Food economist Brenna Ellison, Ph.D., analyzed lunch receipts from a restaurant in Stillwater, Okla., over a 19-week period in 2010. The restaurant was divided into three different sections: the control group with guests receiving menus with only the item and price, a section that gave guests calorie counts for each entrée, and a third section that had both calorie counts and a traffic light symbol that indicated caloric ranges. Diners had a choice of 51 different options that had anywhere from 50 to 1,540 calories.
During this 19-week period, Ellison kept tabs on patrons by occasionally busing tables, or also sending in diners she knew to make sure that they were given the "correct" menu. Each day, Ellison would pick up receipts and chat with servers, who "said that people talked about the traffic lights a lot. And we did find that larger tables which received the traffic light menus did order fewer calories, on average, which suggests there was some peer pressure to order lower-calorie items," Ellison said in a statement.
The study found that, despite previous research that traffic light symbols can influence food choices and lower caloric intake, peers can have a bigger role than calorie labeling when it comes to deciding what to order.
Ellison found that people were happier when they made similar choices as their dining companions. "We want to fit in with the people we're dining with," she explained in the statement. In theory, this dining peer pressure can work in two ways -- diners can be pressured to eat more high-calorie food, or if they are eating with healthier eaters, perhaps the same diners will order something more low-calorie. Ellison found significant evidence of the latter.
Ellison also found that there is some hope for those that eschew salad. "The most interesting thing we found was that no matter how someone felt about the category originally, even if it was initially a source of unhappiness, such as the items in the salad category, this unhappiness was offset when others had ordered within the same category," Ellison said. "Given this finding, we thought it would almost be better to nudge people toward healthier friends than healthier foods."
In other words, maybe peer pressure is actually a good thing.