The Effect of Alcohol on Contrast Sensitivity

Abstract

Contrast sensitivity was measured for subjects having different levels of blood alcohol content (BAC) under photopic and mesopic luminance conditions. In general, alcohol intoxication of less than 0.1% resulted in contrast sensitivity changes at all spatial frequencies tested. Most gains in contrast sensitivity occured at the higher spatial frequencies and the higher luminance levels. Losses of contrast sensitivity were perceived at all spatial frequencies. There were significant differences in the patterns of sensitivity gains and losses for individuals. For some subjects, the highest intoxication levels produced the greatest change in contrast sensitivity, while others demonstrated a delayed change in contrast sensitivity. Recovery of contrast sensitivity also varied. While some subjects returned to baseline sensitivity as BAC decreased, the contrast sensitivity of others increased or remained suppressed even after BAC returned to initial levels. These alcohol produced contrast sensitivity losses are significant when compared to previous performance-based target acquisition research. Results of this study suggest that the person who drinks alcohol, even moderately, might experience some serious loss in visibility of certain objects, especially under low luminance conditions. These results have implications for the general interpretation of tests of alcohol intoxication in visual task performance, especially for night driving. Further research is required.