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The Science Behind Social Influence

Why we follow the crowd.

Key points

  • We learn by direct experience and by observing others.
  • Seeing what others want improves how we learn.
  • Different parts of the brain are involved in direct learning and learning from social influence.

By Lei Zhang, Ph.D.; edited by Patricia Lockwood, Ph.D., and Jo Cutler, Ph.D.

It is no secret that we are influenced by the preferences of others around us. What to watch on TV or even which factual statements to believe can be profoundly shaped by what other people watch or believe. This phenomenon, referred to as social influence, was reported in early research in the 1950s by social psychologist Solomon Asch.

Asch’s now-infamous experiments worked as follows: Imagine you have signed up to a psychology experiment and are asked to take a vision test in a room with other people. In the test, you see a card with a black line and have to choose which of three lines on a separate card is the same length as the target line. Before revealing your answer, you get to hear what the other people in the room picked. To start with, everyone chooses the same one as you, the one that is clearly correct. Then, on the third round, everyone else unanimously chooses a line you’re sure is wrong. How do you answer when it is your turn? Asch showed that people were willing to ignore reality and give an incorrect answer when it conformed to the rest of the group.

Since this early work, several questions remain. Often, we don’t make one-off decisions, but we need to learn what to choose over time, so it’s important to understand how social influence affects learning. We also don’t know how social influences on learning work in the brain. For example, we don't know whether learning about what other people want relies on the same or different brain areas to learning based on our own preferences.

Vova Krasilnikov/Pexels
Following the crowd
Source: Vova Krasilnikov/Pexels

Measuring Social Influence in the Brain

In a recent study, of which I am a coauthor, 185 volunteers performed a multiplayer decision-making experiment in groups of five. Each participant had to make lots of choices between two abstract pictures where one was a better choice than the other for earning them money.

These kinds of experiments have been done by researchers before. Previous studies using this type of experiment have shown that people are generally very good at learning to pick the best picture to gain more money. This process seems to rely on the neurotransmitter dopamine, which is particularly interested in outcomes being better than we expect and, therefore, really important for learning.

However, in this new experiment, there was a twist. After deciding between two pictures, people had the opportunity to observe what four other people had selected. Now they had the chance to change their opinion. Did they want to stick with the picture that they picked before, or did they want to change their choice to copy the group?

In fact, which picture was the best one to pick changed throughout the experiment without participants knowing. At the beginning of the experiment, one of the two symbols returned money 70 percent of the time, and after a few rounds, it changed and gave money only 30 percent of the time. These changes took place multiple times throughout the experiment. This so-called reversal learning paradigm created just enough uncertainty for volunteers so that they would always need to learn and relearn to gain more money.

We found that people switched more often when they were confronted with opposing choices from the others, but, interestingly, the second choice (after considering social information) improved people’s choices—if they followed the crowd, they made more money. Advanced mathematical models showed that, when learning from others, people can keep track of how well the other people were doing on the task and use that social information to optimise their own choices. In simple words, learning from others was very helpful.

What was also very important about this study was that one of the five participants in each group completed it during functional magnetic resonance imaging (fMRI). This brain-imaging technique allowed us to measure whether the same or different parts of the brain were involved in learning from direct experience compared to learning from social influence. We found that learning from other people happened in the anterior cingulate cortex, a part of the brain that has been shown to have individual neurons that prefer to respond to rewards for other people, and even in monkeys. When learning without any social influence, a different part of the brain, the ventromedial prefrontal cortex was involved.

Together, these findings showed that when situations are changing and uncertain, learning from others can be a useful strategy.

Is Social Learning Always Good?

Understanding when and how learning from others is beneficial becomes particularly important as we try to address global challenges. One important area is the role of social influence in political polarisation. A recent study found that, rather than people always being influenced toward agreeing with others’ political views, those who held extreme views would hold their own opinion even more strongly if they encountered opposing views on social media. This suggests that whilst social influence is often the norm, and we are often influenced to be more like those around us, in some contexts, the opposite can occur, and we become more different from others.

Another important question is how we might seek out other people’s opinions in the first place. Studies have shown that we have a bias to seek out information if it is positive. We don’t yet know how this might work when information is about other people, which is an important question for future research.


Asch, S. E. (1951). Effects of group pressure upon the modification and distortion of judgments. Organizational influence processes, 58, 295-303.

Zhang, L., & Gläscher, J. (2020). A brain network supporting social influences in human decision-making. Science advances, 6(34), eabb4159.

O'Doherty, J. P., Cockburn, J., & Pauli, W. M. (2017). Learning, reward, and decision making. Annual review of psychology, 68, 73-100.

Joiner, J., Piva, M., Turrin, C., & Chang, S. W. (2017). Social learning through prediction error in the brain. NPJ science of learning, 2(1), 1-9.

Bail, C. A., Argyle, L. P., Brown, T. W., Bumpus, J. P., Chen, H., Hunzaker, M. F., ... & Volfovsky, A. (2018). Exposure to opposing views on social media can increase political polarization. Proceedings of the National Academy of Sciences, 115(37), 9216-9221.

Charpentier, C. J., Bromberg-Martin, E. S., & Sharot, T. (2018). Valuation of knowledge and ignorance in mesolimbic reward circuitry. Proceedings of the National Academy of Sciences, 115(31), E7255-E7264.

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