UC Riverside

The present dissertation examined collision detection in the context of motion pooling, aging, and training. Three aims were developed to investigate these issues. The focus of Aim 1 was motion pooling, collision detection and performance of young adults. With Aim 2 aging, motion pooling, and collision detection were assessed. Lastly, the purpose of Aim 3 was to examine the effectiveness of training of older adults on a collision detection task. In Experiments 1-10 the effect of additional optic flow information—from adjacent velocities—on collision detection was examined for college-aged and older adults. Results suggest that velocity information adjacent to an approaching object alters the ability to determine bearing information and this decrement in collision detection was greatest when adjacent velocities were in close proximity to an adjacent object. In addition, this decrement was not found to be due to the mere presence of velocities in the flow field. Further, the presence of adjacent velocities did not alter the utility of expansion information but did alter the use of constant bearing information. Given the results of Experiments 1-7, in Experiments 8-10 the effect of motion pooling on older adults’ abilities to detect impending collisions was assessed. Previous studies have indicated a decline in the ability of older adults to detect impending collisions and results of Experiments 8-10 suggest that older adults have reduced collision detection sensitivity. Additionally, older adults may use the presence of adjacent velocities to compensate for declines by using the objects that provide adjacent velocity information as landmarks for determining bearing. Finally, Experiment 11 examined whether perceptual learning can improve performance of older participants on a collision detection task. The experiment was conducted over seven days with each day consisting of a 1-hr session. Results indicate a significant reduction in the time needed to detect a collision for the trained condition as well as an untrained observer speed condition. Results demonstrate that collision detection performance for older participants can be improved with perceptual learning and may transfer to untrained observer speeds.