The Effect of Repeated Play in the IPG and IPD Team Games

Repeated interaction in integroup conflict was studied in the context of two team games: the intergroup public goods (IPG) game and the intergroup prisoner's dilemma (IPD) game. The results reveal (a) a main effect for game type; subjects were twice as likely to contribute toward their group effort in the IPG game than in the IPD game, and (b) a Game-Type × Time interaction; subjects contributed less over time in the IPD game while continuing to contribute at about the same rate in the IPG game. The second finding supports the hypothesis that subjects learn the structure of the game and adapt their behavior accordingly and is compatible with a simple learning model, which assumes that choices that have led to good outcomes in the past are more likely to be repeated in the future. A reciprocal cooperation hypothesis, which assumes that players make their choices contingent on the earlier choices of the other players, received little support.