[MUSIC] So before we talked about the concept of immersion as being the affordances that the system gives you, but very important in that is what affordances does the system give your for perception? So for example, if I'm wearing a head mounted display that has no head tracking, I can move my head as much as I like and I won't get sensory motor contingencies which are caused by moving my head. The image I see will always just move with me, nothing will change. But if I have head tracking with let's say 46 degrees of freedom head tracking, as I turn around and as I move my head, so the visual system, the visual input I get will update accordingly. Which means that I have sensory motor contingencies that are more or less the same like real life. But sensory motor contingencies has another aspect. It's not just simply the interaction, the input, it's also how we input it. So part of sensory motor contingencies is that, as I said, if I want to see close up to this object, I just move my head closer to it and I see that object closer. But how is VR involved in this? VR is involved because in VR if I do the same, not exactly the same thing will happen, because eventually what I'll see is not the object but pixels. The closer I get to an object, the more likely is it's just going to dissolve into a whole set of pixels. So sensory-motor contingency is this kind of combination together of how you perceive and what you perceive. The more that that matches, the more that the how matches reality, and the more the what you perceive matches what you would expect to see in reality through the act of perception. So you're getting closer and closer to natural sensory-motor contingencies. Now, there's a very big consequence of that. If you think about it, if I'm in virtual reality and the system affords the natural sensory-motor contingencies so that I am perceiving in the virtual world much the same way as I do in the real world, what does the brain make of this? Really, the simplest hypothesis for the brain to make out of this is, okay, this is where I am. Because in real life, how do I know where I am? Well I look around, I hear, I touch, I see, and I use my body in certain ways. If I use my body in the same ways, and the same kind of changes to my perception occur, then the simplest hypotheses for the brain to make is to give you the illusion that this is where you are. The virtual world is where you are. So, these sensory-motor contingencies are very very tied up with what we talked about right at the beginning, this wow factor. I'm somewhere else, I'm not in the lab anymore, I'm in this forest or wherever it happens to be. >> Yeah, very interesting because it actually reminds me of an examples like actually it was the very first time I tried HTC. And the graphics were very nice and the tracking was working beautifully. So I was doing this task like there was a little robot something I was trying to fix things. It was an amazing task, but I was really in it. And at some point I heard the door open and I heard a group of students walking in, and I know that's probably something happening in the physical reality. And I'm a lecturer, normally when students come into the room I might behave myself a little bit. But for some reason at that moment, consciously I just decided I don't care about these students, I just want to try to duck my body away from this thing that's going to fall one me. I didn't care how ridiculous I may have looked in front of the students. Which is amazing, because definitely want to have that head-mounted display off, I was like okay, that was embarrassing what I did. Yes, I just felt that thing was actually really sort of overwhelming experience that is difficult to explain, it's really a bit like magic in a sense. >> Yeah. [MUSIC]