There’s nothing like an open bar to turn a mandatory office gathering into a late-night party, where even the most argumentative coworkers can get along. But while alcohol has a reputation for breaking down social barriers, does it really work as a social lubricant?

To answer this question, researchers from the University of Pittsburgh put strangers together in groups of three and told them they were studying how alcohol would affect their execution of certain tasks. In reality, though, those sneaky scientists were zeroing in on how a few cocktails impacted their interactions with each other. And even sneakier: One group was knowingly given vodka and cranberry, another was knowingly given cranberry juice, and the last was given a virgin cocktail in glasses wiped with alcohol—so they only thought they were drinking.

Ultimately, the study—published in the journal Psychological Science—found that the group downing the vodka and cranberries reported getting along better with each other, compared to the people who weren’t imbibing. The researchers also noticed that the members of the alcohol group looked like they were having a better time—measured by how they smiled more, talked more, and were less likely to wrinkle up their nose or purse their lips.

So moderate drinking really does open things up when people—even strangers—interact. This doesn’t give you a free pass to keep a bottle of vodka in your desk at work, but it can explain the festive atmosphere at the office party.