Attention Mobilization as a Modulator of Listening Effort: Evidence From Pupillometry.

Only 19 young adults were enrolled, and 17 were analyzed, so the study is small and not powered for clinical decisions. The participants had normal hearing and normal cognitive screening scores, so the results may not apply to people with hearing loss, cognitive impairment, or communication disorders. The study was done in a laboratory MEG chamber with controlled lighting and a 60-second audiobook task, which is not the same as everyday listening. Each passage was repeated three times in a row, and the authors note that exact repetition is not a frequent feature of real-world listening. 69 of 228 trials were excluded, and two participants were excluded because they had two or more excluded trials for a condition. Comprehension questions were designed to ensure attention but were not very difficult, and participants received no feedback. Self-rated intelligibility was collected only after the first presentation, so later presentations were not checked against subjective understanding. The study did not measure mind wandering, motivation, or listening aversiveness, which the authors considered as possible explanations for pupil responses. Baseline pupil size was compared across participants using quartiles, but individual people may have occupied different parts of the arousal range, and the study did not have a personal reference range for pupil size. The pupil response was interpreted as a measure of effort, but the authors note that a smaller response in the harder condition may reflect giving up, least effort, or good-enough understanding rather than a direct measure of effort.

The study was supported by the National Institute on Deafness and Other Communication Disorders, the SBE Office of Multidisciplinary Activities, and the National Institute on Aging. The supplied text does not report author conflicts of interest.

Do not conclude that a larger pupil response always means more listening effort. The overall pupil response did not simply increase in the harder condition, and at some starting pupil sizes the harder condition produced a smaller response. Comprehension accuracy also did not differ between conditions.