Previous Mental Load and Incentives Influence Anticipatory Arousal as Indexed by the Baseline Pupil Diameter in a Speech-in-Noise Task.
Defne Alfandari, Michael Richter, Dorothea Wendt and 2 others
PMID 37847850WHAT IT FOUND
After 30 minutes of hard listening, baseline pupil size shrank, suggesting lower arousal.
However, the actual effort spent on subsequent sentences did not change, regardless of whether participants were offered money or faced difficult noise. Fatigue lowered readiness but did not reduce the work done.
Key findings
01Baseline pupil diameter was significantly smaller after the fatigue-inducing task than before it, across all conditions.
02Task-evoked pupil dilation, the measure of listening effort, showed no significant change from pre- to post-fatigue and was not affected by monetary incentives.
03Baseline pupil size was larger when anticipating hard trials only if high monetary incentives were offered, suggesting motivation affects anticipatory arousal.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The study lacked a control group, so it is impossible to definitively separate fatigue effects from habituation or learning. The participants were middle-aged (mean 54.67 years), and the monetary incentives used may have been insufficient to motivate this age group. The fatigue manipulation was relatively short (30 minutes) and constrained by ethics, meaning participants may not have been truly fatigued. The trial design had a very short pause between sentences, which may have prevented the full pupil dilation response from being recorded.
Declared interests
The authors declared no conflicts of interest. The work was supported by the Medical Research Council and Marie Skłodowska-Curie Actions.
The easy way to misread this
Do not conclude that fatigue does not affect listening effort. The study found that *task-induced* fatigue over 30 minutes did not reduce the physiological effort (pupil dilation) spent on subsequent sentences, but this does not mean chronic fatigue or hearing loss-related fatigue have no impact. The null result for effort may be due to the mild fatigue manipulation and the lack of a control group.