Glass Shape Can Affect Amount of Alcohol Poured A researcher at Cornell University has found that even when bartenders are told to be very careful, they pour about 30 percent more alcohol into a tumbler-sized glass than a highball-sized glass. The result can mean people have more to drink than they think they're getting.
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Glass Shape Can Affect Amount of Alcohol Poured

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Glass Shape Can Affect Amount of Alcohol Poured

Glass Shape Can Affect Amount of Alcohol Poured

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If you've stopped into a bar or poured yourself a stiff one this holiday season, you may have had more alcohol than you think. You see, it depends on the bartender's or for that matter your choice of glassware. This is what a Cornell University marketing expert says. We asked NPR's Joanne Silberner to get to the bottom of this story.


What better place to start than bar?

(Soundbite of drinks being mixed)

SILBERNER: In this case, RFD Washington, just around the corner from NPR headquarters.

Mr. RACHMAN BANKS(ph) (Bartender): My name's Rachman Banks. I've been a bartender for three and a half years. The best.

SILBERNER: We're giving a test to local bartenders.

I want two drinks. I want both of them to be rum and Coke. I want one in a tall glass and one in a short glass.

The idea is to see if Banks pours exactly a shot of alcohol into each glass. A couple of blocks away, at the decidedly upscale Clyde's Restaurant, Billy Raldaffer(ph) is counting on his 10 years of experience.

Mr. BILLY RALDAFFER (Bartender): I've been doing this for so long that I can pour it in my sleep.

SILBERNER: But there's a well known perceptual illusion that's working against Raldaffer and Banks. Brian Wansink of Cornell University explains.

Professor BRIAN WANSINK (Cornell University): When people look at an object like a glass for instance, they tend to focus on the vertical dimensions and they don't compensate for the width.

SILBERNER: Wansink studied two groups, 86 experienced bartenders in Philadelphia and 198 college students. They were asked to pour one shot of alcohol, 1.5 ounces, into two different-sized glasses.

Prof. WANSINK: What we end up finding is that people have a tendency to pour 20 to 30 percent more alcohol in the short, wide glasses than in tall, skinny glasses.

SILBERNER: They get those close to correct. Wansink published his research in the BMJ, a medical journal based in England where the proper alcohol amounts are etched into the side of each bar glass. Wansink gets similar results when he used orange juice. He says he knows why people can't pour the right amounts.

Prof. WANSINK: They end up looking up and down and up and down and up and down as they pour and they don't compensate for the width in a tumbler. So you keep pouring. And that's what causes you to overcompensate because you don't account for the width, you pour.

SILBERNER: In NPR's decidedly unscientific effort, we took along a shot glass to measure the results.

Let me use your strainer and give me a big glass.

Mr. RALDAFFER: OK. That's the idea. Freshness.

(Soundbite of applause)

Mr. RALDAFFER: Now keep in mind in the process of doing this, the ice is melting.

SILBERNER: Raldaffer poured two perfect shots. At RFD Washington, Banks went against predictions and poured a little more into the tall glass, but both did better than the Philadelphia bartenders in Wansink's study. Raldaffer offers two explanations.

Mr. RALDAFFER: When you're pouring in a glass, they want to make sure that it has a certain appearance, OK, as opposed to just follow your count.

SILBERNER: Raldaffer counts silently as he pours. He doesn't even look at the level in the glasses. His second explanation for the poor Philadelphia showing? Football.

Mr. RALDAFFER: Well, I mean, you know, they're having a tough year out there, you know, with the Eagles. They're having a tough year.

SILBERNER: Researcher Brian Wansink says visual clues make a big difference, not just in how much people pour for themselves, but in how much food they take. In previous research, he showed that students watching a football game offered a cracker, pretzel and nut mix from large containers stake and eat 53 percent more than students offered the mix from half-size containers, which is why Wansink recommends if you want to cut down on eating and drinking this holiday season, use smaller bowls and taller glasses. And in case you're wondering, we did pay for the drinks, but we didn't drink them. Joanne Silberner, NPR News, Washington.

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