It’s January again, which means the gym is packed with individuals whose New Year’s resolutions are to get back into shape and eat healthier. Luckily, new research may provide a way to help this process along, by stopping those pesky cravings.
A new study by researchers at Carnegie Mellon University, published in the December 10 issue of Science, shows that when you imagine eating a certain food, it reduces your actual consumption of that food. These findings may seem counter-intuitive compared to the idea of food sensitization, which is also called the “whetting effect.” According to this effect, thinking about eating a steak can cause an increase in salivation and the desire to eat it. Similarly, imagining the sight or the smell of a burning cigarette will increase a smoker’s craving to light up.
Prior research has shown close links between the processes of perception and mental imagery, demonstrating how both engage the same neural machinery and can similarly affect emotions, response tendencies, and skilled motor behavior. For example, the thought of a spider crawling across your leg can produce the same increases in perspiration and heart rate that the presence of a real spider would cause.
Along the same lines, the CMU research team hypothesized that thinking about the consumption of a particular food should habituate you to that food. This led to the finding that simply imagining the consumption of a food decreases one’s appetite for it.
The researchers attributed this effect to the physiological phenomenon of habituation. “In real life, what we find is that people tend to show a diminished physiological and psychological response to stimulus after we’ve had repeated exposures,” said lead author Carey Morewedge in a Science podcast. Morewedge is an assistant professor of Social and Decision Sciences at CMU. “For example, the tenth bite of that pancake you eat might taste worse, and be less appealing than the first. So although imagining and thinking about pancakes extensively might lead you to crave them a little bit, we find that if you actually imagine the process of eating, and chewing, and swallowing the pancake, […] the imagined consumption will have a similar effect […].”
The research team consisted of two other CMU researchers: Young Eun Huh, a Tepper School of Business PhD candidate, and Joachim Vosgerau, an assistant professor of marketing. Over a period of three years, the team ran a series of five experiments that tested whether mentally visualizing the consumption of a food reduces its subsequent actual consumption.
The first four experiments required participants to imagine a set of 33 repetitive tasks, followed by freely eating from a bowl of a particular type of food. The control group was asked to imagine inserting 33 quarters into a laundry machine, a motion similar to eating. Participants who imagined eating 30 M&M’S or 30 cubes of cheddar cheese actually ate significantly fewer morsels of the imagined food than did participants in the other two groups.
The last experiment measured whether this reduced consumption was due to diminished wanting or liking for the food. This involved a reinforcement game, in which participants saw a picture of a cube of cheese and a picture of a stop sign. They could click on the picture of the cheese cube to earn more cheese at the end of the study, or click on the stop sign to quit.
“We found that people basically click less often when they imagine eating 30 cubes of cheese than when they imagine consuming three. So in other words, they worked harder for cheese when they imagined consuming fewer cubes of cheese beforehand,” said Morewedge. These results suggest that visualizing the act of eating cheese diminished their appetite for it, instead of how much they liked it.
The researchers also observed that the results were food-specific. People who imagined eating chocolate didn’t lose their appetite for cheese. Merely thinking about the food repeatedly, or imagining consuming a different food, did not affect the amount of food consumed.
It is far too early, however, to tell what the implications for this study could be in other areas of research, such as addictive behaviors. “We don’t know the answer to that yet, […] we find people tend to habituate to a variety of substances — everything from the brightness of a light, to their income. So we would expect that this kind of result that we’ve obtained in the domain of eating should extend to these other kinds of domains, such as drinking or smoking, or other kinds of similar processes. […] This is certainly something we are interested in following up, and we’ve started to look at,” said Morewedge, who hopes to look next at habituation and cigarette use.
But the results so far may offer some hope of eventually diverting people to healthier diets. According to Morewedge, “In terms of therapeutic implications of this research, […] a lot of peopletend to try to avoid eating unhealthy foods by suppressing their thoughts for them. That tends to be a flawed strategy, because it suggests that you are going to stay at the initial stage of craving, whereas our research suggests […] they might actually be better off imagining consuming the foods that they crave, rather than trying to repress thoughts of them.”
