Perceived Effectiveness of Anti-Marijuana Messages in Adult Users and Nonusers: An Examination of Responses to Messages About Marijuana's Effects on Cognitive Performance, Driving, and Health.

Objective: Marijuana use is associated with negative cognitive and health outcomes and risky driving. Given the rapidly changing policies regarding legal recreational and medicinal marijuana use, it is important to examine what types of marijuana prevention messages may be effective in minimizing such outcomes. This study examined cognitive and affective responses to anti-marijuana public health messages in a sample of adult marijuana users and nonusers to determine the correlates of perceived message effectiveness. Method: Participants (N = 203; mean age = 37.7 years) were adult marijuana users and nonusers recruited via Amazon Mechanical Turk (August 2017). After completing self-report measures of marijuana use, they viewed six anti-marijuana messages presented in a random order, addressing marijuana's effects in each of three topic areas: cognitive performance. driving. and adverse health outcomes (e.g., two messages per topic). Participants completed assessments of cognitive and affective perceptions after viewing each message. For each message topic, a linear regression model was used to determine which cognitive and affective perceptions were most predictive of perceived message effectiveness. Results: For all message topics, nonusers perceived the messages as more effective than did users (p < .001). in the majority of analyses, greater message effectiveness was associated with increased perceived harm of marijuana and increased liking of the message. For driving and health messages, greater message effectiveness was also significantly correlated with lower pleasant ailed. Conclusions: The findings suggest that audience perceptions may be uniquely predictive of message effectiveness, depending on the topic.