Setting the stage: Biopsychosocial predictors of early childhood externalizing behaviors.

Research has indicated that biological (self-regulation), psychological (temperament), and social (maternal parenting behaviors) factors predict childhood externalizing behaviors. Few studies, however, have evaluated psychological, biological, and social factors in conjunction as predictors of childhood externalizing behaviors. Further, limited research has examined whether these biopsychosocial predictors during infancy and toddlerhood predict the onset of externalizing behaviors in early childhood. The present study aimed to examine the longitudinal relations between biopsychosocial predictors of child externalizing behaviors. Children and their mothers (n = 410) participated when children were 5, 24, and 36 months old. Child self-regulation was assessed via baseline respiratory sinus arrhythmia (RSA) at age 5 months, and child psychology was measured via maternal report of effortful control at age 24 months. Additionally, maternal intrusiveness was assessed during a mother-child interaction at age 5 months. At 36 months, mothers reported on child externalizing behaviors. Longitudinal path modeling was used to examine the direct and indirect effects of maternal intrusiveness and child effortful control on child externalizing behavior, as well as whether these effects were conditional upon child baseline RSA. Results showed a significant indirect effect of maternal intrusiveness on externalizing behavior through effortful control, and this pathway was moderated by baseline RSA after controlling for orienting regulation at age 5 months. These results suggest that early childhood externalizing behaviors are jointly affected by biological, psychological, and social factors during toddlerhood.