The proposed research includes three studies that are conceptually related and utilize similar procedures. These studies are designed to investigate the nature of information processing deficits in schizophrenia by incorporating recent developments from experimental psychology. The studies will use the same groups of subject: medicated schizophrenic patients, unmedicated schizophrenic patients, bipolar patients, the siblings for each patient group, and normal controls. These groups allow us to test vulnerability and specificity issues as they relate to information processing deficits. Study 1 will investigate the possibility that deficits shown by schizophrenic patients across a variety of tests (Continuous Performance Test (CPT), Span of Apprehension, Backward Masking, and Critical Stimulus Duration (CSD) can be explained by a common deficit in early visual processing. It appears that negative symptoms are associated with deficits on each of these measures; hence a rating scale for negative symptoms will also be administered. Recent developments in the experimental literature offer the possibility of identifying the mechanism of backward masking under certain conditions. It is hypothesized that an early visual processing deficit can account for a large proportion of the variance on the CPT and Span, but is unrelated to performance on a verbal memory test. Study 2 will consider whether performance deficits on these measures represent episode markers or vulnerability markers. This study will investigate information processing deficits in normal controls and siblings of psychiatry patients using the same measures as Study 1. Presence of a deficit in a disproportionate number of first-degree relatives supports its role as a vulnerability marker. Despite the increasing importance of backward masking and CSD to schizophrenia research, these task have never been used with any first-degree relatives. Study 3 will use a metacontrast masking procedure with targets of high and low spatial frequency. This study is designed to test the hypothesis that certain visual sustained channels are dysfunctional in schizophrenia.
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