It sounds as a study soon to pop up at Freakonomics, and I know for sure some people will be offended by the idea, but researchers from Brigham Young University and Cornell observed three schools adjust to new school lunch standards that require a serving of fruits or vegetables on every student’s tray – whether the child intends to eat it or not. As they report in the December issue of Public Health Nutrition, students discarded 70 percent of the extra fruits and vegetables. “We saw a minor increase in kids eating the items, but there are other ways to achieve the same goal that are much, much cheaper,” said BYU economics professor Joe Price.

Strange as it sounds, directly paying students to eat a fruit or vegetable is less expensive and gets better results.

Also from the press release:

With Cornell’s David Just, Price conducted a second study to measure the effect of small rewards in the lunchroom. The week-long experiments took on different twists in the 15 different schools – some could earn a nickel, others a quarter, and others a raffle ticket for a larger prize. But the results were generally the same. As the scholars report in The Journal of Human Resources, offering small rewards increased the fruit and vegetable consumption by 80 percent. And the amount of wasted food declined by 33 percent.

Which begs the question: Is benevolent bribery a better way?

“Parents are often misguided about incentives,” Price said. “We feel a sense of dirtiness about a bribe. But rewards can be really powerful if the activity creates a new skill or changes preferences.”

The case against using bribes in parenting is perhaps best articulated in Alfie Kohn’s 1999 book “Punished by Rewards.” In many scenarios, the use of rewards can crush internal motivation. With healthy eating, for example, some fear that prizes will prevent children from developing their own motivation to eat things that are good for them. Another danger, known as a boomerang effect, is the possibility that some children would eat less fruits and vegetables when the rewards disappeared.

That’s why Price and Just measured fruit and vegetable consumption before and after the week-long experiments. When the week of prizes ended, students went back to the same level of fruit and vegetable consumption as before – no lasting improvement, but no boomerang effect either.

Now the researchers are studying whether extending the experiments over three to five weeks might yield lasting change. So far things look promising.

“I don’t think we should give incentives such a bad rap,” Price said. “They should be considered part of a set of tools we can use.”

There are other ways to improve eating vegetables at school, offering enough choice e.g. When given a variety of healthy choices, children choose a more balanced and nutrient-rich meal.

From the press release from another research:

For this recent study, 100 children aged 7 to 10 years old were invited to the laboratory to select and serve themselves a meal from a small buffet of fake foods (The Fake Food Buffet*). The foods on the “buffet” included chicken strips and pasta, along with the vegetable choices of cooked carrots and beans. Children were randomly assigned to the experimental conditions: they could either serve one vegetable with the meal or they were offered both vegetables.

The children in the group that were offered two vegetables instead of only one served themselves significantly more vegetables. Interestingly, however, they did not serve themselves a meal with higher calorie content. This means that the children offered two vegetables had a higher proportion of energy from vegetables, composing a more nutrient-dense meal. Even children that reported not liking these vegetables served themselves more veggies if they were offered two types rather than one.

So why did children choose more vegetables when offered two instead of only one? Researchers explain that this occurs due to a ‘consumption norm’. This theory suggests that if children are presented with several different foods to choose and serve from, they will serve themselves at least a taste of all of the dishes. Thus, when children are given the choice of more varieties of healthy foods, in the end, they serve themselves a more nutrient-rich meal.

Researchers conclude from this experiment that offering a variety of vegetables to children might be a simple and effective strategy to nudge them to eat more vegetables and healthier meals, not just at home, but also in school cafeterias.

Photo credit: Mark Philbrick/BYU

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