No consistent cooling of the real hand in the rubber hand illusion

A controversial and unresolved issue in cognitive neuroscience is whether humans can experience supernumerary limbs as part of their own body. Some previous experiments have claimed that it is possible to elicit supernumerary hand illusions based on modified versions of the rubber hand illusion. However, other studies have provided conflicting results that suggest that only one rubber hand can be perceived as one’s own. To address this issue, we developed a supernumerary hand illusion paradigm that allowed us to disambiguate ownership of individual rubber hands from simultaneous ownership of two fake hands. In our setup, the participant’s real right hand was hidden under a platform, while two identical right rubber hands were placed in parallel on top of the platform in direct view of the participant. We applied synchronous strokes to both rubber hands and the real hand (SS), synchronous strokes to one rubber hand and the real hand and asynchronous strokes to the other model hand (AS and SA) or asynchronous strokes to both fake hands in relation to the real hand (AA). Our results demonstrate that a genuine illusion of owning two rubber hands can be elicited and that such a supernumerary hand illusion can be isolated from the sense of ownership of a single rubber hand both in terms of questionnaire ratings and threat-evoked skin conductance responses (SCRs). These findings advance our knowledge about the dynamic flexibility and fundamental constraints of body representation and emphasize the importance of correlated afferent signals for causal inference in body ownership.

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The Relationship Between Referral of Touch and the Feeling of Ownership in the Rubber Hand Illusion

Frontiers in Psychology ◽

10.3389/fpsyg.2021.629590 ◽

2021 ◽

Vol 12 ◽

Author(s):

Arran T. Reader ◽

Victoria S. Trifonova ◽

H. Henrik Ehrsson

Keyword(s):

Positive Relationship ◽

Research Question ◽

Rubber Hand Illusion ◽

Body Ownership ◽

Experimental Paradigm ◽

Rubber Hand ◽

The Real ◽

Strong Positive Relationship ◽

The Relationship ◽

Real Hand

The rubber hand illusion (RHI) is one of the most commonly used paradigms to examine the sense of body ownership. Touches are synchronously applied to the real hand, hidden from view, and a false hand in an anatomically congruent position. During the illusion one may perceive that the feeling of touch arises from the false hand (referral of touch), and that the false hand is one's own. The relationship between referral of touch and body ownership in the illusion is unclear, and some articles average responses to statements addressing these experiences, which may be inappropriate depending on the research question of interest. To address these concerns, we re-analyzed three freely available datasets to better understand the relationship between referral of touch and feeling of ownership in the RHI. We found that most participants who report a feeling of ownership also report referral of touch, and that referral of touch and ownership show a moderately strong positive relationship that was highly replicable. In addition, referral of touch tends to be reported more strongly and more frequently than the feeling of ownership over the hand. The former observations confirm that referral of touch and ownership are related experiences in the RHI. The latter, however, indicate that when pooling the statements one may obtain a higher number of illusion ‘responders’ compared to considering the ownership statements in isolation. These results have implications for the RHI as an experimental paradigm.

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Decreased motor cortex excitability mirrors own hand disembodiment during the rubber hand illusion

eLife ◽

10.7554/elife.14972 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 35

Author(s):

Francesco della Gatta ◽

Francesca Garbarini ◽

Guglielmo Puglisi ◽

Antonella Leonetti ◽

Annamaria Berti ◽

...

Keyword(s):

Motor Evoked Potentials ◽

The Body ◽

Rubber Hand Illusion ◽

Body Ownership ◽

Rubber Hand ◽

Significant Drop ◽

Theoretical Understanding ◽

The Real ◽

Motor Cortex Excitability ◽

Real Hand

During the rubber hand illusion (RHI), subjects experience an artificial hand as part of their own body, while the real hand is subject to a sort of 'disembodiment'. Can this altered belief about the body also affect physiological mechanisms involved in body-ownership, such as motor control? Here we ask whether the excitability of the motor pathways to the real (disembodied) hand are affected by the illusion. Our results show that the amplitude of the motor-evoked potentials recorded from the real hand is significantly reduced, with respect to baseline, when subjects in the synchronous (but not in the asynchronous) condition experience the fake hand as their own. This finding contributes to the theoretical understanding of the relationship between body-ownership and motor system, and provides the first physiological evidence that a significant drop in motor excitability in M1 hand circuits accompanies the disembodiment of the real hand during the RHI experience.

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Is This Hand for Real? Attenuation of the Rubber Hand Illusion by Transcranial Magnetic Stimulation over the Inferior Parietal Lobule

Journal of Cognitive Neuroscience ◽

10.1162/jocn.2009.21095 ◽

2009 ◽

Vol 21 (7) ◽

pp. 1311-1320 ◽

Cited By ~ 90

Author(s):

Marjolein P. M. Kammers ◽

Lennart Verhagen ◽

H. Chris Dijkerman ◽

Hinze Hogendoorn ◽

Frederique De Vignemont ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Repetitive Transcranial Magnetic Stimulation ◽

Rubber Hand Illusion ◽

Rubber Hand ◽

Double Blind ◽

Independent Manner ◽

Posterior Parietal ◽

Parietal Lobule ◽

Real Hand

In the rubber hand illusion (RHI), participants incorporate a rubber hand into a mental representation of one's body. This deceptive feeling of ownership is accompanied by recalibration of the perceived position of the participant's real hand toward the rubber hand. Neuroimaging data suggest involvement of the posterior parietal lobule during induction of the RHI, when recalibration of the real hand toward the rubber hand takes place. Here, we used off-line low-frequency repetitive transcranial magnetic stimulation (rTMS) in a double-blind, sham-controlled within-subjects design to investigate the role of the inferior posterior parietal lobule (IPL) in establishing the RHI directly. Results showed that rTMS over the IPL attenuated the strength of the RHI for immediate perceptual body judgments only. In contrast, delayed perceptual responses were unaffected. Furthermore, ballistic action responses as well as subjective self-reports of feeling of ownership over the rubber hand remained unaffected by rTMS over the IPL. These findings are in line with previous research showing that the RHI can be broken down into dissociable bodily sensations. The illusion does not merely affect the embodiment of the rubber hand but also influences the experience and localization of one's own hand in an independent manner. Finally, the present findings concur with a multicomponent model of somatosensory body representations, wherein the IPL plays a pivotal role in subserving perceptual body judgments, but not actions or higher-order affective bodily judgments.

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The relationship between virtual body ownership and temperature sensitivity

Journal of The Royal Society Interface ◽

10.1098/rsif.2013.0300 ◽

2013 ◽

Vol 10 (85) ◽

pp. 20130300 ◽

Cited By ~ 46

Author(s):

Joan Llobera ◽

M. V. Sanchez-Vives ◽

Mel Slater

Keyword(s):

Temperature Sensitivity ◽

Tactile Stimulation ◽

Body Ownership ◽

Rubber Hand ◽

The Real ◽

Person Perspective ◽

Visual Presence ◽

Palm Of The Hand ◽

Real Hand ◽

Virtual Body

In the rubber hand illusion, tactile stimulation seen on a rubber hand, that is synchronous with tactile stimulation felt on the hidden real hand, can lead to an illusion of ownership over the rubber hand. This illusion has been shown to produce a temperature decrease in the hidden hand, suggesting that such illusory ownership produces disownership of the real hand. Here, we apply immersive virtual reality (VR) to experimentally investigate this with respect to sensitivity to temperature change. Forty participants experienced immersion in a VR with a virtual body (VB) seen from a first-person perspective. For half the participants, the VB was consistent in posture and movement with their own body, and in the other half, there was inconsistency. Temperature sensitivity on the palm of the hand was measured before and during the virtual experience. The results show that temperature sensitivity decreased in the consistent compared with the inconsistent condition. Moreover, the change in sensitivity was significantly correlated with the subjective illusion of virtual arm ownership but modulated by the illusion of ownership over the full VB. This suggests that a full body ownership illusion results in a unification of the virtual and real bodies into one overall entity—with proprioception and tactile sensations on the real body integrated with the visual presence of the VB. The results are interpreted in the framework of a ‘body matrix’ recently introduced into the literature.

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Forward modelling the rubber hand: illusion of ownership modifies motor-sensory predictions by the brain

Royal Society Open Science ◽

10.1098/rsos.160407 ◽

2016 ◽

Vol 3 (8) ◽

pp. 160407 ◽

Cited By ~ 5

Author(s):

Laura Aymerich-Franch ◽

Damien Petit ◽

Abderrahmane Kheddar ◽

Gowrishankar Ganesh

Keyword(s):

Haptic Perception ◽

Forward Model ◽

Rubber Hand Illusion ◽

Body Parts ◽

Rubber Hand ◽

Self And Other ◽

Sensory Predictions ◽

Motor Actions ◽

The Brain ◽

Real Hand

The question of how we attribute observed body parts as our own, and the consequences of this attribution on our sensory-motor processes, is fundamental to understand how our brain distinguishes between self and other. Previous studies have identified interactions between the illusion of ownership, and multi-sensory integration and cross-sensory predictions by the brain. Here we show that illusory ownership additionally modifies the motor-sensory predictions by the brain. In our preliminary experiments, we observed a new numbness illusion following the classical rubber-hand illusion (RHI); brushing only the rubber hand after induction of the RHI results in illusory numbness in one's real hand. Previous studies have shown that self-generated actions (like tickling) are attenuated by motor-sensory predictions by the so-called forward model . Motivated by this finding, here we examined whether the numbness illusion after the RHI is different when the rubber hand is brushed oneself, compared with when the brushing is performed by another. We observed that, all other conditions remaining the same, haptic perception in the real hand was lower (numbness higher) during self-generated brushing. Our result suggests that RHI reorganizes the forward model, such that we predict haptic consequences of self-generated motor actions on the rubber hand.

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When a rubber hand ‘feels’ what the real hand cannot

Neuroreport ◽

10.1097/00001756-199901180-00025 ◽

1999 ◽

Vol 10 (1) ◽

pp. 135-138 ◽

Cited By ~ 43

Author(s):

Chris Rorden ◽

Joost Heutink ◽

Eve Greenfield ◽

Ian H. Robertson

Keyword(s):

Rubber Hand ◽

The Real ◽

Real Hand

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Tactile information counteracts the attenuation of rubber hand illusion attributable to increased visuo-proprioceptive divergence

PLoS ONE ◽

10.1371/journal.pone.0244594 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0244594

Author(s):

Piotr Litwin ◽

Beata Zybura ◽

Paweł Motyka

Keyword(s):

Elbow Joint ◽

Discrimination Task ◽

Tactile Stimulation ◽

Rubber Hand Illusion ◽

Body Ownership ◽

Joint Position ◽

Rubber Hand ◽

Tactile Information ◽

The Real ◽

Position Discrimination

Sense of body ownership is an immediate and distinct experience of one’s body as belonging to oneself. While it is well-recognized that ownership feelings emerge from the integration of visual and somatosensory signals, the principles upon which they are integrated are still intensely debated. Here, we used the rubber hand illusion (RHI) to examine how the interplay of visual, tactile, and proprioceptive signals is governed depending on their spatiotemporal properties. For this purpose, the RHI was elicited in different conditions varying with respect to the extent of visuo-proprioceptive divergence (i.e., the distance between the real and fake hands) and differing in terms of the availability and spatiotemporal complexity of tactile stimulation (none, simple, or complex). We expected that the attenuating effect of distance on illusion strength will be more pronounced in the absence of touch (when proprioception gains relatively higher importance) and absent in the presence of complex tactile signals. Additionally, we hypothesized that participants with greater proprioceptive acuity—assessed using an elbow joint position discrimination task—will be less susceptible to the illusion, but only under the conditions of limited tactile stimulation. In line with our prediction, RHI was attenuated at the farthest distance only when tactile information was absent or simplified, but the attenuation was effectively prevented by the use of complex tactile stimulation—in this case, RHI was comparably vivid at both distances. However, passive proprioceptive acuity was not related to RHI strength in either of the conditions. The results indicate that complex-structured tactile signals can override the influence of proprioceptive signals in body attribution processes. These findings extend our understanding of body ownership by showing that it is primarily determined by informative cues from the most relevant sensory domains, rather than mere accumulation of multisensory evidence.

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