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Aparna Raghuram, Vasudevan Lakshminarayanan; Age effects on certain two dimensional motion paradigms. Journal of Vision 2004;4(8):753. doi: https://doi.org/10.1167/4.8.753.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: We investigated the effects of aging on certain motion perception tasks. Methods: Two age groups were used young (mean age of 24, n=10) and older (mean age of 63, n=3). Direction of heading was estimated using random dots moving in a radial motion. Data was collected for dots moving at two different reference speeds and number of dots was varied from 25, 100 or 400. Time to collision (TTC) was estimated by having subjects determine which of the two targets will reach destination first. Method of constant stimuli was used and psychometric curves were generated at 66% criterion to record threshold. Speed discrimination (SD) was assessed using a pair of grating stimuli moving in opposite directions. The threshold was estimated using a staircase technique. Two reference speeds of 2 and 8 deg/sec were tested. The stimulus presentation time was also varied between 500 and 1000ms. Results: Direction of heading showed a significant difference across age and the different speeds tested at p=0.000. Time to collision difference did vary significantly with age with the elderly group rarely performing above chance. 2-AFC was easier to perform resulting in lower thresholds compared to 3-AFC for both older and younger subjects. SD tasks showed significant age effect at p=0.000. Age effect was more pronounced for 8 deg/sec compared to2 deg/sec. Increasing stimulus presentation time from 500 to 1000 ms improved thresholds for both reference speeds tested. Additional data from older subjects will be presented.
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