Abstract
Causal inference—the process of deciding whether two incoming signals come from the same source—is an important step in audiovisual (AV) speech perception. This research explored causal inference and perception of incongruent AV English consonants. Nine adults were presented auditory, visual, congruent AV, and incongruent AV consonant-vowel syllables. Incongruent AV stimuli included auditory and visual syllables with matched vowels, but mismatched consonants. Open-set responses were collected. For most incongruent syllables, participants were aware of the mismatch between auditory and visual signals (59.04%) or reported the auditory syllable (33.73%). Otherwise, participants reported the visual syllable (1.13%) or some other syllable (6.11%). Statistical analyses were used to assess whether visual distinctiveness and place, voice, and manner features predicted responses. Mismatch responses occurred more when the auditory and visual consonants were visually distinct, when place and manner differed across auditory and visual consonants, and for consonants with high visual accuracy. Auditory responses occurred more when the auditory and visual consonants were visually similar, when place and manner were the same across auditory and visual stimuli, and with consonants produced further back in the mouth. Visual responses occurred more when voicing and manner were the same across auditory and visual stimuli, and for front and middle consonants. Other responses were variable, but typically matched the visual place, auditory voice, and auditory manner of the input. Overall, results indicate that causal inference and incongruent AV consonant perception depend on salience and reliability of auditory and visual inputs and degree of redundancy between auditory and visual inputs. A parameter-free computational model of incongruent AV speech perception based on unimodal confusions, with a causal inference rule, was applied. Data from the current study present an opportunity to test and improve the generalizability of current AV speech integration models.
Highlights
Mismatch responses were more common for visual consonants associated with high visual accuracy
When participants could accurately identify visual consonants, they were more likely to notice that what they saw and heard did not match. These results suggest stimulus uncertainty governs causal inference in AV speech perception
The same relationship was not observed for auditory consonant accuracy, this analysis was limited by the overall high accuracy of identification for most auditory consonants
Summary
In face-to-face communication, we automatically combine speech information from the face and voice. Perception of incongruent audiovisual English consonants demonstrated in the popular McGurk illusion [1]. When presented an auditory /bɑbɑ/ paired with visual /gɑgɑ/, participants often perceive a fused /dɑdɑ/ that was not present in either modality. The McGurk illusion demonstrates that the brain integrates signals from across modalities into a single perceptual representation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
