Abstract
It has been well documented that declines in perceptual and cognitive abilities emerge as we age. As a result, older drivers have significantly increased accident risks, especially under low visibility conditions such as at night or in fog. Research has shown optic flow is a useful source of information for performing driving tasks such as perceiving heading direction and self-speed. However, there has been little research examining age-related differences in processing optic flow information, specifically under deteriorated conditions. The current study investigated this question by manipulating both the quantity and the quality of optical flow information. Twenty-two young (M = 20.9 years) and 17 older (M = 78.1 years) drivers were presented with displays simulating driving through a 3D array of dots randomly located on a ground plane. The lateral position of the vehicle was perturbed by the simulated side wind gust according to a sum of three sinusoidal functions. Deteriorated optic flow information was achieved by reducing the quantity of dots (125, 25) and the quality of the dots (high, medium, and low contrast). Driving performance was evaluated by computing the root mean square of the deviations between vehicle position and designated straight path. A three-way ANOVA analyses showed significant main effects of dot number, dot contrast, and age. Overall, more steering error was found with decreased dot number and decreased dot contrast for both age groups, with better performance for younger participants as compared with older participants. Further, the results suggest that older participants suffer more from decreased quality and quantity of optical flow information. Overall, the results indicate increased accident risks for older drivers under deteriorated optical flow conditions. To address this issue, it is necessary to improve the roadway environment, or develop driving assisting systems accommodating age-related deficit in driving safety, especially under low visibility conditions.
WSU RIA Gridley-Hoover Grant.