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Michael Melnick, Kevin Dieter, Duje Tadin; Highly abnormal visual context processing in older adults. Journal of Vision 2014;14(10):215. doi: 10.1167/14.10.215.
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Visual context can have strong effects on the appearance of local visual elements. Although these contextual illusions are examples of non-veridical visual perception, they are functionally advantageous because they enhance relative differences among visual features (Albright & Stoner, 2002). A neural implementation of such contextual effects must strike a balance between the enhancement of feature differences and the veridical representation of the same features. Thus, both atypically weak or strong contextual modulations are likely maladaptive as both constitute departures from typical vision. Given the growing evidence for visual processing changes in old age, including changes in inhibitory efficacy, we aimed to determine how contextual processing changes with age. We administered a large battery of contextual tasks to 50 older adults (mean age = 68) and 29 young adults. The results revealed drastically different contextual processing in older adults relative to younger observers. Repulsive surround tilt and repulsive surround motion illusions were on average twice as strong in older adults (p <0.0001 and 0.01, respectively). Similarly, brightness induction by the surround was also about twice as strong in older subjects (p <0.001). On the other hand, aging was linked with a 25% reduction in surround contrast effect (p = 0.02). We also found weaker spatial suppression with moving stimuli in older adults (p <0.0001), replicating previous results (Betts et al., 2005). No group differences were found for the Ebbinghaus size illusion (p = 0.43). Interestingly, performance across these tasks was largely uncorrelated for both groups, arguing against a global contextual processing deficit and ruling out low-level explanations (e.g., age-related reduction in retinal luminance). Evidently, older adults exhibit a highly atypical pattern of visual context processing. Given the important role of contextual modulations in visual perception, these strong abnormalities are likely to have large effects on overall visual function.
Meeting abstract presented at VSS 2014
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