The Bottomless Soup Bowl Experiment
Featured in the Annals of Improbable Research and winning an Ignoble Prize, Brian Wansink’s experiment “first makes people laugh, and then makes them think.” He wondered how we determine when we’ve eaten enough food.  Do we stop eating at the physical feeling of fullness or do we use external cues (that everyone else has already finished, or that our plate is empty)?  Wansink presented students with a bowl of soup to eat while they chatted with other participants.  The catch was that half of the the soup eaters could never actually empty their bowls.  By using gravity, sterile plastic tubing pumped tomato soup from a 6-quart container into the bowl.  Thus, half the bowls slowly refilled as the participants sipped their soup.
First of all, no one noticed that they never made progress on the soup. Â And secondly, it turns out that we eat more with our eyes than our stomachs. Â Wansink discovered that people ate a lot more than one bowl’s worth when they did not make visible progress. Â People eating from the regular bowls ate about 9 ounces of the soup, while the people with the never-ending bowls ate about 15 ounces. Â Some even ate more than a quart! Â Nonetheless, the bottomless bowl participants guessed they had eaten only about half a bowl’s worth.
It’s funny how our eyes compel us to eat more than our stomachs.  Wansink, though, believes that this phenomenon is primarily an American one.  A survey found that the French report they stop eating based on fullness far more than frequently than Americans claim.  This could be one of the reasons for the “French Paradox.” The French can stay healthy while they eat cheeses, wine, and fat laden pastries because they actually stop when they are full.  Americans will eat until the baguette is gone and drink until the wine glass is empty (unless some clever experimenter rigs their stemware…).  Interestingly, the survey also showed that the heavier a person is – American or French – the more they rely on external cues to decide when they’ve had enough.  Clearly, the lesson to learn here is that we don’t need restrictive diets.  Instead, we can try to control our external cues by using smaller bowls.  It might also help to make an effort to conciously focus on our internal feelings of fulness to tell when to stop.
For more tips on altering the impact of environmental cues have on how much you eat, see this post on re-engineering your “tablescape”.
February 20, 2009
Tags: education, food, food safety, obesity, trvia Posted in: Fun Food Facts, Health
6 Responses
This is a really interesting experiment! I bought “Mindless Eating” on your recommendation!
I’ve read it twice-over now, and it was just as fascinating and fun the second time. (It short-ish and not full of technical jargon, so that helps.) Anyways, you’ll have to write back what you thought of the book. I think you’ll enjoy it.
This experiment reminds me of the saying, “My eyes were bigger than my stomach.” I hear that often. I have used that phrase a time for two.
The experiment was done as a group of people all sitting around eating. If it was just one person, all by themselves, wouldn’t you think the person would notice that their bowl of soup was never getting smaller?
Excellent point, Bridgette. You’re right that having the participants eat in groups is a confound, especially in light of other studies (featured in Mindless Eating) that show people tend to eat more when they eat with more people. However, it remains that the people with the endless bowls still ate a lot more than the ones with the normal bowls, who would have been affected by the same tendency to eat more in a group. Can you think of a way of getting around group thing while making it so they couldn’t tell the bowl was refilling? You’d have to distract a little still, but not so much that they lost track of how much they ate. It sounds like a tight line to walk. Anyway, I’d love to hear your ideas.
I read about this some time ago so the details are a little fuzzy, but someone did a similar experiment with candy and the size of spoon. They set the same bowl out with the same candy on different days, but switched up the spoon size and noted how much candy people took, obviously it was more on the days the spoon was larger.
Another experiment found when there is a variety of something even if the only difference is color, like in M&M’s, people ate more of the multi variety kind than if offered something in all one color or even with just one color missing.
The mind does some funny things to our bellies.
Treadmill Necessities » college graduette - January 27, 2012
[...] sat people in front a bowl of tomato soup that could never become empty–found that people didn’t notice that they weren’t making a dent in their dinner and that they ate 15 ounces of soup (as opposed to nine for people with bowls that emptied at a [...]
Leave a Reply