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Amanda Beers, Allison Sekuler, Patrick Bennett; Classifying Mixed Percepts During Binocular Rivalry in Younger and Older Adults. Journal of Vision 2016;16(12):1325. doi: https://doi.org/10.1167/16.12.1325.
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© ARVO (1962-2015); The Authors (2016-present)
Several categories of mixed percepts can be seen during binocular rivalry, including the perception of both exclusive images overlapping, a mosaic comprising of pieces of each exclusive image, and a wave-like transition from one exclusive percept to the other (Yang et al., 1992). Recently, we demonstrated the overall proportion of mixed percepts decreases with aging (Beers et al., VSS 2013). However, it is unknown if all categories are affected by aging. To answer this question, we presented pairs of orthogonal, oblique sine wave gratings (diameter = 4.4; contrast level = 0.45) to fifteen younger (aged 18-26) and twenty older (aged 64-84) adults. On each trial, participants recorded each instance of a mixed percept category (overlapping, pieces, or wave-like) with a handheld button box. The total number of reported mixed percepts and the tallies for each category were analyzed. Older adults reported significantly fewer mixed percepts. Interestingly, the proportion of each category of mixed percept decreased at similar rates with aging. Eight participants from each age group returned for a second experiment in which stimulus size (diameter = 1.4 or 4.4) and contrast level (0.2 or 0.8), factors with well-known effects on characteristics of mixed percepts in younger adults, varied across trials. Overall both younger and older observers reported increased occurrences of mixed percepts at high compared to low contrast, primarily for the wave-like category. Younger adults reported fewer mixed percepts when viewing the smaller compared to the larger stimuli, consistent with previous results (Blake et al., 1992), a decrease primarily affected by the wave-like category. Older adults had significantly fewer instances of mixed percepts when viewing the small stimuli at low contrast, but the decrease was primarily affected by the pieces category. These classifications, and age-related differences, enhance our understanding of rivalry, as distinct neural mechanisms have been linked to specific categories.
Meeting abstract presented at VSS 2016
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