Research Papers

Driving is perceived as more difficult for lower blood alcohol volume, but performance is not necessarily impaired

Filename Hegg-Deloye.pdf
Filesize 117 KB
Version 1
Date added June 6, 2010
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Category 2010 CMRSC XX Niagara
Tags Session 1C
Author/Auteur Sandrine Hegg-Deloye, Martin Lavallière, Angelo Tremblay, Normand Teasdale


Alcohol affects perceptual and motor responses. Several researchers have explored the impact of alcohol on driving performance for a BAC (blood alcohol concentration) over 0.065%. In this study, we assessed the effect of BAC on the driving performance at low to moderate alcohol concentration. Twelve males, (aged: 20-40 years) were tested on four different days with one of four doses of alcohol through beer drinking (1 to 3 bottles, 330 ml at 5% and 1 placebo at 0.05%). Dose administration was single-blinded and randomized. Each participant was tested in a fully interactive driving simulator (STISIM Drive 2.0). Participants estimated their level of intoxication and driving capacity using 100 mm analog visual scales. These scales were completed before consumption of alcohol, after consumption-before driving and after driving. After each driving session, subjects also completed a NASA-TLX to estimate their total mental workload. Their visual acuity (Snellen chart) was also measured. The average BACs (%) during the driving simulation increased with the number of beers taken (placebo: 0 %, 1 beer: 0.019 ± 0.005, 2 beers: 0.036 ± 0.006, 3 beers: 0.054 ± 0.009; p<.05). Participants reported an increased sensation of alcoholic intoxication with the number of beverages drank (on average on a maximum score of 10, 0.08, 1.33, 3.49, and 4.97 for the placebo, 1-, 2-, and 3-beers conditions, respectively; p<.05). They also reported a decreased driving capacity (9.74, 8.83, 6.49 and 4.85, for the placebo, 1-, 2-, and 3-beers conditions, respectively; 10 being the highest score; p<.05). Their visual acuity did not vary with an increasing BAC. As measured with the NASA-TLX, participants reported an increasing mental workload with an increasing BAC (30, 32, 41 and 45 for the placebo, 1-, 2-, and 3-beers conditions, respectively; p<.05). The driving, however, was not affected by the level of BAC. Compared to the placebo condition, participants were not involved in more accidents and traffic violations after drinking beer. Their control of the vehicle (variability in the lateral position of the car, control of distances at intersections...) did not differ with and without beer drinking. The low to moderate dose of alcohol in male normal drinkers that were tested may still put the driver at higher risk for errors but more demanding driving contexts resulting from various causes like night driving, difficult weather conditions, or when an additional cognitive load is added through a secondary task may be additional factors needed to increase the likelihood of an error.

Sandrine Hegg-Deloye, Martin Lavallière, Angelo Tremblay and Normand Teasdale