A new study from Duke University (written by Robin Smith on the Duke University blog) explores how young children develop a sense of morality – including an understanding of what ‘being fair’ means.

Most young children consider that ‘being fair’ simply means treating everyone equally.  How often haven’t you heard a young child object to being sent to bed earlier than an older sibling, or having a classmate being allowed to do something forbidden to others.

As children get older, they begin to understand that sometimes things can be unequal and still be fair—especially when people have different needs, circumstances, or abilities. Up until 8 to 10 years of age, most children aren’t yet capable of such moral subtlety, but a new study shows they can be helped to develop it, surprisingly by using disagreement.

Having a 20-minute conversation with a pre-schooler with someone who disagrees with them or who asks them to justify their ideas can encourage them to adjust their beliefs about what it means to be “fair.”

This theory was tested by a study by Leon Li and Michael Tomasello of Duke University that appeared in the Journal of Experimental Child Psychology. They asked 129 children aged four to five years to discuss simple moral dilemmas with a puppet and try to make the most fair decision.

In one experiment for example, they asked the children to imagine two boys, one of whom missed breakfast, and decide how to split cookies between them at snack time. In another, the question was whether two girls should get in the same amount of trouble for throwing away someone’s lunch, when one of them mistook it for rubbish.

No matter what the child decided, the puppet responded by either agreeing or disagreeing, and by either asking the child to explain their reasoning or not. Then the researchers observed how the puppet’s responses affected the child’s thinking in future trials.

They found that children who had previously encountered different points of view, or had to justify their decisions, were more likely to favour the more deserving recipient, rather than fall into “fair must mean equal” thinking.

Li cautions, however, that disagreeing with a child or asking them to justify themselves won’t necessarily make them more honest, or hardworking, or generous.

“Those are other domains of morality, but we only found this in fairness,” Li said.  It’s possible it wouldn’t have an effect with some other aspect of moral behaviour that this research didn’t examine.