This project uses experimental psychological techniques to examine whether schizophrenic deficits in ocular-motor, cognitive, and social tasks result from an impaired ability to suppress inappropriate responses linked to dysfunction of the prefrontal cortex and related brain areas. Data collection from our core sample of 65 medicated schizophrenics and 44 matched normals is complete, but we are continuing to test subjects available in both a medicated and a drug free state. In FY96 we were deeply involved in editing and preparing our data for analysis, but carried out some important analyses. Those of our Stroop data led to results of substantial theoretical import accepted this year for publication in a major journal. These findings suggest that """"""""out of sight"""""""" is """"""""out of mind"""""""" for schizophrenic individuals and confirm conjectures by Goldman-Rakic about the effects of prefrontal cortex dysfunction on the working memory of schizophrenic individuals. Analyses examining individual differences among schizophrenic subjects indicate that the 15% with deficit syndrome have more trouble than the others in maintaining representation of the """"""""task-relevant context. Analyses of other experimental tasks compared the effects of foreperiod variations in saccadic and manual reaction time (RT) tests. Although manual RT showed the characteristic schizophrenic slowness and exaggerated foreperiod effects, no differences were found between our schizophrenic and normal subjects in saccadic RT performance. These results raise major questions about the locus of the RT deficits seen as characteristic of schizophrenia.
