Cosc 6326/Psych6750X Presence, Telepresence and Co-presence
Presence • the subjective experience of being physically present in the VE rather than the real environment • ‘Being there’ • Considered important in telecommunications, film, VEs • Sensory depravation, mental disorders, drugs can affect presence in the real world
Related Terms • Telepresence: phenomenon that a human operator of a remotely controlled machine feels physically present at remote location • Co-presence: • ‘social’ presence is sense that one is near or co-located with another person (at a remote location via teleconferencing, telephone, CVE, chat room …) -> not necessarily linked to physical presence • Does other actually exist? Are they real? Are the present? Co-located? • Co-presence typically implies mix of physical and social presence (being there together)
Immersion: ‘degree to which sensory input to all modalities is controlled by the SE interface’ (Draper, Kabur & Usher 1998) • Probably should consider the degree to which the VE responds to user action as well (active perception) • Distinct but may contribute to presence (same with realism, fidelity, interactivity …) • Feature of the system/technology not user’s experience
Immersion increased by • large field of view • Multi-modal displays • Fidelity of displays (spatialised audio, lo latency tracking … ) • Visualization of body in VE, avatars • Elimination of environmental interference
Presence theory and application • Three main questions for us: • What does it mean to be present? • Can presence be measured? • Is it useful as a concept for design and evaluation of systems?
What does presence mean? • Literature is confused and uses presence for many different phenomena • Draper et al (1998) provided three different definitions or classes of (tele)presence: • Simple: ability of a user to operate in a VE • Cybernetic: efficiency/compatibility of the HCI with the capabilities and limitations of human user • Experiential: “mental state in which a user feels physically present within the computer-mediated environment” • Experiential presence is our focus here
‘Cybernetic telepresence is the projection of human capability into a computer-mediated environment; experiential telepresence is the projection of human consciousness into a computer-mediated environment. The distinguishing characteristic of experiential telepresence is the mental state involving the suspension of the user's awareness of the remoteness of the computer-mediated environment. The quality of the human-machine interface is often mentioned as a determinant of the strength of the experience, but experiential telepresence is clearly something beyond cybernetic telepresence.’ Draper et al, 1998
Held & Durlach, 1992; Sheridan 1992: • presence is sense that one is physically present in the VE rather than in laboratory • Subjective, introspective but could have measurable correlates • Another view- the extent that the user of the VE environment ceases to be aware that it is computer mediated (Lombard & Ditton 1997). • Degree that users remember VE as a place they visited rather than computer program (Slater 1999)
Zohoric & Jenison, 1998; see also Flach & Holden 1998: • Presence is indicated when user can successfully perform tasks in VE • “doing there” rather than “being there” • Grounded in functionality and action facilitated by affordances of the interface • VE has presence by permitting user to do things in it • Very different concept. More measurable? More useful?
Many interrelated technological, perceptual and psychological factors • Presence can be operationally defined as the extent to which behaviour in the virtual environment matches behaviour in an equivalent real situation?
Most presence definitions circular and refer to internal sense of “being there” • Does experiential presence exist at all? • The concept of presence is relevant if there are two competing environments (Slater). • does the user act as if they are present in the alternative environment? • does the user believe they are present in the alternative environment?
Normally presence is binary - either present or not (hallucinations, sensory depravation, …). Can presence be partial? • Unlike fear, anxiety, happiness and other mental states • we have experience with variations of these feelings and can • anchor judgements for subjective measures • identify physiological or behavioural correlates • Perhaps presence can only be defined by its absence?
What does it mean to be there? • Embodiment? • Engagement? • Attention? • Interest? • Do engaging novels, movies etc create presence? • Loss of sense of computer mediation?
Users believed to act differently if present • Have realistic emotional and social reactions • Exhibit realistic behaviour on tasks • Act as if present in environment not simply observing
Many investigators have attempted to build models of presence. Factors: • Number and quality of sensory inputs stimulated or missing (Sheridan 1992). Role of sensory conflict? • Match between sensory input and action in VE • Previous knowledge/experience and individual differences play a role • One idea is that the more transparent the technology the better the illusion of ‘non-mediation’ • Content and compellingness of simulation plays a role
Hendrix & Barfield - presence as a function of display parameters (stereo, head tracking, field of view) • Slater, Ellis, Kalawsky etc. • Develop equation relating presence to personal and technological parameters. • Experiments could then manipulate inputs and set parameters.
Techniques to enhance presence • Virtual anterooms • fostering suspension of disbelief • priming
Measuring presence • Since presence is hard to define it should come as no surprise that its measurement is controversial • Some methods for measuring presence • questionnaires • behavioural responses • physiological responses
Task performance • Error, time to completion, transfer of training to reality, dual task measures • Useful measures but relation to presence? • Immersion, fidelity, affordances, … all also play a role • Performance can increase or decrease in relation to improvements in these factors in complex ways (due to multimodal systems, complex scenarios, distraction, attentional demand, arousal, …)
Case studies/Qualitative studies • Ask questions or introspection of relatively few individuals • Sometimes useful, Gilkey & Weisenberg (1995) found reports of a loss of sense of presence in adults who had sudden onset hearing loss. • This is interesting evidence that there is such an experience as presence. • Relationship between sensory input and presence
Behavioural responses generated in VE • After effects, postural sway • Startle/looming responses • Socially conditioned response such handshaking • Social or other phobias, physiological or psychological response to extreme stimuli (pit room) • Logic: if VE generates response similar to real environment subject can be presumed to feel present - corroborative measures or correlates
Do these behavioural response really depended on ‘being there’ • Some responses may be deeply ingrained reflexive (e.g. vection induced sway) • May not correlate with any ‘mental state’ of ‘being there’ • Measuring these responses often requires interfering with or modifying the VE or using extreme stimuli
Comparison or interaction with real environment • Amount real environment must be degraded to give same presence • Similarly can look at degree external events are incorporated into VE experience
Most popular measure of presence is post-exposure questionnaires • Sheridan argued (1992) that subject reports are basic measure for presence since it is subjective experience • Early work by Slater, Barfield and others used Likert scales and fairly direct questions • Essentially static or average measures obtained over the test (but see Ijsselstein et al 1997) • Assessment during test can interfere with sense of presence
Problems • Stability of results (Ellis 1996) • Inter-rater reliability • Do subjects have a notion of what presence is? • Questions strongly influenced by model of what contributes to presence • Confounding of personal and technological aspects of VE • Questionnaires do not seem to be able to distinguish real from virtual environments (‘VR Turing test’)
Witmer & Singer (1998) have developed one of the more elaborate tests based on a model of presence • 2 questionnaires a presence questionnaire and an immersive tendencies questionnaires • Evaluate presumed technological and personal determinants of presence • Has been criticized by Slater and others (see Seminar from last week)
Witmaer and Singer, Presence Questionnaire (also an Immersive Tendencies Questionnaire) • 1. How much were you able to control events? • 2. How responsive was the environment to actions that you initiated (or performed)? • 3. How natural did your interactions with the environment seem? • 4. How completely were all of your senses engaged? • 5. How much did the visual aspects of the environment involve you? • 6. How much did the auditory aspects of the environment involve you? • 7. How natural was the mechanism which controlled movement through the • environment? • 8. How aware were you of events occurring in the real world around you? • 9. How aware were you of your display and control devices? • 10. How compelling was your sense of objects moving through space? • 11. How inconsistent or disconnected was the information coming from your • various senses? • 12. How much did your experiences in the virtual environment seem consistent • with your real-world experiences? • 13. Were you able to anticipate what would happen next in response to the • actions that you performed? • 14. How completely were you able to actively survey or search the environment • using vision? • 15. How well could you identify sounds? • 16. How well could you localize sounds?
17. How well could you actively survey or search the virtual environment using • touch? • 18. How compelling was your sense of moving around inside the virtual environment? • 19. How closely were you able to examine objects? • 20. How well could you examine objects from multiple viewpoints? • 21. How well could you move or manipulate objects in the virtual environment? • 22. To what degree did you feel confused or disoriented at the beginning of • breaks or at the end of the experimental session? • 23. How involved were you in the virtual environment experience? • 24. How distracting was the control mechanism? • 25. How much delay did you experience between your actions and expected outcomes? • 26. How quickly did you adjust to the virtual environment experience? • 27. How proficient in moving and interacting with the virtual environment did • you feel at the end of the experience? • 28. How much did the visual display quality interfere or distract you from performing • assigned tasks or required activities? • 29. How much did the control devices interfere with the performance of • assigned tasks or with other activities? • 30. How well could you concentrate on the assigned tasks or required activities • rather than on the mechanisms used to perform those tasks or activities? • 31. Did you learn new techniques that enabled you to improve your performance? • 32. Were you involved in the experimental task to the extent that you lost track • of time?
Witmer Singer Table 3. Immersive Tendency Questionnaire Item Stems (Version 2.0) 1. Do you ever get extremely involved in projects that are assigned to you by your boss or your instructor, to the exclusion of other tasks? 2. How easily can you switch your attention from the task in which you are currently involved to a new task? 3. How frequently do you get emotionally involved (angry, sad, or happy) in the news stories that you read or hear? 4. How well do you feel today? 5. Do you easily become deeply involved in movies or TV dramas? 6. Do you ever become so involved in a television program or book that people have problems getting your attention? 7. How mentally alert do you feel at the present time? 8. Do you ever become so involved in a movie that you are not aware of things happening around you? 9. How frequently do you find yourself closely identifying with the characters in a story line? 10. Do you ever become so involved in a video game that it is as if you are inside the game rather than moving a joystick and watching the screen? 11. On average, how many books do you read for enjoyment in a month? 0.16 12. What kind of books do you read most frequently? — 13. How physically fit do you feel today? 14. How good are you at blocking out external distractions when you are involved in something? 15. When watching sports, do you ever become so involved in the game that you react as if you were one of the players?
16. Do you ever become so involved in a daydream that you are not aware of things happening around you? 17. Do you ever have dreams that are so real that you feel disoriented when you awake? 18. When playing sports, do you become so involved in the game that you lose track of time? 19. Are you easily disturbed when working on a task? 20. How well do you concentrate on enjoyable activities? 21. How often do you play arcade or video games? (OFTEN should be taken to mean every day or every two days, on average.) 22. How well do you concentrate on disagreeable tasks? 23. Have you ever gotten excited during a chase or fight scene on TV or in the movies? 24. To what extent have you dwelled on personal problems in the last 48 hours? 25. Have you ever gotten scared by something happening on a TV show or in a movie? 26. Have you ever remained apprehensive or fearful long after watching a scary movie? 27. Do you ever avoid carnival or fairground rides because they are too scary? 28. How frequently do you watch TV soap operas or docu-dramas? 0.28** 29. Do you ever become so involved in doing something that you lose all track of time? Note. Subscales: INVOL 5 Tendency to become involved in activities, FOCUS 5 Tendency to maintain focus on current activities, GAMES 5 Tendency to play video games Witmer and Singer 235
Slater and Steed (2000, 2003) measured presence continuously • used frequency of breaks in presence as metric for strength in presence • Dominance of VE over reality as metric for degree of presence • Interference by intrusion or attention to presence measure?
Is presence a useful concept? • Is measure of presence just a dimensionless measure or does it have utility? • Does it correlate with performance, enjoyment, ….? • Is it easier to measure performance, enjoyment, therapeutic benefit than presence?
It is presumed that presence is likely to be associated with ‘normal’ behaviour for a given situation • Positive transfer of training to the real world. • Realistic simulation and interaction. • No evidence for this argument. • Real world skills can be used if user feels present in a similar VE situation
Could trade-off factors contributing to presence to reach equivalence classes of presence (Ellis 1996) • Allows for rationale engineering decisions • But depends on presence improving performance or having some other benefit • Depends on stable and valid measures • Should/can presence be maximised or optimised?