If you want to eat less of something, first imagine eating it

A fascinating report just published in the journal Science further illustrates the biological power of imagery, in this case the ability to decrease the desire to eat a particular food by first  repeatedly imagining that you have eaten it. The authors state:

"People believe that thinking about a desirable food or drug sensitizes one to it, increasing their hedonic response to the stimulus. Indeed, picturing oneself eating a delicious steak elicits an increase in salivation and the desire to eat it, and imagining the sight or smell of a burning cigarette increases smokers’ craving."

They note, however, that this...

"...seems to contradict decades of research examining the overlap between direct perception and mental imagery."

Furthermore...

"Perception and mental imagery differ in their source (the senses and memory, respectively), but there is great overlap within modalities. Both engage similar neural machinery and similarly affect emotions, response tendencies, and skilled motor behavior. The thought of a spider crawling across one’s leg can produce the same increases in perspiration and heart rate that would result from a spider’s actual presence. Even the mere simulation of a motor skill can result in an improvement in its subsequent performance."

Therefore...

"Because perception and mental imagery tend to elicit similar responses, one would expect that thinking about the consumption of a stimulus should habituate one to it...Habituation denotes the decreased physiological and behavioral responses induced by extended or repeated exposure to a stimulus. A 10th bite of chocolate, for example, is desired less than the first bite. People habituate to a wide range of stimuli, from the brightness of a light to their income."

So why would exposure to a stimulus sometimes elicit sensitization (with an increase in desire) and sometimes habituation? The authors state:

"...having participants vividly imagine a single exposure to a stimulus...is more analogous to the initial exposure...that whets the appetite and induces sensitization than to the repeated experience of a stimulus necessary to engender habituation."

By contrast...

"We suggest that mentally simulating an experience that is more analogous to repeated exposure (such as repeatedly imagining the consumption of units of a food) might engender habituation to the stimulus."

They conducted five different experiments designed to test whether the repeated mental simulation by only imagining eating a food could engender habituation and reduce the subsequent consumption of that food. What did their data show?

"We demonstrated that habituation to a food item can occur even when its consumption is merely imagined. Five experiments showed that people who repeatedly imagined eating a food (such as cheese) many times subsequently consumed less of the imagined food than did people who repeatedly imagined eating that food fewer times, imagined eating a different food (such as candy), or did not imagine eating a food. They did so because they desired to eat it less, not because they considered it less palatable. These results suggest that mental representation alone can engender habituation to a stimulus."

An accompanying editorial in the same journal notes:

"The findings should have practical applications, says Frances McSweeney, a psychologist at Washington State University, Pullman. One possible strategy for weight watchers might be to spend a few minutes before each meal imagining eating exactly the foods they're about to consume, she says. This type of mental exercise might also help counter sudden cravings between meal times, adds Suzanne Higgs, a psychologist at the University of Birmingham in the United Kingdom...Ironically, Morewedge says, many diets urge people to suppress thoughts of the foods they crave."