In-group favoritism in social dilemma situations is one of the main findings of studies in Social Identity Theory. We investigate what causes the in-group bias: is it due to mere group affiliation or, alternatively, is guilt-aversion a possible explanation? We induce group membership in a...

We conduct a real-effort task experiment where subjects’ performance translates into a donation to a charity. In a within-subjects design we vary the visibility of the donation (no/private/public feedback). Confirming previous studies, we find that subjects’ performance increases, that is,...