Active production and passive observation of hand movements shift visual hand location.

Which factors influence the perception of our hand location is a matter of current debate. Here, we test if sensorimotor processing contributes to the perception of hand location. We developed a novel visuomotor adaptation procedure to measure whether actively performing hand movements or passively observing them, influences visual perception of hand location. Participants had to point with a handheld controller to a briefly presented visual target. When they reached the remembered position of the target, the controller presented a tactile buzz. In adaptation trials, the tactile buzz was presented when the hand had not yet reached the target. Over the course of trials, participants adapted to the manipulation and pointed to a location between the visual target and the tactile buzz. We measured the perceived location of the hand by flashing a virtual pair of left and right hands before and after adaptation. Participants had to judge which hand they perceived closer to their body on the fronto-parallel plane. After adaptation, they judged the right hand, that corresponded to the hand used during adaptation, to be located further away from the body. We conclude that sensorimotor prediction of the consequences of hand movements shape sensory processing of hand location.