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The perspective matters! Multisensory integration in ego-centric reference frames determines full-body ownership.

Petkova VI, Khoshnevis M, Ehrsson HH - Front Psychol (2011)

Bottom Line: Recent advances in experimental science have made it possible to investigate the perceptual processes involved in generating a sense of owning an entire body.Here we investigate the fundamental question of the reference frames used in the process of attributing an entire body to the self.This demonstrates that the multisensory integration processes producing the sense of corporeal self operates in an ego-centric reference frame.

View Article: PubMed Central - PubMed

Affiliation: Brain, Body and Self Laboratory, Department of Neuroscience, Karolinska Institutet Stockholm, Sweden.

ABSTRACT
Recent advances in experimental science have made it possible to investigate the perceptual processes involved in generating a sense of owning an entire body. This is achieved by full-body ownership illusions which make use of specific patterns of visual and somatic stimuli integration. Here we investigate the fundamental question of the reference frames used in the process of attributing an entire body to the self. We quantified the strength of the body-swap illusion in conditions where the participants were observing this artificial body from the perspective of the first or third person. Consistent results from subjective reports and physiological recordings show that the first person visual perspective is critical for the induction of this full-body ownership illusion. This demonstrates that the multisensory integration processes producing the sense of corporeal self operates in an ego-centric reference frame.

No MeSH data available.


Related in: MedlinePlus

Introspective and objective evidences from the three experiments. (A) Experiment #1: The participants rated the illusion-related questions significantly higher than the control questions; this difference was significantly greater when the mannequin's body was perceived from the first person perspective (i.e., significant interaction of the main factors “Perspective” vs. “Question type”). Dark bars represent the ratings in the first person perspective and light bars represent the ratings in the third person perspective respectively. The error bars indicate standard errors. (B) Experiment #2: The threat-evoked increase in the skin conductance responses (SCR) was significant only in the condition in which the participant observed the synchronized visuo-tactile stimulation from the first person perspective. The error bars indicate standard errors. (C) Experiment #3: The full-body illusion can be evoked without the help of HMDs and video-technology. The specific threat-evoked increase in the SCR when the body was observed from the first person perspective again emphasizes the importance of this visual perspective for the mechanism of attributing a body to oneself. The error bars indicate standard errors.
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Figure 3: Introspective and objective evidences from the three experiments. (A) Experiment #1: The participants rated the illusion-related questions significantly higher than the control questions; this difference was significantly greater when the mannequin's body was perceived from the first person perspective (i.e., significant interaction of the main factors “Perspective” vs. “Question type”). Dark bars represent the ratings in the first person perspective and light bars represent the ratings in the third person perspective respectively. The error bars indicate standard errors. (B) Experiment #2: The threat-evoked increase in the skin conductance responses (SCR) was significant only in the condition in which the participant observed the synchronized visuo-tactile stimulation from the first person perspective. The error bars indicate standard errors. (C) Experiment #3: The full-body illusion can be evoked without the help of HMDs and video-technology. The specific threat-evoked increase in the SCR when the body was observed from the first person perspective again emphasizes the importance of this visual perspective for the mechanism of attributing a body to oneself. The error bars indicate standard errors.

Mentions: The experiment consisted of two conditions, each of which lasted for 2 min. The order of the conditions was balanced across the participants. In the condition corresponding to the 1PP, the participant was asked to tilt his head downward as if to look at his own body while actually looking through the HMDs at the body of mannequin #1 at a location and orientation similar to the participant's own body. In the second condition, referred to as the 3PP condition, the participant was asked to position his head as if to look forward toward the body of a person standing just opposite him. In the HMDs, the participant saw the body of mannequin #2 facing him at a distance of 75 cm. In both conditions the experimenter used two plastic rods to apply the same number of synchronized strokes on the right lateral parts of the mannequin's abdomen and the participant's abdomen. After each condition, the participants were asked to complete a questionnaire, in which they had to affirm or deny nine possible perceptual effects using a seven-point Likert scale (Figure 3A).


The perspective matters! Multisensory integration in ego-centric reference frames determines full-body ownership.

Petkova VI, Khoshnevis M, Ehrsson HH - Front Psychol (2011)

Introspective and objective evidences from the three experiments. (A) Experiment #1: The participants rated the illusion-related questions significantly higher than the control questions; this difference was significantly greater when the mannequin's body was perceived from the first person perspective (i.e., significant interaction of the main factors “Perspective” vs. “Question type”). Dark bars represent the ratings in the first person perspective and light bars represent the ratings in the third person perspective respectively. The error bars indicate standard errors. (B) Experiment #2: The threat-evoked increase in the skin conductance responses (SCR) was significant only in the condition in which the participant observed the synchronized visuo-tactile stimulation from the first person perspective. The error bars indicate standard errors. (C) Experiment #3: The full-body illusion can be evoked without the help of HMDs and video-technology. The specific threat-evoked increase in the SCR when the body was observed from the first person perspective again emphasizes the importance of this visual perspective for the mechanism of attributing a body to oneself. The error bars indicate standard errors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108400&req=5

Figure 3: Introspective and objective evidences from the three experiments. (A) Experiment #1: The participants rated the illusion-related questions significantly higher than the control questions; this difference was significantly greater when the mannequin's body was perceived from the first person perspective (i.e., significant interaction of the main factors “Perspective” vs. “Question type”). Dark bars represent the ratings in the first person perspective and light bars represent the ratings in the third person perspective respectively. The error bars indicate standard errors. (B) Experiment #2: The threat-evoked increase in the skin conductance responses (SCR) was significant only in the condition in which the participant observed the synchronized visuo-tactile stimulation from the first person perspective. The error bars indicate standard errors. (C) Experiment #3: The full-body illusion can be evoked without the help of HMDs and video-technology. The specific threat-evoked increase in the SCR when the body was observed from the first person perspective again emphasizes the importance of this visual perspective for the mechanism of attributing a body to oneself. The error bars indicate standard errors.
Mentions: The experiment consisted of two conditions, each of which lasted for 2 min. The order of the conditions was balanced across the participants. In the condition corresponding to the 1PP, the participant was asked to tilt his head downward as if to look at his own body while actually looking through the HMDs at the body of mannequin #1 at a location and orientation similar to the participant's own body. In the second condition, referred to as the 3PP condition, the participant was asked to position his head as if to look forward toward the body of a person standing just opposite him. In the HMDs, the participant saw the body of mannequin #2 facing him at a distance of 75 cm. In both conditions the experimenter used two plastic rods to apply the same number of synchronized strokes on the right lateral parts of the mannequin's abdomen and the participant's abdomen. After each condition, the participants were asked to complete a questionnaire, in which they had to affirm or deny nine possible perceptual effects using a seven-point Likert scale (Figure 3A).

Bottom Line: Recent advances in experimental science have made it possible to investigate the perceptual processes involved in generating a sense of owning an entire body.Here we investigate the fundamental question of the reference frames used in the process of attributing an entire body to the self.This demonstrates that the multisensory integration processes producing the sense of corporeal self operates in an ego-centric reference frame.

View Article: PubMed Central - PubMed

Affiliation: Brain, Body and Self Laboratory, Department of Neuroscience, Karolinska Institutet Stockholm, Sweden.

ABSTRACT
Recent advances in experimental science have made it possible to investigate the perceptual processes involved in generating a sense of owning an entire body. This is achieved by full-body ownership illusions which make use of specific patterns of visual and somatic stimuli integration. Here we investigate the fundamental question of the reference frames used in the process of attributing an entire body to the self. We quantified the strength of the body-swap illusion in conditions where the participants were observing this artificial body from the perspective of the first or third person. Consistent results from subjective reports and physiological recordings show that the first person visual perspective is critical for the induction of this full-body ownership illusion. This demonstrates that the multisensory integration processes producing the sense of corporeal self operates in an ego-centric reference frame.

No MeSH data available.


Related in: MedlinePlus