Fake hand illusion: The role of hand-size and hand-dimensionality
Poster Presentation

Francesco Pavani
University of Trento

Massimiliano Zampini
University of Trento

     Abstract ID Number: 34
     Full text: Not available
     Last modified: March 10, 2006
     Presentation date: 06/19/2006 4:00 PM in Hamilton Building, Foyer
     (View Schedule)

Abstract
When a visible fake-hand is stimulated in synchrony with our own hand concealed from view, the felt position of the real hand can be biased towards the location of the fake-hand. This phenomenon, known as the fake-hand illusion, rely on the brain’s ability to detect statistical correlations in the multisensory inputs (i.e., visual, tactile, and proprioceptive), but it is also modulated by the pre-existing representation of one’s body. In the study reported here, we used a real-time video-image of the participant’s hand to elicit the fake-hand illusion, and show that the illusion can emerge also for 2D images of the body. In addition, by changing hand-size in the video-image (reduced, veridical or enlarged with respect to the real hand) we show that reduced hand size prevents the illusion, while the illusion is stable for the enlarged image of the hand. Taken together, these novel findings demonstrate that specific aspects of our own body image (i.e., hand-size, but not hand-dimensionality) can constraint the multisensory modulations of the body schema subtending the fake-hand illusion. In addition, they reveal an asymmetric role of the fake-hand size on emergence of the illusion.