Sense of Presence in Virtual Reality

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

Visual – Auditory – Olfactory – Haptic – Taste 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

Cued Gestalt We enter the virtual environment carrying the baggage of our beliefs, experiences, fears and expectations. What we bring to the VE is as important as what we find there.

Virtual Elevator

Approximation Being better than reality may be an option! Recreating reality is not an option.

What creates a virtual experience? Approximation Cued Gestalt Immersion Sense of Presence

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.

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

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? Operational - Repeatable by anyone using the proper procedures.

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?

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

Zeltzer’s AIP Cube Autonomy - Ability to react to events and stimuli. VR 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 Autonomy Presence Interaction

How to measure Presence? Subjective measures Psychophysical measures Objective measures

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?

Widely Used Subjective Presence Measures Steed, Usoh, Slater  (SUS) Presence Questionnaire (M. Usoh, E. Catena, S. Arman, M. Slater, Using Presence Questionnaires in Reality. Presence, 2000, 9(5), 497-503).  Witmer and Singer (WS) Presence Questionnaire (B.G. Witmer, M.J. Singer, Measuring Presence in Virtual environments: A Presence Questionnaire, Presence, 1998, 7(3), 225-240), Has been shown to be less effective in assessing the sense of Presence in virtual environments as opposed to a real world experiences, see: http://www.cs.ucl.ac.uk/staff/m.slater/Papers/questionnaire-paper.pdf

Psychophysical measures Generally, psychophysical techniques are used to relate the physical magnitude of a stimulus with the observer’s 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.

Objective measures Physiological measures Performance measures

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

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

Performance measures Behavior Suspension of belief Ducking Socially conditioned reactions

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.

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

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.

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.

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

Presence? Fidelity and attention to Sensory Channels Gestalt Consequences of Actions

Why is this important? Therapy Entertainment Pain control Training Rehabilitation Entertainment Training Education