Overinclusion and transactional thinking on the Object Sorting Test of schizophrenic and nonschizophrenic patients

Two aspects of "disordered thinking", overinclusion and transactional thinking were studied on the Object Sorting Test responses of 20 young schizophrenic patients and 20 comparable nonschizophrenic patients. Patients' parents were also studied for comparison. In addition, idiosyncratic responses from WAIS Comprehension items were assessed for comparison of another measure on another test. Transactional thinking and idiosyncratic responses were greater in schizophrenic patients. Conceptual overinclusion and bizarre responses also tended to be more frequent in schizophrenics, but behavioral overinclusion showed no differences. Conceptual overinclusion was consistently correlated with transactional thinking and idiosyncratic responses, while behavioral overinclusion showed an inconsistent pattern. The differences were attributed to the differences in the specificity of measures of disordered thinking.