SCHIZOPHRENIA HETEROGENEITY--A SEMANTIC PRIMING APPROACH

Recent research suggests that a defect in language information processing may be pathognomic of schizophrenia; however, no single explanatory model of abnormal cognition has been able to encompass the clinical and biological heterogeneity of this illness. Indeed, current reports which examine structural and processing aspects of semantic memory reveal that there are significant differences in the language information processing performance of various schizophrenic subgroups. These approaches derive from the field of cognitive psychology, which has witnessed a formidable explosion over the past fifteen years both in terms of experimental data and models which illuminate thought processes in normal subjects. In this project, we will systematically investigate semantic priming effects in schizophrenia and their relationship to clinical phenomenology and neuropsychological performance. We will compare and contrast both automatic and controlled levels of information processing, with an emphasis on distinguishing the performance of subgroups of schizophrenics on these tasks. We hypothesize that: A subgroup of schizophrenics shows virtually no semantic priming effects in tasks which rely mainly on automatic information processing, but shows normal (or greater-than-normal) priming in experiments which evoke controlled processes. This subgroup manifests paranoid/delusional features, less of a negative symptom/deficit syndrome, normal performance on neuropsychological testing which examines mainly executive functions, and abnormal performance in neuropsychological tasks examining aspects of working memory. A second subgroup of schizophrenics shows greater-than-normal semantic priming ("hyperpriming") in automatic information processing conditions plus evidence of impaired strategic/controlled priming mechanisms. This subgroup is characterized by disorganized and undifferentiated features, a negative symptom/deficit syndrome, and impairment on executive functions.