Body transfer illusion

Last updated

Body transfer illusion is the illusion of owning either a part of a body or an entire body other than one's own, thus it is sometimes referred to as "body ownership" in the research literature. It can be induced experimentally by manipulating the visual perspective of the subject and also supplying visual and sensory signals which correlate to the subject's body. [1] [2] For it to occur, bottom-up perceptual mechanisms, such as the input of visual information, must override top-down knowledge that the certain body (or part) does not belong. This is what results in an illusion of transfer of body ownership. [3] It is typically induced using virtual reality. [3]

Contents

Rubber hand illusion

Ehrsson, Spence, and Passingham (2004) did studies on the "rubber hand illusion", originally reported by Botvinick and Cohen in 1998. Subjects with normal brain function were positioned with their left hand hidden out of sight. They saw a lifelike rubber left hand in front of them. The experimenters stroked both the subjects hidden left hand and the visible rubber hand with a paintbrush. The experiment showed that if the two hands were stroked synchronously and in the same direction, the subjects began to experience the rubber hand as their own. When asked to use their right hand to point to their left hand, most of the time they pointed toward the rubber hand. If the real and rubber hands were stroked in different directions or at different times, the subjects did not experience the rubber hand as their own.[ citation needed ]

While the experiment was going on the experimenters also recorded the activity of their brains with a functional MRI scanner. The scans showed increased activity in the parietal lobe and then, right after, as the subjects began to experience the rubber hand as their own, in the premotor cortex, the region of the brain involved in planning movements. On the other hand, when the stroking of the real and rubber hands was uncoordinated and the subjects did not experience the rubber hand as their own, the premotor cortex did not become activated. From this the experimenters concluded that the parietal cortex was involved with visual and touch processing. The premotor cortex, getting transmitted information from the parietal cortex, was involved with the feeling of ownership of the rubber hand.

Another study from the same laboratory provided further evidence of this ownership of the rubber hand (Ehrsson et al., 2007; Slater et al., 2009). The experimenters used the same procedure as the previous experiment to establish that feeling of ownership involved with the stimulation of the premotor cortex. Then, threatened the rubber hand by making a stabbing movement toward it with a needle (not actually making contact with the rubber hand). MRI scans showed increase activity in a region of the brain called the anterior cingulate cortex that is normally activated when a person anticipates pain, along with the supplementary motor area, that is normally activated when a person feels the urge to move his or her arm (Fried et al., 1991; Peyron, Laurent, and Garcia-Larrea, 2000). The anticipation of the needle made the subjects react as if the rubber hand was their own, moving their real hand to avoid the needle even though it was never actually in danger. [4]

Illusion induced through virtual reality

One of the ways in which body transfer illusion has been studied is through virtual reality simulation where a first person perspective of a life-sized virtual human female body has appeared to substitute the male subjects' own body. This was demonstrated subjectively by questionnaire and physiologically through heart-rate deceleration in response to a threat to the virtual body. The results support the notion that bottom-up perceptual mechanisms, such as those involving the premotor cortex and cerebellum, can temporarily override top down knowledge therefore resulting in a radical illusion of transfer of body ownership. In the study, male participants entered the virtual reality simulation and experienced various forms of stimulation including arm-stroking and other physical sensations. Afterwards the heart rate was monitored and a questionnaire was completed. [5]

Applications

Body transfer illusion has been used in order to treat the experience of phantom limb pain by giving visual feedback of the missing limb. The mirror box gives visual feedback that can allow a person using it the opportunity to "see" the missing hand, and to manipulate the hand in an attempt to relieve pain or discomfort. Virtual reality is also used to treat phantom limb pain in a similar way, by allowing the user to "see" the missing limb within the virtual world and manipulate it however they choose.

Neural basis

The integration of touch stimulation via the somatosensory system with visual input is essential for creating the body transfer illusion. When the body is not in motion, it perceives its position in space through the integration of multi-modal afferent signals. Motion of the body adds efferent signal information and leads to a more fluid perception of body transfer. When information from one form of signal (e.g. touch) does not match the signals from another sense (e.g. vision), the body still attempts to integrate this information. [6] Specifically the rubber hand illusion is associated with activity in the multisensory areas, most notably the ventral premotor cortex. However, it remains to be demonstrated that this illusion does not simply reflect the dominant role of vision and that the premotor activity does not reflect a visual representation of an object near the hand. [7]

Drug-induced enhancement

With ketamine, the body transfer illusion is ultimately enhanced and participants are more vulnerable to a false sense of limb ownership than without the use of ketamine. Although the precise nature of ketamine's impact is speculative, two features of its effects are noteworthy. First, it promotes an overall increase in the subjective and behavioral indices of the illusion. Second, this effect is found even when a sensory asynchrony is present, a manipulation that would normally reduce the experience of the illusion. This pattern may be understood in terms of the drug's impact on the top-down–bottom-up balance that would normally account for the illusion's characteristic features since ketamine produces an overall increase in tendency to the illusion, whereas this sensitivity to the coherence of visual and tactile input is preserved. A further possibility is that ketamine enhances the salience of the visual input (the sight of a rubber hand in a position compatible with one's own hand) at the expense of information arising from the temporal asynchrony between sensory inputs. This would explain why the presence of the rubber hand is enough to enable the illusion to persist, even when in attenuated form, when visuo-tactile inputs are asynchronous. [8]

A very similar effect occurs with the administration of the dopamine and noradrenaline releasing agent dextroamphetamine. The similarities include increased subjective reports of embodiment of the rubber hand during the illusion, and that the dextroamphetamine enhancing effect is also seen during sensory asynchrony. [9]

Mind-body connection

Human bodily experience is characterized by the immediate and continuous experience that our body and its parts belong to us, often called self-attribution, body ownership and or mineness. It is unknown if the origin of body representation is innate or if it is constructed from sensory experience. [10] A related, but distinct, bodily experience is self-localization or embodiment that is defined as the experience that the self is localized at the position of our body at a certain position in space. Recent philosophical and neurological theories converge on the relevance of such bodily experiences and associated processing of bodily information as one promising approach for the development of a comprehensive neurobiological model of self-consciousness. Yet, the scientific investigation of bodily experiences in general, and self-attribution/body ownership and self-localization/embodiment more specifically, have proven difficult and have not received the attention they deserve given their importance for neuroscientific models of self and self-consciousness. [11]

Doubts about suggestion effects

In 2019, Lush et al reported correlations between response to the rubber hand illusion and both response to imaginative suggestions in hypnosis and participant expectations for illusion experience and argued that body transfer illusions may be suggestion effects generated by participants' expectations. [12] In 2020, Lush reported that demand characteristics (contextual cues which prime participant expectations) have not been controlled in rubber hand illusion experiments, and argued that existing reports of body transfer illusions may be entirely accounted for by suggestion effects. [13] In 2022, Slater and Ehrsson argued that Lush's claims were not supported by the data and that the major factor driving the rubber hand illusion is multisensory integration. [14]

See also

Related Research Articles

<span class="mw-page-title-main">Out-of-body experience</span> Phenomenon in which the soul (astral body) is said to exit the physical body

An out-of-body experience is a phenomenon in which a person perceives the world from a location outside their physical body. An OBE is a form of autoscopy, although this term is more commonly used to refer to the pathological condition of seeing a second self, or doppelgänger.

Alien hand syndrome (AHS) or Dr. Strangelove syndrome is a category of conditions in which a person experiences their limbs acting seemingly on their own, without conscious control over the actions. There are a variety of clinical conditions that fall under this category, which most commonly affects the left hand. There are many similar terms for the various forms of the condition, but they are often used inappropriately. The affected person may sometimes reach for objects and manipulate them without wanting to do so, even to the point of having to use the controllable hand to restrain the alien hand. Under normal circumstances however, given that intent and action can be assumed to be deeply mutually entangled, the occurrence of alien hand syndrome can be usefully conceptualized as a phenomenon reflecting a functional "disentanglement" between thought and action.

<span class="mw-page-title-main">Phantom limb</span> Sensation that an amputated or missing limb is attached

A phantom limb is the sensation that an amputated or missing limb is still attached. Approximately 80–100% of individuals with an amputation experience sensations in their amputated limb. However, only a small percentage will experience painful phantom limb sensation. These sensations are relatively common in amputees and usually resolve within two to three years without treatment. Research continues to explore the underlying mechanisms of phantom limb pain (PLP) and effective treatment options.

<span class="mw-page-title-main">Parietal lobe</span> Part of the brain responsible for sensory input and some language processing

The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.

Multisensory integration, also known as multimodal integration, is the study of how information from the different sensory modalities may be integrated by the nervous system. A coherent representation of objects combining modalities enables animals to have meaningful perceptual experiences. Indeed, multisensory integration is central to adaptive behavior because it allows animals to perceive a world of coherent perceptual entities. Multisensory integration also deals with how different sensory modalities interact with one another and alter each other's processing.

Phantom pain is a painful perception that an individual experiences relating to a limb or an organ that is not physically part of the body, either because it was removed or was never there in the first place.

Sensory processing is the process that organizes and distinguishes sensation from one's own body and the environment, thus making it possible to use the body effectively within the environment. Specifically, it deals with how the brain processes multiple sensory modality inputs, such as proprioception, vision, auditory system, tactile, olfactory, vestibular system, interoception, and taste into usable functional outputs.

<span class="mw-page-title-main">Premotor cortex</span>

The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans. The functions of the premotor cortex are diverse and not fully understood. It projects directly to the spinal cord and therefore may play a role in the direct control of behavior, with a relative emphasis on the trunk muscles of the body. It may also play a role in planning movement, in the spatial guidance of movement, in the sensory guidance of movement, in understanding the actions of others, and in using abstract rules to perform specific tasks. Different subregions of the premotor cortex have different properties and presumably emphasize different functions. Nerve signals generated in the premotor cortex cause much more complex patterns of movement than the discrete patterns generated in the primary motor cortex.

Body schema is an organism's internal model of its own body, including the position of its limbs. The neurologist Sir Henry Head originally defined it as a postural model of the body that actively organizes and modifies 'the impressions produced by incoming sensory impulses in such a way that the final sensation of body position, or of locality, rises into consciousness charged with a relation to something that has happened before'. As a postural model that keeps track of limb position, it plays an important role in control of action.

The sense of agency (SA), or sense of control, is the subjective awareness of initiating, executing, and controlling one's own volitional actions in the world. It is the pre-reflective awareness or implicit sense that it is I who is executing bodily movement(s) or thinking thoughts. In non-pathological experience, the SA is tightly integrated with one's "sense of ownership" (SO), which is the pre-reflective awareness or implicit sense that one is the owner of an action, movement or thought. If someone else were to move your arm you would certainly have sensed that it were your arm that moved and thus a sense of ownership (SO) for that movement. However, you would not have felt that you were the author of the movement; you would not have a sense of agency (SA).

<span class="mw-page-title-main">Somatosensory system</span> Nerve system for sensing touch, temperature, body position, and pain

In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch, as well as temperature (thermoception), body position (proprioception), and pain. It is a subset of the sensory nervous system, which also represents visual, auditory, olfactory, gustatory and vestibular stimuli.

<span class="mw-page-title-main">Proprioception</span> Sense of self-movement, force, and body position

Proprioception is the sense of self-movement, force, and body position.

<span class="mw-page-title-main">Visual capture</span>

In psychology, visual capture is the dominance of vision over other sense modalities in creating a percept. In this process, the visual senses influence the other parts of the somatosensory system, to result in a perceived environment that is not congruent with the actual stimuli. Through this phenomenon, the visual system is able to disregard what other information a different sensory system is conveying, and provide a logical explanation for whatever output the environment provides. Visual capture allows one to interpret the location of sound as well as the sensation of touch without actually relying on those stimuli but rather creating an output that allows the individual to perceive a coherent environment.

<span class="mw-page-title-main">Embodied cognition</span> Interdisciplinary theory

Embodied cognition is the concept suggesting that many features of cognition are shaped by the state and capacities of the organism. The cognitive features include a wide spectrum of cognitive functions, such as perception biases, memory recall, comprehension and high-level mental constructs and performance on various cognitive tasks. The bodily aspects involve the motor system, the perceptual system, the bodily interactions with the environment (situatedness), and the assumptions about the world built the functional structure of organism's brain and body.

Mirror-touch synesthesia is a rare condition which causes individuals to experience a similar sensation in the same part or opposite part of the body that another person feels. For example, if someone with this condition were to observe someone touching their cheek, they would feel the same sensation on their own cheek. Synesthesia, in general, is described as a condition in which a concept or sensation causes an individual to experience an additional sensation or concept. Synesthesia is usually a developmental condition; however, recent research has shown that mirror touch synesthesia can be acquired after sensory loss following amputation.

<span class="mw-page-title-main">Tactile hallucination</span>

Tactile hallucination is the false perception of tactile sensory input that creates a hallucinatory sensation of physical contact with an imaginary object. It is caused by the faulty integration of the tactile sensory neural signals generated in the spinal cord and the thalamus and sent to the primary somatosensory cortex (SI) and secondary somatosensory cortex (SII). Tactile hallucinations are recurrent symptoms of neurological diseases such as schizophrenia, Parkinson's disease, Ekbom's syndrome and delirium tremens. Patients who experience phantom limb pains also experience a type of tactile hallucination. Tactile hallucinations are also caused by drugs such as cocaine and alcohol.

<span class="mw-page-title-main">Medial pulvinar nucleus</span>

Medial pulvinar nucleus is one of four traditionally anatomically distinguished nuclei of the pulvinar of the thalamus. The other three nuclei of the pulvinar are called lateral, inferior and anterior pulvinar nuclei.

<span class="mw-page-title-main">Olaf Blanke</span> Swiss and German physician, neurologist and neuroscientist

Olaf Blanke is a Swiss and German physician, neurologist and neuroscientist. He holds the Bertarelli Foundation Chair in Cognitive Neuroprosthetics at the École Polytechnique Fédérale de Lausanne (EPFL). He directs the Laboratory of Cognitive Neuroscience at the Brain Mind Institute of EPFL and is professor of Neurology at Geneva University Hospitals. Blanke is known for his research on the neurological bases of self-consciousness and out-of-body experiences.

<span class="mw-page-title-main">Limb telescoping</span>

Limb telescoping is the progressive shortening of a phantom limb as the cortical regions are reorganized following an amputation. During this reorganization, proximal portions of the residual limb are perceived as more distal parts of the phantom limb. Such effect is responsible for increased phantom pain due to the discrepancy between the patient’s body perception and their actual body. This effect may last from weeks up to years after post-amputation.

Sense of ownership (SO), in psychology, is the feeling of identifying sensations as affecting, establishing, and belonging to one's identified-self. and is the pre-reflective awareness or implicit sense that one is the owner of an action, movement or thought.

References

  1. ↑ Petkova VI, Ehrsson HH, 2008 "If I Were You: Perceptual Illusion of Body Swapping". PLoS ONE 3(12): e3832. doi : 10.1371/journal.pone.0003832
  2. ↑ M.P.M. Kammers, I.J.M. van der Ham, H.C. Dijkerman, "Dissociating body representations in healthy individuals: Differential effects of a kinaesthetic illusion on perception and action", Neuropsychologia , Volume 44, Issue 12, 2006, pp. 2430–2436, ISSN   0028-3932, doi : 10.1016/j.neuropsychologia.2006.04.009.
  3. 1 2 Slater M, Spanlang B, Sanchez-Vives MV, Blanke O, 2010 "First Person Experience of Body Transfer in Virtual Reality". PLoS ONE 5(5): e10564. doi : 10.1371/journal.pone.0010564
  4. ↑ Carlson, N. R. (2010). Physiology of behavior, 11th Edition. New York: Allyn & Bacon. A LA CARTE version MyPsychLab w/e-Text.
  5. ↑ Slater M, Spanlang B, Sanchez-Vives MV, Blanke O, 2010. First Person Experience of Body Transfer in Virtual Reality. PLoS ONE 5(5): e10564. doi : 10.1371/journal.pone.0010564
  6. ↑ Manos Tsakiris, Simone Schutz-Bosbach, Shaun Gallagher, "One agency and body-ownership: Phenomenologial and neurocognitive reflections" Consciousness and Cognition Volume 16, 2007, Pages 645-660 doi : 10.1016/j.concog.2007.05.012
  7. ↑ H. Henrik Ehrsson,1 Nicholas P. Holmes,2 and Richard E. Passingham1Touching a Rubber Hand: Feeling of Body Ownership Is Associated with Activity in Multisensory Brain Areas The Journal of Neuroscience, November 9, 2005, 25(45):10564-10573; doi : 10.1523/JNEUROSCI.0800-05.2005
  8. ↑ L. Morgana, Danielle C. Turnerb, Philip R. Corlett, "Exploring the Impact of Ketamine on the Experience of Illusory Body Ownership" Biological Psychiatry Volume 69, Issue 1, 1 January 2011, Pages 35-41 doi : 10.1016/j.biopsych.2010.07.032
  9. ↑ MA Albrecht, MT Martin-Iverson, G Price, J Lee, R Iyyalol, F Waters, "Dexamphetamine effects on separate constructs in the rubber hand illusion test" Psychopharmacology Volume 217, Issue 1, 2011, Pages 39-50 doi : 10.1007/s00213-011-2255-y
  10. ↑ Marcello Costantini, Patrick Haggard, "The rubber hand illusion: Sensitivity and reference frame for body ownership", Consciousness and Cognition, Volume 16, Issue 2, June 2007, Pages 229–240, ISSN 1053-8100, doi : 10.1016/j.concog.2007.01.001.
  11. ↑ C. Lopez, P. Halje, O. Blanke, "Body ownership and embodiment: Vestibular and multisensory mechanisms" Neurophysiologie Clinique/Clinical Neurophysiology Volume 38, Issue 3, June 2008, Pages 149-161 doi : 10.1016/j.neucli.2007.12.006
  12. ↑ Lush, P., Botan, V., Scott, R. B., Seth, A., Ward, J., & Dienes, Z. (2019, April 16). Phenomenological control: response to imaginative suggestion predicts measures of mirror touch synaesthesia, vicarious pain and the rubber hand illusion. doi : 10.31234/osf.io/82jav
  13. ↑ Lush, P. (2020). Demand Characteristics Confound the Rubber Hand Illusion. Collabra: Psychology, 6(1), 22. doi : 10.1525/collabra.325.
  14. ↑ Slater, M., Ehrsson, H.H. (2022, June 16). Multisensory Integration Dominates Hypnotisability and Expectations in the Rubber Hand Illusion. [Frontiers in Psychology, 16:834492. doi : 10.3389/fnhum.2022.834492.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.