On the origin of intentions

Any model of motor control or sensorimotor transformations starts from an intention to trigger a cascade of neural computations, yet how intentions themselves are generated remains a mystery. Part of the difficulty in dealing with this mystery might be related to the received wisdom of studying sensorimotor processes and intentions in individual agents. Here we explore the use of an alternative approach, focused on understanding how we induce intentions in other people. Under the assumption that generating intentions in a third person relies on similar mechanisms to those involved in generating firstperson intentions, this alternative approach might shed light on the origin of our own intentions. Therefore, we focus on the cognitive and cerebral operations supporting the generation of communicative actions, i.e. actions designed (by a Sender) to trigger (in a Receiver) the recognition of a given communicative intention. We present empirical findings indicating that communication requires the Sender to select his behavior on the basis of a prediction of how the Receiver will interpret this behavior; and that there is spatial overlap between the neural structures supporting the generation of communicative actions and the generation of first-person intentions. These results support the hypothesis that the generation of intentions might be a particular instance of our ability to induce and attribute mental states to an agent. We suggest that motor intentions are retrodictive with respect to the neurophysiological mechanisms that generate a given action, while being predictive with respect to the potential intention attribution evoked by a given action in other agents.