In-group and out-group social influence on punishment in unfair situations

People’s beliefs and behaviors are influenced by the preferences and behaviors of those around them. This effect is known as “social influence.” Previous studies have found that ingroup favoritism can modulate the effect of social influence on individuals’ attitudes and behaviors. In this study, we investigated the interaction of ingroup favoritism and social influence on punishment decisions in unfair situations. In experiment 1, the ultimatum game was used to assess participant’ response to unfairness directed toward oneself in in-group and out-group social influence contexts. In experiment 2, we used a third-party dictator game to examine how ingroup favoritism modulates the effect of social influence on participants’ responses to unfairness toward others. The interaction effect demonstrated that ingroup favoritism was particularly pronounced when the social influence suggested punishment, and absent when social influence suggested no punishment. Conversely, no such interaction was found in the ultimatum game. Our findings suggest that people draw psychologically relevant distinctions between unfairness toward themselves and unfairness toward others.