Empirical evaluation of language disorder in schizophrenia

Objective: Studies of the content of speech and of verbal hallucinations in schizophrenia point to dysfunction at multiple levels of language. In this study, we empirically evaluated language processes. Methods: We examined the performance of 22 schizophrenia patients and 11 healthy control subjects with procedures designed to explore the sublexical, lexical, semantic, syntactic and discourse levels of language processing. Results: Schizophrenia patients exhibit impairment in the recognition of incorrect, but not correct, linguistic stimuli at all but the sublexical level of language processing. The patients were not impaired in the recognition of nonlinguistic stimuli. Conclusion: This language-specific differential impairment could explain speech abnormalities in schizophrenia. The nonrecognition of incorrect linguistic information would prevent patients from correcting the abnormal speech they may occasionally produce. A model of decreased power of linguistic computations (reduced number of operations) adequately accounts for this differential impairment.