beer in mug(Photo: Courtesy of Men's Health)

Researchers at the University of Bristol gave 160 people a drink--either a half or full beer or non-alcoholic beverage--then sat them down in front of a nature documentary and told them to sip at their own pace. (Right. Because everyone likes to get smashed watching White Wilderness.)

It took about 11 minutes to finish the full lager from a straight glass, but only seven minutes from the curved one. Later, subjects were shown 60 pictures of beers ranging between empty and filled glasses and judged whether each was more or less half full.

Turns out, it's not as easy as it looks. The people who couldn't quite spot the halfway point in the curved glasses were also the ones who drank quicker from them, says lead researcher Angela Attwood, Ph.D., a teaching associate in experimental psychology at Bristol. Those who took longer to finish their beers had taken more time in between sips, which Attwood attributes to their easier time monitoring how much they had already drank.

Want to slow your sips? Just ask for a different glass or opt for a beer bottle, which is straight at the middle and therefore less ambiguous. (Want more indispensable drink and food tips delivered to your inbox?