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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

2020

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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