TEST OF 2 VIEWS OF IMPULSIVITY IN HYPERACTIVE AND CONDUCT-DISORDERED CHILDREN

The nature of impulsivity in hyperactive and conduct disordered childr en was examined in two experiments, one involving a priming task, the other a delayed reaction time task. Four groups of children, aged 7 to 8 sears and with IQs in the normal range, were recruited for study: ( 1) a pure hyperactive group (HA), (2) a hyperactive/conduct-disordered group (HA+CD), (3) a pure conduct-disordered group (GD), and (4) a no rmal control group (N). When the stimulus configuration and presentati on were simple and well organized, none of the three clinical groups d isplayed any sign of impulsivity at the input/perceptual stage; there was no tendency to rush responding before adequate consideration of th e relevant stimuli, i.e. a trading of accuracy for speed. Instead, the HA children were found to be disinhibited at the output/motor stage, i.e. failing to temporarily withhold activated responses. This deficit was found to be specific to the HA children; it was not observed in t he CD and HA+CD children.