How Accurate Are Older Drivers’ Judgments of the Effects of Headlight Glare on Acuity?

Abstract

Visual performance declines at night and this effect is more pronounced for older drivers. Despite the fact that high beam headlights can increase visibility when driving at night, drivers tend to underuse their high beams at night. Little is known about why high beams are underused, but the desire to minimize glare to oncoming drivers has been cited as a possible explanation. In this study 12 older drivers judged the distance at which they would just be able to recognize the orientation of a non-retroreflective Landolt C if it were present adjacent to the headlights of an opposing vehicle. The beam setting (low vs. high) of both vehicles was manipulated. Both the participants’ judgments of their own visual performance and their actual visual performance decreased when the participants faced the high beams of the opposing vehicle. Reports of glare-induced discomfort increased when participants faced high beams. Interestingly, the participants overestimated their visual performance when their own vehicle used low beams but were more accurate when their own vehicle used high beams. These results may help explain why drivers underuse their high beam headlights even when in conditions that favor their usage.