This Labor Day, take a moment to notice your beer glass shape: it might be influencing how much booze you down. New research shows that an optical illusion makes curved glasses seem more alcoholically innocent than they really are.
To see if glass shape might influence drunkenness, researchers in the U.K. divided 160 students and faculty at the University of Bristol, plus some random volunteers, into eight groups. They were given either a greater (about 354 milliliters) or lesser (177 milliters) amount of soda or lager to drink. (The study subjects were screened ahead of time to make sure they were “social drinkers” rather than binge drinkers or full-fledged alcoholics.) Some groups drank out of straight glasses; other had curved glasses. They also had to watch a nature movie and, at the end of the test, complete a word search, meant to throw them off the experiment’s real aim.
During each session, the researchers recorded how long it took for the thirsty participants to finish their beverages. One group, they found, consistently outpaced their colleagues: the group drinking the 354 milliliter glass of lager out of cured flute glasses. People with straight glasses took about 13 minutes to finish their round, while people with the curved glasses clocked in at less than 8 minutes, about the same time the soda group took to finish their alcohol-free brews. There was no time difference between those drinking 177 milliliters of beer out of straight versus curved glasses, however.
The researchers think this difference may be due to the ambiguity of the curved glasses. While it’s easy to judge the half-way point in of a straight glass—a technique social drinkers reportedly use to pace themselves—the curved glass is not so straight-forward. The researchers wonder if curved glass-drinkers might slow down if a half-way point were marked on the glass to clue them in.
Luckily, follow-up experiments to test this hypothesis should not be a problem. ”People tend to be quite happy to get free lemonade or beer,” the researchers told ScienceNow.
More from Smithsonian.com: