Intergroup Competition Promotes Intragroup Cooperation: A Meta-Analysis of Social Dilemmas.

Current theories pose that intergroup competition elevates intragroup cooperation and put forward hypotheses about conditions that increase the magnitude of this effect. Here, we report a preregistered meta-analysis of studies using experimental games that manipulate the presence of intergroup competition and its effect on intragroup cooperation. Our investigation reveals the overall direction and magnitude of the effect, which addresses mixed empirical findings. We identified 25 articles to meet inclusion criteria, which yielded 70 effect sizes. A multilevel random effects model revealed a medium positive effect of intergroup competition on intragroup cooperation (g = .677, N = 6,051). Studies involving intergroup competition with interdependence produced a strong effect, whereas this effect was weaker for studies without interdependence. Our findings present meta-analytic evidence that intergroup competition promotes intragroup cooperation and identify opportunities for future research.