Presence and Immersion

Ruth Aylett

Overview

!  Concepts – Presence –  Immersion – Engagement

•  social presence

!  Measuring presence – Experiments

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!  A psychological state !  The sensation of being ‘physically present’ in the scene –  Rather than in actual

location

!  Aspects: –  Attention –  Physical or emotional

reactions to events in the space.

–  Memories of events in the space.

–  Can be produced by books..

Presence

4 Visual – Auditory – Olfactory – Haptic – Taste

Immersion !  A physical state !  Being isolated from the outside

world –  in a computer-generated

space. –  cut off from real-world stimuli

!  Provide computer-generated stimuli to one or more of the human senses. –  Degree of control of sensory

channels –  How far captures attention

Rate of Engagement !  Immersion develops slowly when watching a film

–  the storyline may need some understanding before senses focus on the film not the cinema

–  Presence may influence immersion via degree of attention

!  A very fast rate of immersion can be achieved when a camera is on the front of a roller coaster –  The viewer experiences a plunging effect as the ride dips –  Activates the reflexive system –  Big changes in sensory input –  High degree of control by system

Rate of Immersion

!  Visual cues improving immersion a powerful way to gain a sense of presence in a VE

!  The quicker the immersion, the more a person feels engrossed

!  Extended immersion time leads to adaption and a sense of ‘complete’ presence

Factors Inhibiting Presence

!  The sensation of presence can break down when –  the user is tired –  the weight of an HMD becomes uncomfortable or

heavy for the user –  other intrusive equipment: trailing cables etc –  unnatural movement or lags during the experience –  sudden expectation fails

Engagement

!  The state of caring more about the VR world than just it being a VR world –  The tasks become important –  Forgetting it’s a simulation –  An affective state

!  Enhanced by: –  Strong sense of presence –  Well-designed tasks

•  e.g. intuitive navigation

–  Autonomous characters"

Co-presence

!  Feeling present with others in the virtual environment – You and they share the same location – Ability to make common references to the

virtual world – ‘it’s behind you’; ‘over there’

Social presence

!  Not the same as co-presence !  Feeling that others in the environment are ‘real people’ –  Their opinion counts –  You have a reputation to uphold –  You have a history with them

!  Does not depend on physical presence –  Has been documented in text-only multi-user

environments such as chat rooms

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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 tasks 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?

Achieving a strong sense of presence

!  In general: –  Transparency of technology –  Sensory fidelity

!  Good graphics ––especially depth cues –  Seeing parts of your own body –  High resolution and large field of view –  Familiarity of the VE or scene

!  Binaural sound

Dynamic aspects

!  Good interaction – Amount: what can be changed – Quality: whole body, unencumbered

!  Responsiveness – Absence of lags – Maintaining convincing stereo vision and

hearing as user moves

Seeing parts of your own body – Seeing computer generated parts of your

own body tends to lower the feeling of presence

– Seeing actual parts of your own body tends to produce a strong feeling of presence

Achieving a strong sense of presence

High resolution and large field of view – Presence is reduced:

•  If the edge of the image is visible •  If the field of view is restricted

–  Ideally the user should be able to move their eyes to see objects just outside the region of peripheral vision • Engagement of peripheral vision has strong

sensory consequences

Achieving a strong sense of presence

Familiarity of the VE or scene –  If the VE is one that relates to a real world

then the time taken to adapt to it appears to be shorter

– However, a user’s own experience may impede presence because of artefacts in the VE

Achieving a strong sense of presence

Measuring Presence

Requires understanding of: –  the way a human interacts with the real

world –  the adaptation that takes place when

things change in the real or external environment

[Ellis, 1991] Our knowledge is constantly being updated

by behavioural plasticity of visual-motor coordination and vestibular reflexes

“Thus, a large part of our sense of physical reality is a consequence of internal processing rather than being something that is developed only from the immediate sensory information we receive”

[Sheridan, 1992] “Presence is a subjective manifestation, much

like mental workload and mental model - it is a mental manifestation, not so amenable to objective physiological definition and measurement”

“Presence is a subjective sensation and as such any subjective measures are likely to be multidimensional”

The aim..

!  Ideally we would like a set of repeatable objective measures for presence that indicate the degree of presence created by a particular system

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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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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

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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.

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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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Performance measures !  Behavior !  Suspension of belief

–  Ducking

–  Socially conditioned reactions

The cliff experiment

!  Subjects put into a virtual room – Large hole or pit in the floor

!  Asked to move their virtual representation around the room – Very reluctant to ‘walk over’ the pit

Zeltzer’s AIP Cube

!  One solution for characterising VE’s was proposed by Zeltzer

!  Assumes any VE has 3 components – A set of models/objects or processes – A means of modifying the states of these

models – A range of sensory modalities to allow the

user to experience the VE

Zeltzers Autonomy, Presence, and Interaction Cube

(1,0,1) (1,1,1)

(0,1,1)

(1,1,0) (1,0,0)

(0,0,0)

(0,0,1)

(0,1,0) interaction

presence

autonomy

virtual reality

We would not be able to distinguish between the virtual environment and the real world

Zeltzer’s AIP Cube !  Autonomy

A qualitative measure of a virtual object’s ability to react to events and stimuli

–  For no reaction, autonomy = 0 –  For fully comprehensive reaction, autonomy = 1

This scaling between 0 and 1 is purely qualitative

Zeltzer’s AIP Cube !  Interaction

The degree of access to the parameters or variables of an object

–  For no real time control of variables, interaction = 0 –  For real time control of variables, interaction = 1 Whilst modern VE systems are capable of a high degree

of interaction, the complexity of an application may inhibit or prevent interaction

Zeltzer’s AIP Cube

!  Presence A crude measure of the fidelity of the

sensory input and output channels –  It is affected by the application of the VE

Zeltzer’s AIP Cube

!  The point (0,0,0) represents very early graphics systems –  programmed in non-real-time batch mode –  no interactivity

!  Diagonally opposite, at (1,1,1) is ideal virtual reality –  maximum autonomy, interaction and presence –  so good that you wouldn’t realise it wasn’t real

Zeltzer’s AIP Cube

!  The point (0,1,0) can sometimes be achieved today –  user can control all the variables of some objects

in real time

!  The point (0,1,1) represents experiencing a high degree of interactivity and presence –  Some environments support regions close to this –  many VE’s lack autonomy, though this is changing

with the increasing use of physically based models and autonomous agents

Zeltzer’s AIP Cube !  The point (1,0,1) represents a high degree of

presence and autonomy –  a VE where the viewer is a passive observer but is

fully immersed –  may be able to modify the viewpoint, but no

objects should respond to a change in the viewpoint

–  an IMAX film with stereo glasses & sound could possibly be considered here

Determinants of Presence Sheridan and Kalawsky proposed a total of 4

determinants of presence –  Extent of sensory information –  Ability of the viewer to change their viewpoint (for

visual parallax or visual field) –  Ability to modify the spatial relationships of objects in a

VE –  Closed loop performance due to a user induced motor

movement (also includes the natural dynamic behaviour of moveable objects in the VE)

Determinants of Presence

There is a temptation to concentrate on stimulating the senses –  rich 3D photo realistic display –  rich 3D soundscape –  tactile & force feedback

but matching hardware interfaces to human sensory system is difficult, so we need to consider trade-offs

The sculpture experiment

!  Constructing 3d rod-based sculptures

The aim

!  Is it quicker/easier: –  From a workstation screen –  From a 3D VR representation

!  Experiment 1 (1999) –  Physical example v Graphics display v HMD –  HMD and graphics display equal

•  Low resolution of HMD •  Eyestrain and nausea •  One subject fainted

Experiment 2

!  Various setups in a CAVE –  Stereo v mono with shutter glasses –  Small-scale v immersive sculpture –  Tracking v joystick navigation

Results

!  Life-size better than super-scale – Super-scale produced longer times – And more errors

!  Head-tracking better than joystick use – Joystick 20-40% longer

Phobias and Presence !  Specific ‘phobias’

–  fear of heights, flying, bridges, post-traumatic stress

•  requires presence

!  Social ‘phobias’ –  extreme shyness, fear of public speaking, stage

fright, social anxiety, post-traumatic stress

•  requires co-presence

Fear of Public Speaking Study Mel Slater, UCL

!  FOPS an ‘interpersonal phobia’ –  part of the general class ‘social phobia’

!  Social phobia ‘A persistent fear of one or more situations..... in

which the person is exposed to possible scrutiny by others and fears that he or she may do something or act in a way that will be humiliating or embarrassing’.

•  American Psychiatric Association manual DSM-IV

Co-Presence Requirement !  To elicit social phobic response

– VE must maintain illusion that there are other intelligent beings there

– capable of observing and reacting to the individual

!  Our major question: – To what extent will speakers react with

appropriate affect to an entirely virtual audience?

FOPS Experiment (Summer ‘98 - D-P. Pertaub)

!  10 subjects rehearse in front of a virtual audience

!  Talk repeated 3 times !  Two factor design

–  Immersion • HMD, desktop

– Audience response • positive/negative audience (talks 1 and 2) • negative through positive (ethical conclusion)

!  Audience response –  5 subjects - first negative –  5 subjects - first positive

!  by –  5 subjects immersed –  5 desktop display

!  Third talk –  Each subject concluded

with a standing ovation

Avatar Design

!  Avatars are moving, blinking, fidgeting, expressive

!  Aim is portrayal of emotions – expressionism rather than realism

!  Two generations of avatar design –  first experiment – stage fright scene + 2nd planned exp.

Response Variables

!  Self-Rating – subjects' evaluation of their performance.

• How would you rate your own performance in the talk you have just given?

• Assign to yourself a score out of 100, where 0 = completely dissatisfied with your performance, and 100 = completely satisfied.

Response Variables

!  Modified PRCPS –  Personal Report Confidence as a Public Speaker

•  I was in constant fear of forgetting my speech •  At the conclusion of the speech I felt I’d had a pleasant

experience •  I had no fear of facing the audience •  I felt disgusted with myself after giving my presentation •  I had no fear of facing the audience

–  Count out of 16 such (negative) statements

Explanatory Variables

!  Background – age, gender, status. – Ages 20s or 30s. – There were 7 post-graduate students, 1

undergraduate, and 2 faculty members. • None of the subjects were from Computer

Science • all were unknown to the experimenters before

the study.

Explanatory Variables !  Co-Presence

– extent of being with a real audience • 4 questions 1-7 scale

–  In the last presentation to what extent did you have a sense that there was an audience there in front of you?

–  To what extent did you have a sense of giving a talk to people? – When you think back about your last experience, do you

remember this as more like just talking to a computer or communicating to an audience?

–  To what extent were you aware of the audience in front of you?

• Co-presence measured as no. of 6-7 responses/4

Explanatory Variables

!  Perceived Audience Response – subject's own impressions of the audience

behaviour – 3 questions, each on a 1 to 7 scale:

• How would you characterise the prevailing mood of the audience? How friendly were they?

• How would you characterise the interest of the audience in what you had to say?

• What sort of impression do you consider that you made on the audience?

Perceived Audience Response

!  Independently of order –  there was a significant difference in

'perceived audience response'. •  'good audience' (4.7 ± 1.2) •  'bad' audience (2.3 ± 1.0).

Self-Rating by Avatar ‘Interest’

rating

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1 2 3 4 5 6 7

rating

Self-Rating Regression

Non-Immersed ImmersedNegative Audience 21 – 5*C + 13*I 21 – 19*C + 13*I

Positive Audience 73 – 5*C 39 + 16*C

C = co-presence I = perceived audience interest R-Squared = 0.89 on 8 d.f.

Self Rating for Negative Audience

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0 1 2 3 4

Co-Presence

Sel

f R

atin

g

Non-Immersed

Immersed

For a fixed level of ‘perceived audience interest’ immersion interacts with co-presence on self-rating.

Self-Rating for Positive Audience

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0 1 2 3 4

Co-Presence

Sel

f R

atin

g

Non-Immersed

Immersed

Perceived audience interest not-significant. Co-Presence amplifies response for immersed subjects

Self-Rating Conclusions !  Lowest self-rating:-

–  negative audience, immersion, maximum co-presence, and minimum perceived audience interest.

!  Highest self-rating:- – Negative audience:

•  lowest co-presence and highest perceived interest – Positive audience:

•  highest co-presence

Modified PRCPS Logistic Regression

Non-Immersed ImmersedNegative Audience -0.9 – 0.3*I 0.1 –0.3*I

Positive Audience 0.2 – 0.3*I – 0.8*C 1.2– 0.3*I – 0.8*C

Co-Presence amplifies response for Positive Audience

Chi-Squared = 12.2 on 12 df

Response = modified personal report of confidence as public speaker (high score means less confidence)

Strong Observed Responses

–  Clear (unmeasured) physical responses •  avoiding eye contact with experimenters •  skin colour and postural changes

–  Spontaneous verbal statements •  I really bored them to tears. •  I’m sorry about last time, I’ll try to improve this time. •  Wake up! •  I see that my topic of the fetal heart doesn’t interest

you. •  That's a tough audience. I came out and my hands were

sweating. •  Oh, how rude! •  Thank you, thank you very very much!

Co-Presence and Immersion

!  No significant difference in reported co-presence between immersed and non-immersed subjects.

!  A familiar result from our previous studies.

!  Utility of Questionnaires???

Questionnaire Study !  Recent study (Martin Usoh++) !  Between-subjects, 2 groups !  10 subjects per group !  Experimental group - immersed (HMD) !  Control group - in real world !  Both groups carry out search task !  Environments the ‘same’.

Conclusions !  When designing VE’s we must look to human

performance metrics and the subjective experience of presence to provide a measure of the effectiveness

!  Presence and immersion play a very important role in VE’s as they provide the only means of assessing the performance benefits of these systems

Credits

!  Antony Steed, UCL !  Mel Slater, UCL !  William Winn, University of Washington !  Doron Friedmann, IDC, Herzilya