Abstract
This study evaluated the de Boer rating scale for discomfort glare. The aim was to determine if the scale was effective in rating discomfort glare and, if not, what modifications are necessary to improve the scale. The results indicate that (1) there is a problem with the way the de Boer scale is numbered, and (2) some of the verbal descriptors are confusing and can lead to improper scaling of glare. These results are consistent with the hypothesis that the de Boer scale is not the optimal scale for rating discomfort glare by American observers, and research on an improved scale is necessary.