Give and you shall receive. Give more and you shall be honored. Experimental evidence for altruism as costly signaling

In two studies, we measured the degree and manner of reciprocation of a public good in subsequent two-by-two interactions. Both studies consisted of two phases: a public good phase and a subsequent give some game (i.e. a gradual Prisoner's dilemma game). In the first study, the public good was a financial game in the lab. In the second study, the public good games were real life student projects. The observed behavior in the subsequent interactions was consistent with the reciprocity rule, but only up to the fairness norm of equality. Students who had invested more than their fair share, did not receive more financial returns than those who had invested a fair share. However, despite the lack of financial benefits, these high investors were preferred more as future team mates (Study 1), or received more social rewards (Study 2). We interpret these findings in terms of altruism as costly signaling.status: publishe