the ‘‘tragedy of the commons’’

to trust altruistic individuals more than nonaltruistic individuals. I also included a condition whereparticipants had to choose only one person to trust (instead of being able to trust all players) in the dyadic trust game that followed the cooperative group game, and contributions towards the group were maintained best in this condition. This provides some evidence that competition for scarce reputational benefits can help maintain cooperative behaviour because of competitive altruism