Effecten van alcohol op rijgedrag: een gecontroleerde replicatie van de ervaringsproeg in het project "Alcoholvrij op Weg"

This report is about an experiment in which young drivers drove various rides in the instrumented vehicle of the Centre for Environmental and Traffic Psychology, with and without alcohol in a controlled experimental design. The experiment was carried out to validate the life-experience setup in the project “Alcohol-free on the road” in the south-east of the Dutch province Drenthe, and therefore had a comparable setup. “Alcohol-free on the road” is a an experience for young drivers in which they are confronted under strict surveilance and on a closed circuit with the effects of alcohol on driving behaviour. In this study the demonstration-setup is validated by a more structured and methodologically sound replication with more measures. Thus, the experience is embedded in the scientific body of knowledge about alcohol effects. The setup was as follows: on a closed circuit subjects drove two rides of five laps each, in which they had to drive through cone-gates, react to a traffic light, drive straight and manage curves. Each ride ended with a backparking manoeuvre into a cone-marked parking space. During the rides a driving instructor was present to judge the behaviour of the subjects on various aspects. In the instrumented vehicle various driving parameters were recorded. Supplementary a reaction task was performed with a duration of 20 minutes. Before and afterwards self-raing scales were answered. The addition of alcohol (wodka) to the beverages (orange juce) was kept as secret as possible for both subjects and judges. The results showed that driving behaviour was influenced by the use of alcohol, but not for all subjects in the same way. Some subjects drove more sloppy and more roughly, wereas others started to drive more careful, as to compensate the alcoholeffect which they apparently noticed. The judgements of the driving instructors and the driving parameters showed on various measures a significant difference between sober and alcohol, and in general there was a trend in the expected direction. Also in the self-rating measures and in the reaction task measures there were significant results. These results show that this setup effects are obtained that are comparable to known effects in the literature, and therefore that the life-experience setup of the original project “Alcohol-free on the road” is based upon scientific knowledge of the effects of alcohol on driving behaviour