It’s no secret that adults are on their best behavior when they know someone is watching. They are also more likely to be generous when they’re being observed, particularly when the contents of their generosity are made public. But less has been known about how these tendencies develop in younger people, and at what age they may appear.

A new study set out to look at how generosity works in very young kids – five-year-olds. Would they be more generous with their belongings in the presence of the recipient? And, like adults, would they be more likely to give when the contents of their generosity were made known?

Children likely use much more sophisticated prosocial strategies than we previously assumed.

To test these questions, the authors gave five-year-olds four stickers and told them they could share any number of them with another child who was either present or hidden from the child’s view. The children were much more generous when the other child was in plain sight than when he or she was hidden.

The experiment also looked at what happened when the number of stickers offered was made "public," so to speak. The children deposited the stickers they chose to give away into either an opaque or a transparent container. As you might guess, the kids were much more likely to give away their stickers when the recipient could see what they were getting. And the most generous kids were the ones who were both in the presence of the recipient and when the recipient could see what they were getting.

The results match adult behavior very closely, which is somewhat surprising, given the young age of the kids. "Although the frequency with which children acted antisocially is striking, the conditions under which they chose to act generously are even more interesting and suggest that children likely use much more sophisticated prosocial strategies than we previously assumed," said author Kristin Lyn Leimgruber in a news release.

The authors point out that the concept of "reputation" (or more specifically, "self-promotional reputation enhancement") doesn’t usually develop until about eight years of age. So it’s intriguing that children so young would behave as if they had developed that concept already. It’s possible that the children thought the experiment was a game or competition, which could have made them more likely to "hoard" the stickers than they normally would; this possibility might explain why previous evidence hadn’t found the same level of "ungenerosity" as the current study.

More research will be needed to determine how complex concepts like generosity evolve in young children. You can always test the theory in your own kids, by telling them that you’ll know whether they’re sharing nicely with their friends or not.

The study was carried out by researchers at Yale University and published in the journal, PLoS ONE.