Open peer commentary on the article “The Plasticity of the Bodily Self: Head Movements in Bodily Illusions and Their Relation to Gallagher’s Body Image and Body Schema” by Marte Roel Lesur, Michael Gaebler, Philippe Bertrand & Bigna Lenggenhager.: In my commentary, I raise some questions about the applicability of Gallagher’s distinction between body image and body schema to the experimental research reported and discussed in the target article. I suggest that the distinction between body image (...) and body schema is of limited help in this context, and that Gallagher’s distinction between sense of ownership and sense of agency provides a more natural and fruitful theoretical framework to discuss that research. (shrink)

This paper analyzes in the use of virtual reality when used to induce full-body ownership in violent offenders in order to elicit empathetic feelings by allowing them to embody the virtual body of a victim of domestic abuse. The authors explore potentially harmful effects to individuals participating in this kind of therapy and question whether consent is fully informed. The paper concludes with guidelines for ethical research and rehabilitation using this innovative technology.

In rubber hand illusions and full body illusions, touch sensations are projected to non-body objects such as rubber hands, dolls or virtual bodies. The robustness, limits and further perceptual consequences of such illusions are not yet fully explored or understood. A number of experiments are reported that test the limits of a variant of the rubber hand illusion. Methodology/Principal Findings -/- A variant of the rubber hand illusion is explored, in which the real and foreign (...) hands are aligned in personal space. The presence of the illusion is ascertained with participants' scores and temperature changes of the real arm. This generates a basic illusion of touch projected to a foreign arm. Participants are presented with further, unusual visuotactile stimuli subsequent to onset of the basic illusion. Such further visuotactile stimulation is found to generate very unusual experiences of supernatural touch and touch on a non-hand object. The finding of touch on a non-hand object conflicts with prior findings, and to resolve this conflict a further hypothesis is successfully tested: that without prior onset of the basic illusion this unusual experience does not occur. Conclusions/Significance -/- A rubber hand illusion is found that can arise when the real and the foreign arm are aligned in personal space. This illusion persists through periods of no tactile stimulation and is strong enough to allow very unusual experiences of touch felt on a cardboard box and experiences of touch produced at a distance, as if by supernatural causation. These findings suggest that one's visual body image is explained away during experience of the illusion and they may be of further importance to understanding the role of experience in delusion formation. The findings of touch on non-hand objects may help reconcile conflicting results in this area of research. In addition, new evidence is provided that relates to the recently discovered psychologically induced temperature changes that occur during the illusion. (shrink)

We investigate two issues about the subjective experience of one's body: first, is the experience of owning a full-body fundamentally different from the experience of owning a body-part?Second, when I experience a bodily sensation, does it guarantee that I cannot be wrong about whether it is me who feels it? To address these issues, we conducted a series of experiments that combined the rubber hand illusion (RHI) and the “body swap illusion.” The subject (...) wore a head mounted display (HMD) connected with a stereo camera set on the experimenter's head. Sitting face to face, they used their right hand holding a paintbrush to brush each other's left hand. Through the HMD, the subject adopted the experimenter's first-person perspective (1PP) as if it was his/her own 1PP: the subject watched either the experimenter's hand from the adopted 1PP, and/or the subject's own hand from the adopted third-person perspective (3PP) in the opposite direction (180°), or the subject's full body from the adopted 3PP (180°, with or without face). The synchronous full-body conditions generate a “self-touching illusion”: many participants felt that “I was brushing my own hand!” We found that (1) the sense of body-part ownership and the sense of full-body ownership are not fundamentally different from each other; and (2) our data present a strong case against the mainstream philosophical view called the immunity principle (IEM). We argue that it is possible for misrepresentation to occur in the subject's sense of “experiential ownership” (the sense that I am the one who is having this bodily experience). We discuss these findings and conclude that not only the sense of body ownership but also the sense of experiential ownership call for further interdisciplinary studies. (shrink)

Previous studies on body ownership illusions have shown that under certain multimodal conditions, healthy people can experience artificial body-parts as if they were part of their own body, with direct physiological consequences for the real limb that gets ‘substituted’. In this study we wanted to assess (a) whether healthy people can experience ‘missing’ a body-part through illusory ownership of an amputated virtual body, and (b) whether this would cause corticospinal excitability changes in muscles associated with (...) the ‘missing’ body-part. Forty right-handed participants saw a virtual body from a first person perspective but for half of them the virtual body was missing a part of its right arm. Single pulse transcranial magnetic stimulation was applied before and after the experiment to left and right motor cortices. Motor evoked potentials (MEPs) were recorded from the first dorsal interosseous (FDI) and the extensor digitorum communis (EDC) of each hand. We found that the stronger the illusion of amputation and arm ownership, the more the reduction of MEP amplitudes of the EDC muscle for the contralateral sensorimotor cortex. In contrast, no association was found for the EDC amplitudes in the ipsilateral cortex and for the FDI amplitudes in both contralateral and ipsilateral cortices. Our study provides evidence that a short-term illusory perception of missing a body-part can trigger inhibitory effects on corticospinal pathways and importantly in the absence of any limb deafferentation or disuse. (shrink)

This metatheoretical paper develops a list of new research targets by exploring particularly promising interdisciplinary contact points between empirical dream research and philosophy of mind. The central example is the MPS-problem. It is constituted by the epistemic goal of conceptually isolating and empirically grounding the phenomenal property of “minimal phenomenal selfhood,” which refers to the simplest form of self-consciousness. In order to precisely describe MPS, one must focus on those conditions that are not only causally enabling, but strictly necessary to (...) bring it into existence. This contribution argues that research on bodiless dreams, asomatic out-of-body experiences, and full-body illusions has the potential to make decisive future contributions. Further items on the proposed list of novel research targets include differentiating the concept of a “first-person perspective” on the subcognitive level; investigating relevant phenomenological and neurofunctional commonalities between mind-wandering and dreaming; comparing the functional depth of embodiment across dream and wake states; and demonstrating that the conceptual consequences of cognitive corruption and systematic rationality deficits in the dream state are much more serious for philosophical epistemology (and, perhaps, the methodology of dream research itself) than commonly assumed. The paper closes by specifying a list of potentially innovative research goals that could serve to establish a stronger connection between dream research and philosophy of mind. (shrink)

Anorexia nervosa patients exhibit distorted body-representations. Specifically, they represent their bodies as larger than reality. Given that this distortion likely exacerbates the condition, there is an obligation to further understand and, if possible, rectify it. In pursuit of this, experimental paradigms are needed which manipulate the spatial content of these representations. In this essay, I discuss how virtual reality technology that implements full-body variants of the rubber-hand illusion may prove useful in this regard, and I discuss (...) some issues related to the clinical application of this method. -/- . (shrink)

Body ownership concerns what it is like to feel a body part or a full body as mine, and has become a prominent area of study. We propose that there is a closely related type of bodily self-consciousness largely neglected by researchers—experiential ownership. It refers to the sense that I am the one who is having a conscious experience. Are body ownership and experiential ownership actually the same phenomenon or are they genuinely different? In our (...) experiments, the participant watched a rubber hand or someone else’s body from the first-person perspective and was touched either synchronously or asynchronously. The main findings: (1) The sense of body ownership was hindered in the asynchronous conditions of both the body-part and the full-body experiments. However, a strong sense of experiential ownership was observed in those conditions. (2) We found the opposite when the participants’ responses were measured after tactile stimulations had ceased for 5 s. In the synchronous conditions of another set of body-part and full-body experiments, only experiential ownership was blocked but not body ownership. These results demonstrate for the first time the double dissociation between body ownership and experiential ownership. Experiential ownership is indeed a distinct type of bodily self-consciousness. (shrink)

The paper proposes a minimal definition of dreaming in terms of immersive spatiotemporal hallucination (ISTH) occurring in sleep or during sleep–wake transitions and under the assumption of reportability. I take these conditions to be both necessary and sufficient for dreaming to arise. While empirical research results may, in the future, allow for an extension of the concept of dreaming beyond sleep and possibly even independently of reportability, ISTH is part of any possible extension of this definition and thus is a (...) constitutive condition of dreaming. I also argue that the proposed ISTH model of dreaming, in conjunction with considerations on the epistemic relationship between dreaming and dream reports, raises important questions about the extent to which dreams typically involve a detailed body representation—an assumption that plays an important role in philosophical work on dreaming. As a commonly accepted definition of dreaming is lacking in current dream research, the ISTH model, which integrates conceptual analysis and epistemological considerations with results from empirical research, is an important contribution to this field. By linking dreaming to felt presence, full-body illusions, and autoscopic phenomena such as out-of-body experiences in wakefulness and in the hypnagogic state, the ISTH model of dreaming also helps integrate dream research, both theoretically and experimentally, with the study of other altered states of consciousness involving hallucinations. It makes straightforward and investigable predictions by claiming that all of these experiences have amodal spatiotemporal hallucinations as their common denominator. Finally, it is theoretically relevant for the philosophical discussion on minimal phenomenal selfhood. (shrink)

Self-location—the sense of where I am in space—provides an experiential anchor for one's interaction with the environment. In the studies of full-body illusions, many researchers have defined self-location solely in terms of body-location—the subjective feeling of where my body is. Although this view is useful, there is an issue regarding whether it can fully accommodate the role of 1PP-location—the sense of where my first-person perspective is located in space. In this study, we investigate self-location by comparing (...) body-location and 1PP-location: using a head-mounted display (HMD) and a stereo camera, the subjects watched their own body standing in front of them and received tactile stimulations. We manipulated their senses of body-location and 1PP-location in three different conditions: the participants standing still (Basic condition), asking them to move forward (Walking condition), and swiftly moving the stereo camera away from their body (Visual condition). In the Walking condition, the participants watched their body moving away from their 1PP. In the Visual condition, the scene seen via the HMD was systematically receding. Our data show that, under different manipulations of movement, the spatial unity between 1PP-location and body-location can be temporarily interrupted. Interestingly, we also observed a “double-body effect.” We further suggest that it is better to consider body-location and 1PP-location as interrelated but distinct factors that jointly support the sense of self-location. (shrink)

We previously showed that the illusory sense of ownership and agency over a moving body in immersive virtual reality can trigger subjective and physiological reactions on the real subject’s body and, therefore, an acute improvement of cognitive functions after a single session of high-intensity intermittent exercise performed exclusively by one’s own virtual body, similar to what happens when we actually do physical activity. As well as confirming previous results, here, we aimed at finding in the elderly an (...) increased improvement after a longer virtual training with similar characteristics. Forty-two healthy older subjects completed a parallel-group randomized controlled trial including an adapted version of the virtual training previously used: while sitting, participants observed the virtual body in a first-person perspective or a third-person perspective performing 20 min of virtual high-intensity intermittent exercise. This was repeated twice a week for 6 weeks. During the vHIE, we measured the heart rate and administered questionnaires to evaluate illusory body ownership and agency. Before the beginning of the intervention, immediately after the first session of vHIE, and at the end of the entire intervention, we evaluated the cognitive performance at the Stroop task with online recording of the hemodynamic activity over the left dorsolateral prefrontal cortex. While we confirm previous results regarding the virtual illusion and its physiological effects, we did not find significant cognitive or neural improvement immediately after the first vHIE session. As a novelty, in the 1PP group only, we detected a significant decrease in the response time of the Stroop task in the post-intervention assessment compared to its baseline; coherently, we found an increased activation on left dorsolateral prefrontal cortex after the entire intervention. While the current results strengthen the impact of the virtual full-body illusion and its physiological consequences on the elderly as well, they might have stronger and more established body representations. Perhaps, a longer and increased exposure to those illusions is necessary to initiate the cascade of events that culminates to an improved cognitive performance. (shrink)

Commentary on: Olaf Blanke, Thomas Metzinger, Full-body illusions and minimal phenomenal selfhood, Trends in Cognitive Sciences, Volume 13, Issue 1, January 2009, Pages 7-13, ISSN 1364-6613, DOI: 10.1016/j.tics.2008.10.003.

According to one theory, the brain is a sophisticated hypothesis tester: perception is Bayesian unconscious inference where the brain actively uses predictions to test, and then refine, models about what the causes of its sensory input might be. The brain’s task is simply continually to minimise prediction error. This theory, which is getting increasingly popular, holds great explanatory promise for a number of central areas of research at the intersection of philosophy and cognitive neuroscience. I show how the theory can (...) help us understand striking phenomena at three cognitive levels: vision, sensory integration, and belief. First, I illustrate central aspects of the theory by showing how it provides a nice explanation of why binocular rivalry occurs. Then I suggest how the theory may explain the role of the unified sense of self in rubber hand and full body illusions driven by visuotactile conflict. Finally, I show how it provides an approach to delusion formation that is consistent with one-deficit accounts of monothematic delusions. (shrink)

Under normal circumstances, we experience that our center of awareness is located behind our eyes and inside our own body. To learn more about the perceptual processes that underlie this tight coupling between the spatial dimensions of our consciously perceived self and our physical body, we conducted a series of experiments using an ‘out-of-body illusion’. In this illusion, the conscious sense of self is displaced in the testing room by experimental manipulation of the congruency of (...) visual and tactile information and a change in the visual perspective. We demonstrate that when healthy individuals experience that they are located in a different place from their real body, they disown this body and no longer perceive it as part of themselves. Our findings are important because they reveal a relationship between the representation of self-location in the local environment and the multisensory representation of one’s own body. (shrink)

In this commentary, I confront Ganeri’s theory of self with two case studies from cognitive neuroscience and interdisciplinary consciousness research: mind wandering and full-body illusions. Together, these case studies suggest new questions and constraints for Ganeri's theory of self. Recent research on spontaneous thought and mind wandering raises questions about the transition from unconscious monitoring to the phenomenology of ownership and the first-person stance. Full-body illusions are relevant for the attenuation problem of how we distinguish between (...) self and others. Discussing these examples can help refine key transitions in Ganeri’s theory of self and ensure its empirical plausibility. This discussion also identifies points of contact between Ganeri's self and cognitive neuroscience, raising new questions for future research, both philosophical and empirical. (shrink)

The Illusion of the Body: Introducing the Body Alive Principle is the divinely inspired work of author David Almeida. This book opens the door to a new understanding in metaphysical thinking. The author draws on the philosophy of panpsychism to support his contention that an unseen ocean of consciousness exists all around us, and within our own bodies (i.e. cells, organs, and systems). The author refers to the Body Alive Principle as “panpsychic healing.” This text offers (...) proven techniques for communicating with the body intelligences the author terms the “little minds.” This process is intended to bring healing to those with both minor and severe medical conditions. Some of the most common medical complaints treated by the Body Alive Principle includes:1. Back or neck pain2. Allergies3. Arthritis/rheumatism4. Difficulty walking5. Headaches6. Lung problems7. Digestive8. Gynecological9. Anxiety disorders10. Heart conditionsThe author contends that even the most nefarious medical issues are curable or can be successfully managed using the Body Alive Principle. This is accomplished through the action of human “super mind”, which will at times consciously supervise the activities of the little minds. The Illusion of the Body instructs its Body Alive practitioners to approach their recovery using several time-tested techniques. Three widely recognized methods are employed in the application of the panpsychic healing philosophy. These modalities are creative visualization and empathetic listening followed by affirmative commands. Each technique is essential to the effectiveness of the Body Alive Principle.This book also discusses guilt and its deleterious effect on the body. True guilt has a beneficial quality when it prevents us from repeating an unacceptable behavior. Beyond this, guilt causes us to become ineffectual. The author holds that this antiquated form guilt needs to be purged, so that we may move on with our lives. A step-by-step process for liberating oneself from the chains of guilt is provided.There is also a section dedicated to trauma because of its potential to immobilize an affected person. Traumatic experiences suddenly unleashed on the body may produce waves of acute anxiety, which wreak havoc on its finely tuned systems. The author recounts his personal experience of negotiating the discharge of negative experiences with the entities supporting them.The Body Alive Principle promotes the importance of adhering to high moral standards in order to maintain homeostasis within ourselves. Integrity is of the outmost importance to the little minds. The author emphasizes the necessity for one to act within the domain of moral excellence. However, the author makes it clear that integrity is a process we work to perfect throughout our lives.The Illusion of the Body represents the author's many years of metaphysical study and experimentation. The author hopes to generate a greater awareness and appreciation of our precious bodily intelligences. The organic vessels that contain our consciousness are alive. They are almost countless in number. If we, the super mind can learn to communicate with the little minds in a positive way, we can ensure ourselves of a more comfortable journey. (shrink)

Recent studies of the rubber hand illusion (RHI) have shown that the sense of body ownership is constrained by several factors and yet is still very flexible. However, exactly how flexible is our sense of body ownership? In this study, we address this issue by investigating the following question: is it possible that one may have the illusory experience of owning four hands? Under visual manipulation, the participant adopted the experimenter’s first-person perspective (1PP) as if it was (...) his/her own. Sitting face to face, the participant saw four hands—the experimenter’s two hands from the adopted 1PP together with the subject’s own two hands from the adopted third-person perspective (3PP). We found that: (1) the four-hand illusion did not occur in the passive four-hand condition. (2) In the active four-hand condition, the participants tapped their index fingers, imitated by the experimenter. When tactile stimulations were not provided, the key illusion was not induced, either. (3) Strikingly, once all four hands began to act with the same pattern and received synchronous tactile stimulations at the same time, many participants felt as if they had two more hands. These results show that the sense of body ownership is much more flexible than most researchers have suggested. (shrink)

Although it has been shown that immersive virtual reality can be used to induce illusions of ownership over a virtual body , information on whether this changes implicit interpersonal attitudes is meager. Here we demonstrate that embodiment of light-skinned participants in a dark-skinned VB significantly reduced implicit racial bias against dark-skinned people, in contrast to embodiment in light-skinned, purple-skinned or with no VB. 60 females participated in this between-groups experiment, with a VB substituting their own, with full-body (...) visuomotor synchrony, reflected also in a virtual mirror. A racial Implicit Association Test was administered at least three days prior to the experiment, and immediately after the IVR exposure. The change from pre- to post-experience IAT scores suggests that the dark-skinned embodied condition decreased implicit racial bias more than the other conditions. Thus, embodiment may change negative interpersonal attitudes and thus represent a powerful tool for exploring such fundamental psychological and societal phenomena. (shrink)

In a recent study (Chen et al., 2018), we conducted a series of experiments that induced the “four-hand illusion”: using a head-mounted display (HMD), the participant adopted the experimenter’s first-person perspective (1PP) as if it was his/her own 1PP. The participant saw four hands via the HMD: the experimenter’s two hands from the adopted 1PP and the subject’s own two hands from the adopted third-person perspective (3PP). In the active four-hand condition, the participant tapped his/her index fingers, imitated by (...) the experimenter. Once all four hands acted synchronously and received synchronous tactile stimulations at the same time, many participants felt as if they owned two more hands. In this paper, we argue that there is a philosophical implication of this novel illusion. According to Merleau-Ponty (1945/1962) and Legrand (2010), one can experience one’s own body or body-part either as-object or as-subject but cannot experience it as both simultaneously, i.e., these two experiences are mutually exclusive. Call this view the Experiential Exclusion Thesis. We contend that a key component of the four-hand illusion—the subjective experience of the 1PP-hands that involved both “kinesthetic sense of movement” and “visual sense of movement” (the movement that the participant sees via the HMD)—provides an important counter-example against this thesis. We argue that it is possible for a healthy subject to experience the same body-part both as-subject and as-object simultaneously. Our goal is not to annihilate the distinction between body-as-object and body-as-subject, but to show that it is not as rigid as suggested by the phenomenologists. (shrink)

When subjects view stimulation of a rubber hand while feeling congruent stimulation of their own hand, they may come to feel that the rubber hand is part of their own body. This illusion of body ownership is termed ‘Rubber Hand Illusion’ . We investigated sensitivity of RHI to spatial mismatches between visual and somatic experience. We compared the effects of spatial mismatch between the stimulation of the two hands, and equivalent mismatches between the postures of the (...) two hands. We created the mismatch either by adjusting stimulation or posture of the subject’s hand, or, in a separate group of subjects, by adjusting stimulation or posture of the rubber hand. The matching processes underlying body ownership were asymmetrical. The illusion survived small changes in the subject’s hand posture, but disappeared when the same posture transformations were applied to the rubber hand. Mismatch between the stimulation delivered to the subject’s hand and the rubber hand abolished the illusion. The combination of these two situations is of particular interest. When the subject’s hand posture was slightly different from the rubber hand posture, the RHI remained as long as stimulation of the two hands was congruent in a hand-centred spatial reference frame, even though the altered posture of the subject’s hand meant that stimulation was incongruent in external space. Conversely, the RHI was reduced when the stimulation was incongruent in hand-centred space but congruent in external space. We conclude that the visual–tactile correlation that causes the RHI is computed within a hand-centred frame of reference, which is updated with changes in body posture. Current sensory evidence about what is ‘me’ is interpreted with respect to a prior mental body representation. (shrink)

This essay examines control discourse in and out of educational settings, arguing that illusions of control are among the means by which governance is accomplished in domains far from schools. The tactical productivity of such illusions in non-school settings "necessitates" and explicates their prevalence in education. The first installment of this essay identifies some assumptions undergirding dominant control and management discourse; analyzes discussions of control in fields other education; and briefly examines the role that social location plays in fostering specific (...) understandings of control. A later installment will focus more narrowly on education, music education specifically. The author maintains that recognizing the limits of governmentality, bankrupting illusions of control, and uncoupling associations between uncertainty and terror, are powerful political disruptions. Acknowledging that classroom control may be neither achievable nor desirable may open the door to different understandings of classroom power relations and to re-articulations of the purposes of schooling. (shrink)

In the final installment of her two-part essay, Julia Eklund Koza analyzes prevalent control and management discourse in education, specifically, music education. Arguing that dominant understandings are hierarchical, gendered, illusory, and integrally related to projects and practices largely unrelated to schooling, she invites teachers and teacher educators to explore the possibilities created when different assumptions about teaching and control are applied. Koza maintains that recognizing the limits of governmentality, bankrupting illusions of control, and uncoupling associations between uncertainty and terror are (...) powerful political disruptions. Acknowledging that classroom control may be neither achievable nor desirable may open the door to different understandings of classroom power relations and to re-articulations of the purposes of schooling. Koza calls for the use of different metaphors and frames as a first step in achieving different educational outcomes. (shrink)

In the final installment of her two-part essay, Julia Eklund Koza analyzes prevalent control and management discourse in education, specifically, music education. Arguing that dominant understandings are hierarchical, gendered, illusory, and integrally related to projects and practices largely unrelated to schooling, she invites teachers and teacher educators to explore the possibilities created when different assumptions about teaching and control are applied. Koza maintains that recognizing the limits of governmentality, bankrupting illusions of control, and uncoupling associations between uncertainty and terror are (...) powerful political disruptions. Acknowledging that classroom control may be neither achievable nor desirable may open the door to different understandings of classroom power relations and to re-articulations of the purposes of schooling. Koza calls for the use of different metaphors and frames as a first step in achieving different educational outcomes. (shrink)

Sydney Shoemaker argues that a certain class of self-ascriptions is immune to error through misidentification relative to the first-person pronouns. In their “Self-Consciousness and Immunity,” Timothy Lane and Caleb Liang question Shoemaker’s view. Lang and Liang present a clinical case and an experiment and argue that they are counterexamples to Shoemaker’s view. This paper is a response to Lane and Liang’s challenge. I identify the desiderata that a counterexample to Shoemaker’s view must meet and show that somatoparaphrenia and the (...) class='Hi'>Body Swap Illusion fail to meet those desiderata. Thus, despite being puzzling phenomena, somatoparaphrenia and the Body Swap Illusion are not counterexamples to Shoemaker’s view. (shrink)

Bodily experience in dreams should be considered illusory to the extent that they cannot be satisfactorily explained or fruitfully investigated by appealing to brain activity alone; rather, to wholly understand the unique phenomenology of embodied selfhood in dreams, one must understand how the brain processes real-body inputs to produce the phenomenology of embodied selfhood in dreams, and why the brain responds the way it does to external stimuli during sleep.

"Fascinating and insightful.... I cannot recall a book that has made me think more about the nature of thinking." -- Richard C. Lewontin Harvard University Everyone knows that optical illusions trick us because of the way we see. Now scientists have discovered that cognitive illusions, a set of biases deeply embedded in the human mind, can actually distort the way we think. In Inevitable Illusions, distinguished cognitive researcher Massimo Piattelli-Palmarini takes us on a provocative, challenging, and thoroughly entertaining exploration of (...) the games our minds play. He opens the doors onto the newly charted realm of the cognitive unconscious to reveal the full range of illusions, showing how they inhibit our ability to reason--no matter what our educational background or IQ. Inevitable Illusions is stimulating, eye-opening food for thought. (shrink)