Embodiment of an alien hand interferes with intact-hand movements

Can we fully incorporate into our body schema the body parts of others, altering our sense of ownership [1]? And, to what extent, given the tight link between body and motor representations, does an altered sense of body-ownership affect motor awareness [2] and the sense of agency [3,4]? The new study we report here demonstrates that a body part of one individual can become so deeply embedded in another’s sensory-motor circuits as to have objective effects on the latter’s motor execution. Indeed, we found, in right-brain damaged hemiplegic patients who identified another person’s hand as belonging to themselves, significant interference effects of the alien hand movements on the actual movements of their own intact hand.