Cast Shadow and Color Change Improve Social Impression of Robotic Massage with Virtual Out-of-Body Experience

Massage therapy has been shown to have numerous benefits, including improvements in physical and mental health. In this study, we examined how integrating virtual reality with a robotic massage system could enhance users' social perception of the robot. We implemented a virtual out-of-body experience in the robotic massage system, allowing users to view their own bodies as avatars and observe the robot's approach. Our hypothesis was that adding visual information, such as a color change or cast shadow motion, could improve the social impression of the robot. The results of our human-subject study demonstrated that the robot was perceived as more competent and warmer when the approach of the robotic arm was accompanied by a gradual change in color, while the robot was evaluated as more comfortable when the approach was accompanied by a cast shadow motion. These findings suggest that the combination of a robotic massage system with virtual reality, such as a virtual out-of-body experience, could improve users' social perception of the robotic system, resulting in a feeling of safety, warmth, and comfort during the massage.