The Impact of Social Ties on Group Interactions: Evidence from Minimal Groups and Randomly Assigned Real Groups
通过实验比较随机分配的最小群体和涉及真实社交互动的群体，发现社会纽带会增强群体内合作偏好，但会改变利他规范执行模式，提醒不能简单将最小群体结论推广到有社会背景的群体。
Economists are increasingly interested in how group membership affects individual behavior. The standard method assigns individuals to “minimal” groups, i.e. arbitrary labels, in a lab. But real groups often involve social interactions leading to social ties between group members. Our experiments compare randomly assigned minimal groups to randomly assigned groups involving real social interactions. While adding social ties leads to qualitatively similar, although stronger, in-group favoritism in cooperation, altruistic norm enforcement patterns are qualitatively different between treatments. Our findings contribute to the micro-foundation of theories of group preferences, and caution against generalizations from “minimal” groups to groups with social context.