Lunch trays with images of good foods proved powerfully persuasive, University of Minnesota research has found.
Want kids to eat their vegetables? Try pictures, not words.
Using a Richfield elementary school as their lab, researchers from the University of Minnesota placed images of green beans and carrots on the cafeteria food trays for one day. More kids took vegetables, and more kids ate them, according to a study published online Wednesday.
The images sent the students a subtle signal that they should be putting veggies on their trays and -- more importantly -- that their friends would be doing the same, said Traci Mann, a psychologist and one of five faculty members leading the study.
"Kids -- they don't want to do what they're told. Tell them to eat their vegetables? Forget about it," Mann said. "What kids want to do is ... what their friends are doing or what they think their friends are doing."
The results exceeded the researchers' expectations and suggested that a simple, low-cost strategy could be used by schools to improve students' nutrition and curb the rising rate of obesity among children in the United States.
In psychological terms, the pictures might have created a new social "norm" for the students. Of course, the research showed that students not only opted to take vegetables. They actually ate them.
To test the strategy, researchers first monitored how many students chose vegetables for lunch on a typical day. They also weighed how many green beans or carrots were thrown away or left behind on the cafeteria tables or floor. Then they repeated the exercise a few weeks later, on a day when the students' trays had pictures of beans and carrots on them.
On the typical day, 42 students took green beans. Each student who took beans ate about 19 grams of them. On the study day, 96 students took beans; each student who took them ate about 19.1 grams.
On the typical day, 77 students took carrots, and each ate about 31 grams. On the study day, 238 students took carrots; each student who took them ate about 27.1 grams.
This means that the students who always took carrots probably ate their usual amount, but that the students who took them for the first time ate less.
Either way, students need to be eating more carrots to meet nutrition guidelines, Mann said.
But the research at least showed that more children tried carrots, and that is an important first step, she said.
"The more you have a bite or two of a carrot," she said, "the more you're going to slowly start to get used to the taste."
The U team, which includes professors in marketing, applied economics and food science, tested several different ways to "nudge" students at the Richfield STEM school (a science magnet school) to eat more veggies. In one instance, they moved vegetables to the front of the food line.
In another, they had the lunch lady offer verbal encouragement to each student to try vegetables.
Results of those efforts haven't been published yet, but Mann said she had been most excited about the potential of putting images on trays because it was so subtle.
The idea came from a separate study in which researchers tested if shoppers would buy more fruits and vegetables if their grocery carts included special sections for produce. Mann said she couldn't find any prior studies using the approach with school lunch trays.
"I was much more hopeful for this kind of nudge," she said, "when the students did not feel like they were being pushed into doing something."
Jeremy Olson • 612-673-7744