Electrophysiological (Event-Related Potentials) Indices of Cognitive Processing in Autistic Learners.

Event-related Potentials (ERPs) were recorded to both auditory and visual stimuli from the scalps of nine autistic males and nine normal controls (all Ss between 12 and 22 years of age) to examine the differences in information processing strategies. Ss were tested on three different tasks: an auditory missing stimulus paradigm, a visual color discrimination, and an auditory tone discrimination task. The brain electrical activity was recorded and analyzed (both trial by trial and averaged waveform) for one thousand milliseconds following the target stimuli. Results indicated that the amplitude of the averaged P300 component was significantly reduced in the autistic group compared to the normal group. The N100 component was also smaller in amplitude, but it did not reach statistical significance. The latency of components was not significantly different among groups during the visual tasks; however, the latency of the P300 component was significantly longer in the autistic group during auditory tasks. The accuracy of performance with the operant button press and the appearance of the N100-P200 components in the autistic group suggested that the autistic individuals were attentive to the task. The sporadic occurrence of the P300 (when analyzed trial by trial) indicated that the autistic group was not consistently engaged in active stimulus evaluation at the higher information processing level. The delayed latency of the P300 component during auditory tasks in the autistic group hinted that there was more time required to complete stimulus evaluation in the auditory modality at the higher processing level than was required of the visual system at the same level. Results are consistent with the view that autistic learners show higher order processing deficits as displayed by their profound language defects and problems with complex thoughts. (Author/CL)