As young as 3 years old, children rely on a mutual intentionality framework to confer group membership--that is, agreement between a joiner ("I want to be in your group") and group ("We want you to be in our group"). Here, we tested whether children apply this cognitive framework in the context of identity-based groups,…

Group membership is a strong driver of everyday life in humans, influencing similarity judgments, trust choices, and learning processes. However, its ontogenetic development remains to be understood. This study investigated how group membership, age, sex, and identification with a team influenced 39- to 60-month-old children (N = 94) in a series…

This study investigated trajectories of time spent in structured activities from middle childhood to early adolescence by using data from the National Institute of Child Health & Human Development (NICHD) Study of Early Child Care. We used latent class growth analyses and identified five trajectories (stable low, increasing high, decreasing low,…

"Interpersonal" rejection and "intergroup" exclusion in childhood reflect different, but complementary, aspects of child development. Interpersonal rejection focuses on individual differences in personality traits, such as wariness and being fearful, to explain bully-victim relationships. In contrast, intergroup exclusion focuses on how in-group…