In the experiment there are three players A, B, and C. Player A gets an initial endowment of 10, player B gets 0 and player C gets 5 points. First, player A decides how many of his 10 points to transfer to B. Then, player C observes the decisions of A and gets the possibility to leave the payoffs unaffected or to punish A by deducting 3 (or 6) points from A at a cost of 1 point (or 2 points) for C....

Protocol: Experiments on Parochial Altruism in Humans; Procedures and Instructions