Impaired context processing during irony comprehension in schizotypy: An ERPs study

Mentalizing deficits are a core manifestation of schizophrenia spectrum disorders. They contribute to the social handicap associated with the pathology, leading to disruption in autonomy, professional achievement, and interpersonal relationships. However, the underlying mechanisms of these deficits remain poorly understood. The aim of the present study was to test the hypothesis that context processing deficits would be responsible for mentalizing difficulties in schizotypy (personality traits considered as attenuated manifestations of schizophrenic symptoms) by using an irony comprehension task. Irony processing is a mentalizing exercise that requires the ability to take into account the semantic context to understand the literal meaning of the utterance, and to integrate the pragmatic context to infer the speaker's intention. These two steps of processing can be indexed by the N400 and P600 components, respectively, of event-related brain potentials (ERPs). Forty participants were assigned to high or low schizotypy groups according to their Schizotypal Personality Questionnaire (SPQ) score, and ERPs were recorded while they read short stories ending with a literal, ironic, or incompatible statement. In the low-SPQ group, there was a significant N400 semantic context effect (literal targets elicited less negative N400 amplitudes compared to incompatible targets) followed by a P600 pragmatic context effect (ironic targets evoked greater positive P600 amplitudes than literal targets). In contrast, there was neither a N400 nor P600 effect in the high-SPQ group. These abnormalities were associated with high interpersonal SPQ factor scores. These results show a strong association between context processing, mentalizing abilities, and interpersonal functioning in schizophrenia spectrum.