Peer approval was a stronger predictor of driving after using alcohol and cannabis together than seeing others do it | Research

The takeaway

Among nearly 2,000 young adults in Washington State, perceived peer approval of driving after combined alcohol and cannabis use predicted DUI behavior more strongly than simply believing peers did it.

Traffic safety researchers, prevention program designers, and social norms campaign developers

49.8% overestimated peer SAM-impaired driving

What the researchers found

DUI after simultaneous alcohol and cannabis use (DUI-SAM) was reported by 2.7% and riding with an impaired driver (RWI-SAM) by 5.3%. Nearly half of participants overestimated how often peers drove impaired. After controlling for frequency of use and descriptive norms, perceived peer approval (injunctive norms) was significantly associated with all DUI and RWI behaviors.

Why it matters

Identifying that peer approval matters more than perceived prevalence for driving under combined substances points to a specific, actionable target for prevention campaigns.

The numbers in context

1,941 participants; 2.7% DUI-SAM; 5.3% RWI-SAM; 49.8% believed average young adult drove after SAM use at least monthly; 68.8% called DUI-SAM totally unacceptable; injunctive norms significantly predicted all DUI/RWI behaviors

How the study worked

Cross-sectional survey of 1,941 young adults (ages 18-25) from the 2019 cohort of the Washington Young Adult Health Survey. Logistic regression models assessed associations between descriptive norms, injunctive norms, and past-month DUI/RWI behaviors with post-stratification weighting.

What this study cannot tell us

Cross-sectional design cannot establish causality; self-reported DUI likely underestimated; single state sample; 2019 data predates pandemic; cannot distinguish between types of cannabis products used

How to read the evidence

Large statewide survey with appropriate statistical methods, but cross-sectional design limits causal inference.

When this study was published

2024 publication with 2019 survey data

The bigger picture

Prevention efforts often focus on correcting misperceptions about how common a behavior is. This study suggests that for impaired driving after combined substance use, changing perceived approval may be more effective.

Questions still open

Would social norms campaigns specifically targeting approval of SAM-impaired driving reduce these behaviors? Do injunctive norms operate differently for single-substance versus polysubstance impaired driving?

Common questions

What matters more for preventing impaired driving: what people think peers do or what they think peers approve of?

This study found that perceived peer approval (injunctive norms) was a stronger predictor of driving after combined alcohol and cannabis use than beliefs about how often peers did it (descriptive norms). This suggests prevention campaigns should focus on communicating that most young adults find this behavior unacceptable.

How common were misperceptions about peer DUI?

Nearly half (49.8%) of young adults believed the average person their age drove after using alcohol and cannabis together at least once a month. In reality, only 2.7% reported doing so, revealing a large gap between perceived and actual behavior.

Read the original research

Young adult impaired driving behaviors and perceived norms of driving under the influence of simultaneous alcohol and cannabis use.

Alcohol, clinical & experimental research, 48(12), 2319-2330

View on PubMed ↗Publisher’s paper ↗

Citation

Hultgren, Brittney A; Delawalla, Miranda L M; Szydlowski, Victoria; Guttmannova, Katarina; Cadigan, Jennifer M; Kilmer, Jason R; Lee, Christine M; Larimer, Mary E. (2024). Young adult impaired driving behaviors and perceived norms of driving under the influence of simultaneous alcohol and cannabis use.. Alcohol, clinical & experimental research, 48(12), 2319-2330. https://doi.org/10.1111/acer.15459