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Hyun-Jun Jeon, Yeojeong Yun, Oh-Sang Kwon; Integration of position and predictive motion signals in older adults. Journal of Vision 2018;18(10):343. doi: https://doi.org/10.1167/18.10.343.
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Motion induced position shift (MIPS) and slow speed bias (SSB) are suggested to be consequences of optimal integration of position and motion signals (Kwon et al., 2015). It implies MIPS and SSB are proper tasks to characterize individual differences in position-motion integration. We measured the magnitudes of MIPS and SSB in older and young adults to examine the aging effects on position-motion integration. METHODS: 24 elderly and 21 young adults participated in Experiment 1. In a trial, each MIPS stimulus was presented in both sides of visual fields (eccentricities 5°, 10°, or 15°) for 1s. Subjects had to judge the relative heights of stimuli in a position task and the relative speeds of stimuli in a speed task. The magnitudes of MIPS and SSB were measured for three eccentricities. In Experiment 2, 10 elderly and 8 young adults participated. The identical stimulus as in Experiment 1 (eccentricity 10°) was presented for a duration that varied between 31ms and 1000ms. The size of MIPS was measured as a function of stimulus durations. RESULTS: The MIPS sizes of elderly observed in three eccentricities (0.63°, 0.86°, 1.03°) were 2.5 times larger than those of young participants (0.13°, 0.24°, 0.40°) on average. As a function of duration, two groups showed a similar trend in that the magnitudes of MIPS peaked around 56ms-97ms (Young: 0.39°, Elderly: 0.77°) and stabilized at lower magnitudes. The SSB magnitude significantly increased as eccentricity increases, but group difference was not significant (Young: 1.14°/s, 2.11°/s, 2.87°/s, Elderly: 0.27°/s, 1.50°/s, 2.82°/s). DISCUSSIONS: The result that MIPS magnitude doubled in elderly group implies older adults would rely more on motion signals in visual tracking possibly due to large positional uncertainties. Results of Experiment 2 suggest that aging has a minimal impact on the time for the integration of position and motion signals.
Meeting abstract presented at VSS 2018
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