BACKGROUND: Zero-alcohol drinks (<0.5 % alcohol by volume) appear and taste like alcoholic drinks; they may feature brands from alcoholic drinks ("brand extensions") or "new-to-world" brands. These drinks are not consistently included within many restrictions aimed at reducing adolescents' exposure to alcohol products and advertising. This online study examined whether adolescents implicitly categorise images of zero-alcohol drinks as alcoholic beverages.

METHODS: 331 Australian adolescents aged 15-17 years participated in an online within-subjects reaction time experiment. Participants viewed 20 randomly-ordered images of alcohol, zero-alcohol, and soft drink products and were asked to indicate as quickly as possible whether these images made them think of alcohol, with both response time and agreement recorded. Generalised linear mixed effects models were used to examine differences in response time and agreement by drink type, adjusting for clustering of responses within participants, recent consumption, survey device (mobile/computer), and parental presence.

RESULTS: Most images of alcoholic (94.4 %), brand extension zero-alcohol (90.7 %), and "new-to-world" zero-alcohol (85.6 %) drinks prompted participants to think of alcohol, compared to 5.2 % of soft drinks. In the mixed effects model, compared to alcoholic drinks, participants on average responded 72 ms slower to brand extension zero-alcohol drinks and 215 ms slower to "new-to-world" brand zero-alcohol drinks.

CONCLUSIONS: The combination of high levels of agreement and slower reaction times suggest that adolescents categorise zero-alcohol drinks as non-typical alcoholic drinks, rather than soft drinks. Thus, exposure to zero-alcohol drinks had similar effects to exposure to alcoholic drinks. Urgent regulatory action is required to ensure that restrictions on alcohol advertising and availability to minors extend to zero-alcohol drinks.