INFORMATION-PROCESSING DURING EYE TRACKING AS REVEALED BY EVENT-RELATED POTENTIALS IN SCHIZOPHRENICS, ALCOHOLICS, AND HEALTHY CONTROLS

To further explore the hypothesis that schizophrenics are more distrac table and/or have reduced processing resources available, event-relate d potentials (ERPs) and smooth pursuit eye movements (SPEM) were inves tigated in 20 medicated schizophrenics, 19 detoxified chronic alcoholi cs, and in a control group of 20 healthy subjects. Groups were matched for age and education. Eye tracking tasks and auditory oddball tasks were performed separately as well as simultaneously. In addition, an e ye tracking condition with a task-irrelevant tone sequence was used to assess the effect of distraction. Schizophrenics showed a trend for p oorer SPEM performance; alcoholics had no dysfunction in this task. Tr acking accuracy did not change in either group when additional auditor y stimuli were presented. P300 latency was delayed in both schizophren ics and alcoholics. P300 amplitude showed no overall group difference but it increased during the dual task in normals whereas it remained c onstant in patients. N100 amplitude was generally larger during the mo re complex conditions indicating heightened unspecific arousal. It is suggested that normals use increased arousal to mobilize additional re sources and to allocate them to stimulus evaluation but schizophrenics and alcoholics are unable to do so. Results are more conform to a lim ited resources concept than to a filter deficit model of cognitive dis turbances in schizophrenia and alcoholism.