When it comes to getting preschoolers to share their toys, a new study finds that giving them a choice to share, rather than a reward, helps them share more with others in the future.

In new evidence announced Monday, investigators from Cornell University in the U.S. conducted a series of experiments on 72 preschool-aged children, from three to five years old.



Findings suggest that sharing when given a difficult choice leads children to see themselves in a new, more beneficent light, researchers said.

"Perceiving themselves as people who like to share makes them more likely to act in a prosocial manner in the future," they said.



Previous research has shown that this idea -- as described by the over-justification effect -- explains why rewarding children for sharing can backfire, the researchers said. Children come to perceive themselves as people who don't like to share since they had to be rewarded for doing so.

Because they don't view themselves as "sharers," they are less likely to share in the future.



"Making difficult choices allows children to infer something important about themselves," the researchers said. "In making choices that aren't necessarily easy, children might be able to infer their own prosociality."



In one experiment, researchers Nadia Chernyak and Tamar Kushnir introduced children to Doggie, a puppet who was feeling sad. Some of the children were given a difficult choice: share a precious sticker with Doggie, or keep it for themselves. Other children were given an easier choice between sharing and putting the sticker away, while children in a third group were required by the researchers to share.



Later on, all the children were introduced to Ellie, another sad puppet. They were given the option of how many stickers to share. The kids who'd earlier made the choice to help Doggie shared more stickers with Ellie. The children who were initially confronted with an easy choice or who were required to give their sticker to Doggie, however, shared fewer stickers with Ellie.



"You might imagine that making difficult, costly choices is taxing for young children or even that once children share, they don't feel the need to do so again," Chernyak said. "But this wasn't the case: Once children made a difficult decision to give up something for someone else, they were more generous, not less, later on."



"Allowing children to make difficult choices may influence their sharing behavior by teaching them greater lessons about their abilities, preferences, and intentions towards others."



Findings were published online last week in the journal Psychological Science.