Chances are you’ll pour yourself 12% more wine in a wide glass than you would in a narrow one, and 9% more white wine than red in a clear glass, says a new study conducted on drinking-age college students at Iowa State University. “People have trouble assessing volume,” says ISU’s Laura Smarandescu, Ph.D. “They tend to focus more on the vertical than the horizontal measures. That’s why they also tend to drink less from a narrow glass—they think they’re drinking more.” And pouring white wine into a clear glass makes it hard to gauge depth, leading to heavy-handed pouring. Hear that, pinot grigio? We told you it wasn’t our fault.