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.

27 May, 2012

Inverse Presence

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Inverse Presence

People use virtual reality for a purpose - like any 
kind of media the purpose of experiencing it is
to effect some change. This change might be simply 
at the level of enjoying something (entertainment), or viewing something (for the sake of understanding, design or development), or to learn something new, or to have some new kind of experience that is not available or difficult to achieve in everyday reality.

In some sense there is always a task to be realised - whether it is "enjoy yourself"or something more concrete than that such as to realise a specific set of actions. 

Now for many years there has been research on factors that contribute to 'presence'. Here by 'presence' I mean that aspect where people tend to respond to situations and events in the virtual world as if they were real: an avatar smiles at you and you smile back, or an avatar comes close to you and you feel uncomfortable and possibly step backwards, since this breaks the norms of proxemics. 

Even if only implicitly most applications of VR rely on presence occurring. For example, using VR for psychotherapy would be useless unless the patients, to some extent, respond realistically to what is depicted in the VR. So VR therapy, for example, for fear of heights would not be useful if patients did not feel some anxiety around their experience of precipices in VR.

Lydia Reeves Timmins and Matthew Lombard used the term 'inverse presence' to describe situations where something happens in reality that is perceived as if it were not real - real events (especially horrific ones) may be experienced as 'simulated' - i.e., we have all experienced moments in which we think "this is not really happening". Here I want to give a different meaning to the term "inverse presence" - to mean that we assume that presence in a VR will happen, and therefore we exploit this to get participants to achieve some particular tasks that they had never explicitly been told to do. For example, suppose the task is "get this person to smile" - then elements of the virtual environment (such as avatars) must learn to carry out actions that evoke this response. Probably here it would be quite easy - since from 'presence theory' we know that if an avatar smiles at the participant they are very likely to smile back - and so introduction of smiling avatars would probably do the trick.

Most experiment studies on presence vary factors that are thought to contribute to presence, and then see when and if presence occurs. 'Inverse presence' means - we know that presence will occur and so certain behaviours are likely to follow from this, and let's utilise it to get people to do certain specified actions.

In the recently published paper (PDF) of Jason Kastanis and myself in ACM TAP we described a quite simple example of this approach. When you interact with a virtual human character in immersive VR you tend to respond realistically. In particular several other works have shown that the rules of 'proxemics' operate - that is, if the avatar approaches too closely to you, you step backwards (the implicit rules of social, personal and intimate space seem to apply in your interactions with avatars too). Our goal was for an avatar to learn how to get the participant to go to a particular place within the virtual environment - a place some metres behind where they were initially standing. The avatar was programmed with a number of actions it could take - like move forward or back, do nothing or wave to the participant saying "come here". At first the avatar chose these actions at random, but over time it converged on the right behaviours - get the person close to the avatar and then move forward towards the person so that the person backed away. The avatar was controlled by a Reinforcement Learning agent, that received a reward when the person moved towards the target, and a loss when the person didn't do that. The RL algorithm is designed to maximise long term reward. What we found is that in circumstances when the avatar was allowed to move to intimate distance to the person, it learned how to drive them to the pre-specified place within 7 minutes. It took much longer if they could only move to personal distance, and didn't work at all if it just selected random actions (move forward or back or wave).

The purpose of VR is to get people to 'do' things (doing includes experiencing). Here we let the VR system learn how to get the person to do things by relying on their likely responses to events, as predicted by presence theory. The RL worked efficiently, but of course this was a very simple 1D problem. Nevertheless I think that the paradigm is worth pursuing with more complex scenarios.

20 May, 2012

The Presence of Shy Men

We recently had a paper published in PLoS ONE:

Socially Anxious and Confident Men Interact with a Forward Virtual Woman: An Experimental Study




A man goes alone to a party. There are not many people there, a few sitting around, and one lone woman who starts looking at him. Very soon, the lone woman walks towards him and starts a conversation. At first the conversation is mundane and she maintains a normal social distance from the man. But eventually she tells him that she thinks he looks very nice, moves much closer to him breaking normal social boundaries, and then asks him whether he is involved with anyone at this time.

How does the man react? Well for the experiment we recruited men who were either were quite socially confident in their relationships with women, or quite socially anxious. Our expectation was that those who were socially confident would simply enjoy the encounter, whereas the anxiety level of those who were socially anxious would go through the roof.

Oh - don't forget that all this happened in virtual reality, in the Cave system at UCL, London.

So what happened in fact? On the whole the men in both groups were more anxious than previously, when the woman first approached. Then for the confident group the anxiety levels returned to what they had been beforehand, but, and to our surprise, the anxiety levels of the anxious group actually seemed to go even lower than they had been beforehand.

I believe that what happened is that men who are socially anxious with women tend to avoid such encounters (because it makes them anxious). In particular they do not initiate encounters, and avoid situations where they might be required to approach the opposite sex - such as dances, parties etc (except perhaps unless they are fortified by alcohol). But here there was a 'woman' who was doing all the work, making all the small talk, and also interspersing a more mundane conversation (about living in London etc) with the more challenging topic of relationships. This allowed the anxious men to relax more than usual, certainly more than they would have expected than when the woman first approached.

I think that this points an interesting way forward in therapy for such social phobic conditions. In this case the virtual woman initiates the conversation, and reduces the 'threat' level, by keeping it at a mundane level for a while. Then more problematic issues can be raised. This interspersing of mundane and more difficult topics in the conversation, could, I think, be a key to therapy in this area.

We carried out this study quite some time ago, but only recently wrote and submitted the paper. Now we can do avatars and scenarios of much higher quality than we used then. Moreover, we now routinely animate virtual characters through motion capture, so overall the experience for any participant has a much greater level of realism. But the interesting point is that in spite of the low level of realism in this study, the men still tended to respond as if it were real. I'm not sure how much additional realism would actually change things.

Finally, social phobia is a hidden illness, with very severe consequences for the sufferers. Many years ago we were doing a case study with Prof. David M. Clark and the patient had a particular form of social phobia - fear of public speaking. This had affected his career - choosing a career where he could avoid speaking in public was a critical consideration for him. He told us he was worried about making a speech at his daughter's wedding. His daughter was, at the time, 3 years old.