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.