A visual illusion has people believing they've poured less liquid into a short, wide glass than a tall, thin one, according to the Cornell University Food and Brand Laboratory. They've done many interesting studies on how packaging and marketing contribute to unknowingly overeating; glassware elongation research concluded that the tendency to pour more into a short glass leads to a 32-43% increase in consumption.

The studies, conducted by researchers at the Food and Brand Lab went to a Health and Fitness Camp for teenagers and gave campers either short wide glasses as they entered the cafeteria line or tall, slender glasses. Both glasses held 22 ounces. As the campers exited the line, they were stopped and asked how much soda, milk, or juice they had taken and their glass was measured. People given short wide glasses poured 76% more than those who had randomly been given tall slender glasses. They believed, however, that they had poured less. The same was true when the study was repeated with adults.

This bias is caused by a visual illusion known as the vertical-horizontal illusion. ... "When pouring into glasses, we tend to focus on the height of the beverage and basically ignore the width," said Brian Wansink Ph.D.

If it's Coke/Pepsi, lemonade or other sugary beverage, the risk is gaining weight. With beer and wine and New Year's Eve champagne, the risk is more dangerous and antisocial. Hosting a party? Use champagne flutes. (Though if you're out with Steve, you may prefer the squat steins.) ;-) Me, I'm fine with a water glass of any size.

Find out more...

More food psychology tips (they'll even mail you a free fridge magnet with tipsheet) and unintentional overeating research at the Cornell web site.

Link: Bottoms Up! The Influence of Elongation on Pouring and Consumption Volume, Wansink and Van Ittersum, 2003, Journal of Consumer Research free PDF
Link: full text of consumer article