The Effects of Expectancy, Clothing Reflectance, and Detection Criterion on Nighttime Pedestrian Visibility

Abstract

Nighttime pedestrian visibility was studied under various combinations of driver expectancy (to see a pedestrian on the road), pedestrian clothing characteristics (dark clothing, light clothing, and dark clothing with retroreflective tags), and the detection criterion (pedestrian versus retroreflective tag). It was found that visibility distance increases with expectancy, but the magnitude of the effect varies as a function of whether or not the pedestrian is wearing the tag. Furthermore, it was shown that when the pedestrian is unexpected, the usefulness of the tag is significant only if the driver can rely on it as a criterion for detection (by prior knowledge of the association between the tag and the pedestrian). The difference in visibility when the tag is not associated with the pedestrian may explain the less-than-expected effectiveness of retroreflective materials on accident reduction.