Selective deficits in visual perception and recognition in schizophrenia

The purpose of this study was to evaluate the performance of patients with schizophrenia on tests of visual discrimination and recognition of different stimulus features.

Thirteen medicated male schizophrenic patients and 13 normal comparison subjects were tested on four stimulus features: spatial frequency, pattern, location, and trajectory. Subjects had to make both discrimination and recognition judgments at three levels of stimulus disparity.

The responses of the patient group were slower and less accurate than those of the comparison group on both the discrimination and recognition tasks. The patients were less accurate than the comparison subjects in processing spatial features of the stimuli, particularly trajectory, but were unimpaired in processing form attributes (high spatial frequencies and patterns). When the results of pattern and trajectory tasks were matched against the accuracy performance of the comparison group, the patients were less accurate on trajectory than on pattern judgments and less accurate on recognition than on discrimination performance.

Schizophrenia may be accompanied by impaired visual spatial perception and representation. In schizophrenia, deficits in trajectory discrimination may reflect a disturbance of the dorsal pathway of the visual system, while disturbances of trajectory recognition performance may reflect a deficit in prefrontal systems involved in visual working memory operations.