The advent of neuroeconomics has led to an explosion of knowledge regarding how reward and value are encoded in the brain. Although value based behaviour is usually understood in the context of prior learning here I will also consider how we make value-based choices in the absence of prior experience; how we make value-based choice for others; and how overlapping value representations for self and other might impact on each other at the level of the brain. Some of these ideas provide a quantitative means to understand the nature and underpinnings of psychopathological conditions. I will provide examples that serve to illustrate the wider issue of how these approaches might provide a framework for the development of computational-based assays of psychiatric disorders. These in turn can be exploited to probe underlying neurobiological mechanisms and possible help foster a new approach to psychopathology.