Visual appearance of the virtual hand affects embodiment in the virtual hand illusion

Maria Pyasik,Gaetano Tieri,Lorenzo Pia

doi:10.1038/s41598-020-62394-0

Maria Pyasik, Gaetano Tieri + Show 1 more

Open Access

https://doi.org/10.1038/s41598-020-62394-0

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Abstract

Body ownership (the feeling that one’s body belongs to oneself) is commonly studied with Rubber hand illusion (RHI) paradigm that allows inducing a temporary illusory feeling of ownership of a life-sized rubber hand. However, it remains unclear whether illusory ownership of the fake hand relies on the same mechanisms as ownership of one’s own real hand. Here, we directly compared ownership of the own hand (OH) and fake hand (FH) in the same set of conditions within immersive virtual reality. We obtained behavioral (proprioceptive drift) and subjective (questionnaire) measures of ownership and disownership for virtual OH, FH and object (Obj) that were located congruently or incongruently with the participant’s real hand and were stimulated synchronously or asynchronously with the real hand. Both OH and FH (but not Obj) were embodied after synchronous stimulation in both locations. Crucially, subjective ownership of the OH was stronger than of the FH in congruent location after synchronous stimulation. It was also present after asynchronous stimulation, being stronger when the virtual OH was subjectively more similar to the real hand. The results suggest that the detailed appearance of the body might act as an additional component in the construction of body ownership.

Highlights

Body ownership is commonly studied with Rubber hand illusion (RHI) paradigm that allows inducing a temporary illusory feeling of ownership of a life-sized rubber hand
Differently from the classical RHI setup where the fake hand is usually placed near the real hand, in a virtual reality setup, the virtual hand can be placed in the same position as the real one, giving the experimental advantage of the congruence in visuo-proprioceptive information
Neither own hand (OH), nor fake hand (FH) ratings differed between Congr and Incongr location, while for Obj, the ratings in Congr location were significantly higher compared to Incongr

Summary

Introduction

Body ownership (the feeling that one’s body belongs to oneself) is commonly studied with Rubber hand illusion (RHI) paradigm that allows inducing a temporary illusory feeling of ownership of a life-sized rubber hand. We obtained behavioral (proprioceptive drift) and subjective (questionnaire) measures of ownership and disownership for virtual OH, FH and object (Obj) that were located congruently or incongruently with the participant’s real hand and were stimulated synchronously or asynchronously with the real hand. Recent studies demonstrated that, in a VR setup, the simple passive observation of a virtual limb (without visuo-tactile stimulation) is a sufficient condition for eliciting illusory ownership over the virtual limb itself[24,25,28,29,30,31] Such enhanced role of visual information from the virtual scene can provide ample opportunities for experimental manipulations of body ownership by maintaining the visuo-proprioceptive information constant. It allows creating a mismatch between the movements performed by the virtual and the real body, which the participant remains unaware of[32,33]

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