Turns out that “holding your liquor” doesn’t mean what you think it means.

A recent study by the University of Chicago found that heavy drinkers experience significant fine motor and cognitive impairment after drinking — even if they don’t feel the effects. The research group says that alcohol use disorder is “more nuanced than commonly believed,” as consistently heavy drinkers displayed notably higher impairment than expected, according to a June 19 press release.

The findings were published in “Alcohol: Clinical and Experimental Research” this week, as part of professor Andrea King’s ongoing Chicago Social Drinking Project study.

“There’s a lot of thinking that when experienced drinkers (those with alcohol use disorder) consume alcohol, they are tolerant to its impairing effects,” senior study author King says in the release.

Researchers examined three participant groups based on alcohol consumption: those who didn’t engage in binge drinking, those who are social binge drinkers, and those who binge drink frequently. Each participant was given a beverage with the alcohol equivalent of four to five drinks (adjusted by body weight and sex) to be consumed within 15 minutes. To adjust for typical drinking patterns, heavy binge drinkers were given an alcohol sample more consistent with usual consumption (about seven or eight drinks) in a separate session.

The researchers conducted a breathalyzer test at 30, 60, 120, and 180 minutes after drinking. They also led drinkers through a fine motor task — inserting metal pegs into a board — and a cognitive assessment. Participants also recorded how impaired they felt (from “not at all” to extremely”) throughout the study. Participants with alcohol use disorder initially showed less impairment across the duration of the first session. However, during the second session with adjusted alcohol content, these participants displayed over double the amount of impairment in the separate session than after the first sample.

The findings are contrary to the common assumption that “experienced” drinkers are better at handling the effects of alcohol.

“I was surprised at how much impairment that group had to that larger dose, because while it’s 50% more than the first dose, we’re seeing more than double the impairment,” King says.