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Psychological Science
Completed Project

Neural Substrates of Peer Influence in Adolescents

Chloe Wheeler, Vassar College ’15 and Prof. Abigail Baird

Previous research has shown that the presence of peers has profound effects on adolescent behavior. The present study used structural and functional MRI during three tasks designed to isolate the neural substrates of adolescent decision-making in both the absence and perceived presence of peers. Ten female participants (Mage = 13.7) underwent brain scans while answering questions about pop culture on a fabricated website during three different conditions: 1) “Offline” where they believed their answers could not be seen by peers, 2) “Online” where they were informed that their peers may see their answers, and 3) “Emulation” where they were asked to answer questions according to how they thought their peers would answer. All participants believed they were online in the first condition, and that their peers would be able to see at least one of their answers (none were actually shown). Analysis revealed that in the “online” condition, participants showed more activity in areas traditionally associated with emotional processing: the insula, specifically the medial insula and posterior insula. Conversely, in the “offline” condition, there was more activity in cognitive areas, such as the prefrontal cortex. In the “emulation” condition, there was activity in the anterior insula, which is known to integrate both emotion and cognition. Individuals who reported relatively higher social anxiety displayed more activity in emotional networks, such as the posterior insula and amygdala only when they were “online” and believed peers might see their answers. Together, the data suggest that believing that peers could be watching introduces increasingly emotional processes, especially for those who are more sensitive to social anxiety. Finally, the present results hint at an underlying evolutionary advantage to heightened awareness of peer presence in adolescents because peers may provide the best opportunity to learn about, and adjust to, their increasingly complex social world.