Are people more honest when they're drunk?

The old Latin adage "In vino veritas" — meaning "In wine, there is truth" — is just one of a litany of sayings perPetuating the idea that alcohol is a sort of truth serum. The phrase is attributed to Pliny the Elder, a Roman scientist, historian and soldier, though similar aphorisms can be traced back even further, to ancient Greece.

But does alcohol really make people more honest? The answer is both yes and no, experts told Live Science.

Alcohol "makes us more likely to say whatever's on our minds," said Aaron White, leader of the National Institute on Alcohol Abuse and Alcoholism's Epidemiology and Biometry Branch. "In some cases, that could be the truth. In some cases, it could be what you think is the truth in your intoxicated state."

So there's definitely a higher likelihood that someone will speak their mind after a few drinks. But there's also a chance that they will say something that feels real while drunk but that they wouldn't take seriously while sober. For example, a drunk friend might make bold promises they're going to move cities or quit their job only to take them back the next morning.

While an extensive online search didn't turn up any direct results for research on how alcohol influences honesty, studies about alcohol's impact on personality, emotion and cognition help support this idea.

For example, a 2017 study in the journal Clinical Psychological Science explored how participants' personalities changed after they'd consumed enough vodka lemonades to bring them to 0.09% blood alcohol concentration — just over the federal legal driving limit in the U.S. and England. Outside observers remarked that the biggest change in participants' personalities after drinking was that they became much more extroverted. Though the study didn't investigate whether alcohol was a truth serum, it makes sense that someone who feels more at ease in a social setting is also more likely to be candid.

Alcohol's ability to help people come out of their shell may help them say what's on their minds, but White says its effects on emotions can make those thoughts more mercurial.