Explaining human cooperation in large groups of non-kin is a major challenge to both rational choice theory and the theory of evolution. Recent research suggests that group cooperation can be explained by positing that cooperators can punish non-cooperators or cheaters. The experimental evidence...

We experimentally test the social motives behind individual participation in intergroup conflict by manipulating the framing and symmetry of conflict. We find that behavior in conflict depends on whether one is harmed by actions perpetrated by the out-group, but not on one’s own influence on...

According to Adam Smith (1790), human selfishness can be restrained by introspection. We test the effect of introspection on people’s willingness to cooperate in a public good game. Drawing on the concept of identity utility (George A. Akerlof and Rachel E. Kranton, 2000), we show...