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Jutta Billino, Frank Bremmer, Karl R. Gegenfurtner; The effect of age on the detection of coherent motion and radial flow. Journal of Vision 2006;6(6):636. doi: 10.1167/6.6.636.
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© ARVO (1962-2015); The Authors (2016-present)
Several studies have shown that motion sensitivity declines with increasing age. This decline cannot be attributed to optical changes but is due to changes in the central visual pathways. However, there is little knowledge which subsystems are prone to degeneration. The purpose of our study was to evaluate the effect of aging on motion processing at different stages in the visual system. We investigated age-related differences in the detection of coherent motion and radial flow. Whereas the former task is related to early processing stages, the latter task is supposed to rely on processing at advanced stages in the visual system. Data was collected from younger (19–57 years; n=16) and older subjects (63–82 years; n=27). The first task required subjects to detect which one of two random dot kinematograms displayed at 7.6° eccentricity and a size of 9.6° contained coherent motion. In the second task, subjects had to decide about the direction of heading of a radial flow large-field stimulation whose focus of expansion was shifted to 5.8° eccentricity. In both tasks, noise levels of the kinematograms were varied and thresholds were estimated. Thresholds for coherent motion detection differed significantly between age groups (14.4% vs. 26.9%). There was an overall effect of age on performance (r=.562). In contrast, ability to detect radial direction was not affected by age. The results suggest that older observers' ability to analyze optic flow is preserved despite elevated detection thresholds for coherent motion. This finding puts into question a hierarchical view of visual motion processing.
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