The effects of collaboration and minimal-group membership on children’s prosocial behavior, liking, affiliation, and trust

• Compared the effects of collaboration and minimal group membership in children.
• Effects on prosocial behavior, liking, affiliation, and trust were measured.
• Five-, but not 3-year-olds’, behavior was similarly affected by both processes.
• Minimal groups thus exert a surprisingly powerful influence on children’s behavior.
• By 5 years, collaboration and group membership affect social preferences similarly.

Recent theoretical work has highlighted potential links between interpersonal collaboration and group membership in the evolution of human sociality. Here we compared the effects of collaboration and minimal-group membership on young children’s prosocial behavior (i.e., helping and resource allocation), liking, affiliation, and trust. In a design that matched as closely as possible these two ways of connecting with others, we showed that 5-year-olds’ behavior was affected similarly by collaboration and minimal-group membership; both increased children’s preference for their partners on multiple dimensions and produced overall effects of a similar magnitude. In contrast, 3.5-year-olds did not have a strong preference for either collaborators or minimal in-group members. Thus, both collaboration and minimal-group membership are similarly effective in their influence on children’s prosocial behavior and social preferences.