Disinhibited behaviors in young children: relations with impulsivity and autonomic psychophysiology.

Cardiac activity has long been considered as a psychophysiological marker of adaptive psychological adjustment. Irregularities in autonomic nervous system activity have long been implicated in both externalizing and disinhibitory behaviors. The present study used a battery of assessments in children ages 4.5-5.5 years to examine the relation among disinhibitory measures. Additionally, cardiovascular activity and reactivity was examined. Mothers rated impulsivity and internalizing/externalizing behaviors. Reward-dominance and passive-avoidance response inhibition (i.e., via errors of commission) tasks were included. Results showed that behaviorally uninhibited children began with an attenuated sympathetic response (i.e., lengthened pre-ejection period) to an interview with a novel experimenter, while inhibited children began with a high level of sympathetic activity. Further, behavioral impulsivity was related to low sympathetic activity at rest. Consistent with theories of disinhibition, externalizing behaviors and measures of behavioral impulsivity were related to a reward-dominant response style. Findings are discussed with regard to motivational theories of behavior.