Roles of synchronous visuo-tactile and visuo-motor stimulations in self-location during whole body embodiment: an exploratory study

Sachiyo Ueda^1*Kento Higashihata²Takayoshi Hagiwara³Benjamin Navarro⁴Michiteru Kitazaki^2*Ganesh Gowrishankar^4*

• ¹Tsudajuku Daigaku, Kodaira, Japan
• ²Department of Computer Science and Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan
• ³National Institute of Technology, Nagano College, Nagano, Japan
• ⁴Laboratoire d'Informatique de Robotique et de Microelectronique de Montpellier, Montpellier, France

The human sense of self is plastic and can be modulated by multisensory and sensorimotor coupling in immersive virtual reality. In particular, synchronous visuo-tactile stimulation and visuo-motor coupling via first-person control are widely used to induce embodiment. However, when these two streams promote different candidate self-locations, their relative contribution to perceived self-location remains unclear. Here we examined perceived self-location using a robot-mediated self-touch paradigm that creates a cue conflict: synchronous visuo-tactile stimulation may bias self-location toward the participant's physical body, whereas visuo-motor coupling via first-person control is expected to bias self-location toward a remote robot viewpoint. We compared this conflict condition with control conditions in which either visuo-tactile or visuo-motor stimulation was reduced or removed. Perceived self-location was assessed using questionnaire ratings and a behavioral estimate, Self-Location EstimatEd Pointing (SLEEP), which estimated participants' perceived self-location using a finger-pointing task in a virtual image. Overall, the results are consistent with a stronger contribution of synchronous visuo-tactile stimulation than visuo-motor coupling to perceived self-location in this whole-body embodiment setting.