A validation study of forms A and B of the Whitaker Index of Schizophrenic Thinking

Hospitalized psychiatric patients (n = 115) completed either Form A or Form B of the Whitaker Index of Schizophrenic Thinking, along with the Beck Depression Inventory, State Anxiety Inventory, and the MMPI. Only error scores on the WIST were calculated in an effort to assess validity of the WIST for use in group testing situations where individual timing and administration is cumbersome. Results supported the convergent and discriminant validity of Form A where significant correlations were found with measures of thought disorder (MMPI F, Pt, Sc and Pa) but not with indices of other symptomatology, such as depression and anxiety. Form B did not show such validity, with only one significant correlation with other measures (MMPI Pd). Both WIST Forms correctly identified nonschizophrenics (76% for Form A and 73% for Form B) more often than schizophrenics (57% for each form). Also, Form A was found to be negatively related to years of education. Suggestions for further research on the influence of intelligence and social class variables on WIST scores were made. Overall, Form A emerged as the most valid WIST form, with suggestions for its clinical use being offered.