Error Patterns in Progressive Matrices in Schizophrenia and Bipolar Disorders

Conventional scoring of matrix reasoning focuses on total accuracy, overlooking qualitative error patterns that may reflect distinct cognitive mechanisms, especially in psychiatric populations where total scores often have limited discriminatory value. We examined performance in terms of accuracy and error patterns using MatriKS, a digital matrix reasoning task, in 430 individuals (28 with schizophrenia, 31 with bipolar disorder, and 371 healthy controls). Both clinical groups showed lower accuracy and more total errors than controls. To isolate qualitative differences, four conceptual error types were analyzed: repetition (R), wrong principle (WP), difference (D), and incomplete correlate (IC). Relative to controls, schizophrenia showed higher odds of D than R errors, though not robustly; bipolar disorder did not differ credibly on any error type. A direct comparison between the clinical groups revealed higher odds of D than R errors in patients with schizophrenia compared to bipolar ones but did not reach credibility; neither IC nor WP errors showed a credible diagnostic effect. A second model, restricted to the clinical sample, tested whether visual attention and verbal working memory can account for this pattern. Neither these measures, diagnosis, nor their interaction credibly predicted error type. Substantial unexplained heterogeneity emerged instead, driven more by individual differences for D errors and by item properties for IC and WP errors. Although preliminary, these findings offer an interesting support for qualitative error profiling alongside total-score metrics, though diagnostic specificity remains to be established in larger samples.