The Glass Is Half Full… Or Is It?

Glass shape of alcoholic drinks affects how quickly people drink

(RxWiki News) Do you chug or do you sip? Regardless of your drinking style, you may be drinking faster than you realize. It all depends on the glass holding the alcohol.

A recent study found that the shape of a glass can affect how quickly people down their drinks.

Understanding the glass shape's impact can help you drink more responsibly.

"Drink alcohol in moderation."

The study, led by Angela Attwood, PhD, of the School of Experimental Psychology at the University of Bristol in the United Kingdom, involved two sets of experiments.

The experiments involved 159 social drinkers, aged 18 to 40, who had no history of alcoholism.

During the first experiment, they were asked to drink either lager or a non-alcoholic soft drink from one of two differently shaped glasses.

One glass was straight-sided, and the other was a curved beer flute. Some of the glasses held 6 fluid ounces, and some held 12 ounces.

The participants drank the soft drink from both glasses at approximately the same rate.

However, when they drank beer from the curved beer flute, they drank it nearly twice as quickly as when they drank it from the straight-sided glass.

Specifically, they drank 60 percent slower from the straight glass compared to the curved flute glass.

The researchers tested one theory about the reason for this difference in drinking speeds in the second experiment.

Their theory was that a flute's shape makes it harder to determine the halfway point. In a straight-sided glass, it's easy to tell when the glass is half full (or half empty).

Therefore, the second experiment asked the participants to judge whether liquid in multiple pictures of both glasses was above or below the halfway point of the glass.

On average, the participants were unable to correctly judge the halfway point on the curved flute glasses as often as they did on the straight-sided glasses.

The participants who made the biggest mistakes on judging the liquid's level were the same ones who showed the biggest difference in how fast they drank alcohol between the two glass types.

Obviously, you get drunker faster when you drink more alcohol at a faster rate. You're also more likely to have more drinks if you're drinking more quickly.

"People often talk of 'pacing themselves' when drinking alcohol as a means of controlling levels of drunkenness," said Dr. Attwood. "I think the important point to take from our research is that the ability to pace effectively may be compromised when drinking from certain types of glasses."

One strategy social drinkers could use is to pace themselves by a predetermined number of drinks they will have instead of playing it by ear. Or, they could request that their drink be served in a straight-edged glass.

"While many people drink alcohol responsibly, it is not difficult to have 'one too many' and become intoxicated," she said. "Because of the negative effects alcohol has on decision making and control of behavior, this opens us up to a number of risks."

The study was published August 17 in the journal PLoS One. The research was funded by an Alcohol Education and Research grant. The authors declared no conflicts of interest.

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Review Date: 
September 3, 2012