Conceptual Thinking in Schizophrenics and their Relatives

Abstract

The hypothesis has been tested that a difficulty in concept formation and use occurs regularly and severely in schizophrenics, regardless of diagnostic sub-type, less regularly and severely in their relatives and occasionally and mildly in "normal" controls. This hypothesis was tested in the above three groups by use of the Shipley-Institute-of-Living-Scale, the Payne Object Classification Test, the Epstein Test for Overinclusiveness and the Benjamin Proverbs Test, with 45 controls, 48 relatives and 30 schizophrenic women on the admission service. The hypothesis was confirmed. "Pathological" scores were obtained in 17 of 18 parents of 9 patients, by the conceptual quotient of the SIL and a P_A of the Payne Object Classification Test. The data are not inconsistent with quantitatively subdominant genetic inheritance of a conceptualizing difficulty which, in homozygotes, has a high penetrance of schizophrenia.