Action intentions modulate visual processing during action perception.

The current debate on mechanisms of action understanding and recognition has re-opened the question of how perceptual and motor systems are linked. It has been proposed that the human motor system has a role in action perception; however, there is still no direct evidence that actions can modulate early neural processes associated with perception of meaningful actions. Here we show that plans for action modulate the perceptual processing of observed actions within 200 ms of stimulus onset. We examined event-related potentials to images of hand gestures presented while participants planned either a matching (congruent) or non-matching (incongruent) gesture. The N170/VPP, representing visual processing of hand gestures, was reliably altered when participants concurrently planned congruent versus incongruent actions. In a second experiment, we showed that this congruency effect was specific to action planning and not to more general semantic aspects of action representation. Our findings demonstrate that actions encoded via the motor system have a direct effect on visual processing, and thus imply a bi-directional link between action and perception in the human brain. We suggest that through forward modelling, intended actions can facilitate the encoding of sensory inputs that would be expected as a consequence of the action.