Researchers at the University of St. Andrews in the United Kingdom and at the University of Windsor in Canada each found that subjects who were told that a particular food had made them sick years earlier not only believed the made-up events but also stopped craving the food. Researchers already knew that generating false memories can alter a person's beliefs, but these studies are the first to show that the practice can change behavior as well.
"Although it's not ethical to create false memories in people, making an association between eating a fattening food and getting ill may be beneficial," says Elke Geraerts, a psychologist from St. Andrews and lead author on one of the studies. "People may avoid those foods in the future."
It may sound implausible that a mere suggestion could alter recollections or create a new (untrue) memory, but it's not so far-fetched. "False memories are a well-established phenomenon. This is because all memories are re-creations, not recordings," says Douglas Fields, a neurobiologist at the National Institutes of Health not involved in the studies.
In the two studies, participants filled out questionnaires about their food history and preferences. Afterward, the researchers fibbed that they had created computer-generated personal profiles detailing the subjects' experiences with food during childhood. In Geraerts' study, the researchers told participants that, as kids, they disliked Brussels sprouts and liked pizza (most children do). The researchers also told half the subjects that they got sick after eating egg salad.
After the suggestion, one-third of the subjects, who were lied to, retained the untrue egg salad memory. And when presented with sandwich choices one week later, those participants left the egg sandwiches virtually untouched while devouring those made with ham, cheese, tuna, and chicken. Even four months later, the made-up memory remained intact, and the subjects continued to avoid egg salad.
Researchers from the University of Windsor also lied to some study participants, saying that they had become quite ill as children after eating peach yogurt contaminated with E. coli. After planting this bogus belief, the researchers found that participants rated peach yogurt less appealing than other foods and ate about half as much yogurt as those not given the false notion.
Researchers from Duke University found regions in the brain that may explain how false memories could slip by as real ones. Using brain scans, the researchers saw that when participants believed a memory was true, they exhibited more activity in part of the brain that processes feelings about an event. However when subjects thought a false memory was true, they showed less activity in another part of the brain that checks memory for facts.
Although not yet tested for combating obesity, manipulating memories could make people less hungry for fatty foods. The tough part involves getting approval to use the technique for weight loss without letting the subject in on the secret. "Practically speaking, a subject can't sign up for this technique if he wants to stop eating pecan pie," says Elizabeth Loftus, co-author of the U.K. study and a psychologist at the University of Washington who specializes in memory. Despite potential ethical issues, this dieting tool could work, for instance, if parents or guardians sign up their overweight children for a new diet without telling them exactly what it is, suggests Loftus.
