Local norms and shared beliefs in cohesive social groups regulate individual behavior in everyday economic life. I use a door-to-door field experiment where a hundred and twenty villagers recruited from twenty-three communities in a Japanese rural mountainous village play a simultaneous prisoner’s dilemma game. To examine whether a set of experiences shared through interactions among community members affect experimental behavior, I compare villagers’ behavior under in-community and out-community random matching protocols. I also report a counterpart laboratory experiment with seventy-two university student subjects to address the external validity of laboratory experiments. The findings are three-fold. First, almost full cooperation is achieved when villagers play a prisoner’s dilemma game with their anonymous community members. Second, cooperation is significantly higher within the in-group compared to the out-group treatment in both the laboratory and field experiments. Third, although a significant treatment effect of social group membership is preserved, a big difference in the average cooperation rates is observed between the laboratory and field.

有凝聚力的社会群体中的地方规范和共同信仰规范了日常经济生活中的个人行为。我使用了一个挨家挨户的实地实验，从日本农村山区的 23 个社区招募了 120 名村民，同时进行了囚徒困境博弈。为了检验通过社区成员之间的互动分享的一组经验是否会影响实验行为，我比较了社区内和社区外随机匹配协议下村民的行为。我还报告了一个对 72 名大学生科目的对应实验室实验，以解决实验室实验的外部有效性。研究结果是三重的。首先，当村民与匿名社区成员玩囚徒困境博弈时，几乎完全合作。第二，在实验室和现场实验中，与组外治疗相比，组内合作显着更高。第三，虽然保留了社会团体成员的显着治疗效果，但观察到实验室和现场之间的平均合作率存在很大差异。