The McGurk Illusion: A Default Mechanism of the Auditory System.

Content Provider	Europe PMC
Author	Iqbal, Zunaira J. Shahin, Antoine J. Bortfeld, Heather Backer, Kristina C.
Editor	Tiippana, Kaisa
Copyright Year	2023
Abstract	Recent studies have questioned past conclusions regarding the mechanisms of the McGurk illusion, especially how McGurk susceptibility might inform our understanding of audiovisual (AV) integration. We previously proposed that the McGurk illusion is likely attributable to a default mechanism, whereby either the visual system, auditory system, or both default to specific phonemes—those implicated in the McGurk illusion. We hypothesized that the default mechanism occurs because visual stimuli with an indiscernible place of articulation (like those traditionally used in the McGurk illusion) lead to an ambiguous perceptual environment and thus a failure in AV integration. In the current study, we tested the default hypothesis as it pertains to the auditory system. Participants performed two tasks. One task was a typical McGurk illusion task, in which individuals listened to auditory-/ba/ paired with visual-/ga/ and judged what they heard. The second task was an auditory-only task, in which individuals transcribed trisyllabic words with a phoneme replaced by silence. We found that individuals’ transcription of missing phonemes often defaulted to ‘/d/t/th/’, the same phonemes often experienced during the McGurk illusion. Importantly, individuals’ default rate was positively correlated with their McGurk rate. We conclude that the McGurk illusion arises when people fail to integrate visual percepts with auditory percepts, due to visual ambiguity, thus leading the auditory system to default to phonemes often implicated in the McGurk illusion.
Journal	Brain Sciences
Volume Number	13
PubMed Central reference number	PMC10046462
Issue Number	3
PubMed reference number	36979322
e-ISSN	20763425
DOI	10.3390/brainsci13030510
Language	English
Publisher	MDPI
Publisher Date	2023-03-19
Access Restriction	Open
Rights License	Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). © 2023 by the authors.
Subject Keyword	McGurk illusion audiovisual integration spoken language processing visemes phonetic encoding
Content Type	Text
Resource Type	Article
Subject	Neuroscience