INHIBITORY CONTROL, IMPULSIVENESS, AND ATTENTION-DEFICIT HYPERACTIVITY DISORDER

This article describes a new measure for studying inhibitory control, the stop signal paradigm, and the race model of inhibitory control of action (Logan & Cowan, 1984) on which it is based. This measure and model permit distinction and measurement of various processes which determine whether or not an action can be inhibited. Three studies are described that find a deficit in attention deficit hyperactivity disorder (ADHD) in inhibitory control of an ongoing action and in the processes involved in the reengagement of an alternative action following inhibition of an ongoing action. No evidence of deficient attentional capacity was found in ADHD that could account for these deficits. These deficits were most pronounced in children who had ADHD according to reports of both parent and teacher (pervasive ADHD) compared to those whose ADHD was reported by either parent or teacher but not both. No deficit was evident in children with conduct disorder (CD) or in those with a combined presentation of ADHD and CD despite the fact that these groups were characterized by clinical impulsiveness. The article discusses the implications of these findings for models of the relationship of cognitive deficit and behavior.