N. Kathmann et al., INFORMATION-PROCESSING DURING EYE TRACKING AS REVEALED BY EVENT-RELATED POTENTIALS IN SCHIZOPHRENICS, ALCOHOLICS, AND HEALTHY CONTROLS, Schizophrenia research, 16(2), 1995, pp. 145-156
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.