Original Research Article
Towards a digital body: the virtual arm illusion
Mel Slater 1, 2, 3*, Daniel Pérez Marcos 4, 5, H. Henrik Ehrsson 6 and Maria V. Sanchez-Vives 1, 4, 5
1 Institució Catalana de Recerca i Estudis Avançats , Spain
2 Centre de Realitat Virtual, Universitat Politècnica de Catalunya, Spain
3 Department of Computer Science, University College London, UK
4 Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Spain
5 Institut d`Investigacions Biomèdiques August Pi i Sunyer , Spain
6 Department of Clinical Neuroscience, Karolinska Institute, Sweden
2 Centre de Realitat Virtual, Universitat Politècnica de Catalunya, Spain
3 Department of Computer Science, University College London, UK
4 Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Spain
5 Institut d`Investigacions Biomèdiques August Pi i Sunyer , Spain
6 Department of Clinical Neuroscience, Karolinska Institute, Sweden
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 minutes 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.
Keywords: rubber hand illusion, virtual reality, virtual environment
Copyright: © 2008 Slater, Pérez Marcos, Ehrsson and Sanchez-Vives. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
*Correspondence: Mel Slater, ICREA-Centre de Realitat Virtual (CRV), Edificio U, Universitat Politècnica de Catalunya, C. Pau Gargallo 16,08028 Barcelona, Spain. e-mail: melslater@lsi.upc.edu
Citation: Slater M, Pérez Marcos D, Ehrsson H and Sanchez-Vives MV (2008) Towards a digital body: the virtual arm illusion. Front. Hum. Neurosci. (2008) 2:0. doi:10.3389/neuro.09.006.2008
Received: 10 January 2008; paper pending published: 16 March 2008; accepted: 07 July 2008; published online: 20 August 2008.
Edited by:
Maurizio Corbetta, Washington University, USA
Reviewed by:
Olaf Blanke, EPFL - Ecole Polytechnique Fédérale de Lausanne, Switzerland; University of Geneva, Switzerland
Nicholas Holmes, Hebrew University., Israel
Nicholas Holmes, Hebrew University., Israel
*Correspondence: Mel Slater, ICREA-Centre de Realitat Virtual (CRV), Edificio U, Universitat Politècnica de Catalunya, C. Pau Gargallo 16,08028 Barcelona, Spain. e-mail: melslater@lsi.upc.edu


