Social brain? Yes, you read that right. And yes, it is a metaphor. The term refers to some situations I think you already know. You know when you post a photo and, a few minutes later, check whether anyone liked it, or who did? Or when you walk into a room and quickly notice who is looking at you? Or when a comment from a friend stays in your head for hours, while a similar criticism from a stranger is perhaps forgotten quickly? Well, at some moments, being left out of a group seems to matter enormously. At others, getting approval only from the people who matter to you can completely change your day. If these situations sound familiar (and who hasn’t been through something similar?), there is a reason for it: during adolescence, social relationships take on new dimensions, while the brain keeps changing the way we process information about ourselves and about other people.
So does that mean teenagers are simply more worried about what others think? No! The question is more interesting than that kind of reductionism. What happens is that adolescence is a period in which autonomy from the family increases, new forms of friendship emerge, groups begin to play different roles and emotional relationships become progressively more complex. In this context, understanding what others think, noticing signs of acceptance or rejection and learning how to act in different groups become especially relevant tasks. And the brain takes an active part in these transformations.
But is there really a “social brain”?
Yes, the expression exists, and when neuroscientists use it they are referring to a set of brain regions and networks involved in processes such as recognizing emotions, imagining what another person might be thinking, interpreting intentions, evaluating social information and reflecting on ourselves in relation to others.
In neurobiological terms, the regions involved in this process include areas of the medial prefrontal cortex, the temporoparietal junction, parts of the superior temporal sulcus, the insula, the anterior cingulate cortex and structures related to reward processing, such as the ventral striatum. However, none of them works in isolation as a “friendship center”, a “rejection area” or a “popularity region”, nor do they form a “brain” apart from the one we know. Social behavior emerges from the coordinated activity of different brain systems, which also interact with previous experiences, personal characteristics and social circumstances.
During adolescence, several components of these networks continue to undergo structural and functional changes. At the same time, there are more opportunities to make decisions involving other people. You need to interpret facial expressions, understand irony, notice changes in your friends’ behavior, imagine how a message will be received, decide whom to trust and adjust your own behavior to different social contexts. Studies on social cognition by Andrews, Ahmed and Blakemore (2021) suggest that this combination of changes in the brain and changes in the social environment helps us understand why peer relationships become so important at this stage of life.
Why does being accepted matter so much?
The key point is that belonging to groups has always been relevant for human beings, because groups offer protection, cooperation, exchange of information, learning and opportunities to build relationships, among other things. After all, since Ancient Greece human beings have been seen as social animals, as Aristotle argued in the Politics (Book I, Chapter 2), when discussing the belonging of human beings to the polis. This idea was later reworked by Rousseau. During adolescence, however, this belonging goes through a reorganization, as bonds with classmates and friends take up more and more space in everyday life.
Peer influence can be understood within this context. Friends tend to share ways of speaking, tastes, behaviors, opinions and interests, building common references that help establish the group’s identity. A broad review of research on social influence in adolescence, carried out by Laursen and Veenstra (2021), suggests that part of this process may help increase compatibility between friends and reduce differences that could lead to distancing or exclusion.
That is why noticing what others approve or disapprove of provides social information. When you observe that a certain behavior provokes laughter, recognition, disapproval or silence in a group, your brain receives cues that can guide future behavior. This mechanism is part of social learning throughout life, taking on particular features during adolescence, when new groups, codes and forms of belonging are constantly being tried out.
And why can rejection hurt so much?
Imagine arriving at school and finding out that all your friends were invited to a party except you, or realizing that your messages are being ignored in a group chat. Have you ever had that experience? Well, even when no physical aggression takes place, situations like these can produce intense emotions and leave a mark on us.
Neuroimaging experiments carried out by Masten and colleagues (2009) sought to investigate what happens during simulated experiences of social exclusion. In a study that became a reference in the field, adolescents played, while undergoing functional magnetic resonance imaging, a virtual game in which they believed they were interacting with other young people. At a certain point, they began to be excluded from the game. The results showed that this kind of experience was associated with activity in regions involved in processing emotionally relevant information and in regulating responses to exclusion, including the insula, parts of the cingulate cortex and prefrontal regions.
Let’s look at these data carefully, though, because a brain image, on its own, does not allow us to state exactly “what someone is feeling”, and the same brain region can take part in many different functions. Even so, the results as a whole indicate that experiences of acceptance and rejection engage systems involved in evaluating the social meaning of events, which helps us understand why an apparently simple experience, such as being ignored by a group, can take on great subjective importance.
Accumulated past experiences also seem to make a difference: research with adolescents who had a history of persistent rejection by their peers found greater responsiveness in regions associated with detecting and evaluating social exclusion, suggesting that our history of relationships may influence the way later social situations are processed (Will et al., 2016).
This question of the social nature of the brain leads us to a sentence that comes up often whenever people talk about adolescence: “When they are with their friends, teenagers do things they would not do on their own.”
Do friends make teenagers make worse decisions?
There is some evidence that the presence and opinion of peers can indeed change decisions, including increasing risk-taking under certain circumstances. However, reducing the influence of friends to a source of bad decisions would leave out a relevant part of the story, since sensitivity to other people can also increase positive behaviors. The research on social development by Andrews, Ahmed and Blakemore (2021), mentioned earlier, indicates that the presence of peers can favor both risky choices and prosocial behaviors, depending on the group’s norms and on the situation.
So if the group values studying for a test, taking part in a project, playing a sport, making art, standing up for a classmate or supporting a cause, social influence can also work in this positive direction. Being sensitive to peers is therefore part of a learning system that allows us to understand the rules and expectations of the social environments we belong to. A reductive either/or, positive or negative, does not work here. As with almost everything in life, by the way. The more interesting question, then, may be to understand what a given group rewards, values and turns into a sign of belonging.
And what if the group is inside your phone?
Then the question is of a different order, because social media added a particular feature to these processes: many forms of social approval came to be artificially quantified as likes, followers, shares, views and comments. This turns part of other people’s responses into visible numbers and into a discourse with a persuasive effect.
In an experiment with adolescents, Lauren Sherman and colleagues (2016) created a situation similar to Instagram while participants underwent functional magnetic resonance imaging. The young people were more likely to like photos that already appeared with many likes, a finding that confirms some classic studies in psychology and communication theory on the conformity effect (Asch, 1955) and on social contagion, or social proof (popularly known as the bandwagon effect) (Cialdini, 2012). In addition, images presented as popular were associated with greater activity in regions involved in reward, attention and social processing.
This helps explain why apparently simple numbers can acquire meaning. A like is not just a small symbol on the screen. Depending on the context and on who gives it, it can work as information about recognition, approval or belonging.
There are, however, great differences among adolescents. The same digital experience can be almost irrelevant to one person and extremely meaningful to another. Recent studies have shown precisely that individual characteristics related to sensitivity to social rewards can influence the relationship between social media use and everyday emotional experiences (Politte-Corn et al., 2024).
For this reason, statements such as “social media is bad for the teenage brain” explain very little. Frequency of use, type of interaction, content consumed, the characteristics of the group, previous experiences, family context and individual differences all need to be taken into account. Longitudinal studies have found associations between the habitual frequency of checking social media and changes, over the following years, in the brain’s responsiveness to the anticipation of social information, although the authors themselves stress that more research is needed to understand the meaning of these associations and to establish their possible causal relationships (Maza et al., 2023).
So are we controlled by other people’s opinions?
That kind of statement is very strong and forceful, but very incomplete. Our choices result from the interaction of countless influences, among them family, friends, school, culture, media, previous experiences, personal goals and the circumstances of the moment, all of which take part in shaping our decisions. So saying that “hell is other people” only works as a catchphrase, without any connection to more grounded reflection. What we can say with certainty today is that during adolescence, as social life and autonomy expand, learning to navigate these influences is part of development itself, with the risks and precautions that this involves.
Recognizing the influence of others can, in fact, increase our capacity to decide. Before sharing a post just because everyone else is sharing it, joining an argument because your friends did, or accepting a challenge to show that you belong to the group, you could ask yourself: would I do this if no one were watching? This question does not eliminate social influence, but it can make it more visible.
At the same time, acknowledging that other people matter should not be understood as a sign of weakness. After all, we are a deeply social species (aren’t we?), constantly learning from our relationships. During adolescence, this system finds a particularly intense environment for experimentation, in which friendships, groups, identity and recognition are being rebuilt.
Perhaps that is precisely why other people’s opinions can seem so important at this stage. While we learn who we are, we are also discovering who we are in front of others, with others and within the different groups we belong to.
For all these reasons, it is worth keeping in mind, the next time you get a like, read a comment or hear a friend’s opinion, that all these communicative gestures can affect the way you feel. It is worth starting to pay attention to three things: who produced the reaction we are having, why that person’s opinion matters, and what that response actually means for your sense of belonging. You may discover that understanding the social brain is also a way of better understanding the relationships we build with life.
References
ANDREWS, Jack L.; AHMED, Saz P.; BLAKEMORE, Sarah-Jayne. Navigating the social environment in adolescence: the role of social brain development. Biological Psychiatry, v. 89, n. 2, p. 109-118, 2021. DOI: 10.1016/j.biopsych.2020.09.012.
ASCH, Solomon E. Opinions and social pressure. Scientific American, v. 193, n. 5, p. 31-35, 1955.
CIALDINI, Robert B. As armas da persuasão. Tradução de Ivo Korytowski. Rio de Janeiro: Sextante, 2012.
LAURSEN, Brett; VEENSTRA, René. Toward understanding the functions of peer influence: a summary and synthesis of recent empirical research. Journal of Research on Adolescence, v. 31, n. 4, p. 889-907, 2021. DOI: 10.1111/jora.12606.
MASTEN, Carrie L. et al. Neural correlates of social exclusion during adolescence: understanding the distress of peer rejection. Social Cognitive and Affective Neuroscience, v. 4, n. 2, p. 143-157, 2009. DOI: 10.1093/scan/nsp007.
MAZA, Maria T. et al. Association of habitual checking behaviors on social media with longitudinal functional brain development. JAMA Pediatrics, v. 177, n. 2, p. 160-167, 2023. DOI: 10.1001/jamapediatrics.2022.4924.
POLITTE-CORN, Madison et al. Neural reactivity to social reward moderates the association between social media use and momentary positive affect in adolescents. Affective Science, 2024. DOI: 10.1007/s42761-024-00237-1.
SHERMAN, Lauren E. et al. The power of the Like in adolescence: effects of peer influence on neural and behavioral responses to social media. Psychological Science, v. 27, n. 7, p. 1027-1035, 2016. DOI: 10.1177/0956797616645673.
WILL, Geert-Jan et al. Chronic childhood peer rejection is associated with heightened neural responses to social exclusion during adolescence. Journal of Abnormal Child Psychology, v. 44, p. 43-55, 2016. DOI: 10.1007/s10802-015-9983-0.
About this publication
This text was originally published in Portuguese on October 28, 2026, in the NeuroTeen section of Ciências e Cognição, and is reproduced here with permission: https://cienciasecognicao.org/neuroteen20260903/.
How to cite
ARANHA, Glaucio. The social brain: why other people’s opinions matter so much in adolescence. Glaucio Aranha, 28 Oct. 2026. Available at: https://glaucioaranha.com/2026/10/28/social-brain-why-others-opinions-matter-adolescence/.
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