Quantitative assessment of the frequency of normal associations in the utterances of schizophrenia patients and healthy controls

BACKGROUND The intrusion of associations into the utterances of schizophrenic individuals typically disrupts the coherence of the patient's utterances. Recent theoretical formulations of these phenomena have emphasized the hyperactivity) of associational networks in such language disturbance (e.g., Maher, B.A. 2003 Schizophrenia, aberrant utterance and delusions of control: the disconnection of speech and thought, and the connection of experience and belief. Mind and Language, 18, 1-22). There has been only limited effort to quantify such features in patient populations. METHODS We hypothesized that (1) coherent utterances elicited from a sample of schizophrenia patients will present a higher mean frequency of normative associations than in normal controls; and (2) there is a positive association between total associations in utterances and hyperassociative activity (positive facilitation) as assessed by a semantic priming task. Participants included 43 schizophrenic patients and 25 healthy controls. Three measures were employed, a new computer program, Computed Associations in Sequential Text (CAST), to quantify normative associations; a picture description technique for eliciting speech samples; and a semantic priming task to measure associative facilitation. RESULTS In coherent utterances, schizophrenia patients produced higher mean totals of associations compared to controls. Patients with positive facilitation scores in the controlled processing interval (1250 ms) of the semantic priming procedure, there was a correlation between facilitation scores and total frequency of associations. This effect was absent in controls. CONCLUSIONS These results are consistent with models of language disturbance in schizophrenia that posit hyperactivity of associational networks.