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Over my fake body: body ownership illusions for studying the multisensory basis of own-body perception.

Kilteni K, Maselli A, Kording KP, Slater M - Front Hum Neurosci (2015)

Bottom Line: On the basis of these principles, we discuss theoretical approaches concerning the underlying mechanism of BOIs.We propose a conceptualization based on Bayesian causal inference for addressing how our nervous system could infer whether an object belongs to our own body, using multisensory, sensorimotor, and semantic information, and we discuss how this can account for several experimental findings.Finally, we point to neural network models as an implementational framework within which the computational problem behind BOIs could be addressed in the future.

View Article: PubMed Central - PubMed

Affiliation: Event Lab, Department of Personality, Evaluation and Psychological Treatment, University of Barcelona Barcelona, Spain ; IR3C Institute for Brain, Cognition, and Behaviour, University of Barcelona Barcelona, Spain.

ABSTRACT
Which is my body and how do I distinguish it from the bodies of others, or from objects in the surrounding environment? The perception of our own body and more particularly our sense of body ownership is taken for granted. Nevertheless, experimental findings from body ownership illusions (BOIs), show that under specific multisensory conditions, we can experience artificial body parts or fake bodies as our own body parts or body, respectively. The aim of the present paper is to discuss how and why BOIs are induced. We review several experimental findings concerning the spatial, temporal, and semantic principles of crossmodal stimuli that have been applied to induce BOIs. On the basis of these principles, we discuss theoretical approaches concerning the underlying mechanism of BOIs. We propose a conceptualization based on Bayesian causal inference for addressing how our nervous system could infer whether an object belongs to our own body, using multisensory, sensorimotor, and semantic information, and we discuss how this can account for several experimental findings. Finally, we point to neural network models as an implementational framework within which the computational problem behind BOIs could be addressed in the future.

No MeSH data available.


Related in: MedlinePlus

Examples of body illusions. (A)The Pinocchio illusion. A blindfolded participant receives vibration on his biceps while touching the tip of his nose with his fingers. The illusory extension of the arm (Goodwin et al., 1972) generates the illusion that his nose, his fingers or both are elongating (Lackner, 1988). (B)The phantom nose illusion. The experimenter moves the finger of a blindfolded participant to tap the nose of another subject, while simultaneously tapping the nose of the participant. As the participant's movements and his finger contact with the other subject's nose are synchronous with the touch he receives on his nose, the participant experiences the illusion of tapping his very long nose (Ramachandran and Hirstein, 1998). (C)An out of body illusion. The participant sees a video of his back as if he were located behind it. The experimenter touches the back of the participant with a stick while the participant sees it online in the video. As the seen and the felt stimulation is synchronous, the participant perceives illusory drifts in his self-location toward the seen body (Lenggenhager et al., 2007). (D)The rubber hand illusion. The participant sees a rubber hand placed in front of him, while his real hand is concealed from view. The experimenter strokes both hands at the same time, and after some time the participant perceives the fake hand as if it were his own hand (Botvinick and Cohen, 1998).
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Figure 1: Examples of body illusions. (A)The Pinocchio illusion. A blindfolded participant receives vibration on his biceps while touching the tip of his nose with his fingers. The illusory extension of the arm (Goodwin et al., 1972) generates the illusion that his nose, his fingers or both are elongating (Lackner, 1988). (B)The phantom nose illusion. The experimenter moves the finger of a blindfolded participant to tap the nose of another subject, while simultaneously tapping the nose of the participant. As the participant's movements and his finger contact with the other subject's nose are synchronous with the touch he receives on his nose, the participant experiences the illusion of tapping his very long nose (Ramachandran and Hirstein, 1998). (C)An out of body illusion. The participant sees a video of his back as if he were located behind it. The experimenter touches the back of the participant with a stick while the participant sees it online in the video. As the seen and the felt stimulation is synchronous, the participant perceives illusory drifts in his self-location toward the seen body (Lenggenhager et al., 2007). (D)The rubber hand illusion. The participant sees a rubber hand placed in front of him, while his real hand is concealed from view. The experimenter strokes both hands at the same time, and after some time the participant perceives the fake hand as if it were his own hand (Botvinick and Cohen, 1998).

Mentions: A representative example of body illusions are the body distortions illusions, in which people can perceive that the size or the posture of their body part(s) have changed dramatically without necessarily satisfying the anatomical constraints of the human body. A method to induce illusory body distortions relies on kinaesthetic illusions, in which blindfolded subjects experience the illusory movement of a static body part and therefore non-veridical proprioceptive states, when the tendon muscle of a physically constrained joint is mechanically vibrated (Goodwin et al., 1972). Importantly, the illusory motion of the stationary body part can capture other non-movable body parts it is in contact with, yielding the impression that these change in size (Lackner, 1988; de Vignemont et al., 2005; Ehrsson et al., 2005b). Similar distortion illusions have been shown to occur for numerous other body parts (Lackner, 1988), to correlate with activation of areas in the lateral parietal cortex (Ehrsson et al., 2005b) and to modulate the tactile processing on the body part perceived as distorted (de Vignemont et al., 2005). A well-known example is the Pinocchio illusion (Figure 1A). Alternatively, a distortion illusion similar in phenomenology can be induced through temporal correlations between undistorted proprioceptive information and tactile input, as for example the phantom nose illusion (Ramachandran and Hirstein, 1998) (Figure 1B). Independently of the employed methodology, the body distortion illusions demonstrate that the brain computes the perceived body posture and shape dynamically and in a flexible fashion, without the need to satisfy the anatomical constrains of the human body.


Over my fake body: body ownership illusions for studying the multisensory basis of own-body perception.

Kilteni K, Maselli A, Kording KP, Slater M - Front Hum Neurosci (2015)

Examples of body illusions. (A)The Pinocchio illusion. A blindfolded participant receives vibration on his biceps while touching the tip of his nose with his fingers. The illusory extension of the arm (Goodwin et al., 1972) generates the illusion that his nose, his fingers or both are elongating (Lackner, 1988). (B)The phantom nose illusion. The experimenter moves the finger of a blindfolded participant to tap the nose of another subject, while simultaneously tapping the nose of the participant. As the participant's movements and his finger contact with the other subject's nose are synchronous with the touch he receives on his nose, the participant experiences the illusion of tapping his very long nose (Ramachandran and Hirstein, 1998). (C)An out of body illusion. The participant sees a video of his back as if he were located behind it. The experimenter touches the back of the participant with a stick while the participant sees it online in the video. As the seen and the felt stimulation is synchronous, the participant perceives illusory drifts in his self-location toward the seen body (Lenggenhager et al., 2007). (D)The rubber hand illusion. The participant sees a rubber hand placed in front of him, while his real hand is concealed from view. The experimenter strokes both hands at the same time, and after some time the participant perceives the fake hand as if it were his own hand (Botvinick and Cohen, 1998).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4371812&req=5

Figure 1: Examples of body illusions. (A)The Pinocchio illusion. A blindfolded participant receives vibration on his biceps while touching the tip of his nose with his fingers. The illusory extension of the arm (Goodwin et al., 1972) generates the illusion that his nose, his fingers or both are elongating (Lackner, 1988). (B)The phantom nose illusion. The experimenter moves the finger of a blindfolded participant to tap the nose of another subject, while simultaneously tapping the nose of the participant. As the participant's movements and his finger contact with the other subject's nose are synchronous with the touch he receives on his nose, the participant experiences the illusion of tapping his very long nose (Ramachandran and Hirstein, 1998). (C)An out of body illusion. The participant sees a video of his back as if he were located behind it. The experimenter touches the back of the participant with a stick while the participant sees it online in the video. As the seen and the felt stimulation is synchronous, the participant perceives illusory drifts in his self-location toward the seen body (Lenggenhager et al., 2007). (D)The rubber hand illusion. The participant sees a rubber hand placed in front of him, while his real hand is concealed from view. The experimenter strokes both hands at the same time, and after some time the participant perceives the fake hand as if it were his own hand (Botvinick and Cohen, 1998).
Mentions: A representative example of body illusions are the body distortions illusions, in which people can perceive that the size or the posture of their body part(s) have changed dramatically without necessarily satisfying the anatomical constraints of the human body. A method to induce illusory body distortions relies on kinaesthetic illusions, in which blindfolded subjects experience the illusory movement of a static body part and therefore non-veridical proprioceptive states, when the tendon muscle of a physically constrained joint is mechanically vibrated (Goodwin et al., 1972). Importantly, the illusory motion of the stationary body part can capture other non-movable body parts it is in contact with, yielding the impression that these change in size (Lackner, 1988; de Vignemont et al., 2005; Ehrsson et al., 2005b). Similar distortion illusions have been shown to occur for numerous other body parts (Lackner, 1988), to correlate with activation of areas in the lateral parietal cortex (Ehrsson et al., 2005b) and to modulate the tactile processing on the body part perceived as distorted (de Vignemont et al., 2005). A well-known example is the Pinocchio illusion (Figure 1A). Alternatively, a distortion illusion similar in phenomenology can be induced through temporal correlations between undistorted proprioceptive information and tactile input, as for example the phantom nose illusion (Ramachandran and Hirstein, 1998) (Figure 1B). Independently of the employed methodology, the body distortion illusions demonstrate that the brain computes the perceived body posture and shape dynamically and in a flexible fashion, without the need to satisfy the anatomical constrains of the human body.

Bottom Line: On the basis of these principles, we discuss theoretical approaches concerning the underlying mechanism of BOIs.We propose a conceptualization based on Bayesian causal inference for addressing how our nervous system could infer whether an object belongs to our own body, using multisensory, sensorimotor, and semantic information, and we discuss how this can account for several experimental findings.Finally, we point to neural network models as an implementational framework within which the computational problem behind BOIs could be addressed in the future.

View Article: PubMed Central - PubMed

Affiliation: Event Lab, Department of Personality, Evaluation and Psychological Treatment, University of Barcelona Barcelona, Spain ; IR3C Institute for Brain, Cognition, and Behaviour, University of Barcelona Barcelona, Spain.

ABSTRACT
Which is my body and how do I distinguish it from the bodies of others, or from objects in the surrounding environment? The perception of our own body and more particularly our sense of body ownership is taken for granted. Nevertheless, experimental findings from body ownership illusions (BOIs), show that under specific multisensory conditions, we can experience artificial body parts or fake bodies as our own body parts or body, respectively. The aim of the present paper is to discuss how and why BOIs are induced. We review several experimental findings concerning the spatial, temporal, and semantic principles of crossmodal stimuli that have been applied to induce BOIs. On the basis of these principles, we discuss theoretical approaches concerning the underlying mechanism of BOIs. We propose a conceptualization based on Bayesian causal inference for addressing how our nervous system could infer whether an object belongs to our own body, using multisensory, sensorimotor, and semantic information, and we discuss how this can account for several experimental findings. Finally, we point to neural network models as an implementational framework within which the computational problem behind BOIs could be addressed in the future.

No MeSH data available.


Related in: MedlinePlus