Pupil Dilation Reflects Perceptual Priorities During a Receptive Speech Task.
Hannah Mechtenberg, Cristal Giorio, Emily B Myers
PMID 37882091WHAT IT FOUND
In this lab study, pupils dilated more when listening to clear speech than casual speech in quiet, contrary to expectations.
Background noise caused much larger pupil dilation than speech style. Results suggest motivation and task demands drive effort more than acoustic clarity alone.
Key findings
01Pupil dilation was significantly larger for masked speech compared to silent speech, indicating greater listening effort in noise.
02Contrary to predictions, pupil dilation was slightly larger for clear speech than casual speech in silence, though this effect was marginal.
03Anticipatory pupil dilation occurred before the target sentence onset, differing by background condition and speech type.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Participants were young adults with normal hearing, so results may not apply to older adults or those with hearing loss. The sentences were semantically meaningless, which removes top-down processing cues used in real conversation. The blocked design allowed listeners to anticipate the upcoming task, which may have influenced pupil responses. The effect of speech style on pupil dilation was small and only marginally significant in silence.
Declared interests
The research was supported by NIH grants. The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that clear speech is more effortful for patients in daily life. The study used meaningless sentences in a lab setting, and the effect of speech style was small and inconsistent. The robust finding was that noise increases effort, not that clarity decreases it.