"Can I have dessert?" "Did you eat all of your vegetables?" This is a common dinner conversation in our house and probably for most other families. Whether we call it bribery or not, parents bribe their kids in small ways every day. Eating more vegetables in exchange for a little dessert. Cleaning a bedroom in exchange for more time on a computer or video game. Good behavior to play with friends.
New research asks the question whether bribing kids to eat more fruits and vegetables can change their eating habits – even after the bribe goes away. Of course for adults, we don't call them bribes. We call them incentives. And incentives are all the rage. The worry is that by creating a financial incentive for a health behavior, you crowd out intrinsic desire. In other words, you lose that internal drive to improve your eating habits or your health. The drive instead comes from a financial incentive. So when the incentive ends, so does the drive to change behavior.
In the new study, 40 elementary schools in Utah implemented an 'incentive' program – kids could earn 25 cent coins (vouchers) every time they had a serving of fruits and vegetables at lunch. The coins or vouchers could only be used at the school store, school carnival, or book fair to make sure that they weren't used to buy junk food. In some schools, the incentives lasted 3 weeks. In other schools, it lasted 5 weeks.
Before the incentive program started, about a one-third of kids had a serving of fruits or vegetables at lunch each day. Once the incentive started, that number shot up to almost 80 percent. The question the researchers asked was, did this newfound hunger for fruits and vegetables persist once the incentive ended? The numbers fell a lot after the incentives ended but, two months later, fruit and vegetable consumption was still higher than before the incentive – about ten percentage points higher in the 3-week incentive schools and about 16 percentage points higher in the 5-week incentive schools.
So what can we take away from this short experiment? Financial incentives can have a large effect on behavior but once they go away – a lot of the effect disappears. But for some people, the positive behavior does persist. And the worry you will make things worse by removing internal drive for behavior change – at least in this experiment with kids – didn't seem to happen.
Incentives are being deployed in all sorts of settings today. Employees are enrolled in wellness programs. Doctors are paid more if they achieve certain goals. Incentives aren't a complete solution, but they can have a role. What other intervention in schools has increased fruit and vegetable consumption so quickly? Even the 10-16 percent change two months later is impressive. We need longer-term follow-up to see whether these numbers last.
So parents – don't feel guilty about all of those bribes. We all know they work – and now we have less to worry about.
Editor's Note: Cross-posted on the Health Policy$ense blog of the Leonard Davis Institute of Health Economics of the University of Pennsylvania.
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