There are standard serving sizes for wine and beer (typically 5 ounces for wine and 12 ounces for beer), but just like recommended portion sizes for food don’t necessarily correspond to the amount we eat, we don’t typically have just a single portion of an alcoholic drink. At a restaurant, whether or not you choose to splurge on a second glass of wine may be influenced by the size of the glass you're served it in, a new study suggests. 

A new study in BMC Public Health, spotted by Science of Us, examined wine ordering habits at one English restaurant over the course of four months. Every two weeks, the restaurant changed its wine glasses, serving the same amount of wine (6 ounces) in either a smaller-than-average (8.5 ounces), average (10 ounces), or large glass (12.5 ounces). 

While it wasn’t clear how smaller glasses affected people’s ordering behavior, large glasses definitely influenced the restaurant’s sales. When wine was served in larger glasses, the restaurant sold 9 percent more each day. Something about drinking out of a big glass made people want to order more. 

A big glass makes a regular amount of wine look slightly smaller. As the researchers point out, this may make people feel less satisfied with their single serving, since they could perceive it as being a smaller portion (as their previous work has shown). They may also drink it faster, leading them to order more throughout the course of their stay at the bar. 

But keep in mind that this study only examined one bar for less than half a year, and it’s always possible that people ordering wine at a different bar in a different place might behave differently. Perhaps customers elsewhere would feel ripped off by their perceived tiny portion, and not order another for fear of wasting their money on overpriced wine. In fact, maybe it’s just best to drink your wine blindfolded. Whatever the true effect, the restaurant in the study has permanently switched to the larger glasses. 

[h/t Science of Us]