Although previous meta-analytic evidence supports the existence of parochialism in cooperation among adults, the extent to which children and adolescents are more willing to incur a personal cost to benefit ingroups, compared to outgroups, is not yet clear. We provide the first meta-analysis on the existence and magnitude of parochialism in cooperation among pre-adults. Based on 20 experimental economics studies (k = 69, N = 5268, age = 3–19, 12 countries, published 2008–2019), a multilevel meta-analytic model revealed a small overall effect size indicating that children and adolescents were more cooperative towards ingroups (d = 0.22, 95% CI [0.07, 0.38]). A series of single-moderator analyses tested for the following conditions: participant age and sex; game type ([mini-]dictator game, prisoner's dilemma, public goods dilemma, trust game, ultimatum game); outcome interdependence; membership manipulation (between- vs. within-subjects); group type (natural vs. experimental); reward type (monetary vs. non-monetary); and country of the participant. Parochial cooperation did not vary with participants' age. Parochialism was larger in non-interdependent (dictator-type) compared to interdependent (bargaining and social dilemma) games. There were no moderating effects of group type, membership manipulation or reward type. To provide more data on how parochialism develops, primary studies should report age ranges more precisely and use more restricted age groups.

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童年和青春期是否存在狭隘的合作？荟萃分析

尽管先前的元分析证据支持成人合作中存在狭隘主义，但与外群体相比，儿童和青少年在多大程度上更愿意承担个人成本以使内群体受益，目前尚不清楚。我们提供了关于在成人之间合作中狭隘主义的存在和程度的第一次元分析。基于 20 项实验经济学研究（k  = 69，N  = 5268，年龄 = 3-19，12 个国家，2008-2019 年发布），多水平元分析模型显示整体效应量较小，表明儿童和青少年更合作对内群体（d = 0.22, 95% CI [0.07, 0.38])。针对以下条件进行了一系列单主持人分析：参与者的年龄和性别；博弈类型（[迷你]独裁者博弈、囚徒困境、公共物品困境、信任博弈、最后通牒博弈）；结果相互依存；成员资格操纵（受试者之间与受试者内）；组类型（自然与实验）；奖励类型（货币与非货币）；和参与者的国家。狭隘的合作不随参与者的年龄而变化。与相互依存（讨价还价和社会困境）游戏相比，非相互依存（独裁者类型）游戏中的狭隘主义更大。没有群体类型、成员操纵或奖励类型的调节作用。为了提供更多关于狭隘主义如何发展的数据，初级研究应该更准确地报告年龄范围并使用更严格的年龄组。