Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Psychology

Supervisor

Stevenson, Ryan A.

Abstract

Multisensory integration, the binding of sensory information from different sensory modalities, may contribute to perceptual symptomatology in schizophrenia, including hallucilllnations and aberrant speech perception. Differences in multisensory integration and temporal processing, an important component of multisensory integration, are consistently found in schizophrenia. Evidence is emerging that these differences extend across the schizophrenia spectrum, including individuals in the general population with higher schizotypal traits. In two studies, the relationship between schizotypal traits and perceptual functioning is investigated. We hypothesized associations between higher schizotypal traits and decreased multisensory integration, increased auditory speech distractibility, and less precise temporal processing. In Study 1, higher schizotypal traits were associated with higher rates of multisensory integration. In Study 2, higher schizotypal traits were not associated with multisensory integration, audiovisual speech-in-noise perception, auditory speech distractibility, or temporal processing. These mixed findings suggest that perceptual differences do not always exist in the lower end of the schizophrenia spectrum.

Summary for Lay Audience

People with schizophrenia have problems combining what they see and hear, which might be why they experience hallucinations and problems with understanding speech. People with a lot of schizotypal traits may have similar issues to people with schizophrenia, just at a lower level. We found that people with more schizotypal traits are sometimes more likely to combine sound syllables and mouth movement syllables that are different. We also found that these people do not have problems telling when a voice and a speaker’s mouth movements happen at different times. Also, they are not more distracted by a voice that does not match a speaker’s mouth movements. This means that people with higher schizotypal traits do not face all the same problems as people with schizophrenia. However, they sometimes incorrectly combine what they see and hear. This may lead to unusual perceptual experiences such as hallucination-like experiences and problems understanding speech.

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