The Accuracy of Drivers’ Judgments of the Effects of Headlight Glare on the Visibility of a Non-retroreflective Object

Abstract

Headlights must balance the conflicting goals of maximizing visibility for the driver and minimizing glare to others. Yet consumer complaints about headlights tend to emphasize only glare. This project extended earlier research by asking 17 young drivers to judge the distance at which they would be able to recognize the orientation of a non-retroreflective stimulus adjacent to the headlights of a stationary opposing vehicle. The beam setting (low vs. high) of both vehicles was manipulated. Participants correctly estimated that the stimulus would be less visible when their own vehicle used low beams and when the opposing vehicle used high beams. Contrary to earlier studies that used high contrast (retroreflective) stimuli, drivers’ estimates of conspicuity were, on average, not significantly different from the actual visibility of the stimulus. These results suggest that drivers’ understanding of headlight glare is more accurate for low contrast stimuli than for high contrast (retroreflective) stimuli and that drivers may overestimate the disabling effects of opposing headlights for higher contrast objects more than for lower contrast objects.

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