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Eluding the illusion? Schizophrenia, dopamine and the McGurk effect

Research output: Contribution to journalArticle

Thomas P. White, Rebekah L. Wigton, Dan W. Joyce, Tracy Collier, Christian Ferragamo, Nisha Wasim, Stephen Lisk, Sukhwinder S. Shergill

Original languageEnglish
Article number565
Number of pages12
JournalFrontiers In Human Neuroscience
Volume8
DOIs
Accepted/In press11 Jul 2014
Published5 Aug 2014

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Abstract

Perceptions are inherently probabilistic; and can be potentially manipulated to induce illusory experience by the presentation of ambiguous or improbable evidence under selective (spatio-temporal) constraints. Accordingly, perception of the McGurk effect, by which individuals misperceive specific incongruent visual and auditory vocal cues, rests upon effective probabilistic inference. Here, we report findings from a behavioral investigation of illusory perception and related metacognitive evaluation during audiovisual integration, conducted in individuals with schizophrenia (n = 30) and control subjects (n = 24) matched in terms of age, sex, handedness and parental occupation. Controls additionally performed the task after an oral dose of amisulpride (400 mg). Individuals with schizophrenia were observed to exhibit illusory perception less frequently than controls, despite non-significant differences in perceptual performance during control conditions. Furthermore, older individuals with schizophrenia exhibited reduced rates of illusory perception. Subsequent analysis revealed a robust inverse relationship between illness chronicity and the illusory perception rate in this group. Controls demonstrated non-significant modulation of perception by amisulpride; amisulpride was, however, found to elicit increases in subjective confidence in perceptual performance. Overall, these findings are consistent with the idea that impairments in probabilistic inference are exhibited in schizophrenia and exacerbated by illness chronicity. The latter suggests that associated processes are a potentially worthwhile target for therapeutic intervention.

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