From the perception of action to the understanding of intention.

Humans have an inherent ability to understand other people’s minds. This process is a component of a ‘theory of mind,’ a well-researched topic in both developmental psychology and cognitive neuroscience. Theoryof-mind research and theory has mainly been applied to high-level cognitive processing, such as understanding that other people can have different desires and beliefs from one’s own. This review will focus on a much lower — although equally important — level of theory of mind: the ability to understand others people’s intentions by observing their actions. Indeed, this basic form of theory of mind might be a prerequisite for the higher-level understanding of others’ minds. We start by describing psychophysical and functional imaging studies showing that biological motion is processed as a special category, to which humans from an early age attribute mental states, such as intention. Next, we suggest a mechanism for inferring intentions from observed actions that might depend on the system that labels the consequences of one’s own actions as being produced by one’s own intentions. This mechanism might be based on simulating the observed action and estimating the actor’s intentions on the basis of a representation of one’s own intentions, a notion that is reminiscent of SIMULATION THEORY. Finally, we review the evidence that simulation and imitation — or overt action simulation — facilitate intentional attribution. In particular, neurophysiological evidence provides support for the existence of a matching system between perception and action, which is recruited during imitation.