Date of Award


Degree Name

Doctor of Philosophy




Lawrence D. Cohn


The national trend toward the legalization of recreational marijuana use will likely increase the number of opportunities for young adults to legally drive under the combined influence of small amounts of marijuana and alcohol (DUI-SAMA). Research suggests that driving performance is moderately impaired when small amounts of marijuana and alcohol are consumed independently; however, driving performance is dramatically impaired when both substances are consumed in combination. The present study investigated the perceived risk of DUI-SAMA under two levels of stress (no stress, stress) and three levels of urgency (non-urgent, semi-urgent, urgent). One-hundred and sixty-five marijuana users (Mage = 20.3) were randomly exposed to a stressful or non-stressful manipulation. Stress did not influence the perceived risk of DUI-SAMA, the perceived dangerousness of DUI-SAMA, or willingness to DUI-SAMA. Level of urgency emerged as a key factor explaining self-reported willingness to DUI-SAMA. Specifically, participants were significantly more willing to DUI-SAMA in urgent conditions than in non-urgent conditions. These findings are favorable from a public health perspective, suggesting that marijuana users evaluate the urgency of situations when making decisions about their willingness to DUI-SAMA. However, participants were significantly more willing to DUI-SAMA than to drive a motor vehicle after consuming enough alcohol to reach a BAC of 0.08. Ironically, research suggest that the driving impairments observed in DUI-SAMA mimic the driving impairments observed when individuals are at or have exceeded the legal BAC of 0.08. Thus findings in the current study suggest that marijuana users underestimate the risks associated with DUI-SAMA.




Received from ProQuest

File Size

122 pages

File Format


Rights Holder

Gabriel Andrew Frietze

Included in

Psychology Commons