23 December 2005

Girth And Length Muddle Bartenders' Brains

by Kate Melville

If you're looking to maximize your alcohol consumption this silly season then you should consider taking advantage of what would appear to be a common perceptual problem amongst bartenders. Researchers from Cornell University have found that bartenders habitually pour more booze into short, wide glasses than long tall ones.

According to Cornell researcher Brian Wansink, people who pour into short, wide glasses consistently believe that they pour less than those who pour into tall, narrow glasses. "People generally estimate tall glasses as holding more liquid than wide ones of the same volume," Wansink said. "They also focus their pouring attention on the height of the liquid they are pouring and insufficiently compensate for its width." He added that "education, practice, concentration and experience don't correct the overpouring."

Wansink speculates that the reason for the difference is the classic vertical-horizontal optical illusion: people consistently perceive equally sized vertical lines as longer than horizontal ones.

The study, in the British Medical Journal, analyzed the pouring habits of both professional bartenders and students. The college students consistently poured 30 percent more alcohol into the short glasses than into the tall, and the bartenders poured 20 percent more. Interestingly, when the researchers asked one group of students to practice 10 times before the actual pour, they still poured 26 percent more into the short glasses. When the researchers asked one group of bartenders to "please take your time," the bartenders took twice as long to pour the drink, but still poured 10 percent more into the short glasses.

Wansink said that the findings were of relevance to health professionals, consumers, law enforcement officials and alcohol addiction and abuse counselors. And for bars and restaurants, Wansink recommends they switch to "tall glasses or glasses with alcohol-level marks etched on them." He also mused that parents could take advantage of this perceptual anomaly by using tall, thin glasses when pouring soda but short, wide glasses for milk and other healthful drinks.

Source: Cornell University