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‘Presence is considered as a perceptual mechanism for selection between alternative hypotheses’ (Slater, 2002: 435)
‘The issue of presence is only interesting when there are competing signals from at least two environments.’ (Slater, 2002: 437)
We wil be using Mel Slater's CAVE at University College London
Mel Slater and colleagues make a distinction between immersion and presence. They define immersion as a quality of the technology used to immerse the participant. Presence, on the other hand, indicates ‘a state of consciousness, the (psychological) sense of being in the virtual environment’ (Slater et al., 1997: 604f).
‘Presence arises from an appropriate conjunction of the human perceptual and motor system and immersion.’ (Slater 2003)
Slater suggests that at any given moment the brain formulates hypotheses about the world based on our perceptions. So, in experiencing a virtual reality environment, for instance, we are at once experiencing a real location and a virtual one. The brain will pick whichever hypothesis corresponds to the location we feel most present in and the most likely choice will be the one with the strongest set of clues. Slight changes in our perception could trigger switches in hypothesis or BIPs, Breaks in Presence. People experiencing a BIP do not report an uncanny effect though their perception of the outside world has mutated or shifted (2004).
How does the use of mixed reality affect social interaction within CAVE?
Does the augmentation of CAVE through a mixed reality environment hinder or increase the viewer's sense of immersion?
Does the augmentation of CAVE through a mixed reality environment hinder or increase the viewer's sense of presence?
What happens with ‘Uncanny valley’, i.e. ‘a sense of unease and discomfort when people look at increasingly realistic virtual humans’, (Brenton, Gillies, Ballin and Chatting, 2005) when a CAVE becomes a mixed reality environment and the viewer encounters agents as well as live performers?
Does the augmentation of CAVE increase, or decrease, the number of 'breaks in presence' a viewer experiences?
CAVE is based on the ‘strategy of dislocating the subject, who experiences the sensation of being in two places at the same time’ (Dinkla in Rieser and Zapp, 2002: 29). Does the presence of a live performer augment or reduce this dislocation?
What are the consequences of performed copresence?
CAVE is a surround screen and sound system that creates the sensation of immersion through the projection of 3D computer graphics into a 10’x10’x10’ cube composed of display screens that surround the viewer. Through head and hand tracking systems, the correct stereo perspective is produced.
CAVE users do not need to wear helmets and are free to move about CAVE as they please.
‘the difference between the CAVE VR and the HMD VR is profound. The HMD brand of VR produces what I call Tunnel VR or perception-oriented immersion. The projection or CAVE brand of VR, on the contrary, produces Spiral VR or apperceptive immersion. The VR that tunnels us down a narrow corridor of perceptions differs subtly but profoundly from the VR that spirals us into higher layers of self-perception.’ (Heim in Featherstone and Burrows, 1998: 71)
The CAVE was developed by Tom DiFanti and Dan Sandin of the Electronic Visualisation Laboratory at the University of Illinois in Chicago.
It was premiered at the ACM SIGGRAPH 92 conference where it was presented as ‘a virtual reality theater’ (Sandin in Janko, Leopoldseder, Stocker, 1996: 85, emphasis added).
CAVE stands for CAVE Automatic Virtual Environment, a title inspired by Plato’s exploration of perception, illusion and reality through the metaphor of the cave in The Republic (c.388-367).
Sandin described the environment as a
'multi-person, room-sized, high-resolution, 3D video and audio environment. Graphics are rear projected in stereo onto three walls and the floor, and viewed with stereo glasses. As a viewer wearing a location sensor moves within its display boundaries, the correct perspective and stereo projections of the environment are updated, and the image moves with and surrounds the viewer.' (in Janko, Leopoldseder, Stocker, 1996: 84)
The viewer uses a pair of lightweight polarised glasses. A lead visitor can guide a group through a position-sensing device while an interactive wand, a kind of 3D mouse, allows them to control the direction and movement.
As in Cynthia Goodman’s words,
'the participant to the CAVE experiences an unprecedented sensation of immersion in a room-sized environment while navigating a wand which transports him or her from one part of a scene as well as from one of the many visually compelling, fanciful worlds which have been created for this system to another.' (Goodman in Sommerer and Mignonneau, 1998: 257-8)