Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Human Factors Psychology


Tyrrell, Richard

Committee Member

Gugerty , Leo

Committee Member

Pagano , Christopher

Committee Member

Switzer , Fred


Designing headlights involves balancing two conflicting goals: maximizing visibility for the driver and minimizing the disabling effects of glare for other drivers. Complaints of headlight glare have increased recently. This project explored the relationship between subjective (discomfort and expected visual problems) and objective (actual visual problems) consequences of glare. Two experiments - a lab-based psychophysical study and a field study - quantified the accuracy of observers' estimates of the effects of glare on their acuity. In both experiments, participants over-estimated the extent to which glare degraded their ability to see a small high contrast target. Observers' estimates of the disabling effects of glare were more tightly linked with subjective reports of glare-induced visual discomfort than with objective measures of glare-induced visual problems.