Ingroup favoritism in cooperation: A meta-analysis
A meta-analysis found that people cooperate more with members of their own group than with outsiders, with a small-to-medium effect (d = 0.32), weaker where group members have no mutual dependence as in dictator games (d = 0.19) and stronger in social dilemmas (d = 0.42). The effect was stronger when group membership was common knowledge and when exchanges were simultaneous rather than sequential. The authors concluded that discrimination in cooperation stems more from favouring the in-group than from derogating the out-group. Reading depth: abstract only; the d values are the abstract's.
A meta-analysis found that people cooperate more with members of their own group than with outsiders, with a small-to-medium effect (d = 0.32), weaker where group members have no mutual dependence as in dictator games (d = 0.19) and stronger in social dilemmas (d = 0.42). The effect was stronger when group membership was common knowledge and when exchanges were simultaneous rather than sequential. The authors concluded that discrimination in cooperation stems more from favouring the in-group than from derogating the out-group. Reading depth: abstract only; the d values are the abstract's.
Written from the abstract, University of Amsterdam repository record and Crossref, 2026-11-01.
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Balliet, D., Wu, J., & De Dreu, C. K. W. (2014). Ingroup favoritism in cooperation: A meta-analysis. Psychological Bulletin, 140(6), 1556-1581. doi:10.1037/a0037737 https://doi.org/10.1037/a0037737