Relative performance and implicit incentives in the intergroup prisoner’s dilemma

This paper illustrates how the payoff matrices of the single group Prisoner’s Dilemma (PD) and the Intergroup Prisoner’s Dilemma (IPD) differentially reinforce cooperation when participants care about relative performance. Examples of particular payoff patterns and thought experiments using a computational simulation demonstrate that withholding cooperation is not always the dominant strategy in the IPD. In the intergroup structure, three conditions differentially reinforce cooperation. When competing groups have equal numbers of cooperators, withholding cooperation is always the dominant strategy just as in the single group structure. In contrast, when one group has more cooperators than the other group, cooperation by its members can dominate withholding cooperation by members of the other group. Thus, the relative advantage of one group over another increases the payoff for cooperation in some configurations of the IPD over the payoff in the PD. Relative payoff is thus an untheorized variable motivating cooperation in the IPD.

► This paper provides a careful examination of the payoff matrix in the IPD.
► Implicit incentives often eliminate the dominance of a withholding strategy.
► When groups are tied, withholding cooperation is always the dominant strategy.
► In the IPD, when a group has more cooperators, cooperation is sometimes dominant.
► In the IPD, when a group has fewer cooperators, withholding is not always dominant.