Mel Slater

Mel Slater is a British computer scientist and a researcher in virtual reality. He is an ICREA Research Professor at the University of Barcelona, where he leads the Event Lab (the Experimental Virtual Environments for Neuroscience and Technology laboratory). He was previously Professor of Virtual Environments at University College London (UCL). His research is concerned with the conditions under which people respond realistically to virtual situations, and he is known for a theoretical framework that separates immersion from presence and decomposes presence into the place illusion and the plausibility illusion.

Education and career

Slater's first degree was in statistics at the London School of Economics and Political Science, and he later took a master's degree in sociology at the University of Essex and a master's degree in statistics at the London School of Economics. He holds a DSc from the University of London for work on presence in virtual reality. He joined Queen Mary and Westfield College, University of London, as a lecturer in 1981.

In 1997 he became Professor of Virtual Environments at University College London, in the Department of Computer Science, where he founded the Virtual Environments and Computer Graphics group. He was a UK EPSRC Senior Research Fellow from 1999 to 2004. In 2006 he moved to Barcelona as an ICREA Research Professor, first at the Universitat Politècnica de Catalunya and then, from 2008, at the University of Barcelona, while keeping a part-time affiliation and a research team at UCL until 2018. At the University of Barcelona he leads the Event Lab.

Research on presence

Slater's central research question is what makes virtual reality work: under what conditions people respond realistically to events in a virtual environment despite knowing the environment is computer generated. An early experimental study of presence is the paper by Slater and Usoh published in 1993.

A key part of his contribution is the distinction between immersion and presence. He defines immersion as an objective property of the technical system, set by the physical capabilities of the hardware and software, and he frames it in terms of the valid actions a system supports: one system is at a higher level of immersion than another if the valid actions of the second form a proper subset of those of the first. Presence, by contrast, is the subjective human response to a given level of immersion.

In a 2009 paper in Philosophical Transactions of the Royal Society B, Slater proposed that this response can be decomposed into two components. The first is the place illusion (PI), which he defines as "the strong illusion of being in a place in spite of the sure knowledge that you are not there." The second is the plausibility illusion (Psi), which he defines as "the illusion that what is apparently happening is really happening (even though you know for sure that it is not)." In his account the two illusions are conceptually distinct, and when both hold, participants tend to respond realistically to the virtual environment. Slater and colleagues later revisited and updated the framework in a 2022 paper in Frontiers in Virtual Reality.

Research on embodiment and body ownership

Slater also studies virtual body ownership, the finding that a participant can come to feel that a life-sized virtual body seen from a first-person perspective is their own. His work has examined how the appearance of the virtual body can change a participant's perceptions, attitudes, and behaviour.

One line of this research concerns implicit racial bias. In a 2013 study, light-skinned participants embodied in a dark-skinned virtual body showed a reduction in their implicit bias against dark-skinned people, an effect not seen with a light-skinned or other virtual body. A 2016 follow-up reported that the reduction could persist for at least a week after the virtual reality exposure.

Applications

Slater has applied his work on presence to social and psychological situations that are difficult to study in physical reality. In a 2006 paper in PLoS ONE, he and colleagues recreated Stanley Milgram's obedience experiment in an immersive virtual environment. Although all participants knew that neither the virtual person nor the electric shocks were real, many responded at subjective, behavioural, and physiological levels as if the situation were real.

His later research includes the use of virtual reality for psychology, empathy, and behaviour change, and the recreation of past events in virtual reality through his ERC-funded MoTIVE project, which studies presence, embodiment, agency, and perspective taking. He is a co-founder of Virtual Bodyworks, a University of Barcelona spin-off company set up to apply immersive virtual reality embodiment to medical, social, and psychological uses.

Awards and grants

In 2005 Slater received the IEEE Virtual Reality Career Award, with a citation recognising "Seminal Achievements in Engineering Virtual Reality." He has held a European Research Council Advanced Grant, TRAVERSE, and a further ERC Advanced Grant, MoTIVE, which began in January 2018, along with two ERC Proof of Concept grants.