title: Category learning and perceptual categorization in schizophrenia.
abstract: The aim of this study was to evaluate category learning in schizophrenia on tests of perceptual abstraction. Participants learned to categorize simple geometrical shapes. The categories were either well-defined (discrete categories, or DCs) or ill-defined (graded categories, or GCs). In DCs, the cues defining category membership can be verbalized in an all-or-none fashion, while in GCs they cannot be defined unambiguously. Three types of learning were used successively: serial presentation of category-exemplars, verbal description, and feedback. After the serial presentation, schizophrenia patients showed a deficit for GCs (p<0.005) but not for DCs (p = 0.98). After the verbal definition of GCs, the difference between schizophrenia patients and controls diminished (p = 0.09). Finally, after the feedback learning of GCs, a significant difference was observed again (p<0.0001), suggesting that schizophrenia patients were impaired in this learning paradigm. The GC-learning impairment after the serial presentation displayed a relationship with the score of the cognitive component assessed with the Positive and Negative Syndrome Scale (r = -0.66). In conclusion, these results suggest that the perceptual stage of abstraction is impaired in schizophrenia. This impairment can be partially compensated by instructions via top-down verbal processes.
authors.affiliation: Department of Psychiatry, Albert Szent-Györgyi Medical University, Szeged, Hungary.
authors.forename: S
authors.initials: S
authors.lastname: Kéri
authors.forename: G
authors.initials: G
authors.lastname: Szekeres
authors.forename: I
authors.initials: I
authors.lastname: Szendi
authors.forename: A
authors.initials: A
authors.lastname: Antal
authors.forename: Z
authors.initials: Z
authors.lastname: Kovács
authors.forename: Z
authors.initials: Z
authors.lastname: Janka
authors.forename: G
authors.initials: G
authors.lastname: Benedek
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000150:complications / Q000503:physiopathology; D003210:Concept Formation / Q000502:physiology*; D005260:Female; D006801:Humans; D007721:Knowledge of Results, Psychological; D007858:Learning / Q000502:physiology; D008297:Male; D008569:Memory Disorders / Q000150:complications / Q000503:physiopathology; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology; D012559:Schizophrenia / Q000150:complications* / Q000503:physiopathology; D012565:Schizophrenic Psychology; D012660:Semantics