なぜ人は非露見状況でも利他的に振舞うのか

抄録

Why do people behave altruistically toward others, even in situations where nobody would observe their behavior? We formulated the following hypothesis regarding this question: “Reputations are decided by behaviors in situations that nobody can observe, rather than by behaviors in situations that can be observed by others.” The validity of this hypothesis was examined through a Prisoner’s Dilemma experiment. In the first stage, participants played the Prisoner’s Dilemma game in a situation where nobody could observe them. In the second stage, participants selected another partner in the game, based on information about their behavior in the first stage. The results indicated that participants tended to choose people that behaved altruistically in situations where nobody could observe them. Furthermore, this tendency was stronger with cooperative participants. These results support the hypothesis of this study.