Nobody likes a freeloader. That's something most grownups know, but where does this sense of fairness come from? A study by researchers at Yale University this year shows that even children as young as four will recognize freeloading and get angry and, if they can, punish the freeloaders.

Yarrow Dunham is an assistant professor of psychology at Yale University and senior author of the study. His team investigated how children from the ages of four to 10 feel about freeloaders to try and answer the question of where this sense of fairness comes from. Is it innate, like an instinct — or do we learn it?

"The big question that we're interested in here is why are we as a species so uniquely cooperative. The ability for us to come together and coordinate our activities — even in large groups — is the foundation of our large societies and our rapid technological progress," Dunham told Quirks & Quarks.

"If you think about paying taxes or a neighborhood watch or communal agriculture, we might not get a benefit until way down the road. And that creates incentives to freeload or for what psychologists usually call a 'free-ride': to not pay the costs, but hope to reap the benefits."

Testing children's sense of fairness

Dunham and his team created scenarios they'd tell the children about, which involved a collaborative activity, like planting a vegetable garden or baking a chocolate cake. In these scenarios, each child has a plant or chocolate to add to the collaborative task.

"We tell children that how this works is that if all four people make their contribution, you'll get the best payoff — you'll get the most vegetables from the garden or the biggest chocolate cake. On the other hand, if only three out of the four people contribute to the garden or to the chocolate cake, there'll be a lower payoff, so less yield from the garden, less vegetables or maybe a smaller chocolate cake," said Dunham.

Once the scenario was established, the researchers told the children that one member of the group withheld their contribution of a plant or chocolate, yet they still reaped the benefits of the reward.

Children in the study were asked to contribute to a collaborative project, such as donating seeds to a vegetable garden. (Credit: iStock/Getty Images)

None of the kids liked the freeloaders

"They were very positive about those who contributed and very negative about those who were freeloaders," said Dunham. "In addition to just expressing dislike for them, they would also be willing to punish them. They would want to take rewards away from them and they would even be willing to pay a cost in their own personal endowment of stickers in order to make sure that those people didn't benefit as much from the eventual outcome."

If anything, we saw the opposite pattern that younger kids actually seemed to be more negative or more punitive towards free-riders than were older kids — suggesting that this is a really pretty early emerging and powerful insight. - Yarrow Dunham , Yale University

When they looked deeper into the data at how kids at different ends of the age scale felt about the freeloaders, the researchers discovered that the younger kids disliked the freeloaders even more than the older kids.

"This was a fascinating question where if we think this is something that's socialized, in other words, something kids are gradually learning through experience, you'd expect that these tendencies would go stronger with age," said Dunham.

"But if anything, we saw the opposite pattern that younger kids actually seemed to be more negative or more punitive towards free-riders than were older kids — suggesting that this is a really pretty early emerging and powerful insight. And if anything older kids get a little more tolerant."

Take-home lesson

Dunham said he still can't conclusively say if our dislike of freeloaders is innate or learned.

"I think what this is suggesting is that even if it is reinforced and supported by parents, it does seem to be something that emerges pretty naturally in children at a certain age — in this kind of three-to-four age range where they begin to get more and more interested in collaborating and kind of working together with others. So I think that there is an emerging idea that this might be part of our kind of innate or natural endowment as a species."

What this means is that if parents and teachers can find ways to support what seem to be the children's natural tendencies to cooperate, they might be able to reinforce the development of pro-social habits to create a more cooperative broader environment.