PRESENCE

Categories of presence» M. Lombard, T. Ditton (1997): At the earth of it all: the concept of

presence

• Physical presence– The sense of being physically located in a mediated space

• Social presence– The sense of social interaction with a virtual or a remotely

located partner

» J. Ijsselsteijn, G. Riva (2003): Being there: the experience of presence in mediated environments

• Co-presence– The sense of being together in a shared mediated space

Types of « techno-presence »• Teleoperation telepresence: feeling of being

physically present at the remote site• Devices for sensing remote environment and communicating it to the

operator

• Simulation virtual presence: feeling of being present in the created environment

• Simulation systems for training, virtual environments for many different applications

• Telecommunication social presence: the feeling of being together

• E-mail, mobile communication devices

• Collaborative virtual environments the feeling of collaborating in a synthetic environment

The need for a mesure

• A mesure of presence must be– Valid– Robust– Reliable

• Mesures at date:• Subjective

– Questionnaire-based evaluations of the sense of presence

• Objective– Mesurement of various behavioral and

psychophysiological responses

Some current conceptualizations

A multidimensional costruct• Presence is a multidimensional costructmultidimensional costruct with many

factors determining the experience of « being there »– Involvement of the participant is considered a central

requirement» T. Schubert et al. (20001): The experience of presenceFactor

analytic insights

• Spatial presence• Involvement• Realness

» Lessiter et al. (20001): A cross-media presence questionnaire: the ITC-sense of presence inventory

• Physical space• Engagement• Naturalness• Negative effects

A complex form of perception

• The experience of presence is a complex form of complex form of perceptionperception – multisensory experiences

– cognitive processes (ie attentional factors)

Are considered as central requirements

An illusion of non-mediation» M. Lombard, T. Ditton (1997): At the earth of it all: the concept of

presence

– Presence is the perceptual illusion of non-mediation • The extent to which a person fails to perceive the existence of a

medium during a technologically mediated experience• And responds as he would do if the medium were not there

• Six different conceptualizations of presence found in literature:» Realism» Immersion» Transportation» Social richness» Social actor within medium» Medium as social actor

Immersion and presence» M. Slater, A. Steed (2000): A virtual presence counter» M. Slater (2002): Siggraph 2002courses notes on understanding

virtual environments: immersion, presence and performance

• The perceptual illusion of non-mediation is gained when the medium provides a high-fidelity reproduction of the psysical reality: it depends on how things look and feelhow things look and feel

– 3 aspects of presence – The sense of being there in the environment depicted by the VE– The extent to which teh VE becomes the dominant one, i.e., that

participants will tend to respond to events in the VE rather than in the real world

– The extent to which participants, after the VE experience, remember it as having visited a place, rather than just having seen images generated by a computer

– Immersion– Immersion is simply a description of overall fidelity in relation to physical

reality provided by the display and interaction systems

Interaction and presence» P. Zahoric, R. L. Jenison (1998): Presence as being-in-the-

world

• The perceptual illusion of non-mediation doesn’t depend on how things look and feel, but on action within a social context– The experience is relative to functionality, rather than to

appearences: • Affordances (Gibson)

• Being-in-the-world (Heidegger)

• Presence is tantamount to successfully supported action in the environment

Cultural concept of presence» G. Mantovani, G. Riva (1999): Real presence: how different

ontologies genberate different criteria for presence, telepresence and virtual presence

» G. Riva, G. Mantovani (2000): The need for a socio-cultural perspective in the implementation of virtual environments

• The perceptual illusion of presence depends on the capacity of the simulation to produce a context in which social actors may communicate and cooperate– The key elements for this capacity of the simulation are:

• A culturalcultural frameworkframework

• The possibility of negociationnegociation of action and of their meaning

• The possibility of actionaction

• The sensory component is not a key element, but the symbolicsymbolic one

A product of the mind» J. Ijsselsteijn, G. Riva (2003): Being there: the experience of

presence in mediated environments

• The experience of presence is a product of the mind– The experience of presence is a default experience:

– In daily life we are seldomly aware of our presence in the world

– We become aware of it in specific situations, as when the perception is mediated

– In the interaction with new computing technologies (VR, immersive displays, …) the presence experience is a relevant condition for evaluation and design

• No intrinsic difference in stimuli arising from the medium or from the real world

• It depends on which of the two becomes the dominant perception

• Role of bottom-up or perceptual processes and top-down processes, as attention, culture, ..

– If attention is allocated to the mediated environment telepresence

Some personal considerations

Double importance of the research on presence

• Instructions for the design and evaluation of tele-applications and virtual-applications

• Understanding the psychophysiological conditions of perception, interaction, communication:

• How do we construct objects and objective worlds from the various stimulations we are subject to?

• What is the role of action? Of multimodal interactions? Of cognition?

– The answers to these questions are necessary to design and evaluate and in the same time the design of « artificial worlds and interactions » is an important tool for answering those questions

Critics to the common definition of presence

• Summary definition of presence as from literature:

– PRESENCE is the « feeling of being » physically present at the remote site or in a created environment and the « feeling of being » together within or without a mediated environment

– PRESENCE is a form of self-perception influenced by many different factors, such as involvement, multisensory stimulations, cognitive conditions

– PRESENCE is a default condition in daily life of which we become aware in special situations such as technologically mediated experiences

• The « feeling » or « sense » are not such conditions that can be evaluated: if we deside to evaluate and mesure presence we cannot think to it as the problem of « what is it like to be » (qualia)

• Presence is instead a problem of operatingoperating in remote conditions, operatingoperating in constructed environments, in social conditions or not

• The operator is able to inter-actinter-act with the objects and people present in the remote site or in the created environment in an adequate wayadequate way, his action on the objects of the remote site is efficient enoughefficient enough

• The efficiency of the action-interactionefficiency of the action-interaction, the success is something we can mesure and evaluate in an objective manner

If Presence is a problem efficient action-interaction then

• Presence does not regard only the user, but can be predicated also of the worldworld, the objects, the environment the operator interacts withthe objects, the environment the operator interacts with

• The undestanding of the psychophysiological conditions of the psychophysiological conditions of the interactioninteraction with the « natural » world is of great importance to reproduce an efficient interaction with the « created » virtual or remote world

• The problem of the transparency of the medium is included in the problem of reproducing effective interactions, considering the effects considering the effects of the mediumof the medium

Founding the research on presence on the psychophysical conditions for interacting and operating permits to go over the simple simulation of real physical world

• Once the psychophysical conditions of the interaction and the effects of the medium are known, the reproduction of the interaction can permit to experience new kind of worlds (with different physics and ontology from the « natural one ») and to extend the possibilities of perception and action

• Presence can go beyond a search for simulation of real environments (fidelity): it can be connected to the perception of a standing, in a sense « realistic » and « objective », world which, in an other sense, is not realistic at all

• From this point of view the research on presence is a reflexion on the purely sensorimotor conditions of objectivity (without appealing to how the world is and how the world causes perception)

Both in the case of the simulation of real worlds and in the case of the creation of new worlds,

• The perceptual elements of the interaction must be accompanied by the motor and cognitive ones, since psychophysiology shows that these elements are strongly interconnected in the deployment of efficient operations

• It is important to be alble to evaluate the mesure in which cognitive processes participate to perception, and to discern which ones do

• Not always, i.e., narrative elements and other symbolic elements are relevant for efficient operating behavior

Approaches to presence

• We can define almost 2 possible approaches to presence:

– Presence as « the user’s presence »• Where am I problem• Shift in the point of view• Selected self-location• Being there

– Presence as « the world’s presence »• Objectivity problem• Constructing an objective world

What is it to be present in a world• In order to detect which factors can influence the « sense of

presence » it is necessary to give correct definitions of the two approaches to presence– User’s sense of presence = shift in the point of view – Object’s sense of presence = construction of an objective world

• We must then ask– What is it a point of view, what does it mean to have a point of view, how

we can construct a point of view– What is it an objective world, what does it mean to have an objective

world, how one can have a world

• The two questions are tied because– To have a point of view is to have a point of view on the world– To have a world is to have a world from a certain point of view

Where am I?

Presence as the where am I problem

or

the user’s presence

From a virtual point of view

» D. Dennett (1978): Where am I?

– Dennet’s brain is separated from his body, but each connection between them is restored by the use of radio transceivers

– Looking at his brain Dennett asks himself: « where am I? »

– « I’m where my point of view is »

– The point of view shifts: « the workers in the laboratories and plants who handle dangerous materials by operating feedback-controlled mechanical arms and hands undergo a shift in point of view… »

Selecting self-location

» M. Slater, A. Steed (2000): A virtual presence counter

– Presence is

• A perceptual mechanism

• for organizing the incoming stream of sensory data

• into a coherent environmental gestalt,

• selecting between alternative hypotheses of self-location

The illusory shift in point of view

» W. Ijsselsteijn, G. Riva (2003) : Being there

– Presence = • the sense of being there =

– Displacement of the self-perception

In telerobotics and virtual environments associated with:• Sense of transparency of the medium• Sense of direct perceptual stimulation without awareness of

the remoteness in time or space of the simulated or reproduced realities

How to determine the user’s presence– External factors = media characteristicsmedia characteristics

• Media formform variables (properties of the display medium)– Extent of sensory information presented – Level of control over the sensory mechanisms– Ability to modify the environment

• Media contentcontent variables– Objects, actors, environments– Narrative– Social elements (reactions of real or virtual actors)

– Internal factors: user’s characteristicsuser’s characteristics (high variability)

– Age, sex, experience– Cognitive states– Emotional states– Perception-interaction conditions

What is like to be an object?

Presence as the objectivity problem

or

the world’s presence

Is it an objective world?

» T. Nagel: What is it like to be a bat?

– Nagel asks himself how can a man know what is it like to be a bat– The question about perceptual states is a question about internal

private states – But a perceptual state is a form of interaction between a human, or a

bat, and a world– Let’s ask then what is it like to be an object:

• Let’s describe how a man or a bat interact with the object, in a motor and perceptual way

• If the interaction responds to certain requirements, than the human, and the bat, are interacting with an object, and are not simply having private internal sensations

• If the interaction responds to those requirements, so that we can say that the human, and the bat, hare interacting with objects, than they are operating in an objective world

Presence and objectivity• Presence is a matter of localization

• I can be here or elsewhere

• Presence as localization is not only a matter of the subject of the experience, but of the object too

• I’m here, and my cup of tea too

• Only a material stuff or a material event can be present

• The ghost is absent

• A sensation of fear is present

• Speaking of presence is possible only if we speak og objects that have a certain form of objectivity

Virtual objects

• A virtual object is not a material object as a chair, or a table

• But there is a certain sense in which a virtual object is « material »:– The operator can act with it, can move it, and

receive responses by it

• There can be a « material » interaction between the operator and the virtual object

Objective world• An objective world is not a matter of facts

– An objective world is the result of an interaction which An objective world is the result of an interaction which responds to some constraintsresponds to some constraints

– The subject of the interaction plays an active role in the active role in the construction of his objective world construction of his objective world

– i.e. Weight illusions: no errors, but effects of the characteristics of the perceptual experience and of the motor constraints of perception

– i.e. intermodal illusions: effects of the interactions between sensory modalities

– i.e. conflict illusions: effects of the effort to mantain the perceptual esperience coherent

Great Expectations• A possible test for « objectivity » is the

reidentification test• Another test for pesence in the sense of

« objectivity » is the test of expectation:• Let the operator play with a simple object, a ball, throwing it

in the air• When the ball is out of his contact, the player will expect it to

come back in a certain way, depending on its physics, and he will prepare himself to catch it

• For exemple he will preshape his hand in a way that is correspondent to the shape and the movement of the ball

• If the operator has expectations of this kind we can say that he has a « sense of prsence » of the virtual ball, or that the ball is objective to him

• Expectation can be tested by– Preshaping– Illusions based on expectations– …

• Expectation can give quantitative mesures of « presence » because it is not a « feeling » r a « sense », but an observable behavior

• Expectation regards the interaction between the operator and the wold and objects:– The operator acts on the objects– The objects respond to the action of the operator

Interaction

• In the perspective of expectation interaction seems to be a key factor for « presence » and « objectivity »– The operator should be active

– The artificial world and object should respond in a significant way to the action of teh operator

• Not necessarily replicate the ontology and physics of the real world (fidelity)

• But respond in a sufficiently regular way (coherence)