A long time ago, although I don’t remember where, I read that the martini glass was invented during the American prohibition to get people to drink more quickly. Supposedly it opened up the rate of consumption so people could gulp and therefore reduce the risk of being caught with a drink in their hand.

The idea sounded strange (ever try to gulp out of a large martini glass?) and was stuck in my head until I read a recent study in ScienceMag that explained how it might actually work. The study describes an observed difference in drinking speeds with curved and straight glasses.

After watching video of both sessions and recording how much time it took for the drinkers to finish their beer or sodas, Attwood’s team found that one group consistently drank much faster than the others: The group drinking a full glass of lager out of curved flute glasses. In a paper published this month in PLoS ONE, the team reports that whereas the group with straight glasses nursed their 354 milliliters of lager for about 13 minutes, the group with the same amount of beer served in curved glasses finished in less than 8 minutes, drinking alcohol almost as quickly as the soda-drinkers guzzled their pop. However, the researchers observed no differences between people drinking 177 milliliters of beer out of straight versus fluted glasses.

Attwood believes that the reason for the increase in speed is that the halfway point in a curved glass is ambiguous. Social beer drinkers, she says, naturally tend to pace themselves when drinking alcohol, judging their speed by how fast they reach half-full. Another experiment in which participants were asked to judge different levels of fluid in photographs of straight and curved glasses showed that people consistently misjudge the volume in fluted glasses, Attwood says. A simple solution to this problem would be to mark beer glasses with the accurate halfway point, she says. “We can’t tell people not to drink, but we can give them a little more control.”

Straight glasses do not seem to include an angled glass like the martini shape. A better distinction might be between a vertically symmetrical glass where consumption has a constant rate versus shapes that make estimation difficult.