Associative learning of social value

Abstract

Using a combination of computational and neuroimaging techniques, Behrens et al. address a key question in social neuroscience: how we learn to value some individuals more than others. It is clear that interactions with other individuals guide behaviour in all social animals, but it is widely held that social learning is distinct from other forms of learning in its mechanism and neural implementation, and that social learning and evaluation mechanisms compete with reward-based learning to drive behaviour. But the new study, which compared the performance of human volunteers in a decision-making task who sometimes had the benefit or disadvantage of advice from a confederate, demonstrates that social valuation is achieved using the same mechanisms that underlie the reward-based learning — that is, by associative learning. Our decisions are guided by information learnt from our environment. This information may come via personal experiences of reward, but also from the behaviour of social partners1,2. Social learning is widely held to be distinct from other forms of learning in its mechanism and neural implementation; it is often assumed to compete with simpler mechanisms, such as reward-based associative learning, to drive behaviour3. Recently, neural signals have been observed during social exchange reminiscent of signals seen in studies of associative learning4. Here we demonstrate that social information may be acquired using the same associative processes assumed to underlie reward-based learning. We find that key computational variables for learning in the social and reward domains are processed in a similar fashion, but in parallel neural processing streams. Two neighbouring divisions of the anterior cingulate cortex were central to learning about social and reward-based information, and for determining the extent to which each source of information guides behaviour. When making a decision, however, the information learnt using these parallel streams was combined within ventromedial prefrontal cortex. These findings suggest that human social valuation can be realized by means of the same associative processes previously established for learning other, simpler, features of the environment.