DRIVER CHARACTERISTICS AND IMPAIRMENT AT VARIOUS BACS

The purpose of this experiment was to determine (a) the magnitude of alcohol impairment of driving skills as blood alcohol concentrations (BACs) varied from zero to 0.10% and (b) whether age, gender, and drinking practice characteristics of the subjects would differentially affect alcohol impairment in a sample of subjects who were broadly representative of the driving population. Using a driving simulator and a divided attention task, 168 subjects were examined at BACs to 0.10% for moderate and heavy drinkers and to 0.08% for light drinkers. Alcohol significantly impaired performance on some measures at all examined BACs from 0.02% to 0.10%. The magnitude of the impairment increased with increasing BAC. Differences in the magnitude of alcohol impairment between categories of age, gender, and drinking practices were small, inconsistent in direction, and did not reach statistical significance. It is possible that significant differences would have emerged if a wider range of subject characteristics and BACs had been examined. BACs over 0.10% were not tested, and the sample did not include subjects under 19 years and over 70 years, or very light and very heavy drinkers. Within those limits, no significant differences in the magnitude of alcohol impairment within the categories of age, gender, and drinking practice appeared for this diverse sample.