Effects of Likeness and Synchronicity on the Ownership Illusion over a Moving Virtual Robotic Arm and Hand

In this study we investigated body ownership over a virtual hand and arm as a function of their visual appearance (likeness) and synchronicity of visuo-tactile stimulation with a virtual electric toothbrush and a vibrotactile glove. In all conditions, participants controlled the movement of arm and fingers, maintaining synchronicity in motor-proprioceptive-visual signals. While the effects of varying likeness and temporal synchronicity of visual and haptic stimuli on the ownership illusion have both been investigated individually before, their relative contribution is still unknown. We find that likeness should be complete: making only the hand robotic reduces the subjective ownership illusion to same level as that of a full robotic arm and hand. Visuo-tactile synchronicity is not a hard prerequisite for an ownership illusion to occur: a high degree of agency with congruent motor-proprioceptive-visual cues and an arm/hand layout similar to one's own body can be sufficiently strong to overrule incongruent visuo-tactile cues. This work is part of a larger study on the relative contribution of factors such as likeness, viewing mode, tactile stimulation and degree of agency on the body ownership illusion. The results may contribute to the enhancement of dexterous performance in remote telemanipulation tasks.