Drunk Smiles Are Contagious

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When a drunk bro smiles, the whole drunk-bro world smiles with him. Alcohol appears to increase the “infectious” spread of smiles in all-guy groups, according to a new paper published in Clinical Psychological Science. But it’s purely a drunk-dude phenomenon; that increase in emotional contagion wasn’t seen in groups of all women or in mixed-gender groups.

People tend to mirror each other’s emotional expressions, but studies of (sober) men and women have found that men do this mimicking less than women. Men also smile less often during social interactions than women do. But Catharine E. Fairbairn, lead author of said study, and her colleagues were curious: What would happen if they added alcohol to the mix?

Thus, they recruited 720 healthy social drinkers and either gave them a vodka-cran, told them they were getting alcohol (when they really just got the cran), or told them (truthfully) they weren’t getting any alcohol. Researchers then divided the participants into groups of three, with each beverage condition containing 20 all-female groups, 20 all-male groups, and 40 mixed-gender groups. Four cameras were positioned around the room, so the researchers could watch and record the individuals’ smiles.

Not surprisingly, the groups given alcohol smiled more than the groups that weren’t given alcohol; the groups who were drinking were also slightly more likely to catch each other’s grins than the groups in the placebo condition (those who were told they’d been given alcohol but hadn’t). When the groups were all female or mixed gender, this increase in smile contagion was very slight. In the group of sober women, for example, about 48 percent of individual smiles led to shared smiles; in the group of women drinking alcohol, that figure only increased to 49 percent.

In comparison, the difference in the all-guy group was more dramatic. In groups of non-drinking dudes, about 38 percent of smiles caught on throughout the rest of the group. But in the groups of drinking guys, that number increased to 50 percent.

That’s a lot of numbers to throw at you. But here’s what Fairbairn believes it may mean: Alcohol appears to increase men’s sensitivity to social rewards, something that could shed some light on problem drinking among men. And men, the authors point out, are 50 percent more likely than women to binge drink; they’re also twice as likely to struggle with alcohol dependence overall.

Dudes’ drunk smiles as a potential method of addressing a pressing public-health issue: Who knew?