Do schizophrenia patients make more perseverative than non-perseverative errors on the Wisconsin Card Sorting Test? A meta-analytic study.

The Wisconsin Card Sorting Test (WCST) is widely used to explore executive functions in patients with schizophrenia. Among other findings, a higher number of perseverative errors has been suggested to implicate a deficit in task switching and inhibitory functions in schizophrenia. Many studies of patients with schizophrenia have focused on perseverative errors as the primary performance index in the WCST. However, do schizophrenia patients characteristically make more perseverative than non-perseverative errors compared with healthy controls? We reviewed the literature where schizophrenia patients were engaged in the WCST irrespective of the primary goal of the study. The results showed that while both schizophrenia patients and healthy participants made more perseverative than non-perseverative errors, the contrast between perseverative and non-perseverative errors is higher in schizophrenia patients only at a marginal level of significance. This result suggests that schizophrenia patients do make a comparable number of non-perseverative errors and cautions against simplistic interpretation of poor performance of schizophrenia patients in WCST as entirely resulting from impairment in set-shifting or inhibitory functions.