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Towards a digital body: the virtual arm illusion.

Slater M, Perez-Marcos D, Ehrsson HH, Sanchez-Vives MV - Front Hum Neurosci (2008)

Bottom Line: Here we demonstrate that a virtual limb can be made to feel part of your body if appropriate multisensory correlations are provided.An experiment with 21 male participants showed displacement of ownership towards the virtual hand, as illustrated by questionnaire responses and proprioceptive drift.A completely virtual object can therefore be experienced as part of one's self, which opens up the possibility that an entire virtual body could be felt as one's own in future virtual reality applications or online games, and be an invaluable tool for the understanding of the brain mechanisms underlying body ownership.

View Article: PubMed Central - PubMed

Affiliation: Institució Catalana de Recerca i Estudis Avançats Barcelona, Spain. melslater@lsi.upc.edu

ABSTRACT
The integration of the human brain with computers is an interesting new area of applied neuroscience, where one application is replacement of a person's real body by a virtual representation. Here we demonstrate that a virtual limb can be made to feel part of your body if appropriate multisensory correlations are provided. We report an illusion that is invoked through tactile stimulation on a person's hidden real right hand with synchronous virtual visual stimulation on an aligned 3D stereo virtual arm projecting horizontally out of their shoulder. An experiment with 21 male participants showed displacement of ownership towards the virtual hand, as illustrated by questionnaire responses and proprioceptive drift. A control experiment with asynchronous tapping was carried out with a different set of 20 male participants who did not experience the illusion. After 5 min of stimulation the virtual arm rotated. Evidence suggests that the extent of the illusion was also correlated with the degree of muscle activity onset in the right arm as measured by EMG during this period that the arm was rotating, for the synchronous but not the asynchronous condition. A completely virtual object can therefore be experienced as part of one's self, which opens up the possibility that an entire virtual body could be felt as one's own in future virtual reality applications or online games, and be an invaluable tool for the understanding of the brain mechanisms underlying body ownership.

No MeSH data available.


Related in: MedlinePlus

The experimental setup. (A) The participant wears passive stereo glasses and a head-tracker, and the virtual image is determined as a function of his head direction. The experimenter taps and strokes the participant's real hand with a 6-degree freedom Wand, whose position is tracked and used to determine the position of the virtual sphere. (B) The participant is standing in front of a 2 m × 2.7 m rear projection screen. The arm in the screen is seen from the participant's point of view as projecting out of his right shoulder, while his own arm is out of view and resting on a support. In the projection the participant also sees a sphere striking in synchrony and in the same place on the virtual hand as the touch stimuli delivered to his own hand.
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Figure 1: The experimental setup. (A) The participant wears passive stereo glasses and a head-tracker, and the virtual image is determined as a function of his head direction. The experimenter taps and strokes the participant's real hand with a 6-degree freedom Wand, whose position is tracked and used to determine the position of the virtual sphere. (B) The participant is standing in front of a 2 m × 2.7 m rear projection screen. The arm in the screen is seen from the participant's point of view as projecting out of his right shoulder, while his own arm is out of view and resting on a support. In the projection the participant also sees a sphere striking in synchrony and in the same place on the virtual hand as the touch stimuli delivered to his own hand.

Mentions: Twenty-one healthy male participants (mean age and standard deviation 22 ± 3.9 years) were recruited for the experiment by advertisement amongst students, research and administrative staff at the Instituto de Neurociencias, UMH. They were each offered 5? for their participation. Upon arrival at the laboratory they were asked to read and sign a consent form, the experiment having been carried out in accordance with the regulations of Comité Ético de Investigación del Hospital Universitario de San Juan de Alicante, Spain. Each participant stood beside a mounted shoulder-high wooden shelf (adjustable in height) and rested his right arm on the shelf. His arm was hidden from his view by a sheet of grey foam fixed to the side of the shelf. The participant wore the stereo glasses and the head-tracker mounted just above the glasses (Figure 1A).


Towards a digital body: the virtual arm illusion.

Slater M, Perez-Marcos D, Ehrsson HH, Sanchez-Vives MV - Front Hum Neurosci (2008)

The experimental setup. (A) The participant wears passive stereo glasses and a head-tracker, and the virtual image is determined as a function of his head direction. The experimenter taps and strokes the participant's real hand with a 6-degree freedom Wand, whose position is tracked and used to determine the position of the virtual sphere. (B) The participant is standing in front of a 2 m × 2.7 m rear projection screen. The arm in the screen is seen from the participant's point of view as projecting out of his right shoulder, while his own arm is out of view and resting on a support. In the projection the participant also sees a sphere striking in synchrony and in the same place on the virtual hand as the touch stimuli delivered to his own hand.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2572198&req=5

Figure 1: The experimental setup. (A) The participant wears passive stereo glasses and a head-tracker, and the virtual image is determined as a function of his head direction. The experimenter taps and strokes the participant's real hand with a 6-degree freedom Wand, whose position is tracked and used to determine the position of the virtual sphere. (B) The participant is standing in front of a 2 m × 2.7 m rear projection screen. The arm in the screen is seen from the participant's point of view as projecting out of his right shoulder, while his own arm is out of view and resting on a support. In the projection the participant also sees a sphere striking in synchrony and in the same place on the virtual hand as the touch stimuli delivered to his own hand.
Mentions: Twenty-one healthy male participants (mean age and standard deviation 22 ± 3.9 years) were recruited for the experiment by advertisement amongst students, research and administrative staff at the Instituto de Neurociencias, UMH. They were each offered 5? for their participation. Upon arrival at the laboratory they were asked to read and sign a consent form, the experiment having been carried out in accordance with the regulations of Comité Ético de Investigación del Hospital Universitario de San Juan de Alicante, Spain. Each participant stood beside a mounted shoulder-high wooden shelf (adjustable in height) and rested his right arm on the shelf. His arm was hidden from his view by a sheet of grey foam fixed to the side of the shelf. The participant wore the stereo glasses and the head-tracker mounted just above the glasses (Figure 1A).

Bottom Line: Here we demonstrate that a virtual limb can be made to feel part of your body if appropriate multisensory correlations are provided.An experiment with 21 male participants showed displacement of ownership towards the virtual hand, as illustrated by questionnaire responses and proprioceptive drift.A completely virtual object can therefore be experienced as part of one's self, which opens up the possibility that an entire virtual body could be felt as one's own in future virtual reality applications or online games, and be an invaluable tool for the understanding of the brain mechanisms underlying body ownership.

View Article: PubMed Central - PubMed

Affiliation: Institució Catalana de Recerca i Estudis Avançats Barcelona, Spain. melslater@lsi.upc.edu

ABSTRACT
The integration of the human brain with computers is an interesting new area of applied neuroscience, where one application is replacement of a person's real body by a virtual representation. Here we demonstrate that a virtual limb can be made to feel part of your body if appropriate multisensory correlations are provided. We report an illusion that is invoked through tactile stimulation on a person's hidden real right hand with synchronous virtual visual stimulation on an aligned 3D stereo virtual arm projecting horizontally out of their shoulder. An experiment with 21 male participants showed displacement of ownership towards the virtual hand, as illustrated by questionnaire responses and proprioceptive drift. A control experiment with asynchronous tapping was carried out with a different set of 20 male participants who did not experience the illusion. After 5 min of stimulation the virtual arm rotated. Evidence suggests that the extent of the illusion was also correlated with the degree of muscle activity onset in the right arm as measured by EMG during this period that the arm was rotating, for the synchronous but not the asynchronous condition. A completely virtual object can therefore be experienced as part of one's self, which opens up the possibility that an entire virtual body could be felt as one's own in future virtual reality applications or online games, and be an invaluable tool for the understanding of the brain mechanisms underlying body ownership.

No MeSH data available.


Related in: MedlinePlus