Science shows that drunk people don’t know how drunk they are

New study shows imbibers measure intoxication relative to other drinkers.

We now have solid scientific evidence that people are completely unable to determine how soused they are when drinking with a group. A team of social scientists recently completed a study of bar and club hoppers in Cardiff, Wales and discovered that most had incredibly inaccurate notions of their drunkenness and the dangers of drinking. But the researchers also learned something non-obvious and intriguing about how people estimate their levels of inebriation.

In a BMC Public Health paper, the researchers write that they wanted to know "how people judge their drunkenness and the health consequences of their drinking whilst they are intoxicated in social drinking environments." So they spent several months going to four different party neighborhoods in Cardiff between 8pm and 3am on Friday and Saturday nights. These neighborhoods had, as the researchers put it, "a high density of premises licensed for the on-site sale and consumption of alcohol." To get a broad sample of bar hoppers, researchers would approach every seventh person they saw and ask them to participate in the survey. The idea was to try to get people who were out with different social groups, because the researchers were interested in how peers influenced people's subjective experience of drunkenness.

Once a Cardiff drinker agreed to participate, the researchers would administer a blood alcohol test to determine their actual level of inebriation. Then they would ask the drinker a series of four questions:

1.  How drunk are you right now, on a 1 (totally sober) to 10 (completely drunk) scale?
2.  How extreme has your drinking been tonight, on a 1 (not at all) to 10 (completely extreme) scale?”
3.  If you drank as much as you have tonight every week, how likely is it that you will damage your health in the next 15 years, on a 1 (definitely will not) to 10 (definitely will) scale?
4.  If you drank as much as you have tonight every week how likely is it that you will get cirrhosis of the liver in the next 15 years, on a 1 (definitely will not) to 10 (definitely will) scale?

As amusing as it is to imagine clubbers being accosted by scientists at 2am with this list of vaguely terrifying questions, the results were anything but a joke. By comparing subjective reports of drunkenness with actual blood alcohol test results, the researchers discerned that people were measuring their drunkenness and health risks on a ranked scale. "People in drinking environments make decisions to drink more on the basis of their observation of people around them," they write.

The researchers speculate that this odd phenomenon could actually be part of humanity's evolutionary predilection for thinking in terms of rank. "Such rank sensitivity may also explain why drinking increases in a society; if everyone drank another 10 units per week, no one would believe themselves to be more at risk of alcohol-related disorder, as their rank positions would remain the same," they write. Put simply, people judged how drunk they were in relation to their peer group. If everyone around him was blackout drunk, an extremely inebriated person would consider himself relatively sober. But by the same token, a tipsy person with sober people was quite conscious of being loaded.

After a rigorous statistical analysis, the researchers found that people were basing their rank sensitivity not on the drunkest people around them but on the most sober. "It appears that drinkers are more self-aware of their own level of intoxication when in the presence of those who are sober," they conclude. As a result, we might be able to curb dangerous drinking just by encouraging the presence of "sober ambassadors" like designated drivers in bars and clubs. Our social groups determine how much we drink, but they often nudge us in a healthier direction more than we realize.

Cardiff University social scientist Simon Moore, an author on the study, remarked in a release that "we could either work to reduce the number of very drunk people in a drinking environment, or we could increase the number of people who are sober. Our theory predicts the latter approach would have greatest impact."