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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

Relationship between EMG activity and subjective illusion ratings. Scatterplot of yt/x and log(yt/x) on the mean of questions Q1–Q3 (qmean), for t = 6. yt is the number of activity onsets during the first t = 6 s that the virtual arm was rotating, x is the number of activity onsets in the 100 s prior to the virtual arm rotating. (A) yt/x by qmean over all observations, (B) log(yt/x) by qmean for observations with yt > 0.
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Figure 3: Relationship between EMG activity and subjective illusion ratings. Scatterplot of yt/x and log(yt/x) on the mean of questions Q1–Q3 (qmean), for t = 6. yt is the number of activity onsets during the first t = 6 s that the virtual arm was rotating, x is the number of activity onsets in the 100 s prior to the virtual arm rotating. (A) yt/x by qmean over all observations, (B) log(yt/x) by qmean for observations with yt > 0.

Mentions: Figure 3A shows the plot of all yt/x by qmean, for t = 6 s, which is the time by which the arm had fully rotated to its new position before rotating back. In Figure 3B the same data is shown with all values with yt = 0 eliminated, in case these were thought to be biasing the result, and on a log scale for the vertical axis. In each case it can be seen that there is a strong relationship between the two variables.


Towards a digital body: the virtual arm illusion.

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

Relationship between EMG activity and subjective illusion ratings. Scatterplot of yt/x and log(yt/x) on the mean of questions Q1–Q3 (qmean), for t = 6. yt is the number of activity onsets during the first t = 6 s that the virtual arm was rotating, x is the number of activity onsets in the 100 s prior to the virtual arm rotating. (A) yt/x by qmean over all observations, (B) log(yt/x) by qmean for observations with yt > 0.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Relationship between EMG activity and subjective illusion ratings. Scatterplot of yt/x and log(yt/x) on the mean of questions Q1–Q3 (qmean), for t = 6. yt is the number of activity onsets during the first t = 6 s that the virtual arm was rotating, x is the number of activity onsets in the 100 s prior to the virtual arm rotating. (A) yt/x by qmean over all observations, (B) log(yt/x) by qmean for observations with yt > 0.
Mentions: Figure 3A shows the plot of all yt/x by qmean, for t = 6 s, which is the time by which the arm had fully rotated to its new position before rotating back. In Figure 3B the same data is shown with all values with yt = 0 eliminated, in case these were thought to be biasing the result, and on a log scale for the vertical axis. In each case it can be seen that there is a strong relationship between the two variables.

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