted to replicate Yamagishi & Mifune (2008). Prediction: (using only private knowledge condition) In-group favoritism should emerge (Without eyes) (With eyes) In-group favoritism should disappear The present study

■ Method – Participants ： 84 (53 males, 31 females) – Participants were categorized into two minimal groups. – One-shot Dictator Game. Dictators had \900 and were asked to choose one from 3 allocation options between themselves and a recipient, i.e., \100, \300, or \450 to a recipient. – All participants were in the private knowledge situation. – Stylized eyes were present in all conditions. ■ Dependent variable – Percentage of dictators who gave 450 yen (of 900 yen) to the recipient. ■ Independent variable (between-participant factor) – Recipient’s group membership (in-group or out-group) Study 1

*Percentage of dictators who gave 450 yen (of 900 yen) to the recipient.  In-group favoritism emerged even in the private knowledge situation. Dictators playing with an in- group recipient were more likely to show fair allocation than when playing with an out-group recipient. (χ2(1) = 3.88, p <.05) Study 1

■ Method – Ps: 142 (M=76, F=66) – Ps were categorized into two minimal groups. – One-shot Dictator Game. Dictators were asked to allocate money to an (in-group or out-group) recipient from an endowment of \900 freely. – All participants were in the private knowledge situation. – Presence of eyes was manipulated. ■ Independent variables (between-participant factors) – Recipient’s group membership (in-group or out-group) – Presence of the eye-figure with eyes (Egyptian or Asian) or without eyes (Windows “bliss”) Study 2

Before the test of hypothesis, we examined the effect of the type of eyes on in-group favoritism. There was no interaction effect of the type of eyes (Egyptian vs. Asian) x recipient (in-group vs. out-group). So, we pooled the type of eyes in later analysis.

 In-group favoritism emerged only in the presence of eyes Percentage of dictators who gave the recipient at least half of the endowment. Study 2 Interaction: χ2(1) = 4.20, p <.05

Study 2 Yamagishi & Mifune’s (2008) (Without eye only) Present study the private knowledge situation only

 In-group favoring behavior does NOT stem from simply “in-group love” based on social category, but is a “strategy” to avoid negative reputation from in- group members. In the present studies, by manipulating the presence of eyes, we replicated the results of Yamagishi & Mifune’s study. － In-group favoring behavior ONLY emerged in the presence of eyes (i.e., when Ps felt that they were being monitored) － Furthermore, absolutely no in-group favoritism occurred in the absence of eyes (study 2). Summary

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It is not surprising that in-group favoritism occurs among real groups which are characterized by a history of inter- group conflict, mutual stereotypes, etc. - Game theoretic view of “shadows of the future” (Axelrod, 1984) - Realistic Resource conflict (e.g., Sherif et al., 1961) In-group favoring behavior in real groups is no surprise; it does not require any evolutional explanation; either the rational actor model or ordinary sociological explanation such as the historically-grounded mutual hate is sufficient. However, in-group favoring behavior in minimal groups escapes such intuitively obvious explanations—it implies the presence of internal dispositions that may be grounded in the evolutionary history of humans. Why Does Minimal Groups Matter?