A multi-institution team across Canada and the West Indies reports that gaze patterns can serve as a sensitive marker of cognitive decline, with associated reductions in explorative, adaptive, and differentiated visual sampling of the environment.
Eye movements are closely linked to encoding and retrieval processes, with changes in viewing behavior often reflecting age and pathology-related memory declines. Previous work has noted that groups differing in memory status diverge across multiple gaze features, suggesting that univariate gaze metrics may not fully capture the complexity of memory-related viewing behaviors.
In the study, “Decoding memory function through naturalistic gaze patterns,” published in PNAS, researchers investigated changes in naturalistic viewing behavior across five participant groups to explore possible gaze-based indicators of memory function.
Two experiments included young adults (Exp 1: n = 35, Exp 2: n = 26), healthy older adults (Exp 1: n = 36, Exp 2: n = 28), individuals at risk for significant cognitive decline based on a below threshold score (< 26) on the Montreal Cognitive Assessment (Exp 1: n = 12, Exp 2: n = 10), individuals diagnosed with MCI (Exp 1: n = 15, Exp 2: n = 11), and individuals diagnosed with amnesia (Exp 1: n = 4, Exp 2: n = 3). Eye movements were tracked using an Eyelink II head-mounted eyetracker.
Experiment 1 involved viewing 120 images (10 images from each of 12 categories) for 5 seconds each across three blocks, with 40 novel images per block. Idiosyncratic gaze similarity was computed as the average correlation of eye movements for every image with every other image within the same block by the same participant using the eyesim package.
Idiosyncratic gaze similarity increased across groups ordered by presumed memory function, with lowest similarity in younger adults and highest in amnesia, and model comparison favored the monotonic specification. Fixation count rose across groups yet did not reach a reliable effect. Fixation dispersion decreased across groups, indicating reduced explorative viewing with decreasing memory function.
Experiment 2 involved three blocks with 120 images per block, 60 presented once and 60 repeated across blocks with 5 second viewing. Analysis focused on repeated images.
Repetitive gaze similarity increased across groups with presumed decreases in memory function, and model comparison slightly favored the linear specification.
Healthy young adults encoded unique image features with each presentation, building up a more comprehensive representation of each image in memory. Participants with decreased memory and/or hippocampal/medial temporal lobe function tended to view the same image features with each presentation.
Even without explicit task demands, gaze patterns varied systematically by group. Findings suggest that suboptimal encoding patterns may underlie the formation of impoverished memory representations in individuals with memory impairment and lay a foundation for future work using multivariate gaze metrics to diagnose and track memory and cognitive function.
The results provide compelling evidence that naturalistic gaze patterns can serve as a sensitive marker of cognitive decline.
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More information:
Jordana S. Wynn et al, Decoding memory function through naturalistic gaze patterns, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2505879122
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Eye movement patterns reveal subtle signs of cognitive and memory decline (2025, August 19)
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