During adolescence, people are uniquely attuned to the complexities of interpersonal relationships. There are significant changes and reorganization in subcortical regions associated with emotion processing and reward. Escalation of risk taking in adolescence may be the result of the dopaminergic system and related regions in the striatum. This may also explain increased desire to spend time with and earn the approval of peers.

In-person communication is necessarily qualitative and involves subjective interpretation. Online environments and interaction allow for quantifiable feedback (e.g. likes). Quantifiable social endorsement (e.g. likes; comments) may act as a powerful motivator.

The presence of peers is associated with increases in the nucleus accumbens which is a hub of reward circuitry. Peer influence is a means by which adolescents learn how to behave appropriately in their sociocultural environment. Peer pressure and social endorsement may influence risky behaviour.

Participants matched their peers more often than chance. The brain regions where more activity was with a lot or few likes depends on the content. When participants viewed neutral photos with many likes, they showed greater activity in the visual cortex. When participants viewed risky photos with many likes there was more activity in one cluster in the left frontal cortex. When participants viewed their own photo, there was more activity in several regions.

Participants had more activity in the bilateral occipital cortex, medial prefrontal cortex and the inferior frontal gyrus when seeing photos of risky photos compared to neutral pictures. There was more activity in the left nucleus accumbens when seeing one’s own photos or neutral photos with many likes but not risky photos.

Adolescents are more likely to like a photo when it had received more likes from peers. This also holds for when there is more risk-taking behaviour in the photo. This effect was especially strong for own photos. This may reflect the importance of self-presentation. People had more brain activity when there were more likes. This occurred in brain areas associated with social cognition and social memories (e.g. medial prefrontal cortex; hippocampus; inferior frontal gyrus). Adolescents perceive information online in a qualitatively different way when they believe that it is more valued by peers.

The nucleus accumbens is implicated in the experience of receiving positive feedback on one’s own images as well as viewing other people’s images that are well liked. This means that self-presentation can be rewarding and a motivation for using social networks.

Peers socialize one another to norms by using modelling and reinforcement. Social media uses both. Risk taking in adolescence may arise from heightened neural sensitivity to reward combined with immature capacity for cognitive control. A cognitive control network in the brain was less active when viewing risky photos.