The effect of a moderate dose of alcohol on the traffic hazard perception profile of young drink-drivers

Hazard perception latency has been identified as one source of individual differences in road accidents, but alcohol's effects on hazard perception has not been addressed thoroughly. Furthermore, individuals convicted of driving while impaired (DWI), in comparison with other drink-drivers, have been found to possess a poor driving record, suggesting that they may also respond poorly to hazards. Therefore, this research studied young drivers across the spectrum of drink-driving practices, from non drink-drivers to DWI offenders. It examined alcohol's effects on their hazard perception profile, including aspects of both driving skill (hazard perception latency) and driving style (the perceived level of risk in hazards). Thirty-two subjects aged 18-25 years underwent two experimental conditions in a counterbalanced design: no alcohol and moderate alcohol. Alcohol was found to affect both driving skill and driving style. With a 0.05% BAC subjects took longer to detect hazards and responded to them in a more abrupt manner and these effects were particularly pronounced for DWI offenders. The results also supported a distinction between active hazards (hazards arising from the driver's own actions) and passive hazards (hazards arising from the actions of other road users). Irrespective of their drink-driving practices, subjects perceived active hazards as less dangerous than passive hazards. Furthermore, compared with other drink-drivers, DWI offenders perceived less risk during passive hazards (with a 0.05% BAC) and active hazards (when sober). It is suggested that these effects may underlie, at least in part, the increase in accident risk associated with impaired driving.