If they know it's good for them, will they eat it?

But new research by University of Chicago Booth School of Business Professor Ayelet Fishbach pinpoints one of the problems: Children reject nourishing fare simply because they know it is good for them, and once they know that, they assume the food won't taste good.

In "If it's Useful and You Know it, Do You Eat? Preschoolers Refrain from Instrumental Food," to be published in the October issue of the Journal of Consumer Research, Fishbach and Michal Maimaran of the Kellogg School of Management at Northwestern University demonstrate that telling children that food will help them achieve a goal, such as growing strong or learning to read, decreases preschooler's interest in eating the food.

"The preschoolers seem to think that food can't serve two purposes, that it can't be something that makes them healthier and something that is delicious to eat at the same time," Fishbach notes. "So telling them that the carrots will make them grow tall (or make them smarter) actually makes them not want to eat the carrots. If you want them to eat the carrots, you should just give the kids the carrots and either mention that they are tasty or just say nothing."

The researchers completed five experiments with 270 preschoolers in which an experimenter read picture stories about a girl who had some food for a snack. In some stories, she was interested in the food because it was good for her, in others she was interested because the food was tasty and in some stories, there was no reason mentioned in the story for why she was interested in the food. In each case, children ate more of a food when no reason for eating it was mentioned or when it was presented yummy, than they did when they thought the food were good for them.

"Our study focused on very young children, and we should keep in mind that older children might rely less on taste when making food decisions due to higher self-control," Fishbach adds. "On the other hand, we all know teenagers who only eat six foods, so it could turn out that their thinking is similar to their younger counterparts."