Physiological and behavioral regulation in two-year-old children with aggressive/destructive behavior problems.

A sample of 99 two-year-old children was selected on the basis of parents' responses to two administrations of the Child Behavior Checklist for two- to three-year-olds. Forty-nine of these children displayed symptoms of aggressive/destructive (externalizing) problems that were in the borderline clinical range (labelled "high risk") and 50 children displayed few such symptoms ("low risk"). The children were assessed in a series of laboratory procedures that were intended to be emotionally and behaviorally challenging, during which time heart rate was recorded and behavior was observed. To assess physiological regulation, resting measures of heart period and respiratory sinus arrhythmia (RSA), and heart period change and RSA suppression were derived from these procedures. To assess emotional and behavioral regulation, children's affect and on-task versus types of off-task behaviors were measured. Results indicated that children in the high-risk group did not differ from children in the low-risk group on the resting measure of heart period. Boys displayed lower heart rate than did girls, regardless of risk group. However, boys in the low-risk group differed from boys in the high-risk group in terms of resting measures of RSA. Children in the high-risk group did display significantly and consistently lower RSA suppression (physiological regulation) during the challenging situations than did the children in the low-risk group. High-risk children displayed more negative affect and dysregulated emotion regulation behaviors than did the low risk children. These findings are discussed in terms of the development of behavioral and emotional regulation that underlie adaptive versus maladaptive behavior.