Visuo-tactile congruency influences the body schema during full body ownership illusion

Previous research showed that full body ownership illusions in virtual reality (VR) can be robustly induced by providing congruent visual stimulation, and that congruent tactile experiences provide a dispensable extension to an already established phenomenon. Here we show that visuo-tactile congruency indeed does not add to already high measures for body ownership on explicit measures, but does modulate movement behavior when walking in the laboratory. Specifically, participants who took ownership over a more corpulent virtual body with intact visuo-tactile congruency increased safety distances towards the laboratory’s walls compared to participants who experienced the same illusion with deteriorated visuo-tactile congruency. This effect is in line with the body schema more readily adapting to a more corpulent body after receiving congruent tactile information. We conclude that the action-oriented, unconscious body schema relies more heavily on tactile information compared to more explicit aspects of body ownership.     

Embodiment, ownership and disownership

There are two main pathways to investigate the sense of body ownership, (i) through the study of the conditions of embodiment for an object to be experienced as one's own and (ii) through the analysis of the deficits in patients who experience a body part as alien. Here, I propose that E is embodied if some properties of E are processed in the same way as the properties of one's body. However, one must distinguish among different types of embodiment, and only self-specific embodiment can lead to feelings of ownership. I address issues such as the functional role and the dynamics of embodiment, degrees and measures of ownership, and shared body representations between self and others. I then analyse the interaction between ownership and disownership. On the one hand, I show that there is no evidence that in the Rubber Hand Illusion, the rubber hand replaces the biological hand. On the other hand, I argue that the sense of disownership experienced by patients towards their body part cannot be reduced to the mere lack of ownership.     

The Feeling of Bodily Ownership

In certain startling neurological and psychiatric conditions, what is ordinarily most intimate and familiar to us—our own body—can feel alien. For instance, in cases of somatoparaphrenia subjects misattribute their body parts to others, while in cases of depersonalization subjects feel estranged from their bodies. These ownership disorders thus appear to consist in a loss of any feeling of bodily ownership, the felt sense we have of our bodies as our own. Against this interpretation of ownership disorders, I defend Sufficiency, the thesis that every experience of bodily awareness suffices for a feeling of bodily ownership. Since Sufficiency conflicts with a face-value interpretation of these ownership disorders, the burden is on me to explain away the apparent tension. To do so, I identify and correct what I believe to be the fundamental mistake in the extant literature on the feeling of bodily ownership, namely the tendency to treat the notion of a feeling of bodily ownership as a single psychological construct. Instead, I distinguish the feeling of minimal ownership, the first-personal character of bodily awareness, from the feeling of affective ownership, the distinctive type of felt concern we have for our bodies. I motivate this distinction by raising the disownership puzzle, the fact that subjects suffering from ownership disorders display an ambiguous set of symptoms, arguing the distinction I draw between minimal and affective ownership is just what is required to resolve the puzzle.     

身体拥有感错觉对疼痛的影响及其作用机制

身体拥有感错觉以多通道的感官整合为基础,包括视觉-触觉、视觉-本体感觉、触觉-本体感觉、视觉-内感受的整合等。来自实验室急性痛以及慢性痛的大量结果表明拥有感错觉可产生镇痛作用。身体部位尺寸大小、肢体透明度等相关影响因素也逐渐得到揭示。拥有感错觉影响疼痛的机制与身体表征的改变有关,该过程可能涉及“身体网络”与“疼痛网络”间的连接,其中后顶叶皮层可能有重要作用。未来研究应更为深入地探索拥有感错觉范式以考察不同因素对疼痛的影响;在现有多感官整合的范式中重视内感受的作用;考察拥有感错觉改变疼痛的认知神经机制;区分急、慢性痛条件下以及不同慢性痛类型中拥有感错觉对疼痛的不同影响。     

Illusory hand ownership in a patient with personal neglect for the upper limb,but no somatoparaphenia

The symptoms of patients with left personal neglect are characterized by inattention towards contralesional (left) body parts while at the same time explicitly ascertaining ownership for the neglected hemibody. It is currently unknown if personal neglect is associated with more subtle or implicit disturbances of own body perception and body ownership as measured with the rubber hand illusion. In this study, we report data from a patient with a right hemispheric lesion and personal neglect, without associated somatosensory deficits. We administered to the patient (and to 12 age‐matched controls) the rubber hand illusion paradigm to the right and left hands, to elicit illusory ownership for a fake hand, before and after recovery from personal neglect for the left arm. In a first session, run when the patient showed personal neglect affecting the left arm, he experienced a significantly enhanced subjective illusion of embodiment for the left fake hand as compared to the right hand (as assessed through a standard questionnaire). After recovery from personal neglect for the left arm (second session), the results of the left and right rubber hand illusion experiments were comparable, with no modulation of hand ownership. We argue that personal neglect may consist not only in an inattentional disorder, but also in a deficit of multisensory body representation characterized by a high sensitivity to experimental manipulations of subjective aspects of body ownership.     

身体拥有感及其可塑性：基于内外感受研究的视角

身体自我表征中的身体拥有感(即我的身体属于我的感受)问题一直是自我意识研究的核心话题。大量的已有研究表明, 身体拥有感的体验涉及不同感官信号的整合, 当前大多数研究只重视视觉、触觉等外感受的作用, 一方面忽视了内感受的作用, 另一方面也缺乏对两类感受整合的关注。橡胶手错觉实验和身体障碍患者身上所表现出的外感受和内感受对身体拥有感的影响支持了身体拥有感的可塑性假设, 自由能量原理认为身体拥有感形成的基础是大脑不断评估更新可能性表征来维持稳定。未来的研究需要从改善内感受的测量和刺激呈现方法, 探索影响内感受的高阶认知因素以及关注某些神经症患者的内感受等方面寻求突破。     

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

A key tool for investigating body ownership is the rubber hand illusion, in which synchronous multisensory feedback can induce feelings of ownership over a fake hand. Much research in the field aims to tease apart the mechanisms that underlie this phenomenon. Currently there is conflicting evidence as to whether increasing the distance between the real and fake hands (within reaching space) can reduce the illusion. The current study examines this further by modulating, not only the absolute distance between the real and fake hands but also their relative distance from body midline. It is found that the strength of the illusion is reduced only when the fake hand is both far from the real hand and far from the trunk; illusion scores over a fake hand in the same position can then be increased by moving the real hand nearer. This is related to peripersonal space surrounding the trunk and the hand. Subjective disownership of the real hand, and proprioceptive drift measures were also taken and may be driven by different mechanisms.     

Out of the body: embodiment and its vicissitudes

Body‐mind dualism and the consequent neglect of the body of the analyst can have important negative effects on the analytical process leading all too often to misinterpretations of the analysand's verbal and non‐verbal communications and to disturbances of analytical temporality. This is intensified when we are dealing with individuals where disembodiment and states of psychic deadness are central features. The paper explores the philosophical roots of the idea of a disembodied mind and the way in which this impacts our relationship with the world. While André Green's concept of the dead mother and disturbances in the sense of self‐agency have been held to play an important role in states of psychic deadness, I suggest that it is rather disturbances in the sense of body ownership and of the body image which are more central. The paper then discusses the particular kinds of countertransference that can be evoked in the analyst when we find ourselves dealing with this type of patient and suggests how we can use our embodied countertransference to become aware of and elaborate our own feelings of deadness in order to overcome the loss of temporality that is characteristic of such states. This is illustrated with reference to my work with a young man with a masochistic perversion and a severe disturbance of the body image with an accompanying profound sense of psychic deadness.     

The multisensory basis of the self: From body to identity to others

By grounding the self in the body, experimental psychology has taken the body as the starting point for a science of the self. One fundamental dimension of the bodily self is the sense of body ownership that refers to the special perceptual status of one’s own body, the feeling that “my body” belongs to me. The primary aim of this review article is to highlight recent advances in the study of body ownership and our understanding of the underlying neurocognitive processes in three ways. I first consider how the sense of body ownership has been investigated and elucidated in the context of multisensory integration. Beyond exteroception, recent studies have considered how this exteroceptively driven sense of body ownership can be linked to the other side of embodiment, that of the unobservable, yet felt, interoceptive body, suggesting that these two sides of embodiment interact to provide a unifying bodily self. Lastly, the multisensorial understanding of the self has been shown to have implications for our understanding of social relationships, especially in the context of self–other boundaries. Taken together, these three research strands motivate a unified model of the self inspired by current predictive coding models.     

控制和外界客体社会效价对身体拥有感的影响

研究采用运动橡胶手错觉范式,操纵了“控制”和“社会效价”两个变量,通过行为实验探讨了控制和社会效价对身体拥有感的影响。结果发现,与“被动控制”条件相比,“主动控制”条件产生了更强的拥有感; 与“不利”条件相比,“有利”条件产生了更强的拥有感。且“控制”和“社会效价”的交互作用显著:无论哪种控制条件,有利条件下的拥有感都显著高于不利条件下的拥有感; 无论哪种效价条件,主动控制条件下的拥有感均显著高于被动控制条件下的拥有感。该结果表明,控制和社会效价是产生身体拥有感的条件。研究结果为提高假肢佩戴者对假肢的心理接纳程度提供了有益的训练途径。     

Body ownership: When feeling and knowing diverge

Individuals with the peculiar disturbance of ‘overcompleteness’ experience an intense desire to amputate one of their healthy limbs, describing a sense of disownership for it (Body Integrity Identity Disorder – BIID). This condition is similar to somatoparaphrenia, the acquired delusion that one’s own limb belongs to someone else. In ten individuals with BIID, we measured skin conductance response to noxious stimuli, delivered to the accepted and non-accepted limb, touching the body part or simulating the contact (stimuli approach the body without contacting it), hypothesizing that these individuals have responses like somatoparaphrenic patients, who previously showed reduced pain anticipation, when the threat was directed to the disowned limb. We found reduced anticipatory response to stimuli approaching, but not contacting, the unwanted limb. Conversely, stimuli contacting the non-accepted body-part, induced stronger SCR than those contacting the healthy parts, suggesting that feeling of ownership is critically related to a proper processing of incoming threats.     

Multisensory integration and age-dependent sensitivity to body representation modification induced by the rubber hand illusion

The aim of the present study was to compare junior and senior healthy participants for their multimodal integration capability. The instrument used for the investigation was the rubber hand illusion (RHI) where synchronous and asynchronous multimodal stimulation were applied. The study focused on assessing the rate of integration for visuo-tactile and visuo-proprioceptive stimuli. Methods: From a large sample of right-handed volunteers, 50 senior employees (containing younger and middle age adults) and 51 senior retired (senior adults) participants were recruited. Results: The between-subject analyses revealed that individuals both the junior and the senior participants responded to induction of RHI with vivid ownership and disownership experiences and a higher mislocalization error in the synchronous condition. However, the between-group analysis showed that participants in the senior group reported less vivid ownership and less vivid total RHI experiences scores compared to members of the junior group, but no mislocalization error differences were found between the groups. Conclusion: The results indicated that when visuo-tactile stimuli synchronously presented, the gain in multisensory integration decreased in seniors group. In contrast, in the case of visuo-proprioceptive synchronous presentation, the efficiency of multisensory integration remained unchanged across the lifespan.     

Assisted Suicide: Do We Own Our Bodies?

Abstract:  The ethics of physician‐assisted suicide is explored here in light of classic philosophical discussions of the ownership of one's body plus biblical discussions of the relationship of body and soul. Motives for individual and group suicide are brought to bear on bioethical principles such as that of autonomy. Ethical analysis is here challenged by the case of a 91 year‐old woman, Ragnhild, who lived after professional judgments that her life should be ended.     

No-Self and the Phenomenology of Ownership

The Abhidharma Buddhist revisionary metaphysics aims to provide an intellectually and morally preferred picture of the world that lacks a self. The first part of the paper claims that the Abhidharma ‘no-self’ view can be plausibly interpreted as a no-ownership view, according to which there is no locus or subject of experience and thus no owner of mental or bodily awarenesses. On this interpretation of the no-self view, the Abhidharma Buddhist metaphysicians are committed to denying the ownership of experiences, and thereby apparently obliged to explain our purported experience of ownership. My experiences seemingly come with the sense that I am the one who is undergoing this experience. But is there a really an experience of ownership—namely, an experience of being a subject that underlies our sense of ownership? I argue that there is nothing that it is like to be an owner of experiences, in the sense that there is no experiential phenomenology associated with the ownership of experience. The second part of the paper argues that, since there is no experience of ownership, there is no onus on the Abhidharma philosopher to give an explanation of the sense of ownership.     

Sense of body ownership in patients affected by functional motor symptoms (conversion disorder)

Background and aimPatients with functional neurological symptoms are commonly seen in neurological practice. Nevertheless their aetiopathology remains unclear. We have recently shown that patients affected by functional motor symptoms (FMS) present lower interoceptive awareness and higher alexithymia levels than healthy controls. Nevertheless sense of body ownership has never been studied in FMS patients.The aim of the present study was to systematically investigate the sense of body ownership, with the rubber hand illusion (RHI) paradigm, in patients with FMS and healthy controls.Materials and methodsWe included in the study 16 patients with FMS and 18 healthy controls (HC). Patients and HC were asked to complete the Toronto Alexithymia Scale (TAS-20) and the self-consciousness scale (self-objectification questionnaire). All participants underwent the RHI paradigm: illusionary experience was measured by self-report and by proprioceptive alteration.ResultsA Mann–Whitney U test performed revealed that FMS (median = 2.11) participants embodied the rubber hand to the same extent than HC participants (median = 2.0, Z = −0.86, p > 0.05, r = −0.15). The same test revealed no significant difference in the Proprioceptive Drift experience between FMS (median = 0.0) and HC participants (median = −0.5, Z = −0.96, p > 0.05, r = −0.16).ConclusionsOur study revealed that sense of body ownership is not impaired in patients affected by FMS. This, together with the results from our previous experiment (studying the interoceptive awareness), supports the hypothesis that interoceptive awareness and sense of body ownership may be dissociated in patients with FMS.     

The role of affective touch in whole-body embodiment remains equivocal

Previous studies have highlighted that affective touch delivered at slow velocities (1–10 cm/s) enhances body-part embodiment during multisensory illusions, yet its role towards whole-body embodiment is less established. Across two experiments, we investigated the role of affective touch towards subjective embodiment of a whole mannequin body within the full body illusion, amongst healthy females. Participants perceived affective touch to be more pleasant than non-affective touch, but this did not enhance subjective embodiment within the illusion and no interaction between synchrony (Experiment 1), or congruency (Experiment 2), and the velocity of touch was observed. Finally, the perceived pleasantness of touch was not modulated by subthreshold eating disorder psychopathology, as measured by means of a self-report questionnaire. Therefore, the present findings suggest that enhancement of embodiment due to affective touch may be body-part specific, and not generalise to greater ownership towards a whole body.     

虚拟所有权关系下的自我参照效应

通过两个实验,探讨了代词所确定的所有权关系对记忆的影响。实验1为2(参照条件:我的与他的)×3(报告类型:主试跟读、被试跟读与被试自己读)的混合设计,实验2为2(参照条件:我的与他的)×2(报告顺序:自己先报告与他人先报告)的被试内设计。实验中被试按相应的要求报告物品的所有权关系。结果发现,被试对自己的物品的回忆成绩显著高于对他人物品的回忆成绩,表现出所有权效应,说明即使由代词确定的虚拟所有权关系也对记忆有影响。     

Body-ownership for actively operated non-corporeal objects

Rubber-hand and virtual-hand illusions show that people can perceive body ownership for objects under suitable conditions. Bottom-up approaches assume that perceived ownership emerges from multisensory matching (e.g., between seen object and felt hand movements), whereas top-down approaches claim that novel body parts are integrated only if they resemble some part of a permanent internal body representation. We demonstrate that healthy adults perceive body ownership for a virtual balloon changing in size, and a virtual square changing in size or color, in synchrony with movements of their real hand. This finding is inconsistent with top-down approaches and amounts to an existence proof that non-corporeal events can be perceived as body parts if their changes are systematically related to one’s actions. It also implies that previous studies with passive-stimulation techniques might have underestimated the plasticity of body representations and put too much emphasis on the resemblance between viewed object and real hand.     

Active control as evidence in favor of sense of ownership in the moving Virtual Hand Illusion

The sense of ownership, the feeling that our body belongs to ourselves, relies on multiple sources of sensory information. Among these sources, the contribution of visuomotor information is still debated. We tested the effect of active control in the sense of ownership in the moving Virtual Hand Illusion. Participants reported sense of ownership and sense of agency over a virtual arm in which we manipulated the morphological congruence of the hand and the visuomotor information. We found that congruent active control enhanced and maintained the reported sense of ownership over a hand that appeared detached from the body, but not in a morphological congruent limb. Also, incongruent active control, achieved by adding noise to the trajectory of the movement, decreased both reported sense of agency and ownership. Overall, our results are consistent with a framework in which active control acts as evidence for eliciting a sense of ownership.     

Bodily ownership and self-location: Components of bodily self-consciousness

Recent research on bodily self-consciousness has assumed that it consists of three distinct components: the experience of owning a body (body ownership); the experience of being a body with a given location within the environment (self-location); and the experience of taking a first-person, body-centered, perspective on that environment (perspective). Here we review recent neuroimaging studies suggesting that at least two of these components—body ownership and self-location—are implemented in rather distinct neural substrates, located, respectively, in the premotor cortex and in the temporo-parietal junction. We examine these results and consider them in relation to clinical evidence from patients with altered body perception and work on a variety of multisensory, body-related illusions, such as the rubber hand illusion, the full body illusion, the body swap illusion and the enfacement illusion. We conclude by providing a preliminary synthesis of the data on bodily self-consciousness and its neural correlates.