Mel Slater | Universitat de Barcelona (original) (raw)

Papers by Mel Slater

It has been shown that it is possible to generate perceptual illusions of ownership in immersive ... more It has been shown that it is possible to generate perceptual illusions of ownership in immersive virtual reality (IVR) over a virtual body seen from first person perspective, in other words over a body that visually substitutes the person's real body. This can occur even when the virtual body is quite different in appearance from the person's real body. However, investigation of the psychological, behavioral and attitudinal consequences of such body transformations remains an interesting problem with much to be discovered. Thirty six Caucasian people participated in a between-groups experiment where they played a West-African Djembe hand drum while immersed in IVR and with a virtual body that substituted their own. The virtual hand drum was registered with a physical drum. They were alongside a virtual character that played a drum in a supporting, accompanying role. In a baseline condition participants were represented only by plainly shaded white hands, so that they were able merely to play. In the experimental condition they were represented either by a casually dressed dark-skinned virtual body (Casual Dark-Skinned - CD) or by a formal suited light-skinned body (Formal Light-Skinned - FL). Although participants of both groups experienced a strong body ownership illusion towards the virtual body, only those with the CD representation showed significant increases in their movement patterns for drumming compared to the baseline condition and compared with those embodied in the FL body. Moreover, the stronger the illusion of body ownership in the CD condition, the greater this behavioral change. A path analysis showed that the observed behavioral changes were a function of the strength of the illusion of body ownership towards the virtual body and its perceived appropriateness for the drumming task. These results demonstrate that full body ownership illusions can lead to substantial behavioral and possibly cognitive changes depending on the appearance of the virtu- l body. This could be important for many applications such as learning, education, training, psychotherapy and rehabilitation using IVR.

Does realistic lighting in an immersive virtual reality application enhance presence, where parti... more Does realistic lighting in an immersive virtual reality application enhance presence, where participants feel that they are in the scene and behave correspondingly? Our previous study indicated that presence is more likely with real-time ray tracing compared with ray casting, but we could not separate the effects of overall quality of illumination from the dynamic effects of real-time shadows and reflections. Here we describe an experiment where 20 people experienced a scene rendered with global or local illumination. However, in both conditions there were dynamically changing shadows and reflections. We found that the quality of illumination did not impact presence, so that the earlier result must have been due to dynamic shadows and reflections. However, global illumination resulted in greater plausibility - participants were more likely to respond as if the virtual events were real. We conclude that global illumination does impact the responses of participants and is worth the effort.

Background Body change illusions have been of great interest in recent years for the understandin... more Background
Body change illusions have been of great interest in recent years for the understanding of how the brain represents the body. Appropriate multisensory stimulation can induce an illusion of ownership over a rubber or virtual arm, simple types of out-of-the-body experiences, and even ownership with respect to an alternate whole body. Here we use immersive virtual reality to investigate whether the illusion of a dramatic increase in belly size can be induced in males through (a) first person perspective position (b) synchronous visual-motor correlation between real and virtual arm movements, and (c) self-induced synchronous visual-tactile stimulation in the stomach area.

Methodology
Twenty two participants entered into a virtual reality (VR) delivered through a stereo head-tracked wide field-of-view head-mounted display. They saw from a first person perspective a virtual body substituting their own that had an inflated belly. For four minutes they repeatedly prodded their real belly with a rod that had a virtual counterpart that they saw in the VR. There was a synchronous condition where their prodding movements were synchronous with what they felt and saw and an asynchronous condition where this was not the case. The experiment was repeated twice for each participant in counter-balanced order. Responses were measured by questionnaire, and also a comparison of before and after self-estimates of belly size produced by direct visual manipulation of the virtual body seen from the first person perspective.

Conclusions
The results show that first person perspective of a virtual body that substitutes for the own body in virtual reality, together with synchronous multisensory stimulation can temporarily produce changes in body representation towards the larger belly size. This was demonstrated by (a) questionnaire results, (b) the difference between the self-estimated belly size, judged from a first person perspective, after and before the experimental manipulation, and (c) significant positive correlations between these two measures. We discuss this result in the general context of body ownership illusions, and suggest applications including treatment for body size distortion illnesses.

Presence-Teleoperators and …, Jan 1, 1994

Presence: Teleoperators and Virtual Environments, Jan 1, 1997

A Framework for Immersive Virtual Environments(FIVE)- Speculations on the role of presence in vir... more A Framework for Immersive Virtual Environments(FIVE)- Speculations on the role of presence in virtual environments. Mel Slater, Sylvia Wilbur Presence: Teleoperators and Virtual Environments 6:66, 603-616, 12/1997. This ...

Presence: Teleoperators & Virtual Environments, Jan 1, 2000

… and interactive …, Jan 1, 1999

ACM Transactions on Computer-Human Interaction (TOCHI), Jan 1, 2000

Nature Reviews Neuroscience, Jan 1, 2005

Presence: Teleoperators & …, Jan 1, 2000

Proceedings of the SIGCHI …, Jan 1, 2001

ACM Transactions on Computer- …, Jan 1, 1995

Presence: Teleoperators & Virtual …, Jan 1, 2002

… and advanced interface …, Jan 1, 1995

12 Presence and Performance Within Virtual Environments WOODROW BARFIELD, DAVID ZELTZER, THOMAS S... more 12 Presence and Performance Within Virtual Environments WOODROW BARFIELD, DAVID ZELTZER, THOMAS SHERIDAN, AND MEL SLATER Recent developments in display technology, specifically head-mounted displays slaved to the user's head position, ...

Presence: Teleoperators and virtual environments, Jan 1, 1993