Vigilance deficits in schizophrenics and affectively disturbed patients.

Vigilance is a concept associated with the early levels of information processing. Vigilance deficits have repeatedly been found in schizophrenic patients. It has not been clear, however, whether such cognitive dysfunctions are specific to schizophrenics or not. In this study, 28 schizophrenics were compared with 19 affectively disturbed patients and 17 normals on a vigilance test that is a hybridization of a Continuous Performance Test (CPT) and a Span of Apprehension Test (SAT). The results showed that schizophrenics performed significantly below the normals only on target hits on the CPT. There were no differences between the two patient groups, either on number of correct hits or on commission errors. On the SAT measures, normals performed better than the two psychiatric groups on all measures. Schizophrenics had more commission errors than the affectives, but there were no differences between the two groups with respect to target hits. Neither CPT nor SAT deficit, thus, seem to be specific schizophrenic characteristics.