Extrait
Chapter One
The Mindless Margin
Did you ever eat the last piece of crusty, dried-out chocolate cake even though it tasted like chocolate-scented cardboard? Ever finish eating a bag of French fries even though they were cold, limp, and soggy? It hurts to answer questions like these.
Why do we overeat food that doesn’t even taste good?
We overeat because there are signals and cues around us that tell us to eat. It’s simply not in our nature to pause after every bite and contemplate whether we’re full. As we eat, we unknowingly–mindlessly–look for signals or cues that we’ve had enough. For instance, if there’s nothing remaining on the table, that’s a cue that it’s time to stop. If everyone else has left the table, turned off the lights, and we’re sitting alone in the dark, that’s another cue. For many of us, as long as there are still a few milk-soaked Fruit Loops left in the bottom of the cereal bowl, there is still work to be done. It doesn’t matter if we’re full, and it doesn’t matter if we don’t even really like Fruit Loops. We eat as if it is our mission to finish them.
Stale Popcorn and Frail Willpower
Take movie popcorn, for instance. There is no “right” amount of popcorn to eat during a movie. There are no rules of thumb or FDA guidelines. People eat however much they want depending on how hungry they are and how good it tastes. At least that’s what they say.
My graduate students and I think different. We think that the cues around us–like the size of a popcorn bucket–can provide subtle but powerful suggestions about how much one should eat. These cues can short-circuit a person’s hunger and taste signals, leading them to eat even if they’re not hungry and even if the food doesn’t taste very good.
If you were living in Chicago a few years back, you might have been our guest at a suburban theater matinee. If you lined up to see the 1:05 p.m. Saturday showing of Mel Gibson’s new action movie, Payback, you would have had a surprise waiting for you: a free bucket of popcorn.
Every person who bought a ticket–even though many of them had just eaten lunch–was given a soft drink and either a medium-size bucket of popcorn or a large-size, bigger-than-your-head bucket. They were told that the popcorn and soft drinks were free and that we hoped they would be willing to answer a few concession stand-related questions after the movie.
There was only one catch. This wasn’t fresh popcorn. Unknown to the moviegoers and even to my graduate students, this popcorn had been popped five days earlier and stored in sterile conditions until it was stale enough to squeak when it was eaten.
To make sure it was kept separate from the rest of the theater popcorn, it was transported to the theater in bright yellow garbage bags–the color yellow that screams “Biohazard.” The popcorn was safe to eat, but it was stale enough one moviegoer said it was like eating Styrofoam packing peanuts. Two others, forgetting they had been given it for free, asked for their money back. During the movie, people would eat a couple bites, put the bucket down, pick it up again a few minutes later and have a couple more bites, put it back down, and continue. It might not have been good enough to eat all at once, but they couldn’t leave it alone.
Both popcorn containers–medium and large–had been selected to be big enough that nobody could finish all the popcorn. And each person was given his or her own individual bucket so there would be no sharing.
As soon as the movie ended and the credits began to roll, we asked everyone to take their popcorn with them. We gave them a half-page survey (on bright biohazard-yellow paper) that asked whether they agreed to statements like “I ate too much popcorn,” by circling a number from 1 (strongly disagree) to 9 (strongly agree). As they did this, we weighed their remaining popcorn.
When the people who had been given the large buckets handed their leftover popcorn to us, we said, “Some people tonight were given medi
