Citation

Dott AB. PHS Injury Control Research Laboratory. Washington, D.C.: U.S. Department of Health, Education, and Welfare, Public health Service, Division of Community Inju, 1972.

Copyright

(Copyright 1972, PHS Injury Control Research Laboratory)

The full document is available online.

Abstract

Twelve male marihuana users operated an optical driving simulator under a nonsmoking condition and under three conditions after smoking crude marihuana leaf. The estimated dosages of delta-9 tetrahydrocannabinol (THC) in the smoking condition were 0 mg., 11.25 mg., and 22.5 mg. During each session, each subject was given the opportunity to pass a lead car with the assistance of a passing aid device under conditions of varying risk. During several of these passing trials, there arose an emergency condition that required immediate response in order to avoid an accident. No differences in performance were noted between the nonsmoking and placebo (0 mg. Thc) conditions. No differences in performance were noted during any of the emergency conditions. Subjects under the influence of marihuana completed fewer passes and took more time to make the elective decision as to whether to pass. Subjects under the influence of marihuana did not have more accidents. It is concluded that chronic users under the influence of marihuana are less likely to accept risks than users not under the influence of marihuana. It is not clear whether this represents a compensatory mechanism for perceived disability or a lack of motivation as an effect of the drug. Comparisons of the performance of these subjects with another group performing the same task under the influence of alcohol are also made.

Keywords: Cannabis impaired driving