Many studies on body representation intend to change the perceived size, material, and structure of the body. However, they focused on the change of a single body part. The human body has a symmetric structure, whose structure could affect the change in body representation. In this study, we focused on the change of both hands and arms in body representation to investigate the following two points. (1) If one hand is trained to change its position in body representation, is the position of another hand in body representation also changed according to the trained hand? (2) Can each hand be trained not to follow the symmetric structure of the body? In our experiment, participants moved their hands to indicated heights observing their hands through a head-mounted display as a training phase, where their hands were displayed at different positions from the actual ones. When we trained the participants’ right hand only, their left hand showed a similar change to the right hand. Meanwhile, when we displayed their hands at positions where did not follow the symmetric structure of the body, they changed their hand position in the body representation as they were trained. Therefore, our study suggested that, in the update process of the symmetric parts in body representation, untrained body parts were updated as their symmetric parts were trained. Whereas, when both symmetric parts were trained, they were updated according to the training content, even if the training was not consistent with their symmetric structure.
