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Jeffrey D. Bower, Rui Ni, George J. Andersen; Age-related decrements in the discrimination of global coherent motion. Journal of Vision 2006;6(6):637. doi: 10.1167/6.6.637.
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© ARVO (1962-2015); The Authors (2016-present)
The present study examined age related differences in the perception of global coherent motion. The stimuli consisted of 256 random dots each moving in slightly different paths that average to a single coherent direction. 13 younger (mean age of 21.8) and 12 older (mean age of 77.3) subjects were asked to discriminate the coherent direction of motion for two sequentially presented stimuli. Two hypotheses were examined in the present study: 1) that older observers have a decreased tolerance for noise, and 2) that older observers have increased difficulty in sampling motion information. To examine the noise tolerance hypothesis we systematically varied the perturbation of each local motion from the coherent direction by sampling from a Gaussian distribution. The distributions had a standard deviation (SD) of, 0, 4.5, 18, or 36. To examine the sampling hypothesis we compared three different types of local motion paths— continuous, limited lifetime, or random walk. The display duration of the stimuli was 150, 280, or 560 msec. Both younger and older subjects showed lowest discrimination thresholds for the random walk motion displays as compared to continuous motion and limited lifetime motion displays, suggesting that general sampling of visual information does not change as a function of age. However, older subjects had elevated thresholds for the highest noise condition, particularly with continuous motion displays. This finding suggests that older subjects have difficulty in sampling visual information under high noise conditions.
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