The Effect of Out-Group Competition on Individual Behavior and Out-Group Perception in the Intergroup Prisoner's Dilemma (IPD) Game

Hebrew University of Jerusalem students participated in two experiments of repeated play of the Intergroup Prisoners' Dilemma (IPD) game, which involves conflict of interests between two groups and, simultaneously, within each group. The experiments manipulated the level of competition exhibited by the out-group members (i.e., their level of contribution to their group's effort in the conflict). Consistent with the hypothesis that participants use strategies of reciprocal cooperation between groups, higher levels of out-group competition caused participants to increase their contribution and lower levels caused them to decrease it. In addition, participants had accurate recall of the contribution levels of out-group members, and they attributed motivations to out-group members in a manner that reflected their level of contribution. The nature of reciprocation with the out-group is discussed in light of both behavioral and cognitive data.