LE3 .A278 2021

2021

Lametti, Daniel

Acadia University

Bachelor of Science

Honours

Psychology

Psychology

The McGurk effect is a perceptual illusion that binds incoming audio-visual information causing the perception of a novel speech sound. A related effect known as Visual Capture occurs when visual stimuli override auditory stimuli, inducing the perception of a speech sound that is congruent with visual stimuli. These effects can be studied to facilitate the understanding of the fusion of sensory modalities within the brain (i.e., multisensory integration). In the current study, the McGurk effect and Visual Capture were tested using an online audio-visual speech perception paradigm developed using Gorilla.sc. Susceptibility to the McGurk effect was compared to susceptibility to Visual Capture in a sample of 47 participants through the examination of perceptual decisions and reaction times. It was hypothesized that the McGurk effect would be observed using this novel online paradigm, and that the effect would require more cognitive resources (measured via longer reaction times) than both Visual Capture and control processing. Results showed significant McGurk and Visual Capture effects, with participants being split into McGurk and NonMcGurk Responders based on illusory susceptibility. For congruent speech stimuli, McGurk Responders reacted significantly faster than NonMcGurk Responders when visual information was present, and significantly slower when lacking visual information. The results suggest that an online platform can be used to examine multisensory processing and susceptibility to the McGurk effect seems to reflect greater responsiveness to visual information during speech.

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https://scholar.acadiau.ca/islandora/object/theses:3608