Are bad drivers more impaired by alcohol? Sober driving precision predicts impairment from alcohol in a simulated driving task

The contribution of driver experience to risk for alcohol-related crashes is based on the tacit assumption that driver experience contributes to driver skill which could mediate the impairing effects of alcohol on driving performance. Surprisingly, few studies of alcohol effects on simulated driving performance have examined the role of driver skill as a mediator of the intensity of alcohol impairment. The present study examined the degree to which individual differences in driving skill mediated the intensity of impairment produced by a moderate dose of alcohol in a group of young adult drivers. Twenty-eight participants were familiarized with a simulated driving road test. After determining their baseline skill level, participants' driving performance was re-tested under either an active dose of alcohol (0.65 g/kg) or a placebo. Results showed that alcohol reduced driving precision, as evident by the increased within-lane deviation observed under the drug. Moreover, those individuals with poorer baseline skill levels showed the greater impairments in response to alcohol. The results highlight the importance of understanding interactions between driver skill level and the effects of alcohol and possibly other drugs.