“Thinking of a food—how it tastes, smells or looks—does increase our appetite. But performing the mental imagery of actually eating that food decreases our desire for it,” according to Carey Morewedge, assistant professor of social and decision sciences at Carnegie Mellon University, Pittsburgh. Morewedge, lead investigator for a recent food-imaging study, was quoted in HealthDay News.
The study set out to evaluate whether imaging the consumption of a specific food might lead to “habituation,” a reduced response to a stimulus from repeated exposure, rather than to “sensitization,” which involves a heightened response from an initial exposure to a stimulus.
Investigators conducted five experiments with 51 subjects, who were divided into a control group and two other groups. The control group imagined inserting 33 quarters into a laundry machine. Another group imagined inserting 30 quarters into a laundry machine and then imagined eating three M&M’s®, while a third group imagined inserting three quarters into a laundry machine and then imagined eating 30 M&M’s. Next, all subjects were presented with a bowl of M&M’s and invited to eat as many as they wished. The group that had imagined eating 30 M&M’s actually ate significantly fewer candies than the other two groups. When the experiment was then adjusted in various ways, the results were similar.
Morewedge noted that the important implication of this study is that imagery, among certain individuals, can produce habituation to a specific stimulus. Study limitations included the small sample size; the possibility that study subjects might not reflect the population at large; and the fact that researchers did not measure how long the “habituation” effect lasted.
The study was published in Science (2010; 330 , 1530–33).