Health messages with detailed descriptions of cannabis-impaired driving behaviors actually increased intentions to drive high by teaching risk-reduction strategies that made people feel safer doing it.
Public health communicators, traffic safety organizations, cannabis policy advocates, and anyone designing substance use prevention messages.
What the researchers found
Exposure to high-detail messages about cannabis-impaired driving was associated with increased DUIC intentions and behaviors, both immediately and at two-week follow-up. The effect was mediated by increased perceptions that risk-reduction behaviors would be effective (response efficacy) and confidence in performing them (self-efficacy).
Why it matters
This is a critical warning for public health communicators: providing too much detail about how to reduce risks of cannabis-impaired driving can backfire by making people feel capable and confident about doing something dangerous. Less detail may be more effective.
The numbers in context
686 cannabis-using adult drivers. Ages 18-50. High-detail messages increased DUIC intentions vs. low-detail and control. Mediated by response efficacy and self-efficacy. Effects persisted at 2-week follow-up.
How the study worked
Online randomized experiment with 686 adult cannabis-using drivers (ages 18-50). Participants viewed messages with high vs. low detail about DUIC risk-reduction behaviors, or a control video. DUIC intentions measured immediately and at 2-week follow-up. Mediation analysis tested mechanisms.
What this study cannot tell us
Online experiment — intentions don't necessarily translate to behavior. Self-selected cannabis users may differ from general population. Hypothetical scenarios vs. real driving decisions. Two-week follow-up is relatively short.
How to read the evidence
Randomized experiment with mediation analysis and follow-up — strong causal evidence for the messaging effect.
When this study was published
Published in 2026, with direct implications for ongoing cannabis public health campaign design.
The bigger picture
This parallels findings in other risk communication fields — detailed risk-reduction information can inadvertently normalize the risky behavior. For cannabis-impaired driving campaigns, the implication is clear: emphasize 'don't drive high' rather than 'here's how to be safer if you do.'
Questions still open
- How should cannabis-impaired driving messages be designed? Does this backfire effect occur with alcohol messaging too? Would focusing on consequences rather than risk-reduction be more effective?
Common questions
Can anti-drug driving messages backfire?
What makes an effective cannabis-driving message?
Read the original research
The Devil is in the Details: Exploring the Impact of Risk Behavior Detail (RBD) in Health Messages Targeting Cannabis-Impaired Driving.
Health communication, 1-13
Citation
Eliash-Fizik, Hadar; Lewis, Nehama; Sznitman, Sharon R. (2026). The Devil is in the Details: Exploring the Impact of Risk Behavior Detail (RBD) in Health Messages Targeting Cannabis-Impaired Driving.. Health communication, 1-13. https://doi.org/10.1080/10410236.2025.2610730