Abstract
Little currently is known about how binocular rivalry changes with aging. However, by studying factors with well-known effects on binocular rivalry, such as contrast and size, a foundation for future studies of aging can be established. The current study measured binocular rivalry in young adults (aged 20-29), junior-seniors (aged 61-69), and senior-seniors (aged 71-78). Stimuli were pairs of orthogonal oblique sine wave gratings presented dichoptically. Stimuli size (diameter = 2.4[sup]o [/sup]or 4.3[sup]o[/sup]) and contrast level (0.2 or 0.8) varied across trials. On each trial, participants tracked alternations among four percepts (i.e., the two exclusive percepts, mixed, and other). Participants were instructed to report the "other" percept if they perceived fading of the stimuli or any percept that did not match the given response options. Dependent measures were the average duration and proportion of time subjects reported viewing each percept. The average durations for both exclusive percepts were longer in older adults, supporting previous findings (Jalavisto, 1964, Gerontologia, 9, 1–8; Ukai et al., 2003, Percept. Mot. Skills, 97, 393–397). Additionally, the strength of monocular dominance increased with age, particularly when viewing our smaller stimuli, and the proportion of mixed percepts decreased with age. Across all participants there was a marginally significant increase in the proportion of mixed percepts for our larger stimuli, consistent with previous results obtained with younger participants (Blake et al., 1992, Vis. Neurosci., 8, 469–478). In the low contrast condition, senior-seniors reported a statistically higher proportion of other percepts, presumably representing a greater amount of stimulus fading. Overall the senior-seniors were the most statistically different. The sequential pattern of alternations between percepts also varied across age groups. Control experiments indicate that these results were not due to age differences in motor response time or retinal illuminance. The theoretical implications of these results will be discussed.
Meeting abstract presented at VSS 2013