Attention in Schizophrenia

Abstract

Earlier evidence has suggested a differential deficit in visual preattentive processes in schizophrenia. An understanding of the level of information processing at which such deficits might occur and links to a possible structural basis for such deficits were sought in an investigation of signal detection in the visual periphery. Acute and chronic schizophrenics alternatively classified as paranoid or nonparanoid and normals were tested in a task requiring simultaneous discrimination of foveal targets as well as detection of peripheral targets at either of two display angles where the use of scanning eye or head movements was experimentally controlled. An analysis of peripheral sensitivity indicated that chronic and particularly nonparanoid subjects were less able to detect peripheral targets than acute or paranoid schizophrenics and normals. An analysis of criterion indicated that paranoid subjects tended to be more conservative in the most difficult detection condition. Corresponding analyses of trial validity and response latency yielded no results indicative of systematic differences in motivation. Differences in sensitivity were therefore attributed to a deficit in early preattentive processes. The performance of nonparanoids also raised the question of differences in midbrain activity associated with the processing of ambient visual information.