scholarly journals How to lose a hand: Sensory updating drives disembodiment

2020 ◽  
Author(s):  
Roland Pfister ◽  
Annika L. Klaffehn ◽  
Andreas Kalckert ◽  
Wilfried Kunde ◽  
David Dignath
Keyword(s):  
Multisensory Integration ◽  
Body Representation ◽  
The Body ◽  
Rubber Hand ◽  
Body Representations ◽  
Dynamic View ◽  
Single Instance ◽  
Multisensory Input ◽  
To Receive ◽  
Real Hand

AbstractBody representations are readily expanded based on sensorimotor experience. A dynamic view of body representations, however, holds that these representations cannot only be expanded but that they can also be narrowed down by disembodying elements of the body representation that are no longer warranted. Here we induced illusory ownership in terms of a moving rubber hand illusion and studied the maintenance of this illusion across different conditions. We observed ownership experience to decrease gradually unless participants continued to receive confirmatory multisensory input. Moreover, a single instance of multisensory mismatch – a hammer striking the rubber hand but not the real hand – triggered substantial and immediate disembodiment. Together, these findings support and extend previous theoretical efforts to model body representations through basic mechanisms of multisensory integration. They further support an updating model suggesting that embodied entities fade from the body representation if they are not refreshed continuously.

scholarly journals Embodied precision: Intranasal oxytocin modulates multisensory integration

2018 ◽  
Author(s):  
Laura Crucianelli ◽  
Yannis Paloyelis ◽  
Lucia Ricciardi ◽  
Paul M Jenkinson ◽  
Aikaterini Fotopoulou
Keyword(s):  
Multisensory Integration ◽  
Tactile Stimulation ◽  
Estimation Error ◽  
The Body ◽  
Multisensory Perception ◽  
Subjective Feeling ◽  
Rubber Hand ◽  
Perceptual Inference ◽  
Double Blind ◽  
Multisensory Input

AbstractMultisensory integration processes are fundamental to our sense of self as embodied beings. Bodily illusions, such as the rubber hand illusion (RHI) and the size-weight illusion (SWI), allow us to investigate how the brain resolves conflicting multisensory evidence during perceptual inference in relation to different facets of body representation. In the RHI, synchronous tactile stimulation of a participant’s hidden hand and a visible rubber hand creates illusory bodily ownership; in the SWI, the perceived size of the body can modulate the estimated weight of external objects. According to Bayesian models, such illusions arise as an attempt to explain the causes of multisensory perception and may reflect the attenuation of somatosensory precision, which is required to resolve perceptual hypotheses about conflicting multisensory input. Recent hypotheses propose that the precision or salience of sensorimotor representations is determined by modulators of synaptic gain, like dopamine, acetylcholine and oxytocin. However, these neuromodulatory hypotheses have not been tested in the context of embodied multisensory integration. The present, double-blind, placebo-controlled, crossed-over study (N = 41 healthy volunteers) aimed to investigate the effect of intranasal oxytocin (IN-OT) on multisensory integration processes, tested by means of the RHI and the SWI. Results showed that IN-OT enhanced the subjective feeling of ownership in the RHI, only when synchronous tactile stimulation was involved. Furthermore, IN-OT increased the embodied version of the SWI (quantified as weight estimation error). These findings suggest that oxytocin might modulate processes of visuo-tactile multisensory integration by increasing the precision of top-down signals against bottom-up sensory input.

scholarly journals Embodied Precision: Intranasal Oxytocin Modulates Multisensory Integration

2019 ◽  
Vol 31 (4) ◽  
pp. 592-606 ◽  
Author(s):  
Laura Crucianelli ◽  
Yannis Paloyelis ◽  
Lucia Ricciardi ◽  
Paul M. Jenkinson ◽  
Aikaterini Fotopoulou
Keyword(s):  
Multisensory Integration ◽  
Tactile Stimulation ◽  
Estimation Error ◽  
The Body ◽  
Multisensory Perception ◽  
Subjective Feeling ◽  
Body Ownership ◽  
Rubber Hand ◽  
Perceptual Inference ◽  
Multisensory Input

Multisensory integration processes are fundamental to our sense of self as embodied beings. Bodily illusions, such as the rubber hand illusion (RHI) and the size–weight illusion (SWI), allow us to investigate how the brain resolves conflicting multisensory evidence during perceptual inference in relation to different facets of body representation. In the RHI, synchronous tactile stimulation of a participant's hidden hand and a visible rubber hand creates illusory body ownership; in the SWI, the perceived size of the body can modulate the estimated weight of external objects. According to Bayesian models, such illusions arise as an attempt to explain the causes of multisensory perception and may reflect the attenuation of somatosensory precision, which is required to resolve perceptual hypotheses about conflicting multisensory input. Recent hypotheses propose that the precision of sensorimotor representations is determined by modulators of synaptic gain, like dopamine, acetylcholine, and oxytocin. However, these neuromodulatory hypotheses have not been tested in the context of embodied multisensory integration. The present, double-blind, placebo-controlled, crossover study ( n = 41 healthy volunteers) aimed to investigate the effect of intranasal oxytocin (IN-OT) on multisensory integration processes, tested by means of the RHI and the SWI. Results showed that IN-OT enhanced the subjective feeling of ownership in the RHI, only when synchronous tactile stimulation was involved. Furthermore, IN-OT increased an embodied version of the SWI (quantified as estimation error during a weight estimation task). These findings suggest that oxytocin might modulate processes of visuotactile multisensory integration by increasing the precision of top–down signals against bottom–up sensory input.

scholarly journals Multisensory integration involved in the body perception of community-dwelling older adults

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Hide ◽  
Y. Ito ◽  
N. Kuroda ◽  
M. Kanda ◽  
W. Teramoto
Keyword(s):  
Older Adults ◽  
Multisensory Integration ◽  
Fall Risk ◽  
Community Dwelling ◽  
The Body ◽  
Risk Of Falling ◽  
Body Perception ◽  
Rubber Hand ◽  
Timed Up And Go ◽  
Community Dwelling Older Adults

AbstractThis study investigates how the multisensory integration in body perception changes with increasing age, and whether it is associated with older adults’ risk of falling. For this, the rubber hand illusion (RHI) and rubber foot illusion (RFI) were used. Twenty-eight community-dwelling older adults and 25 university students were recruited. They viewed a rubber hand or foot that was stimulated in synchrony or asynchrony with their own hidden hand or foot. The illusion was assessed by using a questionnaire, and measuring the proprioceptive drift and latency. The Timed Up and Go Test was used to classify the older adults into lower and higher fall-risk groups. No difference was observed in the RHI between the younger and older adults. However, several differences were observed in the RFI. Specifically, the older adults with a lower fall-risk hardly experienced the illusion, whereas those with a higher fall-risk experienced it with a shorter latency and no weaker than the younger adults. These results suggest that in older adults, the mechanism of multisensory integration for constructing body perception can change depending on the stimulated body parts, and that the risk of falling is associated with multisensory integration.

scholarly journals Effect of Body Representation Level of an Avatar on Quality of AR-Based Remote Instruction

2020 ◽  
Vol 4 (1) ◽  
pp. 3
Author(s):  
Tzu-Yang Wang ◽  
Yuji Sato ◽  
Mai Otsuki ◽  
Hideaki Kuzuoka ◽  
Yusuke Suzuki
Keyword(s):  
Augmented Reality ◽  
Body Representation ◽  
The Body ◽  
Instruction System ◽  
Three Body ◽  
To Receive ◽  
Representation Level

In manufacturing, augmented reality (AR)-based remote instruction systems, which enable workers to receive instructions from an avatar, are widely used. In this study, we developed such a system and investigated the effect of the body representation level of the avatar on the quality of AR-based remote instruction. Drawing on the avatar designs of previous works, three different avatar designs (“Hand only”, “Hand + Arm”, and “Body”), representing three body representation levels, were created. In the experiment with a within-participant design, the avatar pointed at blocks sequentially and participants touched each block as soon as they identified it. The results of the experiment indicate that an AR-based remote instruction system with a “Body” avatar exhibits higher usability and can enable the participants to have a lower workload and higher efficiency.

scholarly journals Remote hand: Hand-centered peripersonal space transfers to a disconnected hand avatar

2021 ◽  
Author(s):  
Daisuke Mine ◽  
Kazuhiko Yokosawa
Keyword(s):  
Virtual Environment ◽  
Body Representation ◽  
Peripersonal Space ◽  
The Body ◽  
The Real ◽  
Novel Technique ◽  
Near Space ◽  
Behavioral Evidence ◽  
Real Hand

The space surrounding our body is called peripersonal space (PPS). It has been reported that visuo-tactile facilitation occurs more strongly within PPS than outside PPS. Furthermore, previous research has revealed several methods by which PPS can be extended. The present study provides the first behavioral evidence of the transfer of PPS in a virtual environment by a novel technique. PPS representation was investigated using a remote-controlled hand avatar presented far from their body in a virtual environment. Participants showed strongest visuo-tactile facilitation at the far space around the remote hand and no facilitation at the near space around the real hand, suggesting that PPS transfers from near the body to the space around the hand avatar. The present results extend previous findings of the plasticity of PPS and demonstrate flexibility of PPS representation beyond the physical and anatomical limits of body representation.

scholarly journals The supernumerary rubber hand illusion revisited: perceived duplication of limbs and visuotactile events

2020 ◽  
Author(s):  
Chenggui Fan ◽  
H. Henrik Ehrsson
Keyword(s):  
Cognitive Neuroscience ◽  
Body Representation ◽  
Rubber Hand Illusion ◽  
Body Ownership ◽  
Rubber Hand ◽  
Real Right ◽  
The Real ◽  
Skin Conductance Responses ◽  
Supernumerary Limbs ◽  
Real Hand

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.

scholarly journals Rubber Hand Illusion does not arise from comparisons with internal body models: a new multisensory integration account of the sense of ownership

2018 ◽  
Author(s):  
Piotr Litwin
Keyword(s):  
Multisensory Integration ◽  
Human Body ◽  
The Body ◽  
Rubber Hand Illusion ◽  
Multisensory Perception ◽  
Top Down ◽  
Rubber Hand ◽  
Sense Of Ownership ◽  
Body Model ◽  
Internal Body

Human body sense is surprisingly flexible – precisely administered multisensory stimulation may result in the illusion that an external object is part of one’s body. There seems to be a general consensus that there are certain top-down constraints on which objects may be incorporated: in particular, to-be-embodied objects should be structurally similar to a visual representation stored in an internal body model for a shift in one’s body image to occur. However, empirical evidence contradicts the body model hypothesis: the sense of ownership may be spread over objects strikingly distinct in morphology and structure (e.g., robotic arms or empty space) and direct empirical support for the theory is currently lacking. As an alternative, based on the example of the rubber hand illusion (RHI), I propose a multisensory integration account of how the sense of ownership is induced. In this account, the perception of one’s own body is a regular type of multisensory perception and multisensory integration processes are not only necessary but also sufficient for embodiment. In this paper, I propose how RHI can be modeled with the use of Maximum Likelihood Estimation and natural correlation rules. I also discuss how Bayesian Coupling Priors and idiosyncrasies in sensory processing render prior distributions interindividually variable, accounting for large interindividual differences in susceptibility to RHI. Taken together, the proposed model accounts for exceptional malleability of human body perception, fortifies existing bottom-up multisensory integration theories with top-down models of relatedness of sensory cues, and generates testable and disambiguating predictions.

scholarly journals Implicit and Explicit Body Representations

2015 ◽  
Vol 20 (1) ◽  
pp. 6-15 ◽  
Author(s):  
Matthew R. Longo
Keyword(s):  
Sensory Information ◽  
Body Representation ◽  
Position Sense ◽  
The Body ◽  
Size Perception ◽  
Somatosensory Processing ◽  
Body Representations ◽  
Size And Shape ◽  
Tactile Localization ◽  
Somatosensory Information

Several forms of perception require that sensory information be referenced to representations of the size and shape of the body. This requirement is especially acute in somatosensation in which the main receptor surface (i.e., the skin) is itself coextensive with the body. This paper reviews recent research investigating the body representations underlying somatosensory information processing, including abilities such as tactile localization, tactile size perception, and position sense. These representations show remarkably large and stereotyped distortions of represented body size and shape. Intriguingly, these distortions appear to mirror distortions characteristic of somatosensory maps, though in attenuated form. In contrast, when asked to make overt judgments about perceived body form, participants are generally quite accurate. This pattern of results suggests that higher-level somatosensory processing relies on a class of implicit body representation, distinct from the conscious body image. I discuss the implications of these results for understanding the nature of body representation and the factors that influence it.

scholarly journals Bodily ownership of an independent supernumerary limb: An exploratory study

2021 ◽  
Author(s):  
Kohei Umezawa ◽  
Yuta Suzuki ◽  
Gowrishankar Ganesh ◽  
Yoichi Miyawaki
Keyword(s):  
Human Brain ◽  
Sensory Feedback ◽  
Body Representation ◽  
The Body ◽  
Artificial Limbs ◽  
Cognitive Measures ◽  
Rubber Hand ◽  
Artificial Limb ◽  
Sense Of Ownership ◽  
Induced Changes

AbstractCan 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 rubberhand illusion experiment, a plethora of studies has 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.

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