This reaction to repeated exposure to food is called habituation, and it's well known to occur while eating. A "tenth bite of chocolate, for example, is desired less than the first bite," the study authors note.

(See "First Chocoholics in U.S. Found in New Mexico?")

But the new research is the first to show that habituation can occur solely via the power of the mind.

"A lot of people who diet try to avoid thinking about stimuli they crave. This research suggests that may not be the best strategy," said study leader Carey Morewedge, a psychologist at Carnegie Mellon University in Pittsburgh.

"If you just think about the food itself—how