Citation

Ellingstad VS, McFarling LH, Struckman-Johnson DL. University of South Dakota, Vermillion. Washington, D.C.: U.S. Department of Transportation, National Highway Traffic Safety Administration, 1973.

Copyright

(Copyright 1973, University of South Dakota, Vermillion)

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Abstract

The performance of six groups of 16 subjects each(marijuana user control, non-user control, .05 bac alcohol, .10 bac alcohol, low dose marijuana, and high dose marijuana) were compared on two laboratory analogs of the automobile passing task. Analysis of the data utilized a multiple discriminant analysis, producing statistically significant discrimination between the six groups. The first dimension of discrimination was related to "judgmental accuracy" and was capable of distinguishing the two marijuana treatment groups from the remaining four groups.

The marijuana subjects tend to overestimate time required to complete passes, and showed considerable variability in their estimates. The second discriminant function dimension was labelled "riskiness/ decisiveness" and appeared capable of distinguishing the alcohol groups from the remaining subjects. The alcohol group subjects tended to exhibit patterns of psychomotor performance suggesting a tendency to make "snap decisions" which were subsequently overridden.

No dose responses were found for either alochol or marijuana.

Keywords: Cannabis impaired driving; DUID; Ethanol impaired driving