11

Sense of Presence in Sense of Presence in Virtual RealityVirtual Reality

Sherman & Craig, p. 9Sherman & Craig, p. 9

22

PresencePresence

Sense of being Sense of being physically present physically present in a computer in a computer generated or generated or remote remote environment environment (Sheridan, 1992).(Sheridan, 1992).

33

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

44

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.

55

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

88

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.

99

Sense of Presence Sense of Presence exists exists in spite of in spite of ::

Cartoon environmentsCartoon environments Missing or incorrect sensory Missing or incorrect sensory

informationinformation Sensors that poorly match human Sensors that poorly match human

capabilitiescapabilities Wires, gadgets and gizmos that the Wires, gadgets and gizmos that the

user must wearuser must wear

1010

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?

1111

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? If presence is a necessary ingredient? If so, how are these applications so, how are these applications different from applications for which a different from applications for which a more traditional display system is just more traditional display system is just as effective?as effective?

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Sheridan (1992)Sheridan (1992)

– Three measurable Three measurable physical variables that physical variables that determine presence: determine 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 variables parameters or variables of an objectof 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

1414

How to measure Presence?How to measure 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

1919

Physiological measuresPhysiological measuresJust 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 in world, given sufficiently realistic stimuli in a virtual environment, the human should a virtual environment, the human should experience similar physiological changes.experience similar physiological 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

– DuckingDucking

– Socially conditioned reactionsSocially conditioned reactions

2222

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? High quality High quality

visualsvisuals Low latencyLow latency Head trackingHead tracking Field of viewField of view Multiple sensesMultiple senses

– AudioAudio– Haptics (passive Haptics (passive

if nothing else)if nothing else) InteractivityInteractivity 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 voiceDisembodied voice CablesCables Audio (people, lab, Audio (people, lab,

etc.)etc.) Called ‘breaks in Called ‘breaks in

presence’presence’

2525

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.

2626

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.

2727

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.

2828

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.

2929

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.

3030

Presence?Presence?

Consequences of Actions

GestaltFidelity and attentionto Sensory Channels

3131

Why is this important?Why is this important?

TherapyTherapy

Pain controlPain control

RehabilitationRehabilitation

EntertainmentEntertainment

TrainingTraining

EducationEducation

3232

Groups studying presenceGroups studying presence Mel Slater – University College Mel Slater – University College

LondonLondon

Effective Virtual Environments – UNCEffective Virtual Environments – UNC