Sam McClure heads the Decision Neuroscience Laboratory at Stanford University. His group investigates the neural basis of human decision making. This includes both how we learn the value of goods and actions in the world and how we use this information to decide between different actions. A lot of recent research in decision science has focused on pro-social behaviors such as altruism and fairness. By contrast, competitive drive has received far less attention. In his talk, Sam will present a series of experiments that were conducted with functional Magnetic Resonance Imaging, in which he studied competition in a multi-player auction task. Auctions present an ideal environment in which to study behavioral biases that arise from competition. Subjects knowingly overbid purely for the sake of winning so that competitive drive can be measured in units of money and compared across individuals. Learning to bid on this task is well characterized by a reinforcement learning model, and fMRI data localize prediction error signals to the ventral striatum (VS) and ventromedial prefrontal cortex (vmPFC). Sam will also introduce a role for the hormones testosterone and cortisolin governing bidding in competitive environment. This provides a potential mechanism by which cortical influences on brain reward processes are modulated.