Social influence and the adaptation of parochial altruism: a dictator-game experiment on children and adolescents under peer influence

Humans tend to treat the ingroup more favorably than the outgroup. The phenomenon of parochial altruism is commonly observed in experimental studies on the division of valuable goods among people from children to adults in modern and indigenous societies. Relatively little known is how parochial altruism evolves in the presence of social influence. We conducted a dictator-game experiment on children and adolescents in different school classes to assess parochial altruism. Subjects divided an endowment of valuable goods with an ingroup and an outgroup person. We then manipulated the social information of how the ingroup and the outgroup person shared their endowments with each other. Our experiment shows that subjects would modify their giving to the two recipients when receiving the information, suggesting that parochial altruism—the difference in how much the ingroup and the ougroup receive—is subject to modification under social influence. Parochialism, in particular, is reduced when social influence is exerted from the ingroup. Our study suggests the research to take into account the social dynamics of interpersonal influence to understand how norms of parochial altruism evolve.