Before dipping your hand into that bowl of M&Ms at the holiday party, think about what you're about to do. A lot. A new study finds that people who imagine themselves consuming many pieces of candy eat less of the real thing when given the chance. The finding, say experts, could lead to the development of better weight-loss strategies. Picturing a delicious food—like a juicy steak or an ice cream sundae—generally whets the appetite. But what about visualizing yourself eating the entire sundae, spoonful by spoonful? There's reason to think that might have the opposite effect, says Carey Morewedge, an experimental psychologist at Carnegie Mellon University in Pittsburgh, Pennsylvania. Researchers have found that repeated exposure to a particular food—as in taking bite after bite of it—decreases the desire to consume more. This process, which psychologists call habituation, dampens appetite independently of physiological signals like rising blood sugar levels or an expanding stomach. But no one had looked to see whether merely imagining eating has the same effect.
To investigate, Morewedge and colleagues Young Eun Huh and Joachim Vosgerau fed M&Ms and cheese cubes to 51 undergraduate students. In one experiment, the participants first imagined performing 33 repetitive motions: Half of them imagined eating 30 M&Ms and inserting three quarters into the slot of a laundry machine. The other half envisioned eating three M&Ms and inserting 30 quarters. Then everyone was allowed to eat their fill from a bowl of M&Ms. Those who'd envisioned eating more candy ate about three M&Ms on average (or about 2.2 grams), whereas the others ate about five M&Ms (or about 4.2 grams), the researchers report in the 10 December issue of Science.