If you know how to do something and people around you start doing it differently, you have two options: stick to what you know, or change to use their strategy. If the new strategy is more efficient than yours, or gets better results, it’s a no-brainer, so you switch. But if it’s exactly as efficient and produces the same results, the decision to switch is based on another factor—conformity.

We know that we have a tendency to fall in line with those around us, sometimes even when this results in obvious mistakes. This tendency can explain why human culture varies so widely among different societies, but is so similar within groups. Our closest primate relatives don’t have cultural variation to the same degree, so what makes humans different?

Previous research on non-human great apes has shown that they learn from their peers. However, what hasn’t been established is whether this process is similar in humans and non-humans, including when the learning involves overriding existing habits. A group of researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, recently found that human children are more likely than chimpanzees and orangutans to change their behavior to conform to their peers.

The researchers used a problem-solving task that produced a reward for the participants—peanuts for chimps and orangutans, and chocolate drops for children. Participants were given the chance to play with a box with three sections. One of the sections would produce a reward when a ball was dropped into it, while the other two wouldn’t. The researchers could control which of the sections produced the reward.

The participants played with the boxes long enough to learn which section would give them a reward. Once they had learned this, they watched three peers (of the same species) dropping balls into a different section—and getting a reward. Finally, the participants were given three new balls and allowed to drop them into any of the sections. With each ball, participants could choose to stay with the initial section that they had learned would dispense rewards, switch to the section they had seen give rewards to their peers, or choose the third section.

Only this time, all of the sections gave a reward. So, if the participant decided to switch, they wouldn’t be put off their decision by a lack of reward.

Only a third of the children stayed with the section they already knew, while two-thirds switched to their peers’ choice with at least one of their three balls. In comparison, only 17 percent of the chimps and orangutans switched.

The researchers write that it’s possible to explain this difference without resorting to conformity. For instance, non-human apes might be more set in their ways and less likely to learn new things than humans. Previous research indicates that this is unlikely, though, says lead researcher Daniel Haun. Chimps will adjust to a new behavior if it produces more value: “They are flexible, and they will change for some reasons, but conformity isn’t one of those reasons.”

Chimps’ tendency to change to a more productive behavior has previously been thought to show that they conform, so this study makes an important point, says Keelin Murray, a cultural evolution researcher who wasn’t involved with this study: “Once non-human apes have a learned behavior in place, they don’t override that for social reasons.”

One of the ongoing difficulties with research on non-human apes is the problem of sample sizes. The number of chimps and orangutans in captivity is small to begin with, and only a certain subset are used to doing tasks like this. To make it even more difficult, those individuals that are used to research tasks need to be protected from being over-exposed, both for their own health, and because overtrained apes’ behavior may not be typical of their species.

Because of this, only 12 chimps and 12 orangutans were used in this study, and a small sample of 18 children was used to keep the group sizes similar for statistical analysis. The small samples increase the need for replication in other groups and other species. But, as we just noted, this will be difficult.

The researchers wanted to clarify the children’s motivations for switching, so they conducted a follow-up study on a larger group of 78 children. This time, they tested whether children were more likely to conform when they were being watched by the peers who had demonstrated the change in section. Being observed did make a difference: children switched more if the peer demonstrators were watching. This indicates that the children’s choice to switch wasn’t based on just having new information, but rather was influenced by the desire to be more like those around them.

Haun suggested he’s interested in seeing how strong conformity is in young children of different cultures. We already know that adults conform more in East Asian cultures than in the US, but we don’t know how early that difference starts emerging. It might be that everyone starts out with the same tendency to conform, and some cultures reinforce or discourage that tendency. But there’s also the possibility that those differences are there right from the start.

The finding that humans conform more than other apes gives us insight into why human cultures have so much more variety than other primates. Chimp groups vary in some behaviors, like termite hunting techniques, but humans have a dazzling repertoire of culturally variable behaviors, with much greater differences between groups. Conformity can explain why, when there are different behavioral choices available, human conformity is what ensures that behavior sticks once each group has picked a strategy, Haun suggests.

Psychological Science, 2014. DOI: 10.1177/0956797614553235 (About DOIs).

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