The shape of the glass can fool folks as to how much is being poured into it. In a survey of teens, adults, and even bar tenders, folks tended to underestimate the amount of fluid in a short, fat glass, vs. a tall, skinny glass.
Three separate studies yielded similar conclusions, regardless of the beverage. Teenagers concerned about their health poured less fruit juice when they were given tall, slender glasses than when they were given short, squat tumblers, although they believed the opposite was true.
What is at work here is how we measure quantities in the mind’s eye, Wansink says. We tend to rely more on a vertical than a horizontal measurement, so it appears at first that a taller glass holds more than a shorter one, even if the short glass is wider. “Elongation,” to use the researchers’ word, is the trickster here.
(via GeekPress)