The joint development of physical and indirect aggression: Predictors of continuity and change during childhood.

A person-oriented approach was adopted to examine joint developmental trajectories of physical and indirect aggression. Participants were 1183 children aged 2 years at the initial assessment and followed over 6 years. Most children followed either low or declining trajectories of physical aggression (PA), but 14.6% followed high stable trajectories. Approximately two-thirds of participants followed low indirect aggression (IA) trajectories (67.9%), and one-third (32.1%) followed high rising trajectories. The results combining both PA and IA group memberships indicate that most children (62.1%) exhibit desisting levels of PA and low levels of IA. A significant proportion followed a trajectory of moderately desisting PA and rising IA (14.2%), and 13.5% followed high level trajectories of both forms of aggression. Virtually no children were high on one type and low on the other. Multinomial regressions analyses were used to predict joint trajectory group membership from selected child and family variables measured at 2 years. Young motherhood and low income predicted membership in the high PA-high IA trajectory, but only hostile parenting remained significant after family processes variables were entered in the model. Being a boy, young motherhood, and hostile parenting were generally associated with higher levels of PA. Girls were more likely than boys to follow a trajectory of desisting PA and rising IA. The results suggest that some children, mostly girls, reduce their use of PA and tend to increase their use of IA, and that highly physically aggressive children also tend to be highly indirectly aggressive. Early family risk characteristics and hostile parenting interfere with the socialization of aggression.