P300 and stimulus evaluation process in autistic subjects.

Cognitive functioning in autistic subjects was investigated by employing ERP recordings. The sample included four autistic patients, with five normal subjects and four Down's syndrome patients serving as the two control groups. The P300 component was investigated under three different experimental conditions, that is; "No-task," "Counting," and "Keypress." Two out of four autistic subjects were able to perform the required task under the Counting condition. However, none of them were able to complete the task for the Key-press condition. Autistic subjects demonstrated a lower amplitude of the P300 component under the No-task condition as compared to the other two groups. It was speculated that the autistic, as opposed to the other two groups, had some cognitive difficulties in the "active stimulus evaluating process."