Visually biased Perception in Cochlear Implant Users: A Study of the McGurk and Sound-Induced Flash Illusions.
Iliza M Butera, Ryan A Stevenson, René H Gifford and 1 others
PMID 37377212WHAT IT FOUND
Cochlear implant users showed a strong visual bias in speech illusions, reporting the seen syllable 43% of the time versus 13% for normal-hearing controls.
However, these perceptual biases did not predict clinical speech scores, so they may not reflect functional communication ability.
Key findings
01Cochlear implant users demonstrated a strong visual bias in the McGurk task, reporting the visual component 'ga' on 43.1% of incongruent trials, compared to 13.0% for normal-hearing controls.
02Among participants who perceived the illusion, cochlear implant users had significantly lower McGurk fusion rates and lower susceptibility to the sound-induced flash illusion than normal-hearing controls.
03Neither McGurk fusion rates nor flash illusion susceptibility predicted variability in clinical speech-in-noise scores for cochlear implant users.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used a single female speaker and specific syllables, so results may not generalize to other voices or languages. The clinical outcome measure (CNC word lists) was auditory-only, which may not capture the benefits of audiovisual integration in real-world communication. The McGurk stimuli were designed to create an unnatural scenario where visual cues are more reliable than auditory ones for both groups, which may exaggerate visual biases.
Declared interests
One author (R.H.G.) served on advisory boards for Advanced Bionics and Cochlear Americas, which are cochlear implant manufacturers. Funding was provided by NIH, NSERC, and SSHRC.
The easy way to misread this
Do not assume that a CI patient's strong visual bias in laboratory illusions indicates poor speech recognition in daily life. These perceptual measures did not correlate with clinical speech scores, so they should not be used to judge a patient's functional communication ability.