Optometry and Vision Sciences - Theses
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ItemCentral and peripheral motion perception in healthy older adults and its potential relevance to driving( 2021)Aging of the population is a common phenomenon in many countries. This increase in the number of older individuals consequently implies an increase in the number of older drivers. Older adults have changes to vision that could potentially influence driving behavior, as visual information is the predominant sensory input for operating a motor vehicle. One visual function that is potentially relevant for driving performance is motion perception, as both the motor vehicle and the surroundings are in motion. This project explored differences to motion perception between older and younger adults and considered in the applied context of driving. Experiment One explored the differences in performance of healthy older and younger adults on different aspects of motion perception under daylight viewing conditions. A battery of seven psychophysical motion perception tasks was applied to a cohort of participants belonging to two age groups (older and younger adults). Motion perception was also studied comparing central and peripheral vision. This experiment demonstrated that older adults had different results to their younger counterparts for some aspects of motion perception. In addition, for most of the tasks, the effects of aging were similar in central and peripheral vision. In Experiments Two and Three, four motion perception tasks were selected from the battery of tasks used in Experiment One to further test under viewing conditions that are commonly described as problematic by older drivers. These conditions included vision at mesopic light levels, such as those found during nighttime driving (Experiment Two) and driving under headlight glare similar to that of oncoming cars (Experiment Three). These two viewing conditions were simulated in a laboratory-based testing procedure. The results showed that thresholds were in general poorer under low light levels in both age groups. Experiment Three demonstrated that the presence of a continuous glare source simulating car headlights did not impact performance on the selected motion perception tasks. Experiment Four explored the relationship between motion perception and the measurement of the ability to predict potential traffic hazards in a computerized video test (the hazard perception test). The results of this experiment showed that two motion perception tasks (Dmin and motion contrast) were statistically related to the scores in the hazard perception test, and better predicted performance than measurements of visual acuity. This thesis, therefore, contributed to the knowledge of how aging impacts different components of motion perception, not only under photopic viewing conditions, but also under mesopic light levels and under simulated glare. This thesis demonstrated that some motion perception tasks clearly distinguished between age groups (Dmin, motion contrast and biological motion), but these group differences were absent for other tasks (global motion coherence). In addition, some motion perception tasks presented a wide range of interindividual differences in performance, suggesting that aging is a very individual process that cannot be assumed from chronological age.