Sense of Presence in Virtual Reality

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Sense of Presence in Virtual Reality

• Sherman Craig, p. 9

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Presence

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

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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
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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.

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

• Immersion

Sense of Presence
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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.

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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

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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?

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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?

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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
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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
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How to measure Presence?

• Subjective measures
• Psychophysical measures
• Objective measures

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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
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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)

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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.

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Objective measures

• Physiological measures
• Performance measures

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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

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Wiederhold with Fear of Flying Patients in VR
Physiological measures Not Anxious
Anxious
Subjective Measures Not Anxious Anxious
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Performance measures

• Behavior
• Suspension of belief
• Ducking
• Socially conditioned reactions

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Example VE

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

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What increases presence?

• High quality visuals
• Low latency
• Head tracking
• Field of view
• Multiple senses
• Audio
• Haptics (passive if nothing else)
• Interactivity
• Avatar

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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

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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.

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What seems to be true? (cont.)

• Each person brings their own Gestalt into a
  virtual reality experience.

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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.

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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.

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What seems to be true? (cont.)

• Virtual reality is consequence-poor relative to
  reality.

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Presence?
Fidelity and attention to Sensory Channels
Gestalt
Consequences of Actions
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Why is this important?

• Entertainment
• Training
• Education

• Therapy
• Pain control
• Rehabilitation

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Groups studying presence

• Mel Slater University College London
• Effective Virtual Environments UNC