Very young children imitate their peers to fit in, while great apes tend to stick to their own preferences

From the playground to the boardroom, people often adapt their behaviour to those around them in order to fit in with a particular group. In humans, this conformity appears in childhood, but it is not evidenced in chimpanzees or orangutans. "Conformity plays a central role in human social behaviour, defining and delimiting different groups and helping them coordinate their activities. It stabilizes and promotes cultural diversity, one of the characteristic features of the human species," says psychologist Daniel Haun of the Max Planck Institute for Evolutionary Anthropology, who headed the study.

This is not to say that it is always best to comply with the majority. Conformity can be good or bad, helpful or unhelpful, appropriate or inappropriate, for both the individual and the group. "The fact is that we often do conform, and our social structure would be completely different if this were not the case. Our study shows that children as young as two adapt their behaviour to fit in, while chimpanzees and orangutans stick with what they know," says Haun.

In an earlier study, Haun and his colleagues found that children and chimpanzees rely on the majority opinion when they are learning something new. This makes a lot of sense, as the group has knowledge that the individual may not be aware of. However, other studies show that human adults sometimes conform even when they already have the relevant knowledge, just to avoid standing out from the crowd. To find out whether young children and apes also show this "normative" conformity, Haun and his co-authors Michael Tomasello and Yvonne Rekers presented two-year-old children, chimpanzees and orangutans with a similar task.

In these experiments, the children and apes were to drop a ball into a box that contained three separate sections. Only one of these sections delivered a reward: a peanut for the apes, and a chocolate drop for the children.

After familiarizing themselves with the box, each participant then watched while several peers deposited their balls into a different section from the one the participant associated with a reward. When it was the participant's turn again, he or she had to choose a section while the other three children looked on.

The results revealed that the children were more likely to adjust their behaviour to that of their peers than were the apes. The children conformed more than half the time, while the chimpanzees and orangutans practically ignored their peers and stuck to their learned strategy.

A follow-up study with two-year-olds showed that children were more likely to switch their choice when observed by their peers, but stayed with their original strategy when left alone. It is interesting to note that participants showed the same propensity to conform independently of whether the alternative was presented by one or three peers. This conformity among toddlers shows that the motivation to fit in emerges very early in humans. "We were surprised to find that children as young as two change their behaviour to avoid the potential disadvantage of being different," says Haun.

The researchers are currently investigating the impact of environmental factors, such as schooling and different child-rearing methods, on children's tendency to conform.