each case, the participant is made aware of the condition. Consistent with our predictions, preliminary data indicates that adolescents activate socio-emotional reward regions (e.g., medial PFC, ventral striatum) more strongly when making risky decisions while being observed by their peers than when they do so alone. In contrast, our early data suggest that adults show few differences in activation of socio-emotional reward centers in the peer condition as compared to when they are alone. In this program of work, we have also replicated the earlier finding, but with completely different tasks, showing that the presence of peers increases adolescents' risk taking but has no such effect on adults. We also have evidence that the presence of peers leads adolescents to more steeply discount delayed rewards, leading to increased preference for immediate, although smaller, ones (O'Brien & Steinberg, 2010). This is a potentially important finding, since it provides further evidence that the impact of peers on risky decision-making may be mediated specifically by their effects on reward processing.
