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

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

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

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

8 The perception of being in a particular space or place. Sense of Presence –Attention –Physical or emotional reactions to events in the space. –Memories of events in the space.

9 Sense of Presence exists in spite of : Cartoon environments Cartoon environments Missing or incorrect sensory information Missing or incorrect sensory information Sensors that poorly match human capabilities Sensors that poorly match human capabilities Wires, gadgets and gizmos that the user must wear 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? 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? What are the factors that create a sense of presence? Are there subjective and objective measures that can quantify 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 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? 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 Control of Sensors Ability to Modify Environment

13 Zeltzer’s AIP Cube Autonomy - Ability to react to events and stimuli. Autonomy - Ability to react to events and stimuli. Interaction - Degree of access to the parameters or variables of an object Interaction - Degree of access to the parameters or variables of an object Presence - Number and fidelity of the sensory input and output channels Presence - Number and fidelity of the sensory input and output channels Interaction Autonomy Presence VR

14 How to measure Presence? Subjective measures Subjective measures Psychophysical measures Psychophysical measures Objective measures Objective measures

15 Subjective measures To what extent did you experience a sense of being “really there” inside the virtual environment? A littleA lot How realistic was your interaction with the virtual objects? A littleA lot

16 Common Presence Questionnaires Witmer and Singer Witmer and Singer –30+ questions Steed Usoh Slater Steed Usoh Slater –7 questions Likert scaled Neither are all that good, SUS slightly more consistent Neither are all that good, SUS slightly more consistent Should be used to compare similar environments, not vastly different ones (like reality vs. HMD) 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. 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. 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 Physiological measures Performance 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 Behavior Suspension of belief Suspension of belief –Ducking –Socially conditioned reactions

22 Example VE Design an experiment to test sense of presence: 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? High quality visuals High quality visuals Low latency Low latency Head tracking Head tracking Field of view Field of view Multiple senses Multiple senses –Audio –Haptics (passive if nothing else) Interactivity Interactivity Avatar Avatar

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

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. 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. 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. Virtual reality is consequence-poor relative to reality.

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

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

32 Groups studying presence Mel Slater – University College London Mel Slater – University College London Effective Virtual Environments – UNC Effective Virtual Environments – UNC