Do you find that some days you drink more beer than other days? Maybe it’s not you, but rather, maybe its the glass you’re using. A recent study by experimental psychologist Angela Attwood of the University of Bristol showed that an optical illusion caused by the shape of a curved glass can dramatically increase the speed at which beer is consumed.
To test the hypothesis, she and her colleagues randomly divided 160 young, healthy people—students and faculty members of the University of Bristol, as well as some members of the general public—into eight groups. It wasn’t difficult to recruit participants, Attwood says. “People tend to be quite happy to get free lemonade or beer.” Using the standard WHO test for hazardous drinking, called AUDIT, the researchers screened the participants to include only “social beer drinkers,” not alcoholics. They assigned each group to drink either about 177 milliliters or about 354 milliliters of lager or soft drink from straight or curved glasses. While the participants drank, they watched a nature documentary deemed emotionally neutral, so that they wouldn’t be “sitting there with nothing to do but drink,” Attwood says. The team videotaped the drinkers over two sessions, disguising the real purpose of the test with a fake word search task at the end of each session.
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.
So what causes the beer to be consumed faster out of the curved glass? The belief is that drinkers are using the glass as a determining factor in how fast they are drinking and adjust their drinking accordingly. This works fine in a straight glass, when the top inch of beer is the same amount as the bottom inch, but doesn’t work well when the volume changes from top to bottom.
If you’re a regular reader of this site you may remember a particular Friday Beer Fun in which we presented the beer gauge chart to know if your bartender is cheating you.
The average pint glass has sloped sides which, like the curved glass, has different volumes at different heights of the glass. To verify this problem of perception another test was done.
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.
While this may not be good news for your drinking, it could be great news for your local barkeep. Lets just say, be cautious of any bar that only uses curved, flute style glasses.