| Successful navigation in the world requires effective visuospatial processing. Unfortunately, older adults have many visuospatial deficits, which can have severe real-world consequences. It is therefore crucial to understand and try to alleviate these deficits whenever possible. One visuospatial process, depth from motion parallax, has been largely unexplored in older adults. Depth from motion parallax requires retinal image motion processing and pursuit eye movements, both of which are affected by age. Given these deficits, it follows logically that sensitivity to motion parallax may be affected in older adults, but no one has yet investigated this possibility. The goals of the current study were to characterize depth from motion parallax in older adults, to explore the mechanisms by which age might affect depth from motion parallax, and to develop training programs that might alleviate the effects of age on motion parallax. In Experiment One, older and younger adults' motion parallax depth thresholds were characterized. Motion thresholds and pursuit accuracies were also measured. The results of Experiment One revealed that older adults had higher MP depth thresholds than younger adults, and that these age changes were primarily driven by age changes in pursuit eye movements. In Experiment Two, older adults were provided with motion and pursuit training programs to use at home, following the logic that training in motion and pursuit would improve older adults' depth thresholds. Improvements of performance at these training tasks were assessed. Depth thresholds, motion thresholds, and pursuit accuracy pre- and post-training were evaluated as well, using the same methods as in Experiment One. The results of Experiment Two revealed that motion and pursuit training did not affect observers' performance throughout the course of training, and there were no effects of training on depth or motion thresholds or pursuit eye movements. The current study is the first to examine age changes in motion parallax depth thresholds, and to investigate the mechanisms of age changes in the perception of depth from motion parallax. Though the training programs in Experiment Two did not produce improvements of perceptual performance, this study was successful in implementing an easy-to-use, at-home training technique. |
