Convergent and discriminant validity of the WIST

Tested the ability of the Whitaker Index of Schizophrenic Thinking (WIST): (1) to distinguish schizophrenics from nonschizophrenics (N = 30); (2) to agree with clinically rated severity of thought disorder; and (3) to correlate with a measure of generalized cognitive deficit. The WIST was not found to discriminate accurately schizophrenics from nonschizophrenics, but was found to agree strongly with the Shipley Institute of Living Scale, a measure of generalized cognitive dysfunction. Finally, clinically rated estimates of schizophrenic thinking (i.e., conceptual disorganization, unusual thought content) failed to predict WIST Index. The WIST appears to be primarily a measure of generalized deficit.