Patterns of Thought Disorder: Overinclusion and Overexclusion in Schizophrenics, Manics, and other Psychopathological Groups

Abstract

This study investigated overinclusive and overexclusive thinking in chronic and acute schizophrenics, manics and schizoaffective schizophrenics. Comparison groups were comprised of depressives, character disorders, and borderline patients. A concept formation task was developed which allowed for a separate analysis of association and accuracy errors. The major findings were: (a) acute and chronic schizophrenics did not differ from each other but did differ from comparison-control groups; (b) the manic pattern differed from all other groups showing severe overinclusion and minimal overexclusion; (c) schizoaffective schizophrenics shared qualities of both the schizophrenic and manic groups but were equivalent to neither.