Which bar patrons underestimate their inebriation the most?

Prior research suggests that college students, males, and people drinking alcohol at restaurants, bars, and nightclubs are at particularly high risk for driving after drinking. Breath-testing devices are not usually found at these drinking establishments, so patrons generally assess their own intoxication levels using internal (feelings of intoxication) and external (number of drinks consumed) cues. This study examined bar patrons' self-estimates of their breath alcohol concentrations (BrACs) in natural drinking environments.

Researchers recruited 510 study participants, on 14 nights between 10 p.m. and 3 a.m., as they exited two bars located close to large universities: one in Florida (n=301) and the other in Texas (n=209). Research assistants conducted a 10-15 minute interview with each of the exiting patrons and measured their BrAC with hand-held testing devices.

Bar patrons with the highest-measured BrACs underestimated their levels the most. Adjusting for their measured BrAC, individuals who felt more intoxicated or who reported consuming more drinks thought that their BrACs were higher. However, more than 20 percent of participants with a BrAC of at least 0.08% (the legal driving limit) thought that their BrAC was below this level. Individuals younger than 26 and those who reported feeling less drunk were more likely to make this error. Study authors called for more research to assess the association between self-estimated BrACs and driving behavior in different contexts, and to investigate how altering drinking environments could improve individuals' ability to self-estimate their BrACs and avoid driving after drinking.