“Dutch courage,” liquid confidence—the value of alcohol as a social lubricant is widely acknowledged, and now science has confirmed its existence. Researchers from the University of Pittsburgh and the University of Oslo dug into the phenomenon of “social bravery” induced by alcohol, and found that the effect is more pronounced in men than women, at least when it comes to smiling in social settings.

They took 720 social-drinking millennials, split them into groups of three, and then randomly gave each person one of three drinks.

Option 1: Vodka Cranberry

Option 2: Virgin Vodka Cranberry

Option 3: Virgin Vodka Cranberry, but labeled as having alcohol (with a few drops of vodka for believability)

The participants in the study were recorded, with their smiles in particular being noted and then modeled using “sophisticated analyses” to determine their genuineness and contagiousness. The men who drank alcohol were caught flashing their pearly whites more often than those who weren’t. And if a person in the group was drinking heavily, smirk levels increased even further. Whether men were paired with women surprisingly had no effect on the rate of smiling.

What were the researchers actually trying to discover? They wanted to find out how important of a role alcohol played in terms of forming relationships, since many men reported that going out with colleagues after work is a bonding experience.

Things start to get a little bit hazy when people who seek that reinforcement start going out more often than they should, build a tolerance, and thus need to drink even more before they start smiling.

That’s probably why, the researchers concluded, “social motives may be highly relevant to the understanding of how alcohol problems develop.”