Three-year-olds have a sophisticated understanding of morality

Despite popular beliefs to the contrary, past research has suggested that even young children have a sophisticated moral understanding. They're also surprisingly pro-social: toddlers tend to enjoy sharing and helping others, for instance.

Now researchers have found that children as young as three not only have a sense of what is right or wrong, but even soften their judgements about a transgression after being given a good, prosocial excuse.

As adults, we'd generally agree that it is better to break a promise in order to help others, rather than for selfish reasons. But Leon Li and colleagues at Duke University wondered whether young children understand this too. To test this, the team recruited two groups of children, with an average age of 3.5 and 5.5 respectively. Both groups had a fairly even mix of genders. On Zoom, the children were introduced to a squirrel puppet, who the kids learned was the "head puppet", operated by an off-screen experimenter. They then saw a slide displaying 12 puppets who would appear later in the study, and the head puppet asked the children to report any bad behaviour the characters exhibited.

Children then watched a series of pre-recorded videos, each featuring a different pair of animal puppets. Each pair of puppets introduced themselves, promised to show the child a cool toy, and then went off screen for fifteen seconds. In two of the trials, the puppets both showed the child interesting toys when they returned, but in three, the puppets did not bring anything back to show the children.

In these latter trials, the puppets each gave an excuse for not fulfilling their promise. Some were "good", prosocial excuses (e.g. "I didn't bring the toy because I had to help my mum, who really needs my help"), while others were "bad", selfish excuses ("I didn't bring the toy because I wanted to watch TV"). Sometimes puppets gave no excuse ("I didn't bring my cool toy, bye!").

At the end of each video, the head puppet returned and asked the child if they had anything to report. The children's responses were then coded as to whether or not they had tattled; they also indicated whether or not they thought it was wrong the puppet hadn't shown them anything and explained why it was either wrong or okay. They also answered questions on which puppet in each pair they had liked more and who they would rather invite to a playdate.

The children judged all of the puppets who had reneged on their promise negatively, no matter the excuse they gave. However, children judged the puppets who gave good excuses less negatively than those who gave bad or no excuses. This was true for both the three year olds and the five year olds.

However, only the five year olds showed differences in the types of statements they used when justifying their judgements for each puppet. When a puppet had a good excuse, these older kids were much more likely to reference social norms, saying, for instance, that the puppets had done something wrong because they had an obligation to act in a prosocial way. However, no matter what excuse the puppet used, children were not more or less likely to tattle on, like, or invite any of the three types of puppets any more than would be expected by chance.

The study suggests that children as young as three-and-a-half have started to recognise that prosocial behaviours are a better justification for a transgression than individual desires. But the data also suggests that it's a bit later before children begin to fully understand the prosocial norms that guide our behaviour.

However, the results also suggest that children may not have a sense of the social implications of certain transgressions – in other words, they may not understand that breaking promises or social rules could make somebody less likeable. Future research could further explore when and how this understanding emerges in development.