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.

04 July, 2010

Presence in a Another Body

We recently published a paper on how we used virtual reality to give people the illusion that their body was temporarily that of another (First Person Experience of Body Transfer in Virtual Reality). In particular we were able to show that to some extent some men can be given the (temporary!) illusion that their body is that of a girl.

The image shows an overview of the scenario. The experimental participants were located in or near the seated girl's body, via wearing a head-tracked wide field-of-view head-mounted display. In one condition of the experiment, when they looked down towards their body they would see the girl's body instead, as if their eyes were located in the same position as hers. If they turned to look to their left, they would see the body of the girl in the virtual mirror, with its head movements matching their own. When the standing woman stroked the arm of the seated girl, they would feel this on their own arm.

This paper seems to have generated a lot of interest judging from press reports and the PLoS ONE metrics.

Some of the comments about the paper are quite funny, and it seems to have awakened kinky fantasies in some men. Other comments are off the mark believing (spurred on by some journalistic takes on the article) that we were transforming men into women. Indeed one angry comment on the paper notes that to give men the experience of being female we would have to also simulate all of the social conditions that women are subject to, and also physiological processes such as menstruation, etc..

I agree very much with this. We were not giving men the experience of what it is like to be a woman! We were generating an illusion that is very hard to describe or understand unless you have experienced it. It is an illusion that the different body that you see when you look down at ‘yourself’ in virtual reality, or when you see ‘yourself’ in a virtual mirror, is somehow your body (even though you know it isn’t).

The brain seems to be quite liberal in deciding what is part of your body, and such illusions have shown that it is not difficult at all to trick the brain into believing that something is part of your body when it is not. It is important to realise that this ‘trick’ does not happen at the cognitive level, that is you never believe that the fake body or body part is really part of you. Rather it is at some lower perceptual and proprioceptive level that you don’t have much conscious control over that this happens. So it is like ‘presence’ in virtual reality - you know for sure that this is not your body, but nevertheless it feels like it is.

These illusions stem from an initial insight by Botvinick and Cohen known as the ‘rubber hand illusion’, and see also the New Scientist video with Olaf Blanke. Here people experience the illusion that a rubber hand is their hand. However, no one would then go on to say that people who experience the rubber hand illusion know what it is like to have a rubber hand! Similarly we do not claim that a male who has the illusion that his body looks like a female one knows what it is like to have female body. These are different things at quite different logical levels.

I hope you find the article interesting, and on the PLoS ONE web page you can see a video which gives some idea of how it looks to the experimental participant. However, the only way to really know how the illusion feels would be to experience it. Welcome to Barcelona.