Refixation saccades and attention in schizophrenia

Saccadic refixation eye movements of 20 schizophrenic, 20 hospitalized nonpsychotic, and 20 normal subjects were compared in two repetitive fixation tasks with high and low target information. Although no differences emerged among groups in the overall frequency or size of saccades, the average and peak velocity of saccades was slower for schizophrenics than for normals. The velocity of saccades for the hospitalized nonpsychotic group was between that of schizophrenics and normals. To evaluate this finding further, saccades in the first two stimulus cycles were examined. The average and peak velocity of saccades was found to be significantly slower for schizophrenics than for normals. Again, the velocity of saccades for hospitalized nonpsychotic subjects was between that of schizophrenics and normals. Moreover, the size of saccades during the first two cycles was smaller for the schizophrenic than for other subject groups. Embedded alphanumeric information in the fixation target generally resulted in increased velocity of saccades for all subjects. The results were interpreted as evidence for an attentional deficit in schizophrenia. Specifically, schizophrenic subjects appeared to be less able to utilize peripheral visual information than hospitalized or normal subjects.