Alcohol Impairment of Performance on Steering and Discrete Tasks in a Driving Simulator

Jex, Henry R.; Allen, R. Wade; DiMarco, Richard J.; McRuer, Duane T. · 1974 · ROSA P / United States. National Highway Traffic Safety Administration

archive: archived pipeline: cataloged verified

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

Summary

This 1974 study, sponsored by the National Highway Traffic Safety Administration, investigates how alcohol impairs driving performance, specifically comparing the effects on continuous steering control versus discrete visual-motor response tasks. The research was motivated by the established link between alcohol and accident probability, particularly above a blood alcohol concentration (BAC) of 0.08 g/100 ml, and the need for efficient, safe methods to study these impairments without dangerous field testing. The study aimed to characterize behavioral elements degraded by alcohol, such as divided attention and peripheral detection, and to determine if impairment differed between moderate and heavy drinkers. The researchers developed a fixed-base laboratory simulator that required subjects to perform two tasks: a continuous steering task to maintain lane position against simulated wind gust disturbances, and an intermittent discrete task requiring the detection and response to peripheral visual signals (horn or brake commands). The study involved two parts. Part I analyzed a mixed group of 18 licensed drivers (ages 21–65) at BAC levels of 0, 0.06, and 0.11. Part II focused on comparing 10 moderate drinkers against 10 heavy drinkers, testing the latter at higher BAC levels up to 0.16. Measurements included lane and heading deviations, steering control dynamics (gain, stability margins, remnant), reaction times, detection rates, and eye-point-of-regard data to analyze scanning behavior. Results indicated that alcohol significantly degraded performance in both tasks. For the steering task, alcohol increased lane and heading deviations, with path-following errors doubling when combined with the discrete task at high BAC levels. Control behavior analysis revealed that intoxicated drivers exhibited reduced control gain and increased "remnant" (unexplained noise in steering), likely due to increased indifference thresholds or intermittent attention. However, the basic closed-loop stability of the driver-vehicle system remained largely unchanged, as phase margins stayed constant. For the discrete task, alcohol increased reaction times and decreased the ratio of signals detected. Eye-tracking data showed that sober drivers used rapid, single saccades to scan for signs, whereas intoxicated drivers exhibited sluggish, multiple saccades with longer dwell times. The addition of the discrete task impaired steering performance, but the steering task did not significantly impair discrete task detection, suggesting the discrete task interrupts continuous control rather than vice versa. The study concluded that the simulator was a valid and efficient tool for alcohol research, providing sensitive measures of intoxication effects. It highlighted that alcohol primarily reduces driver sensitivity and increases attentional intermittency rather than destabilizing the control loop. The findings provided specific insights into the mechanisms of impairment, such as the "tunneling" effect on peripheral vision and the degradation of scanning efficiency. Furthermore, the study established a foundation for understanding differential impairment between moderate and heavy drinkers, noting distinct performance differences at equivalent BAC levels. These results support the development of improved countermeasures for alcohol-impaired driving by identifying specific behavioral deficits.

Key finding

Alcohol impairment increases lane and heading deviations, reduces driver control gain, and increases detection and reaction times on discrete tasks, with heavy drinkers exhibiting distinct impairment patterns at higher blood alcohol concentrations compared to moderate drinkers.

Methodology

simulator

Sample size: 20

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. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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

• alcohol
• drowsy as impairment
• polydrug
• manual
• alcohol detection systems
• cannabis

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: behavioral performance data
• Methodological Resource: validation psychometrics
• Theoretical Contribution: computational model