#183: Mel Slater on VR Presence, Virtual Body Ownership, & the Time Travel Illusion

mel-slaterMel Slater is an ICREA Research Professor at the University of Barcelona, Spain, where he leads the Event Lab. Mel and his fellow Event Lab researchers have been doing some pioneering work in defining the key components of presence as well as the exploring the sense of self within virtual environments.

According to Mel, the illusion of ‘presence’ within VR can be broken up into two major components. First, the Place Illusion is when your perceptual systems are fooled into believing that you’re in another place through more technologically driven factors of low-latency head tracking, a fast framerate, and having accurate 1:1 tracking of your body. The other component is the Plausibility Illusion, which is when you perceive the virtual world as being coherent in it’s construction and it accurately meets your expectations for how it behaves and reacts to your actions. Here’s more details from the abstract of Mel’s paper titled “Place Illusion and Plausibility Can Lead to Realistic Behaviour in Immersive Virtual Environments”

In this paper we address the question as to why participants tend to respond realistically to situations and events portrayed within an Immersive Virtual Reality (IVR) system. The idea is put forward, based on 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 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, and 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.

Mel describes the Place Illusion as being governed by the perceptual system, and that the Plausibility Illusion is more of a cognitive function. When it comes to breaks in presence, the Place Illusion is more resilient to temporary glitches or technological disruptions. As long as the system can recover technologically to issues such as latency, framerate, or graphical fidelity, then subjects can regain their sense of presence of being within in another world.

The Plausibility Illusion however is a lot more sensitive because it’s a cognitive function. Once there is something that is not coherent within the rules of the environment that violates the expectations of the subject, then it’s a lot harder for the experience to recover from this type of break in presence.

The Event Lab has also done a lot of work in investigating the Virtual Body Ownership Illusion and what’s required to create it, as well as it’s impact on your attitudes, beliefs, and behaviors. Here’s an overview view that explores some of these “Positive Illusions of Self in Immersive Virtual Reality:”

Another really interesting experiment from the Event Lab was looking at how to create the illusion of Time Travel. Subjects were put into a virtual museum with full body tracking so as to create a strong illusion of body ownership. They were then presented with a moral dilemma scenario that was based upon decisions that they had already made. The subjects were then brought back a week later to watch their previous actions, and then have an opportunity to intervene on the actions of their previous self.

Subjects from the experiment reported that it felt like they were time traveling because they were able to objectively witness their previously embodied avatar’s actions. More information about this study can be found here:
A method for generating an illusion of backwards time travel using immersive virtual reality—an exploratory study

This time travel illusion has a lot of interesting implications for the future of social interactions and experiences within a VR environment. Imagine hanging out with friends or family, and then being able to revisit those experiences after it had long faded from your memory. Perhaps you’d gain new insight about yourself, or be able to go beyond nostalgia and be able to relive experiences with people who are no longer alive.

Finally, Mel talks about how VR has the potential to be a very powerful tool to be able to change your sense of self. VR has the capability to put you into another body and give you another point of view and perspective, which can then give you a new perspective on your own life. No other medium has the capability to do that, and the ultimate potential of being able to do this is largely unexplored and unknown at this point.

If you’re interested in these types of questions about how VR can the sense of ourselves, then be sure to follow the publications listed on The Event Lab website, keep an eye on The Event Lab YouTube channel for some of their latest results and research, and take a look at the new Frontiers of Virtual Environments publication that Mel is editing.

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