Eye Tracking the Spatial Attention of Aging Adults

Older adults exhibit a decline in visual search performance compared to younger adults. Previous research has suggested various contributing factors, including general slowing of motor and sensory processes, changes in working memory, and altered attentional allocation. In their research paper, “Reduced spatial attentional distribution in older adults,” Laurin, Ouerfelli-Ethier, Pisella, and Khan (2024) used eye-tracking technology to investigate the hypothesis that older adults experience reduced spatial attention to peripheral visual information.

Eye Tracking and Visual Search

To explore this hypothesis, the researchers designed pop-out and serial visual search tasks. In pop-out searches, targets are easily distinguishable by a unique feature (e.g., a vertical line among circles). In contrast, serial searches require more focused attention as targets share features with distractors and demand a conjunction of features for identification (e.g., a specific orientation of a line within a circle). A crucial aspect of their methodology involved the use of gaze-contingent artificial central scotomas of varying sizes (3°, 5°, or 7° diameter). These scotomas temporarily occluded central vision, forcing participants to rely on peripheral vision to complete the tasks, thereby providing direct insights into peripheral attentional distribution. Eye movements were recorded binocularly, using a tower mounted SR Research EyeLink 1000 Plus.

Attentional Differences in Older and Younger Adults

The research yielded several significant findings.

In pop-out searches, older adults showed:

• Increased Saccades: Older adults made significantly more saccades (rapid eye movements) than younger adults as target eccentricity increased. This suggests that older adults had a more restricted “attentional spotlight” and needed to make more eye movements to explore the visual field and locate peripheral targets.
• Longer Fixation Durations: Older adults generally exhibited longer fixation durations, indicating increased effort or difficulty in processing visual information during each gaze.

The researchers found that younger adults were minimally affected by the presence and size of the central scotomas in pop-out tasks, demonstrating their efficient use of peripheral attention. In contrast, the scotomas were increasingly detrimental to older adults’ performance, leading to longer response times and more saccades.

For serial searches, eye-tracking data revealed:

• Similar Scotoma Impact: Both younger and older adults were similarly affected by the presence of central scotomas in serial search. This suggests that serial search, by its very nature, requires a more focused, central attentional distribution for both age groups, making peripheral attention less critical.

By precisely tracking participants’ eye movements, the researchers could directly observe and quantify how attentional resources were deployed and how these strategies differed between age groups and search task types. Eye-tracking technology allowed for a precise and detailed analysis of visual exploration strategies, offering critical insights into the cognitive and sensorimotor changes associated with aging and their impact on visual attention. These insights contribute significantly to our understanding of age-related cognitive decline and highlight potential areas for future research and intervention.

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