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Sense of Presence in Sense of Presence in Virtual RealityVirtual Reality
Sherman & Craig, p. 9Sherman & Craig, p. 9
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PresencePresence
What does presence mean?What does presence mean? How would we measure it?How would we measure it? Sense of being physically present Sense of being physically present
in a computer generated or in a computer generated or remote environment (Sheridan, remote environment (Sheridan, 1992).1992).
http://vvi.virage.com/cgi-bin/http://vvi.virage.com/cgi-bin/visearch?user=pbs-visearch?user=pbs-saf&template=template.html&quesaf&template=template.html&query=spider&category=0&viKeyworry=spider&category=0&viKeyword=spider&submit=Search&page=d=spider&submit=Search&page=22
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ImmersionImmersion
• Physically immerse the participant in a computer-generated space.
• Provide computer-generated sensation to one or more of the human senses.
Visual – Auditory – Olfactory – Haptic – Taste
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Cued GestaltCued Gestalt
• We enter the virtual environment carrying the baggage of our beliefs, experiences, fears and expectations.
• UVA (Pausch) Star Wars example• Poor VR, no back story• Poor VR, w/ back story much
better• What we bring to the VE is as
important as what we find there.
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Virtual ElevatorVirtual Elevator
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Approximation
Recreating reality is not an option. Being better than reality may be an option!
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What creates a virtual What creates a virtual experience?experience?
ImmersionImmersionApproximation Cued Gestalt
Sense of Presence
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The perception of being The perception of being in a particular space in a particular space or place.or place.
Sense of PresenceSense of Presence
–Attention
–Physical or emotional reactions to events in the space.
–Memories of events in the space.
–http://www.vrphobia.com/flying.htm
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Sense of Presence Sense of Presence exists exists in spite of in spite of ::
Cartoon Cartoon environmentsenvironments
Missing or Missing or incorrect sensory incorrect sensory informationinformation
Sensors that Sensors that poorly match poorly match human human capabilitiescapabilities
Wires, gadgets Wires, gadgets and gizmos that and gizmos that the user must the user must wearwear
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Open QuestionsOpen Questions
Is there a definition of presence that Is there a definition of presence that is sufficiently operational and is sufficiently operational and quantitative to be useful?quantitative to be useful?
What are the factors that create a What are the factors that create a sense of presence?sense of presence?
Are there Are there subjectivesubjective and and objective objective measures that can quantify measures that can quantify presence?presence?
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Open Questions Open Questions (cont.)(cont.)
Are there applications for which a Are there applications for which a sense of presence actually improves sense of presence actually improves operator performance?operator performance?
Are there applications for which Are there applications for which presence is a necessary ingredient? presence is a necessary ingredient? If so, how are these applications If so, how are these applications different from applications for which different from applications for which a more traditional display system is a more traditional display system is just as effective?just as effective?
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Sheridan (1992)Sheridan (1992)
– Three measurable Three measurable physical variables physical variables that determine that determine presence: presence: extent of sensory extent of sensory
informationinformation control of sensors control of sensors
relative to environmentrelative to environment ability to modify ability to modify
physical environment.physical environment.
Sensory Information
Control of Sensors
Ability to ModifyEnvironment
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Zeltzer’s AIP Cube Zeltzer’s AIP Cube
Autonomy - Ability to Autonomy - Ability to react to events and react to events and stimuli.stimuli.
Interaction - Degree of Interaction - Degree of access to the access to the parameters or parameters or variables of an objectvariables of an object
Presence - Number and Presence - Number and fidelity of the sensory fidelity of the sensory input and output input and output channelschannels
Interaction
Autonomy
Presence
VR
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How to measure Presence?How to measure Presence?
Let’s first take a look at some of the Let’s first take a look at some of the cybertherapy applications of VRcybertherapy applications of VR– http://www.vrphobia.com/– How would they measureHow would they measure
How ‘successful’ their systems are?How ‘successful’ their systems are? The level of immersionThe level of immersion The participant sense of presenceThe participant sense of presence
Subjective measuresSubjective measures Psychophysical measuresPsychophysical measures Objective measuresObjective measures
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Subjective measuresSubjective measures
To what extent did you experience a sense of being “really there” inside the virtual environment?
A little A lot1 2 3 4 5 6 7
How realistic was your interaction with the virtual objects?
A little A lot1 2 3 4 5 6 7
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Common Presence Common Presence QuestionnairesQuestionnaires
Witmer and SingerWitmer and Singer– 30+ questions30+ questions
Steed Usoh SlaterSteed Usoh Slater– 7 questions Likert scaled7 questions Likert scaled
Neither are all that good, SUS slightly Neither are all that good, SUS slightly more consistentmore consistent
Should be used to compare similar Should be used to compare similar environments, not vastly different environments, not vastly different ones (like reality vs. HMD)ones (like reality vs. HMD)
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Psychophysical measuresPsychophysical measures
Generally, psychophysical techniques Generally, psychophysical techniques are used to relate the physical are used to relate the physical magnitude of a stimulus with the magnitude of a stimulus with the observer’s subjective rating of the observer’s subjective rating of the stimulus magnitude. stimulus magnitude.
Example:Example: R = f(S)R = f(S) where where RR is 1-7 is 1-7 “feeling of being present” and “feeling of being present” and SS is a is a screen resolution or lag time.screen resolution or lag time.
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Objective measuresObjective measures
Physiological measuresPhysiological measures Performance measuresPerformance measures
– Task completion timeTask completion time– BehaviorsBehaviors
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Physiological measuresPhysiological measures
Just as humans experience changes in Just as humans experience changes in physiological parameters in response to physiological parameters in response to novel or unusual stimuli in the “real” novel or unusual stimuli in the “real” world, given sufficiently realistic stimuli world, given sufficiently realistic stimuli in a virtual environment, the human in a virtual environment, the human should experience similar physiological should experience similar physiological changes.changes.
Cardiovascular, Respiratory, Cardiovascular, Respiratory,
Nervous, Sensory, Nervous, Sensory,
Blood ChemistryBlood Chemistry
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Wiederhold with Fear of Flying Wiederhold with Fear of Flying Patients in VRPatients in VR
Physiological measures
Not Anxious AnxiousSubjective Measures
Not Anxious
Anxious
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Performance measuresPerformance measures
BehaviorBehavior Suspension of beliefSuspension of belief
– Instinctual responsesInstinctual responses Ducking at boxer’s punchDucking at boxer’s punch Sense of vertigoSense of vertigo
– Socially conditioned reactionsSocially conditioned reactions VH sneezingVH sneezing Anthropomorphism of VHsAnthropomorphism of VHs
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Example VEExample VE
Design an experiment Design an experiment to test sense of to test sense of presence:presence:– SubjectiveSubjective
SUS/WS afterSUS/WS after
– BehavioralBehavioral cross chasmcross chasm small stepssmall steps curl toescurl toes
– PhysiologicalPhysiological heart rateheart rate
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What increases presence?What increases presence? RenderingRendering
– Poly countPoly count– ShadowsShadows– LightingLighting
Low latencyLow latency Head trackingHead tracking Field of viewField of view Multiple sensesMultiple senses
– AudioAudio– Haptics (passive if Haptics (passive if
nothing else)nothing else) InteractivityInteractivity
– TravelTravel AvatarAvatar
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What decreases presence?What decreases presence? High latencyHigh latency Poor interactivityPoor interactivity Disjoint SensesDisjoint Senses
– what you expectwhat you expect– what you what you
experienceexperience No AvatarNo Avatar Disembodied Disembodied
voicevoice CablesCables Audio (people, Audio (people,
lab, etc.)lab, etc.) Called ‘breaks in Called ‘breaks in
presence’ (BIPs)presence’ (BIPs)
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What seems to be true?What seems to be true? A person's experience of a A person's experience of a
situation in a virtual situation in a virtual environment may evoke environment may evoke the same reactions and the same reactions and emotions as the emotions as the experience of a similar experience of a similar real-world situation. This real-world situation. This may be true even when may be true even when the virtual environment the virtual environment does not accurately or does not accurately or completely represent the completely represent the real-world situation.real-world situation.
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What seems to be true? What seems to be true? (cont.)(cont.)
Each person brings Each person brings their own Gestalt their own Gestalt into a virtual reality into a virtual reality experience.experience.
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What seems to be true? What seems to be true? (cont.)(cont.)
A primary difference between the A primary difference between the experience of an event in a virtual experience of an event in a virtual environment and the experience of environment and the experience of the same event in a real the same event in a real environment is in the intensity or environment is in the intensity or vigor of the experience. vigor of the experience.
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What seems to be true? What seems to be true? (cont.)(cont.)
A person's perceptions of real-world A person's perceptions of real-world situations and behavior in the real-situations and behavior in the real-world may be modified based on his world may be modified based on his experiences within a virtual world.experiences within a virtual world.
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What seems to be true? What seems to be true? (cont.)(cont.)
Virtual reality is consequence-poor Virtual reality is consequence-poor relative to reality. relative to reality.
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Presence?Presence?
Consequences of Actions
GestaltFidelity and attentionto Sensory Channels
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Why is this important?Why is this important?
TherapyTherapy
Pain controlPain control
RehabilitationRehabilitation
EntertainmentEntertainment
TrainingTraining
EducationEducation
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Groups studying presenceGroups studying presence
Mel Slater – University College LondonMel Slater – University College London
Effective Virtual Environments – UNCEffective Virtual Environments – UNC
Future directionsFuture directions– Physiological measuresPhysiological measures– Behavioral measuresBehavioral measures– Expert observationsExpert observations
CopresenceCopresence
The sense of being with The sense of being with others (like presence)others (like presence)
The mode of being with The mode of being with others (like immersion)others (like immersion)
E.g. you are interacting E.g. you are interacting with another personwith another person– Telepresence applicationsTelepresence applications– Virtual human applicationsVirtual human applications
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Measuring CopresenceMeasuring Copresence
Slater Copresence Slater Copresence QuestionnaireQuestionnaire
Behavioral metricsBehavioral metrics Social conventionsSocial conventions
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