Abstract
Very little is known about how older adults move their eyes when they read. There are many reasons to believe that the eye movements of older adults will be different from those of younger adults, in part due to visual changes (e.g. decreased acuity and contrast sensitivity), changes in attentional strategies, and changes in the dynamics of eye movements. These differences may help us to better understand why they read more slowly than do younger adults. While several studies have compared the reading eye movements of normally-sighted and visually-impaired adults, only one (Bowers, 2000; OVS) has compared the eye movements of normally-sighted older and younger adults. We measured the reading rates and eye movements of ten younger (27±3.3 yo; mean±SD) and ten older (69±3.3 yo) adults. Average acuity was — 0.056 logMAR (20/18 Snellen equivalent) for the younger group and — 0.028 logMAR (20/19) for the older group; no observer had acuity worse than 20/25. An ASL 501 video-based eye tracker with a 120 Hz eye-imaging camera recorded eye movements while the observers read from a television monitor. Letters were proportionally-spaced, with a 0.5 deg x-height; each observer read 20 sentences. As has been reported previously, the older group read more slowly than the younger group (195±8.4 vs. 247±20.5 wpm). This was primarily due to the 52% (76 msec) increase in fixation duration for the older group. The older group showed a small but nonsignificant decrease in saccade size. These preliminary findings suggest that the eye movements of older adults can be used, as they are in younger adults, to understand how they sample from and process visual information. In addition, these findings suggest that eye movements can be used to increase our understanding of the impact of visual changes on cognitive function in older adults.