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It’s becoming clearer that unlocking the complexities of human behavior, especially food motivation, can impact good and poor health. In a profound paradox, who would ever have thought the McDonald’s Happy Meal model could be so instructive?

Researchers led by Martin Reimann, PhD, of the University of Arizona’s Eller College of Management, set out to see whether people would opt to eat less if food were paired with a nonedible bonus—comparable to a nonfood toy in a Happy Meal.

In a series of seven experiments, the research team demonstrated repeatedly that kids and adults would often decline larger portions when given the choice of a smaller portion paired with a very modest nonfood bonus. In fact, just the possibility of getting a “prize” incentivized people to forgo larger portions.

According to a University of Arizona press release, in one experiment 78% of sixth-graders passed up a full sandwich when given the option to take a half sandwich plus a set of dollar-store earbuds. In another, university staff and students were significantly more likely to choose half-portion lunches when they were paired with the chance of winning a $100 gift card or 10,000 frequent-flier miles.

Results gathered from multiple studies showed not only that nonfood incentives reliably encourage people to choose smaller portions, but also that

  • when rewards are not guaranteed, knowing the odds of winning can be less motivating than simply knowing that winning is a possibility, even when the odds are relatively good;
  • the same reward can motivate time and again (in one experiment the chance of winning a gift card or frequent-flier miles worked for 3 days straight);
  • participants choosing smaller portions don’t compensate for missed calories by eating more the next day; and
  • smaller portions paired with bonuses/potential prizes activate the same reward, desire and motivation areas of the brain that “light up” for full portions, as shown by fMRI testing.

While there were some notable anomalies, the takeaway is clear: Nonfood rewards—both guaranteed and uncertain—make people significantly more likely to choose less food.

Says Reimann, assistant professor of marketing at Eller, that fact swings open a compelling door of possibilities for personal and social change. “Overconsumption makes people unhealthy and unhappy,” he says in the news release. “Yet trying to regulate consumption by law threatens people’s sense of freedom to choose. If non-food rewards, even small and uncertain ones, can be just as engaging at a neurochemical level, then restaurants can potentially motivate healthier choices without jeopardizing sales, and consumers have more paths to avoid overeating. In general, these studies open up a whole new matrix of ways we might begin to change unhealthy food cultures and behaviors.”

The article appeared in the June 2015 issue of the Journal of Experimental Psychology: Applied.