The role of distance from the body and distance from the real hand in ownership and disownership during the rubber hand illusion

2013 ◽  
Vol 142 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Catherine Preston
eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Francesco della Gatta ◽  
Francesca Garbarini ◽  
Guglielmo Puglisi ◽  
Antonella Leonetti ◽  
Annamaria Berti ◽  
...  

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.


2020 ◽  
Author(s):  
Chenggui Fan ◽  
H. Henrik Ehrsson

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.


2021 ◽  
Author(s):  
Arran T Reader

The sense of body ownership (the feeling that the body belongs to the self) is commonly believed to arise through multisensory integration. This is famously shown in the rubber hand illusion (RHI), where touches applied synchronously to a false hand and to the participant’s real hand (which is hidden from view) can induce a sensation of ownership over the fake one. Asynchronous touches weaken the illusion, and are typically used as a control condition. Subjective experience during the illusion is measured using a questionnaire, with some statements designed to capture illusory sensation and others designed as controls. However, recent work by Lush (2020, Collabra: Psychology) claimed that participants may have different levels of expectation for questionnaire items in the synchronous condition compared to the asynchronous condition, and for the illusion-related items compared to the control items. This may mean that the classic RHI questionnaire is poorly controlled for demand characteristics. As such, Lush (2020) suggested that subjective reports in the RHI may reflect compliance or even the generation of experience to meet expectations (‘phenomenological control’), rather than multisensory processes underlying the sense of body ownership. In the current work a conceptual replication of Lush (2020) was performed with an improved experimental design. Participants were presented with a video of the RHI procedure and reported the sensations they would expect to experience, both in open questions and by rating questionnaire items. In keeping with Lush (2020), participants had greater expectations for illusion statements in the synchronous condition compared to the asynchronous condition, and for illusion statements compared to control statements. However, there was also evidence that some expectations may be driven by exposure to the questionnaire items rather than exposure to the illusion procedure. The role of pre-illusion expectations and expectations driven by questionnaire exposure in the RHI require further examination.


2017 ◽  
Vol 179 ◽  
pp. 68-77 ◽  
Author(s):  
Alyanne M. de Haan ◽  
Haike E. Van Stralen ◽  
Miranda Smit ◽  
Anouk Keizer ◽  
Stefan Van der Stigchel ◽  
...  

2021 ◽  
Vol 12 ◽  
Author(s):  
Arran T. Reader ◽  
Victoria S. Trifonova ◽  
H. Henrik Ehrsson

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.


2014 ◽  
Vol 26 (4) ◽  
pp. 712-721 ◽  
Author(s):  
Mirta Fiorio ◽  
Caterina Mariotti ◽  
Marta Panzeri ◽  
Emanuele Antonello ◽  
Joseph Classen ◽  
...  

The sense of the body is deeply rooted in humans, and it can be experimentally manipulated by inducing illusions in at least two aspects: a subjective feeling of ownership and a proprioceptive sense of limb position. Previous studies mapped these different aspects onto anatomically distinct neuronal regions, with the ventral premotor cortex processing subjective experience of ownership and the inferior parietal lobule processing proprioceptive calibration. Lines of evidence suggest an involvement also of the cerebellum, but its precise role is not clear yet. To investigate the contribution of the cerebellum in the sense of body ownership, we applied the rubber-hand illusion paradigm in 28 patients affected by neurodegenerative cerebellar ataxia, selectively involving the cerebellum, and in 26 age-matched control participants. The rubber hand illusion is established by synchronous stroking of the participants' real unseen hand and a visible fake hand. Short asynchronous stroking does not bring about the illusion. We tested the subjective experience of the illusion, evaluated through a questionnaire and the proprioceptive drift of the real unseen hand toward the viewed rubber hand. In patients with cerebellar ataxia, we observed reduced sense of the subjective illusory experience specifically after synchronous stroking. In contrast, the proprioceptive drift was enhanced after synchronous and after asynchronous stimulation. These findings support the contention that the mechanisms underlying the presence of the illusion and the proprioceptive drift may be differently affected in different conditions. Impairment of the subjective sense of the illusion in cerebellar patients might hint at an involvement of cerebellar-premotor networks, whereas the proprioceptive drift typically associated with synchronous stroking appears to rely on other circuits, likely involving the cerebellum and the parietal regions.


2020 ◽  
Vol 82 (8) ◽  
pp. 4084-4095
Author(s):  
Roberto Erro ◽  
Angela Marotta ◽  
Mirta Fiorio

Abstract In the rubber hand illusion (RHI), simultaneous brush stroking of a subject’s hidden hand and a visible rubber hand induces a transient illusion of the latter to “feel like it’s my hand” and a proprioceptive drift of the hidden own hand toward the rubber hand. Recent accounts of the RHI have suggested that the illusion would only occur if weighting of conflicting sensory information and their subsequent integration results in a statistically plausible compromise. In three different experiments, we investigated the role of distance between the two hands as well as their proximity to the body’s midline in influencing the occurrence of the illusion. Overall, the results suggest that the illusion is abolished when placing the two hands apart, therefore increasing the mismatch between the visual and proprioceptive modality, whereas the proximity of the two hands to the body’s midline plays only a minor role on the subjective report of the illusion. This might be driven by the response properties of visuotactile bimodal cells encoding the peripersonal space around the hand.


2018 ◽  
Vol 31 (6) ◽  
pp. 537-555 ◽  
Author(s):  
Jennifer L. Campos ◽  
Graziella El-Khechen Richandi ◽  
Babak Taati ◽  
Behrang Keshavarz

Percepts about our body’s position in space and about body ownership are informed by multisensory feedback from visual, proprioceptive, and tactile inputs. The Rubber Hand Illusion (RHI) is a multisensory illusion that is induced when an observer sees a rubber hand being stroked while they feel their own, spatially displaced, and obstructed hand being stroked. When temporally synchronous, the visual–tactile interactions can create the illusion that the rubber hand belongs to the observer and that the observer’s real hand is shifted in position towards the rubber hand. Importantly, little is understood about whether these multisensory perceptions of the body change with older age. Thus, in this study we implemented a classic RHI protocol (synchronous versus asynchronous stroking) with healthy younger (18–35) and older (65+) adults and measured the magnitude of proprioceptive drift and the subjective experience of body ownership. As an adjunctive objective measure, skin temperature was recorded to evaluate whether decreases in skin temperature were associated with illusory percepts, as has been shown previously. The RHI was observed for both age groups with respect to increased drift and higher ratings of ownership following synchronous compared to asynchronous stroking. Importantly, no effects of age and no interactions between age and condition were observed for either of these outcome measures. No effects were observed for skin temperature. Overall, these results contribute to an emerging field of research investigating the conditions under which age-related differences in multisensory integration are observed by providing insights into the role of visual, proprioceptive, and tactile inputs on bodily percepts.


2018 ◽  
Author(s):  
Maria Laura Filippetti ◽  
Louise P. Kirsch ◽  
Laura Crucianelli ◽  
Aikaterini Fotopoulou

AbstractOur sense of body ownership relies on integrating different sensations according to their temporal and spatial congruency. Nevertheless, there is ongoing controversy about the role of affective congruency during multisensory integration, i.e. whether the stimuli to be perceived by the different sensory channels are congruent or incongruent in terms of their affective quality. In the present study, we applied a widely used multisensory integration paradigm, the Rubber Hand Illusion, to investigate the role of affective, top-down aspects of sensory congruency between visual and tactile modalities in the sense of body ownership. In Experiment 1 (N = 36), we touched participants with either soft or rough fabrics in their unseen hand, while they watched a rubber hand been touched synchronously with the same fabric or with a ‘hidden’ fabric of ‘uncertain roughness’. In Experiment 2 (N = 50), we used the same paradigm as in Experiment 1, but replaced the ‘uncertainty’ condition with an ‘incongruent’ one, in which participants saw the rubber hand being touched with a fabric of incongruent roughness and hence opposite valence. We found that certainty (Experiment 1) and congruency (Experiment 2) between the felt and vicariously perceived tactile affectivity led to higher subjective embodiment compared to uncertainty and incongruency, respectively, irrespective of any valence effect. Our results suggest that congruency in the affective top-down aspects of sensory stimulation is important to the multisensory integration process leading to embodiment, over and above temporal and spatial properties.


2021 ◽  
Author(s):  
Daisuke Mine ◽  
Kazuhiko Yokosawa

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.


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