The effects of alcohol on speed perception in a closed-course driving situation

The present study examined the effect of alcohol on the perception of speed in a closed-course driving situation. Male subjects (N = 24) classified with respect to previous drinking experience were used in the experiment. Each subject was tested on a speed estimation task at blood alcohol levels (BALs) of 0 and 100 mg/dl. Subjects were required to decelerate from a constant speed of 30 mph to a target speed of 20 mph under two conditions: using their speedometer and being deprived of its use. Of interest were the subjective judgments made under the latter conditions. Results show that there was no significant effect of alcohol on the perception of speed. The expected interaction between previous drinking experience and alcohol dose was found to be nonsignificant. Overall, a significant difference in performance between the two speedometer conditions indicated that subjects overestimated the target speed when they were not given access to their speedometer. Possible explanations and implications of these findings are discussed and future directions for research are suggested.