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?user=pbs-saf&template=template.html&query=spider&category=0&viKeyword=spider&submit=Search&page=2

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? Immersion Approximation Cued Gestalt 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) • Three measurable physical variables that determine presence: • extent of sensory information • control of sensors relative to environment • ability to modify physical environment. Sensory Information Ability to Modify Environment Control of Sensors

13. Zeltzer’s 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? • Let’s 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 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.

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 boxer’s 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. Therapy Pain control Rehabilitation Entertainment Training Education Why is this important?

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