Mel Slater

EVENT Lab, Institute for Brain, Cognition and Behavior (IR3C),
ICREA-University of Barcelona, 08035 Barcelona, Spain 2Department of
Computer Science, University College London, London WCIE 6BT, UK



Place Illusion and Plausibility Can Lead to Realistic Behaviour in Immersive Virtual Environments

Thursday, February 17, 2011
Location: Brooks Building Room 141 at 11:00am

In this talk, I address the question as to why participants tend to respond realistically to situations and events portrayed within an immersive virtual reality system. The idea is put forward, based on the experience of a large number of experimental studies, that there are two orthogonal components that contribute to this realistic response. The first is ‘being there’, often called ‘presence’, the qualia of having a sensation of being in a real place. We call this place illusion (PI). Second, plausibility illusion (Psi) refers to the illusion that the scenario being depicted is actually occurring. In the case of both PI and Psi the participant knows for sure that they are not ‘there’ and that the events are not occurring. PI is constrained by the sensorimotor contingencies afforded by the virtual reality system. Psi is determined by the extent to which the system can produce events that directly relate to the participant, the overall credibility of the scenario being depicted in comparison with expectations. We argue that when both PI and Psi occur, participants will respond realistically to the virtual reality.


Multisensory Stimulation Can Induce an Illusion of Larger Belly Size in Immersive Virtual Reality

Thursday, February 17, 2011
Location: Brooks Building Room 141 at 4:00pm

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.

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.

About the speaker:

Mel Slater is an ICREA Research Professor at the University of Barcelona in the EVENT Lab. He founded the Virtual Environments and Computer Graphics group in the Department of Computer Science, University College London, where he still has several projects and PhD students. Slater is considered as one of the most fruitful theoreticians and most ingenious experimentalists, who is working in the field of virtual environments. Slater and team have collaborated with the VE group at UNC-Chapel Hill.