Mel Slater's Presence Blog

Thoughts about research and radical new applications of virtual reality - a place to write freely without the constraints of academic publishing,and have some fun.

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I still find immersive virtual reality as thrilling now as when I first tried it 20 years ago.

30 August, 2009

Illusion is Part of the Definition

In July there was a conference in Benasque, Spain, Art and Science: Exploring the Limits of Human Perception. We (Mavi Sanchez-Vives and I) teamed up with Nonny de la Peña and Peggy Weil from California, to create a piece based on the idea of immersive journalism. You can read about what it is like to be a prisoner at Guantánamo, but can you get first hand knowledge of what the experience is really like?

We created a scenario in immersive virtual reality, relying on research on body ownership, to give people the illusion that they were in a cell standing in a stress position, while hearing an interrogation going on in the cell next door. There is an article about it in El Pais: Presos de un Guantánamo virtual, and a youtube video: Towards Immersive Journalism: The IPSRESS Experience.

My new paper attempting to give my current understanding of 'presence' has been formally accepted for the Philosophical Transactions of the Royal Society, Series B. This is about deconstructing the concept of presence into two orthogonal concepts: 'place illusion' - the original idea of having a strong illusion of being in the virtual place, and 'plausibility', the illusion that what is happening is really happening. Of course these are illusions, no one really believes that they are in the virtual place or that what is happening is real - the fact that these are illusions is part of the very definition. Also the paper discusses what I think is a good way to understand 'immersion'. Altogether there are four concepts: Place Illusion (PI, based on sensorimotor contingencies), Plausibility (Psi, based ultimately on various correlations between actions and events), immersion (forming a simulation hierarchy) and the virtual body which is the intersection between PI and Psi. I think that it is relatively clear to me now, ideas that I've been trying to find for many years. 'Presence' in the sense of place illusion is not and never really was the main problem - it can be relatively easily achieved most of the time with the right display and especially tracking systems. The real problem is Plausibility. The pre-publication version of the paper can be downloaded from my publication website.