Cooperation in Intergroup and Single-Group Social Dilemmas

Abstract The fundamental intragroup problem in intergroup conflict can be characterized as a social dilemma: All group members are better off if they all cooperate in competing against the outgroup, but, at least when the group is large, each individual group member is always better off defecting. Are people less or more likely to cooperate in a social dilemma when it is embedded in the context of an intergroup conflict? To answer this question we contrasted the Intergroup Prisoners Dilemma (IPD) team game (Bornstein, 1992) with a structurally identical (single-group) Prisoners Dilemma (PD) game. The results indicate that subjects were almost twice as likely to cooperate in the IPD game than in the PD game even though: (a) the cost of cooperation for the individual group member is identical in the two games, (b) the external benefit to the individual′s group resulting from a cooperative choice is also identical, and (c) cooperation in the intergroup dilemma is collectively deficient whereas in the single-group dilemma it is collectively optimal. The motivational implications of this finding are discussed.