Animacy and the prediction of behaviour

To survive, all animals need to predict what other agents are going to do next. Here, we review neural mechanisms involved in the steps required for this ability. The first step is to determine whether an object is an agent and, if so, how sophisticated it is. This involves brain regions carrying representations of animate agents. Once identified, the movements of an agent can be anticipated in the short term on the basis of purely physical constraints. In the longer term, taking into account the agent’s goals and intentions is useful. Goal directed agents are marked by the rationality of their movements, reaching their goals by the shortest or least effortful path. Observing goal directed behaviour activates the brain’s action observation/mirror neuron network, and predicting future goal directed behaviour is helped by the observer’s own action generating mechanisms. Intentions have a critical role in determining actions when agents interact with other agents, as several intentions can lie behind a given action. In these cases, interpretation is helped by prior beliefs about the agent and the brain’s mentalising system is engaged. Biologically-constrained computational models of action recognition are available, but equivalent models for understanding intentional agents remain to be developed.