Different level of virtualization of sight and touch produces the uncanny valley of avatar\u2019s hand embodiment

M D’Alonzo,A Mioli,D Formica,L Vollero,G Di Pino

doi:10.1038/s41598-019-55478-z

Abstract

Humans increasingly often act through virtual and robotic avatars, which can feed back to their user only virtual sensory information. Since avatar is user’s embodiment and body image is mostly based on senses, how virtualization of sensory inputs affects avatar self-attribution is a key question for understanding nowadays human behavior. By manipulating visual and tactile inputs in a series of experiments fashioned after the rubber hand illusion, we assessed the relative weight of the virtualization of sight (Real, Robotic, Virtual) and of touch (Real, Virtual) on artificial hand embodiment. Virtualization decreased embodiment, but unexpectedly lowest embodiment was found when only one sense was virtual. Discordant levels of virtualization of sight and touch elicited revulsion, extending the concept of the uncanny valley to avatar embodiment. Besides timing, spatial constraints and realism of feedback, a matched degree of virtualization of seen and felt stimuli is a further constraint in building the representation of the body.

Highlights

Humans increasingly often act through virtual and robotic avatars, which can feed back to their user only virtual sensory information
The illusion arised in all six experimental conditions, since all the collected measures (i.e. rubber hand illusion (RHI) index, vividness, prevalence and proprioceptive drift) were significantly higher than in the control condition of typical asynchronous RHI stroking, as highlighted by the pre-planned pairwise comparisons (RHI index, vividness and prevalence: p < 0.001; proprioceptive drift: p < 0.05) (Fig. 2a)
This study was designed to assess the relative weight of the virtualization of visual and somatosensory inputs in the embodiment of a robotic or virtual avatar, and in particular of the hand

Summary

Introduction

Humans increasingly often act through virtual and robotic avatars, which can feed back to their user only virtual sensory information. Since avatar is user’s embodiment and body image is mostly based on senses, how virtualization of sensory inputs affects avatar self-attribution is a key question for understanding nowadays human behavior. One of the most astonishing behavioral revolution of present everyday life, based on deep technological and social changes, is that humans are increasingly often acting through virtual or robotic substitutes of their physical body. Virtual human-like-avatars have begun to be employed as proxy of individuals to substitute their real human body and facilitate social and environmental interaction in an immersive virtual reality setting for gaming, social network and entertainment. In exchange of easiness of action, interactions became less experienced and depersonalization makes people feel less responsible of their actions

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Results

Conclusion