presence in virtual environments © mel slater 2001

Presence in Virtual Presence in Virtual EnvironmentsEnvironments

© Mel Slater 2001

OutlineOutline

Presence and hypothesis selectionMeasurementDomainThe Usual Results

Presence and Hypothesis Presence and Hypothesis SelectionSelection

Current in perceptual theory– Perceptual system selects between competing

hypotheses (Richard Gregory)– Scanpath theory suggests that perceptual

system is top-down driven (Lawrence Stark) We see what we expect to see.

Competing SignalsCompeting Signals

Presence is only interesting when there are competing signals from at least two ‘environments’.

How will you act?

Presence as a SelectorPresence as a Selector Given competing signals

– Choose action based on selection amongst hypotheses I am in this world I am in that world (I am mixed up)

Hypotheses relating to the fundamental question: – Where am I?

Totality of signals form into one of several ‘gestalts’ (‘environments’).

ActionsActions

Actions may be – Involuntary/Voluntary– Conscious / Unconscious– Supported / Denied

Obviously not ‘real’– But act as if real

Implications for MeasurementImplications for Measurement Questionnaires deliver an integration over time of

conscious/voluntary/supported responses. Behavioural measures require imposition of events

that may not be part of the environment (eg, looming).

Deliberate introduction of conflicting signals (eg, shadows).

Physiological measures are in response to specific types of event (anxiety provoking).

MeasurementMeasurement

BIPs ‘breaks in presence’ – possible to build a measure based on when these occur.

Sampling (attentional resources).Behavioural observation.Unification of BIPs + physiological?

Domain ResponsesDomain Responses Reading a novel -> physiological Movie -> + some body movement 3D movie -> + more body movement Game -> + more body movement Immersive VR -> + total body movement “Fire!”

– In a movie or computer game, no one would rush out of the room

– In immersive VR – they might do so!

The Usual ResultsThe Usual Results The norm is that in a ‘good’ immersive VR

– Reported presence is often very high!!! CAVE almost

puts us out ofbusiness!

Few BIPs No BIPs when

engaging. Why?

Evolutionary ArgumentEvolutionary ArgumentIn all of personal and evolutionary history:

– What we ‘see’ is where we are … Parallax Responsive actors Spatial extension Interaction

– … and where we actAt some deep level

– Our mind does not know about VR!

Perceptual AugmentationPerceptual Augmentation What we see is where we are,

but…– Where we are is in our heads– (Stark:)“Virtual reality works

because reality is virtual.” Very simple cues required to

trigger presence– Perceptual mechanisms do the

rest– Provided that the VR is ‘good’.

What is ‘good’?