The talking eyes: Pupillometry to index verbal fluency in normal aging

Abstract

BackgroundVerbal fluency tasks are widely used to assess cognitive and linguistic abilities in older adults. In this study, we investigated whether pupillometry can be used to measure verbal fluency in healthy older adults. MethodsWe invited 45 older adults (Mean age = 66.55 years, SD = 4.32) to perform a verbal fluency task, which involves generating as many words as possible beginning with the letter “P” for a duration of one minute. We also invited participants to perform a control task, which involves counting aloud for one minute. In both tasks, we recorded pupil activity with eye-tracking glasses. ResultsAnalysis demonstrated a larger pupil size during the verbal fluency condition than in the counting condition. Significant positive correlations were observed between pupil size and correct responses on the verbal fluency task. ConclusionThe larger pupil size during the verbal fluency condition can be attributed to the cognitive load inherent in the verbal fluency task and/or to the ability of older adults to produce correct answers on this task. Our study demonstrates how pupillometry can be used as an ecological physiological assessment of not only verbal fluency, but also linguistic ability in general, in normal aging.