Few systematic studies of play in foragers exist despite their significance for understanding the breadth of contexts for human development and the ontogeny of cultural learning. Forager societies lack complex social hierarchies, avenues for prestige or wealth accumulation, and formal educational institutions, and thereby represent a contrast to…

The longitudinal association between competitive video game play and aggression among young adults and adolescents was examined. Young adults (N = 1,132; M[subscript age] = 19 years) were surveyed annually over 4 years about their video game play and aggression, and data from a 4-year longitudinal study of adolescents (N = 1,492; M[subscript…

Vocabulary knowledge was tested in a native (Cantonese-Chinese) and foreign (English) language in 150 twins and 150 singletons aged 6-11 years, matched on age, gender, grade level, nonverbal intelligence, parents' education, family income, and number of siblings and household members. The singletons clearly outperformed the twins on the native…

Tested hypothesis that children would compete more playing competitive games in tetrads than in dyads. Found that male target children competed more in tetrads than in dyads; female target children did not show different levels of competition based on group size. Based on a global measure of smiling, the emotional atmosphere was less positive in…