It's all in the cards: effect of stimulus manipulation on Wisconsin Card Sorting Test performance in schizophrenia

Patients with schizophrenia can be taught the Wisconsin Card Sorting Test (WCST) sorting rules based upon expanded feedback. However, few task manipulations have been reported that differentially improve patient performance without altering the nature of feedback provided. The present study tests the hypothesis that deficits in WCST performance in schizophrenia reflect, in part, impaired ability to manipulate abstract stimulus features, rather than impaired ability to utilize feedback. We developed a modified stimulus set - the Rockland Face Sorting Test (RFST) - in which abstract shapes were replaced with faces, which we hypothesized would be more tractable to sorting by patients. Task rules and feedback remained unchanged. Relative RFST and WCST performance was examined in 19 patients as well as 15 normative controls. A comparison group of 15 patients received only repeated WCST administrations. Patients performed significantly better on the RFST vs. the WCST in categories completed, total correct responses and conceptual level responses, whereas no improvement was seen in either the normative or repeated WCST comparison groups. Furthermore, progressive improvement was seen following repeated RFST administration. These findings demonstrate that stimulus characteristics, as well as executive deficits, contribute to impaired WCST performance in schizophrenia.