Beer psychologyThe US football season began this weekend, replete with tailgates, watch parties, and plenty of beer consumption. It’s timely that new research has been released showing that the shape of the glass has a huge effect on how quickly we consume beer.

Curvy Glass, Goes Down Fast

Researchers at the University of Bristol in the UK gave subjects a glass of beer. The subjects, who didn’t realize their consumption was being carefully monitored, watched a short documentary film and answered a few questions. The subjects were served in either a “fluted” glass with a curvy taper to a narrow base or a straight-sided glass. The straight-sided-glass subjects were an amazing 60% slower in finishing their glass of beer – nearly 12 minutes, vs. 7 minutes for the fluted-glass group.
Straight glass vs curved glass

The researchers attribute the difference to the difficulty of estimating the halfway point in the curvy glass. In other words, those drinkers had the wrong impression of how far along they were. Subsequent tests appeared to confirm this. When the glasses were provided half-full, there was no difference in speed of consumption. In addition, the researchers confirmed that subjects viewing the straight glass were much more accurate in estimating the half-full point.

Beer vs. Soft Drinks

Another surprising finding was that the slower consumption effect of the straight glass was totally absent for soft drinks. The soft drink in either glass shape was consumed in about the same time as the “fluted glass” beer was, i.e., the faster rate.

Short and Wide, Tall and Skinny

tall and short glassesAnother shape effect on beverage consumption has been measured, this time with juice. A Cornell study found that subjects both poured and consumed more juice when they used a short, wide glass vs. a tall, thin glass. The effect was most pronounced in children, who poured and drank 74% more juice in the short, wide glass condition. Adults were hardly immune, though, their consumption rose by 19%.

As with the curved/straight study, the cause appears to be our difficulty in estimating volumes. In this case, it’s caused by the “vertical-horizontal illusion,” a term for the human tendency to focus on heights more than widths. According to study author Brian Wansink, “When pouring into glasses, we tend to focus on the height of the beverage and basically ignore the width. That’s why we over pour into wide glasses but think we poured very little.” [Emphasis added.]

Bartenders Fooled, Too

Even professional bartenders are subject to the short/wide pouring error. A variation on the experiment with juice found that experienced bartenders asked to pour a standard shot poured an average of 27% more into short, wide glasses than tall, thin ones. (So, when you order a shot of that 25-year old Macallan Sherry Oak, be sure to point at the shortest, widest rocks glass and tell the bartender, “In THAT glass, please.”)

That the wide vs. narrow effect was found to affect both juice and spirits, it seems likely that it would apply to beer as well.

Shaping a Strategy

Bars and restaurants are in a tricky situation when it comes to alcoholic beverages. While every establishment wants to maximize sales, the operators must also be careful not to encourage over-consumption to the point of inebriation. In my experience, the majority of establishments do use curved, or at least tapered, glasses for serving beer. It may not have been a conscious decision, but they have clearly gravitated toward glass shapes that favor more rapid consumption. Not only does this boost sales, it may also enable restaurant and bar operators to turn over tables more quickly for patrons who plan to consume just one beer – another key factor in profitability.

Shorter, wider glasses may speed up consumption of all beverages, too. But bar owners beware – while beer and soft drinks will be poured to the capacity of the glass regardless of shape, hand-pouring spirits into that kind of glass might result in significant over-pouring even by trained staff. For bars that serve beer by the pitcher, wider glasses could speed up consumption and table turnover.

As individuals, we need to be mindful of these shape effects too. If we’re trying to limit our calorie or alcohol intake, we’re better off with tall, straight, slender glasses for beer and just any other beverage. Both curved glasses and wide glasses are likely to make us underestimate our consumption.

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