Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)




Auto crashes are more likely in the afternoon, and older adults are involved in more crashes later in the day as compared to earlier in the day. Factors that may influence older adult’s driving included visual spatial attention and sleep quality. In addition, circadian preference may also influence driving. The purpose of this study was to evaluate these factors in older adults. This study included younger adults (N= 41, M= 21.6 years) and older adults (N= 40, M= 65.5 years) who were tested between 8 and 10 a.m. or between 3 and 5 p.m. Participants were tested on a computerized driving simulator called Profiler, a computerized visual search test, and the Useful Field of View (UFOV) test. The Profiler provided scores for steering, scanning and concentration. The UFOV provided scores for reaction time, divided attention, and selective attention. Participants were also evaluated on physiological function, field dependence, health, sleep quality, education, computer anxiety and driving experience.

Younger adults performed better than older adults on most measures. Time of testing did not influence visual search, nor was there a synchrony effect evident in older or younger adults. In order to further evaluate driving performance, two groups of older adults were created, post hoc, on the basis of high versus low scores on the practice sessions of the driving simulator. It was found that those who performed well were significantly younger than those who performed poorly. The age range of the older, low performing group was much wider than and overlapped with the younger, high performing group. The older, low performing group also reported very high computer anxiety as compared to the older, high performing group. The use of computerized testing was sub-optimal for the oldest adults, but younger adults have stronger visual spatial abilities than older adults. Given these findings, older adults may be at greater risk for auto crashes than younger adults. Future research with older adults should examine whether there is a synchrony effect that influences driving performance on a closed track or on city streets and may include an evening time of testing.