Group membership increases cooperation in social dilemma games, altruistic donation in dictator games, and fair offers in ultimatum games. While the empirical study of group action has grown rapidly over the years, there is little agreement at the theoretical level on exactly why and how group...

We analyse the experimental outcome of the Traveller's Dilemma under three different treatments - baseline (BT), compulsory ex post players' meeting (CET) and voluntary ex post players' meeting (VET) - to evaluate the effects of removal of anonymity (without preplay communication) in a typical...

Group membership is a powerful determinant of social behaviour in a variety of experimental games. Its effect may be channelled primarily via the beliefs of group members, or directly change their social preferences. We report an experiment with a prisoner's dilemma with multiple actions, in...