EFFECTS OF REWARD AND RESPONSE COST ON RESPONSE-INHIBITION IN AD HD, DISRUPTIVE, ANXIOUS, AND NORMAL-CHILDREN/

In previous research, children with attention deficit/hyperactivity di sorder (AD/HD) have demonstrated impaired response inhibition on the s top paradigm. In this study we examined whether this impairment in fac t reflects a motivational deficit. Four groups of children (age range 7-13 years) participated in the study: 14 AD/HD children, 21 normal co ntrols, 14 disruptive children, and 14 anxious children. The psychopat hological groups were recruited from special educational services and mental health outpatient clinics. Parent, teacher, and child questionn aires were used to select children with pervasive disorders. Normal co ntrols attended regular classes and scored low on all questionnaires. Children were tested once with reward contingencies and once with resp onse cost contingencies in a randomized crossover design. We hypothesi zed that if a motivational deficit underlies poor response inhibition in AD/HD children, this deficit will be remedied by response contingen cies. Despite the presence of response contingencies, AD/HD children s howed poor response inhibition compared with normal controls. Findings argue against a motivational explanation for the response inhibition deficit in AD/HD children.