Tracking Cognitive Spare Capacity During Speech Perception With EEG/ERP: Effects of Cognitive Load and Sentence Predictability.
Cynthia R Hunter
PMID 32282402WHAT IT FOUND
Listening to predictable sentences requires less mental effort than unpredictable ones, even when speech is degraded.
This was shown by brainwave patterns and memory performance in young adults with normal hearing, suggesting predictability frees up cognitive resources.
Key findings
01Alpha brainwave desynchronization was smaller during predictable sentences and low-load conditions, indicating greater cognitive spare capacity.
02Participants recalled more digits correctly when the concurrent speech task involved predictable sentences, though this effect disappeared when incorrect word recognition trials were excluded.
03P300/LPC amplitude, an index of attentional resources, was reduced for unpredictable sentences and high cognitive load.
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 young adults with reported normal hearing, so findings may not generalize to older adults or those with hearing loss. Intelligibility and predictability were confounded, making it difficult to separate the effect of cognitive demand from the ease of recognizing the words. The effect of predictability on digit recall disappeared when incorrect word recognition trials were excluded, suggesting the benefit may be tied to successful recognition rather than predictability alone. No independent measures of working memory or hearing thresholds were taken.
Declared interests
Research supported by N.I.H. Extramural funding. No other conflicts declared.
The easy way to misread this
Do not assume that predictability reduces effort independently of word recognition accuracy. The study found that the benefit of predictability on memory tasks vanished when trials with incorrect word recognition were removed, suggesting that easier listening is closely tied to successful perception rather than a standalone cognitive release.