Give a bartender a tumbler and you'll almost always get a bigger pour.
the source: “Shape of Glass and Amount of Alcohol Poured: Comparative Study of Effect of Practice and Concentration” by Brian Wansink and Koert van Ittersum, in BMJ, Dec. 2005.
From the frontiers of science comes important insight into how to pour yourself a drink. Or, more to the point, what kind of glass to use.
Brian Wansink and Koert van Ittersum, marketing professors at Cornell University and the Georgia Institute of Technology, respectively, armed a group of 198 college students and 86 bartenders with bottles of ersatz rum, whiskey, and vodka, and asked them to pour a shot (1.5 ounces) to make a mixed drink. But some participants were given short, wide tumblers while others were given tall, slender highball glasses. The result: Virtually all those given tumblers poured with a heavier hand than those given highball glasses.
Maybe it’s not surprising that the college students overpoured by 30 percent, but even experienced bartenders who were told to take their time poured 20.5 percent more into the tumblers than they did into the highball glasses. So if you down two rum and cokes at a bar, chances are you have actually consumed closer to two and a half.
These findings have far-reaching consequences. Surveys of alcohol consumption, for example, fail to take into account the tumbler effect. Bar owners with an eye on the bottom line obviously would be well advised to switch to highball glasses, while parents who want their children to drink more milk should switch to tumblers. And while the authors don’t make this suggestion, tipplers who want to cut back might consider sipping their next Absolut from a bud vase.