Fig. 1

The Rubber (a,b) and Robot (c,d) Hand Illusion tasks. In the Rubber Hand Illusion task, participants place their own hand in the black box and gaze at the rubber hand (a). Before and after the brush stroke, the participant points with the opposite hand at the fingertip position of the index finger of his/her right hand and the horizontal difference before and after the task is calculated (b: proprioceptive drift). In the robot hand illusion task, the participant places his/her own hand under the rubber hand and activates the robotic hand while gazing at the rubber hand (c). The joint position of the robotic arm was continuously controlled by the participant’s muscle activity via two electrodes (arrow in c) that captured electromyographic signals from the flexor carpi radialis and extensor carpi ulnaris muscles. Before and after moving the robotic arm, the participant points with the opposite hand at the fingertip position of the index finger of his/her right hand and the vertical difference before and after the task is calculated (d: proprioceptive drift).