In order to more fully understand how individual differences influence adaptation to violence, this study examined the moderating influence of resting heart rate (HR) and HR variability (HRV) between community violence (CV) exposure and child reactive/proactive aggression. Forty 7-13-year-old community children self-reported CV exposure (i.e., victimization, witnessing, or hearing about violence) and were assessed for resting HR and HRV. Parents rated them on reactive/proactive aggression. CV victimization was positively related to proactive aggression only in conditions of low HR, and witnessed CV was positively related to reactive aggression only in conditions of high HRV. Main effects were not found for CV exposure or psychophysiological functioning, suggesting the importance of their interaction. Findings are discussed in terms of HR under-arousal, emotion dysregulation, fearlessness, and behavioral disinhibition as components that can increase aggression in response to violent contexts. Findings support a biosocial basis for childhood aggression and have implications for prevention and treatment. © 2008 Wiley Periodicals, Inc.

Reactive aggression (RA) is an angry response to perceived provocation. Proactive aggression (PA) is a pre-meditated act used to achieve some goal. This study test hypotheses that (1) individuals high in RA and PA will differ in resting levels of autonomic arousal and (2) RA will be related to emotional and behavioral problems, while PA only to behavioral problems. Parents of 68 children (age 6–13) reported on child symptoms, reactive/proactive aggression, and behavior problems. Resting heart rate (HR), skin conductance (SC), and HR variability (HRV) were measured in 42 of the children. RA was significantly related to decreased HRV and a trend for decreased SC, while PA was significantly related to increased SC and HRV. RA was significantly related to increased internalizing behaviors and attention deficits, while PA was significantly related to increased hyperactivity/impulsivity and delinquent behavior problems. Findings support a distinction between child reactive (hot-tempered) and proactive (cold-tempered) aggression in autonomic, emotional (i.e., internalizing problems), and behavioral (i.e., attention deficits, hyperactivity/impulsivity, and delinquent behavior) functioning, and are discussed in relation to theories of antisocial behavior.