Third-party punishment: altruistic and anti-social behaviours in in-group and out-group settings

This study aims at exploring the decision-making process involved in third-party punishment (TPP) within an economic frame, using the TPP game. We investigated altruistic punishment, that is, the behaviour of spending one's own money, with no personal gain, to punish those who violate the norms of cooperation. We analysed this behaviour, in an in-group and out-group game setting, to compare how individuals behave with members of their own group (in-group) and with members of another group (out-group). In particular, groups were defined on a real nationality basis (Chinese or Italian). Our results showed altruistic punishment behaviour in both experimental groups and this tendency emerged as more prominent when faced with unfair play towards a member of one's own group. Furthermore, both groups exhibited a propensity for anti-social punishment behaviour: many participants spent small amounts of money to punish fair behaviour, regardless of national group membership.