Measuring Peer Effects

A new study from psychologists Jamil Zaki, Jessica Schirmer, and Jason P. Mitchell relies on brain scans to evaluate the effects of peer influences. “Participants rated the attractiveness of faces and subsequently learned how their peers rated each face. Participants were then scanned using fMRI while they rated each face a second time,” explain the authors. “These second ratings were influenced by social norms, such that participants changed their ratings to conform to those of their peers.” Most importantly, the “social influence was accompanied by modulated engagement of two brain regions associated with coding subjective value.” The BPS Research Digest explains in more detail: “Let’s focus on those faces that a participant had earlier given equal attractiveness ratings to, and which you’d therefore think they’d find equally rewarding to look at. In fact, among these faces, those that they’d been told earlier were rated as more attractive by previous participants, triggered more reward-related brain activity (the participants also increased the attractiveness ratings they gave to these faces). In contrast, the faces they’d earlier been told were rated as less attractive by peers, triggered less reward activity, and were now rated as less attractive by the participants.” The results put a more positive spin on conformity, according to the researchers: “Rather than the result of individual weakness and faulty character, conformity appears to arise from the same neural systems that guide behaviour towards highly-valued outcomes, including such basic needs as food, water, and opportunities for reproduction.”