Effects of alcohol intoxication on driving performance, confidence in driving ability, and psychomotor function: a randomized, double-blind, placebo-controlled study

Garrisson, Harriet; Scholey, Andrew; Verster, Joris C.; Shiferaw, Brook; Benson, Sarah · 2022 · Crossref

DOI: 10.1007/s00213-022-06260-z

archive: archived pipeline: cataloged verified

Get this paper ↗ (DOI — opens at the source; we link to it, we don't host it)

Summary

This study investigated the effects of alcohol intoxication on driving performance, psychomotor function, and subjective confidence in driving ability, specifically targeting blood alcohol concentration (BAC) levels corresponding to common legal limits (0.05% and 0.08%). The research was motivated by the public health burden of alcohol-related road traffic collisions and the potential for intoxicated drivers to overestimate their capacity to operate a vehicle safely due to impaired judgment. The primary objective was to determine if objective driving deficits occur at these legal thresholds and whether drivers possess accurate subjective awareness of such impairments. The researchers employed a randomized, double-blind, placebo-controlled crossover design involving 17 participants aged 18–40. Participants underwent three testing conditions: placebo, a low alcohol dose targeting 0.05% BAC, and a high alcohol dose targeting 0.08% BAC. On each visit, participants consumed their assigned beverage and completed a baseline four-choice reaction time (FCRT) task, followed by a 1-hour simulated highway drive on a medium-fidelity driving simulator. Driving performance was measured using the standard deviation of lateral position (SDLP) and standard deviation of speed (SDS). Post-drive, participants completed another FCRT task and rated their confidence in their driving ability on a visual analog scale. Actual mean BACs achieved were 0.04% for the low dose and 0.07% for the high dose. Results indicated that the high BAC condition (0.07%) significantly impaired driving performance compared to placebo, evidenced by a 4.06 cm increase in SDLP and a 0.69 km/h increase in SDS. SDLP also worsened significantly over time during the drive under both alcohol conditions, suggesting a vigilance decrement compounded by intoxication. The high BAC treatment also significantly impaired psychomotor function, increasing both reaction time and errors in the FCRT task. In contrast, the low BAC condition (0.04%) did not produce statistically significant differences in driving or psychomotor metrics compared to placebo. Crucially, there were no significant differences in self-rated confidence in driving ability across any of the three conditions. The study concludes that clinically significant impairment in driving and psychomotor functioning occurs at a BAC of 0.07%, which is below the legal limit in some jurisdictions (0.08%) and above in others (0.05%). The findings highlight a critical dissociation between objective performance deficits and subjective awareness; despite measurable declines in driving ability, participants remained unaware of their impairment. This lack of insight suggests that relying on self-assessment for fitness to drive is unreliable under the influence of alcohol, with significant implications for road safety policies and public education regarding drink-driving risks.

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed.

Summary generated by qwen3.6-27b-prismaquant on 2026-06-26; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• alcohol
• drowsy as impairment
• cannabis
• polydrug