Presence and the Content of Virtual Environments

P.C.Fencott@tees.ac.uk

Virtual Reality Applications Research Group
University of Teesside

1 Introduction

This paper considers the role of the content of Virtual Environments (VEs) in generating presence. This is achieved by actively considering the way content affects perception. The thoughts on presence presented here arise not from from direct research into presence itself but from the practical experiences gained in building desktop VEs and then reflecting on the way people did or did not respond to particular content. Of particular importance was a virtual tourist site built for the Saltburn Improvement Company on the North East of England and which has served as a test bed for the ideas put forward here [1].

2 The Nature of Presence

It would seem indisputable that human beings have the ability for not being mentally present in an environment in which they are observably physically present. This sense of presence, the feeling of being there, is at the heart of our experience of virtual reality.

A sense of presence is not restricted to experiencing VEs but is also associated with story telling and reading, and of course film and television. Rather, presence in VEs is just perhaps the most recent example of the degree to which humans are naturally inclined to be taken out of themselves, enjoy immersing themselves in environments artificially created through communications media of all sorts. An intriguing thought experiment using an extreme example of this can be found in Zhai [2]. The difference is that VEs go further than any other communications media in generating artificial stimuli for the perceptual systems to interpret rather than delegating the interpretation and creation to the mind itself as is the case with novels and story telling.

Hence Lombard and Ditton's characterisation of presence as the perceptual illusion of non mediation [3]. This characterises presence as the state of mind of a visitor to a VE as not noticing or choosing not to notice that that which they are experiencing and interacting with is artificially generated. They document the evaluation of the embodying interface of a VE in terms of presence seen largely as the degree of fidelity of sensory immersion. Much of the research to date into presence is particularly concerned with the embodying interface as well as researches into the mental state of people who are present in VEs.

However, as presence is a mental state it is therefore a direct result of perception rather than sensation. In other words, the mental constructions that people build from stimuli are more important than the stimuli themselves. It is the patterns that we, as VE constructors, build into the various cues that make up the available sensory bandwidth for a given VE that help or hinder perception and thus presence. These patterns are the result of what is built into the VE and the way the user behaves in response to them The fidelity of the sensory input is obviously a contributing factor but by no means the most important. In the context of the working VE builder, being able to identify and make effective use of the causes of presence is more important than the nature of presence itself. This means that it is the effective consideration of the perceptual consequences of what we build into VEs that will give rise to the sense of presence that we are looking for. In this sense it is the content of VEs that has the greatest effect on the generation of presence.

Not all researchers have seen presence itself as the main focus of interest. Ellis [4] states that the design of VEs should focus on the efficient communication of causal interaction and that presence is an epiphenomenon of secondary importance for design. This view would also seem to be asserting that effective content design is of primary importance.

Before proceeding to address this question we should note that what we have been referring to here is what Stone [5] refers to as a classical view of presence, i.e.. the unique persona within the physical body transported to a mediated world, rather than the transformation of persona or instances of multiple persona within the same physical body. This is rarely dealt with in the academic discussions recently published but the transformation of self is surely a major contributing factor to presence in many VEs particularly games oriented or those such as the Hubble Space Telescope VTE where the ground team were effectively taking on the roles of astronauts to better help them during EVAs [6].

3 Content for Virtual Environments

It would seem that there are a number of disciplines from which we could gain pointers to help us understand the nature of the content of VEs. Recent research indicates that film and architecture, have much to teach us in this respect. The nature of the content of films has been often been the object of study of film theory over the course of the century and such concepts as montage and mise en scene would seem to have much to teach us [7]. It would seem that space syntax has much to teach us about the generic function of space prior to perception and that the axis is, perhaps the conceptual equivalent of mise en scene [8]. The axis is fundamental because the experience of architecture is the experience of movement - Hillier referring to Le Corbusier [8].

A tentative characterisation of the content of a VE is as a set of perceptual opportunities allowing the visitor to accumulate over time a set of experiences which maintain a sense of purposive presence. Content thus seeks to:

establishment and maintain a sense of purpose which is reinforced by some or all of the accumulating experiences
generate a sense of causal interaction [4]
maintain general belief in the VE irrespective of purpose.

In the next section we will attempt to attempt to identify some design principles for VEs to realise the above.

4 Perceptual Modelling

Establishing the psychological qualities of a VE that seek to gain and hold the visitors attention through the human senses and perceptual system. The mutually supportive effects of:

Movement - both vection and autonomous.
Interaction - all the time we are doing something in a VE we are less likely to be criticising the decor.
Sound - to complement visual and interactive stimuli.
Other - haptics etc. if the system allows.

The perceptual is about details which arise naturally from the spatial world and involve the visitor both consciously and unconsciously. The latter is very desirable because there is something very fundamental about unconscious involvement - accepting a place or activity without thought. Animations are very good for attracting attention, particularly in the distance or at the periphery of vision because the detection of movement is one of our most basic perceptual mechanism.

These details break down into two mutually sustaining forms:

4.1 Cues

Mundane details that are somehow highly predictable - their attraction is their predictability. This is also about small things. Navigation cues, indicators of scale, and distance cues. The latter because distance cues, as people would normally recognise them, are largely absent in VEs. This is also true for cues for the scale of objects and one's own avatar. Such perceptual cues arise directly from the architecture of the space and are concerned with the logic of the environment unconsciously accepted [9].
Examples might be

A very important role of cues is to make VEs more dynamic and cluttered - we are used to the real world being like this so it helps if virtual ones are as well whatever the specific purpose. The following quote gives an insight from photography into the nature of cues in VEs:

Hence the detail that interests me is not, or at least is not strictly, intentional, and probably must not be so, it occurs in the field of the photographed thing like a supplement that is at once inevitable and delightful.

4.2 Surprises

These are "appropriately designed infidelities" [11] which can be used for emphasis in virtual worlds and also relate to conscious learning. In other words, non mundane details that are not predictable but they do arise however surprisingly from the logic of the space consciously accepted.

4.3 Cues and Surprises Working Together

Fidelity in VEs works much in the way jokes do.

The first two lines are unremarkable and mundane, cues. The third line comes as a surprise but is plausible from the logic of the first two statements. Jokes seem to be all much like this - you set up an imagined and consistent, however fantastical, world and then give it a bisaar, implausible twist which must somehow be derivable from the former. Cues and surprises in VEs work together, supporting each other and thus the virtuallity they inhabit by seeking to both establish fidelity and catch and retain the attention of the visitor and thus maintain presence.

5 Conclusions

These ideas arose out of the practical activity of VE building and are the result of trial and error, playing with prototypes and so. It would seem that as the embodying interfaces of virtual reality become established and the sensory bandwidth more widely covered we will need to switch our attention to the nature and content of virtual reality if we are to build effective VEs. If presence is indeed primarily the perceptual result of appropriate content then a deeper understanding of the the way in which the human perceptual systems respond to VE generated content will be a major research area for the near future. It would also seem of great benefit to investigate the theoretical underpinnings of other disciplines, such as film and architecture, to support this activity.

References

[1] Clive Fencott, "Using a VRML World to Investigate content and Presence", http://www-scm.tees.ac.uk/users/p.c.fencott/content/
[2] Philip Zhai, "Get Real: A Philosophical Adventure in Virtual Reality", Rowman & Littlefield, 1998.
[3] Mathew Lombard and Teresa Ditton, "At the Heart of It All: The Concept of Telepresence", in Journal of Computer Mediated Communication, Volume 3, No 2, September 1997 http://jcmc.huji.ac.il/vol3/issue2/
[4] Stephen R. Ellis, "Presence of Mind: A Reaction to Thomas Sheridan's "Further Musings on the Psychphysics of Presence"", in Presence, Volume 5, No. 2, Spring 1996.
[5] Allucquere Rosanne Stone, "The War of Desire and Technology at the Close of the Mechanical Age", The MIT Press, 1996.
[6] R. Bowen Loftin and Patrick J. Kenney, "The Use of Virtual Environments for Training the Hubble Space Telescope Flight Team", http://www.vetl.uk.edu/Hubble/virtel.html
[7] Andrew J. Dudley, "The Major Film Theories: An Introduction", Oxford University Press, 1976.
[8] Bill Hillier, "Space is the Machine", Cambridge University Press, 1996.
[9] L. Spinney, "I Had a Hunch ...", in New Scientist, 5th September, 1998.
[10] Orlando Barthes, "Camera Lucida", Flamingo, 1984.
[11] Denise Whitelock, Paul Brna and Simon Holland, "What is the Value of Virtual Reality for Conceptual Learning? Towards a Theoretical Framework", http://www.cbl.leeds.ac.uk/~paul/papers/vrpaper96/VRpaper.html