Effects of luminance, blur, and age on nighttime visual guidance: A test of the selective degradation hypothesis

H. W. Leibowitz and his students (H. W. Leibowitz & D. A. Owens, 1977; H. W . Leibowitz, D. A. Owens, & R. B. Post, 1982) hypothesized that drivers are overconfident at night because they are unaware that their visual recognit ion abilities are selectively degraded in low illumination while visual gui dance is preserved. This hypothesis was investigated in 2 experiments using a driving simulator. In Experiment 1, steering accuracy was disrupted by v isual field reduction but not by extreme blur or low luminance. Conversely, visual acuity was degraded by blur and low luminance but not by field redu ction. In Experiment 2, older drivers exhibited a progressive degradation o f steering accuracy, not found with younger drivers, in low luminance. Thes e findings support and extend the selective degradation hypothesis and may help account for older drivers' reluctance to drive at night.