EVENT-RELATED POTENTIALS IN CROSS-MODAL DIVIDED ATTENTION IN AUTISM

The behavior and event-related potentials (ERPs) of high functioning s ubjects with autism (Autism group) were contrasted with the results of normal controls (Control group) during a focused visual attention, a focused auditory attention and a visual/auditory divided attention tas k. Detecting targets by the Autism group in the cross-modal divided at tention condition was more difficult (longer RTs,lower % of correct de tections) than attending to one modality. However, both the Autism and Control groups performed all tasks above chance level. The slow negat ive wave (SNW) was the only negative component which reflected Focused vs Divided task effect in Controls, being largest to stimuli in singl e channel-focused attention, intermediate when attention was divided b etween targets of two modalities and smallest to unattended stimuli. T ask effects were more evident in the positive peaks for the Austism gr oup. No significant divided attention task effect was noted for P3b, a lthough it was larger for attended than ignored stimuli, of normal mor phology and only slightly decreased in size in the Autism group as com pared to the Control group. The failure of the Autism group to modulat e the slow negative wave in response to Focused/Divided/Ignored condit ions in a normal manner, the presence of relatively normal morphology despite the reduced amplitude of the P3b and other positive components , together with the high level of correct target detections are discus sed in the context of a selective inhibition deficit and an alternativ e mechanism of selective attention in autism.