Individuals Prioritize the Reach Straightness and Hand Jerk of a Shared Avatar over Their Own

Hagiwara, Takayoshi; Ganesh, Gowrishankar; Sugimoto, Maki; İnami, Masahiko; Kitazaki, Michiteru

doi:10.1016/j.isci.2020.101732

Cited by 31 publications

(22 citation statements)

References 34 publications

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“…The representation of our body in the brain is plastic. Even relatively short multi-sensory (usually visuo-haptic) stimulations can induce an illusion of ownership, and embodiment in general, towards artificial limbs and bodies 1 including human-looking limbs: rubber hands 2 , 3 , virtual avatars 4 – 6 , as well as robotic limbs and bodies 7 – 14 . However, most previous studies on ownership have been conducted in the context of “limb substitution,” where the rubber, virtual, or robotic limb replaces an already-existing limb.…”

Section: Introductionmentioning

confidence: 99%

Bodily ownership of an independent supernumerary limb: an exploratory study

Umezawa

Suzuki

Ganesh

et al. 2022

Sci Rep

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Can our brain perceive a sense of ownership towards an independent supernumerary limb; one that can be moved independently of any other limb and provides its own independent movement feedback? Following the rubber-hand illusion experiment, a plethora of studies have shown that the human representation of “self” is very plastic. But previous studies have almost exclusively investigated ownership towards “substitute” artificial limbs, which are controlled by the movements of a real limb and/or limbs from which non-visual sensory feedback is provided on an existing limb. Here, to investigate whether the human brain can own an independent artificial limb, we first developed a novel independent robotic “sixth finger.” We allowed participants to train using the finger and examined whether it induced changes in the body representation using behavioral as well as cognitive measures. Our results suggest that unlike a substitute artificial limb (like in the rubber hand experiment), it is more difficult for humans to perceive a sense of ownership towards an independent limb. However, ownership does seem possible, as we observed clear tendencies of changes in the body representation that correlated with the cognitive reports of the sense of ownership. Our results provide the first evidence to show that an independent supernumerary limb can be embodied by humans.

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Section: Introductionmentioning

confidence: 99%

Bodily ownership of an independent supernumerary limb: an exploratory study

Umezawa

Suzuki

Ganesh

et al. 2022

Sci Rep

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“…In this study, we explore a new concept called “virtual co-embodiment” where two or more users embody one avatar to collaboratively perform joint tasks. Co-embodiment can be achieved in several ways such as reflecting average movements (or movements in different ratios of control) of multiple users to one avatar/robot 7 , 8 , allowing multiple users to control different sections of one avatar limb/robotic arm 9 , and allowing each user to fully control separate limbs of one avatar 10 , 11 . We are focusing on this third method; We utilized an avatar of which left and right limbs could be controlled by two different individuals at the same time while both of them were immersed in the first-person view of the virtual avatar.…”

Section: Introductionmentioning

confidence: 99%

“…1 A). Hagiwara et al 8 conducted an experiment where two human participants were embodied within a concurrent shared avatar (Fig. 1 A) in VR and showed that the movements of the shared avatar were straighter, and less jerky compared to the movements of the individual participants and the solo body avatar.…”

Section: Introductionmentioning

confidence: 99%

“…These previous studies on virtual co-embodiment have studied avatars of which the movements were determined by averaging the movements of the two participants in real time (occasionally in different ratios of control).

Figure 1 Two types of co-embodiment avatar: ( A ) A shared body avatar is controlled by two individuals, and their movements are averaged and reflected in the shared avatar 7 , 8 . ( B ) A joint body avatar is an avatar in which different body parts such as left and right half bodies are controlled by two different individuals.…”

Section: Introductionmentioning

confidence: 99%

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Knowing the intention behind limb movements of a partner increases embodiment towards the limb of joint avatar

Hapuarachchi

Kitazaki

2022

Sci Rep

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We explored a concept called “virtual co-embodiment”, which enables users to share their virtual avatars with others. Co-embodiment of avatars and robots can be applied for collaboratively performing complicated tasks, skill training, rehabilitation, and aiding disabled users. We conducted an experiment where two users could co-embody one “joint avatar” in first person view and control different arms to collaboratively perform three types of reaching tasks. We measured their senses of agency and ownership towards the two arms of the avatar and changes in skin conductance levels in response to visual stimuli threatening the two virtual arms. We found that sense of agency, ownership, and skin conductance were significantly higher towards the virtual arm with control compared to the arm controlled by the partner. Furthermore, the senses of agency and ownership towards the arm controlled by the partner were significantly higher when the participant dyads shared a common intention or when they were allowed to see their partner’s target, compared to when the partner’s target was invisible. These results show that while embodiment towards partner-controlled limbs is lower compared to limbs with control, visual information necessary for predicting the partner’s intentions can significantly enhance embodiment towards partner-controlled limbs during virtual co-embodiment.

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“…The representation of our body in the brain is plastic. Even relatively short multi-sensory (usually visuo-haptic) stimulations can induce an illusion of ownership, and embodiment in general, towards artificial limbs and bodies (Aymerich-Franch and Ganesh, 2016) including human-looking limbs: rubber hands (Botvinick and Cohen, 1998;Longo et al, 2008), virtual avatars (Slater et al, 2009(Slater et al, , 2010Hagiwara et al, 2020) as well as robotic limbs and bodies (Nishio et al, 2012;Alimardani et al, 2013;Suzuki et al, 2015). However, most previous studies on ownership have been conducted in the context of 'limb substitution,' where the rubber, virtual or robot limb replaces an already-existing limb.…”

Section: Introductionmentioning

confidence: 99%

Bodily ownership of an independent supernumerary limb: An exploratory study

Umezawa

Suzuki

Ganesh

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Can our brain perceive a sense of ownership towards an independent supernumerary limb; one that can be moved independently of any other limb and provides its own independent movement feedback? Following the rubber-hand illusion experiment, a plethora of studies have shown that the human representation of 'self' is very plastic. But previous studies have almost exclusively investigated ownership towards 'substitute' artificial limbs, which are controlled by the movements of a real limb and/or limbs from which non-visual sensory feedback is provided on an existing limb. Here, to investigate whether the human brain can own an independent artificial limb, we first developed a novel independent robotic 'sixth finger.' We allowed participants to train using the finger and examined whether it induced changes in the body representation using behavioral as well as cognitive measures. Our results suggest that unlike a substituted artificial limb (like in the rubber hand experiment), it is more difficult for humans to perceive a sense of ownership towards an independent limb. However, ownership does seem possible, as we observed clear tendencies of changes in the body representation that correlated with the cognitive reports of the sense of ownership. Our results provide the first evidence to show that an independent supernumerary limb can be embodied by the human brain.

show abstract

Individuals Prioritize the Reach Straightness and Hand Jerk of a Shared Avatar over Their Own

Cited by 31 publications

References 34 publications

Bodily ownership of an independent supernumerary limb: an exploratory study

Bodily ownership of an independent supernumerary limb: an exploratory study

Knowing the intention behind limb movements of a partner increases embodiment towards the limb of joint avatar

Bodily ownership of an independent supernumerary limb: An exploratory study

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