Time-specific Components of Pupil Responses Reveal Alternations in Effort Allocation Caused by Memory Task Demands During Speech Identification in Noise.
Patrycja Książek, Adriana A Zekveld, Lorenz Fiedler and 2 others
PMID 36938784WHAT IT FOUND
Adding a memory task to speech-in-noise testing reduced word identification scores but increased pupil baseline dilation.
This suggests listeners reallocate mental effort from listening to memorizing, rather than simply working harder overall. Clinical tests should distinguish acoustic difficulty from cognitive load.
Key findings
01Participants identified fewer sentence-final words when they also had to recall them later, compared to when they only had to repeat them immediately.
02Pupil size before the sentence started (trial baseline) was smaller during recall tasks, but increased more steeply across the list compared to non-recall tasks.
03Pupil responses during speech identification were generally smaller in recall conditions, suggesting effort was shifted away from listening and toward memory maintenance.
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 only normal-hearing adults, so findings may not apply to hearing-impaired populations who may have different baseline effort levels. The counter-intuitive finding that recall was better in noise may be an artifact of the scoring method (recall calculated relative to identified words), not a true cognitive advantage. Pupillometry is an indirect measure of effort and can be influenced by factors other than cognition, such as light adaptation or blink artifacts, though these were controlled. The study design involved short lists (7 sentences); real-world conversations are longer and more complex, so the dynamics of effort allocation may differ over time.
Declared interests
The authors declared no potential conflicts of interest. The study was performed at the Eriksholm Research Centre.
The easy way to misread this
Do not interpret the lower pupil dilation during speech identification in recall conditions as evidence that listening was 'easier.' The paper suggests effort was redistributed to memory maintenance, not that the acoustic task was less demanding. Also, do not conclude that noise improves memory; the better recall in noise was likely because fewer words were identified, reducing the number of items to remember.