Intensity of Aggression in Childhood as a Predictor of Different Forms of Adult Aggression: A Two-Country (Finland and United States) Analysis.

This study examined the prediction of different forms of adult aggression in two countries from child and adolescent aggression. It was based on two longitudinal projects: the Jyväskylä Longitudinal Study of Personality and Social Development (JYLS; N = 196 boys and 173 girls) conducted in Finland and the Columbia County Longitudinal Study (CCLS; N = 436 males and 420 females) conducted in the USA. The same peer-nominated items for aggression were used in both studies at age 8; comparable measures of aggression also were available in adolescence (age 14 in the JYLS/19 in the CCLS) and adulthood (ages 36/30 and 42/48). Results showed that in both countries and in both genders, aggression in childhood was linked significantly to physical aggression and lack of self-control of anger in adulthood but not to verbal aggression. This differential predictability of aggression over 40 years suggests that individual differences in physical aggression are more determined by lasting individual differences (including emotional reactivity) than are individual differences in verbal aggression.