The goal of the research was to evaluate the effects of alcohol on the performance of New Zealand drivers across 0.05% and 0.08% blood alcohol concentration (BAC) levels.
An experimental test was conducted with 61 participants assigned to one of two alcohol dose conditions or a placebo control group.
Comparison of alcohol doses showed that a BAC of 0.08% produced a level of impairment significantly worse than the placebo control. Impairment included edge and centre line crossings in the driving simulator, disinhibition of reactions to vehicles at intersections, and errors learning and recalling a computer-based maze. Moderate alcohol (BAC of 0.05%) produced some performance decrements, but not to the same degree as a BAC of 0.08%.
An analysis comparing the impairment associated with peak and post-peak intoxication revealed that while some aspects of performance (eg motor coordination and response inhibition) showed acute tolerance, other measures (eg maze learning and recall errors, edge and centre line crossings, and maximum speeds) showed acute protracted errors.
Finally, participants were not able to accurately judge how much alcohol they had consumed or their level of intoxication (particularly the high dose group), and subjective ratings of intoxication were not a reliable indicator of their performance impairment.