Sense of Presence in Virtual Reality - PowerPoint PPT Presentation

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Sense of Presence in Virtual Reality

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Sense of being physically present in a computer generated or remote environment (Sheridan, 1992) ... Steed Usoh Slater. 7 questions Likert scaled ... – PowerPoint PPT presentation

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Title: Sense of Presence in Virtual Reality


1
Sense of Presence in Virtual Reality
  • Sherman Craig, p. 9

2
Presence
  • What does presence mean?
  • How would we measure it?
  • Sense of being physically present in a computer
    generated or remote environment (Sheridan,
    1992).
  • http//vvi.virage.com/cgi-bin/visearch?userpbs-sa
    ftemplatetemplate.htmlqueryspidercategory0v
    iKeywordspidersubmitSearchpage2

3
Immersion
  • 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
4
Cued 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.

5
Virtual Elevator
6
Approximation
Being better than reality may be an option!
Recreating reality is not an option.
7
What creates a virtual experience?
Approximation
Cued Gestalt
  • Immersion

Sense of Presence
8
Sense of Presence
  • The perception of being in a particular space or
    place.
  • Attention
  • Physical or emotional reactions to events in the
    space.
  • Memories of events in the space.
  • http//www.vrphobia.com/flying.htm

9
Sense of Presence exists in spite of
  • Cartoon environments
  • Missing or incorrect sensory information
  • Sensors that poorly match human capabilities
  • Wires, gadgets and gizmos that the user must wear

10
Open Questions
  • Is there a definition of presence that is
    sufficiently operational and quantitative to be
    useful?
  • What are the factors that create a sense of
    presence?
  • Are there subjective and objective measures that
    can quantify presence?

11
Open Questions (cont.)
  • Are there applications for which a sense of
    presence actually improves operator performance?
  • Are there applications for which presence is a
    necessary ingredient? If so, how are these
    applications different from applications for
    which a more traditional display system is just
    as effective?

12
Sheridan (1992)
Sensory Information
  • Three measurable physical variables that
    determine presence
  • extent of sensory information
  • control of sensors relative to environment
  • ability to modify physical environment.

Ability to Modify Environment
Control of Sensors
13
Zeltzers AIP Cube
  • Autonomy - Ability to react to events and
    stimuli.
  • Interaction - Degree of access to the parameters
    or variables of an object
  • Presence - Number and fidelity of the sensory
    input and output channels

VR
Autonomy
Presence
Interaction
14
How to measure Presence?
  • Lets first take a look at some of the
    cybertherapy applications of VR
  • http//www.vrphobia.com/
  • How would they measure
  • How successful their systems are?
  • The level of immersion
  • The participant sense of presence
  • Subjective measures
  • Psychophysical measures
  • Objective measures

15
Subjective measures
To what extent did you experience a sense of
being really there inside the virtual
environment? A little A lot 1 2 3 4 5 6 7
How realistic was your interaction with the
virtual objects? A little A
lot 1 2 3 4 5 6 7
16
Common Presence Questionnaires
  • Witmer and Singer
  • 30 questions
  • Steed Usoh Slater
  • 7 questions Likert scaled
  • Neither are all that good, SUS slightly more
    consistent
  • Should be used to compare similar environments,
    not vastly different ones (like reality vs. HMD)

17
Psychophysical measures
  • Generally, psychophysical techniques are used to
    relate the physical magnitude of a stimulus with
    the observers subjective rating of the stimulus
    magnitude.
  • Example R f(S) where R is 1-7 feeling of
    being present and S is a screen resolution or
    lag time.

18
Objective measures
  • Physiological measures
  • Performance measures

19
Physiological measures
  • Just as humans experience changes in
    physiological parameters in response to novel or
    unusual stimuli in the real world, given
    sufficiently realistic stimuli in a virtual
    environment, the human should experience similar
    physiological changes.
  • Cardiovascular, Respiratory,
  • Nervous, Sensory,
  • Blood Chemistry

20
Wiederhold with Fear of Flying Patients in VR
Physiological measures Not Anxious
Anxious
Subjective Measures Not Anxious Anxious
21
Performance measures
  • Behavior
  • Suspension of belief
  • Instinctual responses
  • Ducking at boxers punch
  • Sense of vertigo
  • Socially conditioned reactions
  • VH sneezing
  • Anthropomorphism of VHs

22
Example VE
  • Design an experiment to test sense of presence
  • Subjective
  • SUS/WS after
  • Behavioral
  • cross chasm
  • small steps
  • curl toes
  • Physiological
  • heart rate

23
What increases presence?
  • Rendering
  • Poly count
  • Shadows
  • Lighting
  • Low latency
  • Head tracking
  • Field of view
  • Multiple senses
  • Audio
  • Haptics (passive if nothing else)
  • Interactivity
  • Travel
  • Avatar

24
What decreases presence?
  • High latency
  • Poor interactivity
  • Disjoint Senses
  • what you expect
  • what you experience
  • No Avatar
  • Disembodied voice
  • Cables
  • Audio (people, lab, etc.)
  • Called breaks in presence (BIPs)

25
What seems to be true?
  • A person's experience of a situation in a virtual
    environment may evoke the same reactions and
    emotions as the experience of a similar
    real-world situation. This may be true even when
    the virtual environment does not accurately or
    completely represent the real-world situation.

26
What seems to be true? (cont.)
  • Each person brings their own Gestalt into a
    virtual reality experience.

27
What seems to be true? (cont.)
  • A primary difference between the experience of an
    event in a virtual environment and the experience
    of the same event in a real environment is in the
    intensity or vigor of the experience.

28
What seems to be true? (cont.)
  • A person's perceptions of real-world situations
    and behavior in the real-world may be modified
    based on his experiences within a virtual world.

29
What seems to be true? (cont.)
  • Virtual reality is consequence-poor relative to
    reality.

30
Presence?
Fidelity and attention to Sensory Channels
Gestalt
Consequences of Actions
31
Why is this important?
  • Entertainment
  • Training
  • Education
  • Therapy
  • Pain control
  • Rehabilitation

32
Groups studying presence
  • Mel Slater University College London
  • Effective Virtual Environments UNC
  • Future directions
  • Physiological measures
  • Behavioral measures
  • Expert observations
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