Abstract
Introduction and Aims: The ability to accurately detect alcohol or other drug intoxication is an important skill for people who use these substances and for a variety of professions (e.g., policing, responsible service of alcohol). Previous studies have found that intoxicated people are generally poor at estimating their own level of intoxication (particularly at high Blood Alcohol Concentration; BACs) and the link between intoxication and BAC appears to drop-off at higher BAC levels. But studies of observer ratings of other’s intoxication have yielded mixed results. The aim of this study was to investigate both self- and observer-ratings of intoxication against BAC levels to determine whether we see a similar drop-off in intoxication report for both self- and observer-rated intoxication. Design and Methods: Participants were 388 students interviewed outside three university events. Participants provided demographics, a rating of how intoxicated they felt (0=not at all, 10=very), and provided a breath test. Interviewers recorded a rating of how intoxicated the participant appeared to be. Results: We fitted our data with both polynomial and linear regressions. Polynomial regression provided a better fit when predicting both self-rated intoxication (r2=0.49 vs. r2=0.40, p < 0.001) and observer-rated intoxication from BAC (r2 = 0.58 vs. r2 = 0.52, p < 0.001), suggesting that there is a drop-off for both intoxication ratings. Discussion and Conclusions: Both self-rated and observer-rated intoxication appeared to drop-off at higher levels of BAC. This may be due to either tolerance or a ‘ceiling effect’ for observable signs of intoxication.