Group identity and cooperative behavior: Evidence from a public goods experiment

Using the minimal group paradigm (MGP) and a public goods game, we examine cooperative behavior among children and adolescents aged 9–16 across varying treatments of group identity in China. We find that cooperative behavior differs significantly across group identity configurations, consistent with a pattern of in-group favoritism. Further analysis reveals age-group differences in cooperation, with higher contribution levels observed among older children, but only for in-group treatments. Girls show higher and more consistent levels of cooperation than boys do in contexts of heterogeneous group identity. Only children display stronger behavioral responses to heterogeneous group identity than children with siblings do. Additionally, left-behind children (LBC) and children with experiences of bullying exhibit lower levels of in-group cooperation than their peers do, suggesting that the trust-dependent effects of group belonging may be associated with early adverse social experiences. We further link individuals' responsiveness to changes in group identity with real-life behavioral indicators and find that children who respond more strongly to changes in group identity tend to report lower subjective evaluations of social relationships, experience more frequent peer conflicts, and exhibit weaker cognitive performance. These findings suggest that our experimental design effectively captures individual differences in social adaptability and cognitive functioning in real-life contexts. Our study provides empirical evidence of the developmental patterns of cooperative behavior among children in various social identity contexts and highlights the role of group identity and the social environment in shaping behavior.