Predicting the actions of others taps into one's own somatosensory representations--a functional MRI study

Humans have the striking capacity to predict actions performed by their conspecifics. But how exactly do we perform such predictions? Do we use our own action repertoire and our own body to simulate the reaching range of others? In this functional magnetic resonance imaging study static photographs depicting side views of seated human models were presented to participants, who had to predict whether the models could reach a target placed in front of them. The predictions were performed both fast and accurate, but with an overestimation bias as well as higher error rates and slower predictions for targets close to the models' actual reaching ranges. Specific hemodynamic signal changes were detected in primary and secondary somatosensory cortices, inferior and superior parietal areas, and in right ventral premotor cortex. These findings demonstrate that action prediction in the current context activates a network of areas involved in action recognition, visuo-spatial transformation and somatosensory anticipation. The results are in line with the mirror-neuron system account of action understanding and the notion of the common coding theory that actions are coded in terms of their perceivable effects.