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The talking eyes: Pupillometry to index verbal fluency in normal aging
Mohamad El Haj1, Ahmed A Moustafa2, Philippe Allain3
1Nantes Université, Univ Angers, Laboratoire de Psychologie des Pays de la Loire (LPPL - EA 4638), F-44000 Nantes, France; CHU Nantes, Clinical Gerontology Department, Bd Jacques Monod, F44093, Nantes, France; Institut Universitaire de France, Paris, France.
Background:
Verbal 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.
Methods:
We 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.
Results:
Analysis 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.
Conclusion:
The 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.
