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 mo del permit distinction and measurement of various processes which dete rmine whether or not an action can be inhibited. Three studies are des cribed that find a deficit in attention deficit hyperactivity disorder (ADHD) in inhibitory control of an ongoing action and in the processe s involved in the reengagement of an alternative action following inhi bition of an ongoing action. No evidence of deficient attentional capa city was found in ADHD that could account for these deficits. These de ficits were most pronounced in children who had ADHD according to repo rts of both parent and teacher (pervasive ADHD) compared to those whos e ADHD was reported by either parent or teacher but not both. No defic it was evident in children with conduct disorder (CD) or in those with a combined presentation of ADHD and CD despite the fact that these gr oups were characterized by clinical impulsiveness. The article discuss es the implications of these findings for models of the relationship o f cognitive deficit and behavior.