Explaining the evolution and maintenance of cooperation among unrelated individuals is one of the fundamental problems in biology and the social sciences. Recent experimental evidence suggests that altruistic punishment is an important mechanism to maintain cooperation among humans. In this...

Field evidence suggests that people belonging to the same group often behave similarly, i.e.,behaviour exhibits social interaction effects. We conduct an experiment that avoids theidentification problem present in the field. Our novel design feature is that each subjectsimultaneously is a member...

Economic and social interaction takes place between individuals with heterogeneous characteristics. We investigate experimentally the emergence and informal enforcement of different contribution norms to a public good in homogeneous and different heterogeneous groups. When punishment is not...