The Layers of Presence: A Bio-cultural Approach to Understanding Presence in Natural

and Mediated Environments

GIUSEPPE RIVA, Ph.D.,1,2 JOHN A.WATERWORTH,3,4 and EVA L. WATERWORTH3,4

ABSTRACT

This paper proposes a bio-cultural theory of presence based on four different positions re-lated to the role and structure of presence, as follows. First, presence is a defining feature ofself and it is related to the evolution of a key feature of any central nervous system: the em-bedding of sensory-referred properties into an internal functional space. Without the emer-gence of the sense of presence it is impossible for the nervous system to experience distalattribution: the referencing of our perception to an external space beyond the limits of thesensory organs themselves. Second, even if the experience of the sense of presence is a uni-tary feeling, conceptually it can be divided in three different layers, phylogenetically differ-ent and strictly related to the three levels of self identified by Damasio. In particular we canmake conceptual distinctions between proto presence (self vs. non self), core presence (selfvs. present external world), and extended presence (self relative to present external world).Third, given that each layer of presence solves a particular facet of the internal/external worldseparation, it is characterized by specific properties. Finally, in humans the sense of presenceis a direct function of these three layers: the more they are integrated, the more we are pres-ent. In the experience of optimal presence, biologically and culturally determined cognitiveprocesses are working in harmony—to focus all levels of the self on a significant situation inthe external world, whether this is real or virtual.

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INTRODUCTION

WHAT IS PRESENCE? According to Steuer1: “Pres-ence is closely related to the phenomenon of

distal attribution or externalization, which refer tothe referencing of our perception to an external spacebeyond the limits of the sensory organs them-selves.” Since this statement was made, several dif-ferent authors have acknowledged that presenceshould be considered as a neuropsychological phe-nomenon evolved from the interplay of our biolog-ical and cultural inheritance.2–10 Nevertheless, except

for some preliminary attempts,5,11 no theory foundin the presence literature has been able yet to includethis phenomenon within a truly psychological frame-work. To overcome this limitation, presence is heredelineated as an evolved bio-cultural mechanismthat helps the self in organizing the streams of sen-sory data: the more it can differentiate the externalworld, the more we experience a sense of presence.

In the following paragraphs, we will try to de-scribe the rationale of this hypothesis and its conse-quences. Particularly, even if we experience thesense of presence as a unitary feeling, conceptually

1Applied Technology for Neuro-Psychology Laboratory, Istituto Auxologico Italiano, Milan, Italy.2Center for Communication Psychology, Università Cattolica del Sacro Cuore, Milan, Italy.3Tools for Creativity Studio, The Interactive Institute, Umeå, Sweden.4Department of Informatics, Umeå University, Umeå, Sweden.

AU: Pleaseprovide aca-demic de-grees for allauthors.

AU: All textcitations ofreferenceswere editedto conformto journalstyle—please con-firm all.

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presence can be divided into three different layers,phylogenetically and functionally different, strictlyrelated to the three levels of the self identified byDamasio.12 According to this view, the highest pos-sible degree of presence is achieved in states of con-sciousness characterized by the integration of thesethree layers. In a later section, we present a moredetailed characterization and a few different exam-ples of these states of intense, integrated presence.

Presence, evolution, and culture

With the term “evolutionary psychology” (EP), arelatively new theoretical paradigm is describedwhose main goal is to analyze how the evolved cog-nitive processes of our psyches continue to penetratea wide-ranging area of our present-day behavior.13

According to Bereczkei,14 the evolutionary approachto psychological phenomena entails recognizing cer-tain features of human behavior that have been de-signed by natural selection to be useful for survivaland reproduction in the environment in which hu-mankind evolved. Using this approach, we can ex-plain a wide variety of seemingly different behaviorsand support a new kind of understanding of humannature. Within this vision, an evolved psychologicalmechanism can be described as a set of processes in-side an organism that13:

• Exists in the form it does because it (or othermechanisms that reliably produce it) solved aspecific problem of individual survival or repro-duction recurrently over human evolutionaryhistory

• Takes only certain classes of information or input,where input can be (a) either external or internal,or (b) actively extracted from the environment orpassively received from the environment, and (c)where the input specifies to the organism theparticular adaptive problem it is facing

• Transforms that information into output througha procedure (e.g., a decision rule) in which out-put (a) regulates physiological activity, providesinformation to other psychological mechanisms,or produces manifest action and (b) solves a par-ticular adaptive problem

If many researchers have no problem in accept-ing that some key psychological features are the re-sult of some evolutionary process, they are less readyto accept the application of the same approach topresence. Considering presence simply as a charac-teristic of a given medium, frequently misleads theminto believing that the novelty of our modern envi-ronment precludes any study of presence as adap-

tive because humans today live in a culture unlikethe Pleistocene environment in which human na-ture was shaped. However, the human psyche hasevolved as a device for dealing with individual andsocial problems in the ancient environment, andthese problems frequently resemble those faced bymodern humans. As Alexander15 states: “I am sug-gesting that we are addicted to soap operas (and allother condensed and elaborate social dramas wecall theater) because our ancestors literally enduredsimilar circumstances in small groups of relativesand friends for thousands of generations, in whichnothing was more important than experience andskill in manipulating the people and events in-volved, and such experience and skill came fromobservation as well as actual participation in partic-ular events.”

The words of Alexander also outline the impor-tance of artifacts in the adaptation process. In fact,the adaptation strategy of our species is based onsocial learning and on the production and use of ar-tifacts, material or symbolic.16 This strategy wassupported by specific biological features, such asan upright bodily position, opposable thumbs, andthe impressive growth of brain structures in bothmass and complexity. As suggested by Crook,17 hu-mans evolved specific psychic processes, definedas awareness of the external world and awarenessof one’s own internal state. The symbolic represen-tations of the external world and of individualsthemselves were formalized by means of descrip-tions and behavioral rules stored in the individ-ual’s central nervous system (intrasomatic level)and in material tools, books, and artistic and reli-gious artifacts (extrasomatic level).

Within this vision, we suppose that the ability tofeel “present” in a virtual reality system—an arti-fact—basically does not differ from the ability tofeel “present” in the real world. One of the mainideas expressed in this paper is the link betweenpresence and its evolutionary role.18 In more detail,we suppose that presence is an evolved psycholog-ical mechanism, created by the evolution of thecentral nervous system in its attempt to embed sen-sory-referred properties into an internal functionalspace.19 As noted by Waterworth and Waterworth,19

the appearance of the sense of presence allows thenervous system to solve a key problem for its sur-vival: how to differentiate between internal and ex-ternal states. If, in relatively simple organisms, thisseparation involves only a correct coupling betweenperceptions and movements, in humans it also re-quires the shift from meaning-as-comprehensibilityto meaning-as-significance. Meaning-as-comprehen-sibility refers to the extent to which the event fits

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our view of the world (for example, as controllableor nonrandom) whereas meaning-as-significancerefers to the value or worth of the event for us.20

The emergence of extended consciousness

For organisms in a natural environment, it isvital to pay attention and respond rapidly to pres-ent threats and opportunities. Our emotional andcognitive life is built on this evolutionary substrate.But as the self evolved, imagined situations becameincreasingly important to survival and biologicalsuccess.

According to recent psychological theory, per-ceptions are to a large extent guesses of what is outthere now and predictions of what is about to hap-pen. A way to put this is that perceptions are in someways rather like hypotheses of science—predic-tions of unsensed features of objects and of futuresthat may not happen.21 They are never certainlytrue and often wrong. Yet the guesses of hypothesesare the nearest we ever get to reality. If perceptionsare internal predictions, how can we differentiatethem from other internal processes, such as concep-tual modeling experienced as mental images?

According to current neurobiological work, evo-lution created two different levels of consciousnessto solve this problem12: core consciousness and ex-tended consciousness. Core consciousness is whatwe presumably share with many nonhuman ani-mals—a simple biological phenomenon, the scopeof which is the Here and Now. This basic, integratedrepresentation of one moment and one place is in-dependent of language, reasoning, and memory.22

When we imagine, think, plan, and generally dealwith information that does not only constitute ourexperience of things and events in the currently pres-ent external situation we are exercising extendedconsciousness: “Extended consciousness has to dowith making the organism aware of the largest pos-sible compass of knowledge.” According to Dama-sio,12 extended consciousness emerges from:

• The gradual build-up of memories of the organ-ism’s biography (the experiences of the “coreself”).Each autobiographical memory then becomes anobject, which takes part in inducing and enhancingcore consciousness.

• The ability to hold active, simultaneously, andfor an extended period of time many images thatcollectively define the “autobiographical self”and the object it is interacting with.

It is extended consciousness that allows us to cre-ate an internal world in which we may suspend

disbelief, as compared to a perceptual world expe-rienced as outside the self. Extended consciousnessrelies on working memory,12 which can be seen asthe “active scratchpad” of mental life.23 It is in work-ing memory that the internal world we are currentlyexperiencing is largely created. Its main function isto allow us to consider possibilities not present inthe current external situation. In contrast, core con-sciousness is directed exclusively to the here andnow—the present.

Extended consciousness gives us obvious advan-tages over organisms without it, such as the abilityto plan and generally enact in the imagination possi-ble scenarios of the future, as well as to increase thesophistication of learning from the past. Languagedepends on it, because we must retain linear se-quences of symbols in working memory if we are tounderstand utterances, whether spoken or written.

The advantages of extended consciousness de-pend on the fact that we can distinguish betweenthe experience of the external word and the experi-ence of internal worlds, both remembered andimagined. Confusions of the two indicate seriouspsychological problems, problems which, until re-cent times, would have prevented survival and thepassing on of this condition. As noted by Water-worth and Waterworth9: “if we react as if the exter-nal world is only imaginary we will not survivelong (think of this the next time you cross a busystreet). And if we think that what we are merelyimagining is actually happening, we may omit tocarry out basic activities on which our survival de-pends.” How then do we distinguish perceptionsof the external world (perceptions which are them-selves largely hypothetical mental predictions) fromthe purely mental constructions that constitute imag-ined situations and events? We are suggesting thatpresence is the feeling that evolution has given usto make this vital distinction.

The layers of the self

According to this view, what is the role of self?Damasio proposes important conceptual distinc-tions between a preconscious precedent of self andtwo distinct notions of self-consciousness12,24:

• Proto self: A coherent collection of neural patternsthat map, moment by moment, the physical stateof the organism

• Core self: A transient entity which is continuouslygenerated through encounters with objects

• Extended self: A systematic record of the more in-variant properties that the organism has discov-ered about itself (Damasio refers to this as the

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“autobiographical self.” But because of its intrin-sic dependence on extended consciousness, andbecause it consists of more than autobiographi-cal memories and the self-conscious idea of self,we refer to this third layer as the “extended self”.)

In this vision, the basis for a conscious self is a feel-ing state that arises when organisms represent a non-conscious proto-self in the process of being modifiedby objects. In essence, the sense of self depends onthe creation of a second-order mapping, in certainbrain regions (brainstem nuclei, hypothalamus, me-dial forebrain and insular and somatosensory cor-tices), of how the proto-self has been altered.24 Thisgives the feeling, not just that something is happen-ing, but that something is happening to me.

However, it is only the extended self that gener-ates the subjective experience of possessing a trans-temporal identity. The extended self centers theflow of our interactions with perceptual objects onitself, thereby making them our own experiences(Fig. 1). In summary, the presence of you is the feel-ing of what happens when your being is modifiedby the acts of apprehending something.22

Brain mapping

As we have just seen, core self and core con-sciousness have their origins in a mapping of bodystates and are about two facts: the organism relat-ing to sensory streams and the fact that this relationcauses a change in the organism. It follows that akey starting point for a theory of presence is a de-

scription of how the brain maps its sensorial in-puts, and, most importantly, the dynamics of theirrelationship.

To understand how these components are relatedwe can use an example: the way our self experi-ences our first view of the Colosseum in Rome. Wereceive sensory signals from our eyes, ears, noseand sense of touch that are mapped by the protoself—the feeling of something happening. Somemicroseconds later, this leads to perceptual activitywhich is monitored by the core self and becomesthe content of core consciousness—the feeling ofsomething happening to me. A few microsecondsmore are required for the activation of extendedconsciousness—knowledge of the feeling that some-thing happening to me. Some milliseconds later, itadds dispositional records of that place (or similarplaces), records which typically include stored sen-sory, motor response and emotional data.12 If theserecords are also part of autobiographical memory—the organized record of the main aspects of our bi-ographies—we may consciously recognize the placebecause we studied it in architectural history; andwe may have emotional ties because we associatethe place with special memories (our most recentexperience of the Colosseum was while watching apreferred movie: “Gladiator”). The result is a singleconscious experience integrating perceptions, emo-tions and feeling. Once the event has ended, it is re-stored in dispositional space with new data aboutour most recent experience.

In the previous paragraphs we outlined how theresult of this process is a higher level of self—the

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extended self—created by extended consciousness,which generates the experience of having a perma-nent identity. However, a central nervous system isable to differentiate between internal and externalevents well before the appearance of the extendedself. As noted by Llinás, even an adult lamprey isable to create an internal functional space provid-ing continuity between the sensory derived proper-ties of the external world and subsequent motorinput.19 And this is done by simply experiencing:just by moving into the environment the lamprey isable to experience the unevenness of the terrainand adapt its motor behavior to it.

Is the presence of a lamprey in an external worldsimilar to our presence in the Colosseum? Even ifboth share the possibility of recognizing some fea-tures of an external world and adapting to it, theanswer is surely no. According to recent neurobio-logical theories this difference can be explainedphylogenetically in relation to the evolution of theself.12 Lampreys only have what Damasio definesas the proto self: a coherent collection of neural pat-terns that map, moment by moment, the physicalstate of the organism.12

THREE LAYERS OF PRESENCE

One of the main ideas expressed in this paper isthe link between presence and self. In more detail,we suppose that presence is the result of the evolu-tion of the central nervous system in its attempt toembed the sensory-referred properties into an in-ternal functional space.19 As noted by Waterworthand Waterworth,9 the appearance of the sense ofpresence allows the nervous system to solve a keyproblem for its survival: how to differentiate be-tween internal and external states.

We hypothesize that it is possible to associate aspecific layer of presence with each of the three lev-els of self identified by Damasio12 and outlined inthe previous section. Further, given that each layerof presence solves a particular facet of the internal/external world separation, it is characterized byspecific properties:

• Self versus non-self (proto presence)• Self versus present external world (core presence)• Self relative to present external world (extended

presence)

In the following parts of this section, we will tryto outline the characteristics of each layer in moredetail, by focusing on its peculiar characteristics.

First layer: proto presence

As we have seen, the main activity of the protoself is a non-conscious mapping of the physicalstate of the organism. What is the evolutionary goalof the proto self? To predict the characteristics ofthe external world as it is experienced through sen-sorial inputs.

As suggested by Llinás this can be done even bya lamprey.19 How? According to Llinás,19 the stepsidentify by the latest neurobiological studies are:

• The comparison of the sensory referred proper-ties of the external world with a separate internalsensorimotor representation of those properties

• The transformation/utilization of this premotorsolution into finely timed and executed move-ments

In this process, movement plays a key role (Fig.2). On one side, an adaptive movement is the evo-lutionary goal of the proto self. On the other side, itis only through motility that it can embed the prop-erties of the external world in its sensorimotor rep-resentation. These properties are the constraintsgenerated by the coordinate systems that describethe body: in an evolutionary process that requiredmillions of years the proto self experienced, throughmovement, these constraints and used them tomodel the external world. In this vision how canwe define the sense of presence possessed by theproto self (“proto presence”)? Tentatively, we cansay that the more the proto self is in the body, themore it is different from the external world. Moreprecisely we can define proto presence as an em-bodied presence related to the level of perception-

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action coupling (self vs. non-self). The more the or-ganism is able to couple correctly perceptions andmovements, the more it differentiates itself fromthe external world, thus increasing its probabilityof surviving.

Second layer: core presence

In Damasio’s model, the second level of self iscore self, a transient but conscious entity, ceaselesslyre-created for each and every object with which thebrain interacts. What is the evolutionary goal of thecore self? The integration of specific sensory occur-rences into single percepts. According to Gregory,21

this is done through a coherent world-model thatevolves in real time according to its own internallogic. In such a vision, perception depends verylargely on knowledge derived from past experiencesof the individual and from evolutionary history.

During waking consciousness, this model is mod-ulated by the senses, but it persists even when sen-sory input is temporarily cut off: close your eyesand you’ll still be keenly aware that the Colosseumis in front of you. As far as your inner model is con-cerned, the Colosseum is still there; and as that innermodel is used to generate motor commands, anymovements you choose to make (such as searchingfor a taxi) will be adjusted to take the presence ofthe Colosseum into account.

A critical point here is the identification of whatdrives the flow of core self contents, given the lackat this stage of cognitive structures like “goals” and“beliefs”. A possible answer to this question comesfrom recent research on emotion. According to Rus-sell,25 at the heart of emotions, moods, and any otheremotionally charged events, there are states experi-enced as simply feeling good or bad, energized orenervated. These states—that he defines as “coreaffect”—influence reflexes, perception, cognition,and behavior and are influenced by many causes,both internal and external. Core affect per se is ob-ject free (free-floating), but through attribution canbecome directed at an object.

In our view, one of the main activities of the coreself is to track changes in core affect, in proportionto its rapidity and extent. When the change is sig-nificant, it fills consciousness. When the feelingweakens or stabilizes, it recedes into the back-ground. As noted by Russell25: “Core affect is a con-tinuous assessment of one’s current state, and itaffects other psychological processes accordingly.A change in core affect evokes a search for its causeand therefore facilitates attention to and accessibil-ity of like-valenced material . . . Decisions thus in-

volve predictions of future core affect . . . Core af-fect is involved in motivation, reward, and rein-forcement.”

However, there is a critical point, as also notedby Russell25: “Core affect responds to the contentsof consciousness whether based on reality or fiction.It varies with thoughts, imaginings, daydreams,memories, and anticipations.”

Why is core affect triggered by any conscious con-tent, independent of whether it is external or merelyimagined? The answer is related to the evaluativeprocess: the future and all other alternatives topresent reality can only be imagined. By imaginingthe future, one brings an ancient mechanism (coreaffect) to bear on organizing future behavior. Re-sponding to imaginary events is useful, since theresponse allows one to evaluate different possiblefuture outcomes. In other words, we evaluate imag-ined future outcomes by experiencing the emo-tional responses that such outcomes would actuallyproduce in us in reality.

As suggested by Farber, the core self has twofunctional states26: while “online”—actively syn-chronized with the external world—it can be usedto predict what will happen next or what the likelyoutcomes of different actions will be, and while“offline,” it can model scenarios from memory orimagination, or germinate the realistic (if disordered)worlds of our dreams. On the neurological side,this is also reflected by the shared neural substrateused in both imagined and executed movements.27,28

This link is supplied by the “mirron neurons” foundin the Broca’s area of the human brain, which fire inresponse to observing specific movements as wellas during execution of the same movements.29

As noted by Ramachandran30: “The discovery ofmirror neurons in the frontal lobes of monkeys, andtheir potential relevance to human brain evolu-tion—which I speculate on in this essay—is thesingle most important “unreported” (or at least, un-publicized) story of the decade. I predict that mirrorneurons will do for psychology what DNA did forbiology: they will provide a unifying frameworkand help explain a host of mental abilities that havehitherto remained mysterious and inaccessible toexperiments . . . Mirror neurons can also enable youto imitate the movements of others thereby settingthe stage for the complex Lamarckian or culturalinheritance that characterizes our species and lib-erates us from the constraints of a purely genebased evolution.” http://www.edge.org/3rd_cul-ture/ramachandran/ramachandran_index.html).

However, this model only works if the nervoussystem can differentiate between internal (imagined)

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and external (perceived) states of affairs. As wehave seen, distinguishing the present from the imag-inary is essential for survival in the here and now.

How is this done? Neurobiological research sug-gests the existence of two specific processes: cogni-tive binding and temporal coherence: In Llinás’approach,19 cognitive binding is done by the core selfthrough the temporal linking of the independentlyoperating neural mechanism included in the protoself. By inducing temporal coherence to differentneural structures, the core self can produce a shift inattentional focus. This shift is also able to differenti-ate between dreaming and waking: in dreaming theintrinsic activity of the proto self does not correlatesensory inputs with ongoing thalamocortical activity(the thalamocortical system is considered the site ofthe core self) making them invisible to the core self.31

In these processes what is the role of core pres-ence? Core presence is the activity of selective at-tention made by the self on perceptions (self vs.present external world): the more the organism isable to focus on its sensorial experience by leavingin the background the remaining neural processes,the more it is able to identify the present momentand its current tasks, increasing its probability ofsurviving (Fig. 3).

According to what we have said, core presence isneeded mainly when the core self tracks a signifi-cant change in the level of core affect. When thishappens, it is critical for the core self to focus on itssensorial experience by leaving in the backgroundthe remaining neural processes. In this sense, a shiftin the level of core affect activates the possibility fora high level of core presence.

As we have just seen, core affect is not dependenton any reality judgment: it responds to the contentsof consciousness whether based on reality or fic-tion. It is core presence that allows the organism tomake this essential distinction.

Third layer: extended presence

The result of the activity of the extended self isextended consciousness. But what is the role ofextended presence? The goal hierarchy model ofpersonality and motivation32 can provide the theo-retical underpinning for answering this question.Cropanzano et al.32 described personality as an in-terrelated series of goals that direct and organize anindividual’s behavior. In their model, which hasmany similarities with the description of the ex-tended self of Damasio,12 goals are arranged hierar-chically from abstract orientations (analogous totraits) at the top, through values, self-identities, andultimately down to concrete, behavioral goals. Ab-stract goal orientations, such as a tendency to ap-proach positive stimuli or avoid negative stimuli,are mapped onto distinct response styles that serveas directional orientations. As noted by Brett andeWalle,33 response styles do not offer the specificityto make behavioral predictions, but instead deter-mine the types of goals that individuals will set.These lower level goals regulate the specific behav-iors selected for performance.

The possibility of defining internal goals andtracking their achievement is the element that allowsthe final shift in the evolution of the self: from mean-ing-as-comprehensibility to meaning-as-significance.Meaning-as-comprehensibility refers to the extent to which the event fits with our view of the world(for example, as just, controllable, and nonrandom)whereas meaning-as-significance refers to the valueor worth of the event for us.20 In this vision, the roleof extended presence is to verify the significance tothe self of experienced events in the external world(self relative to the present external world). The morethe self is present in significant experiences, the moreit will be able to reach its goals, increasing the possi-bility of surviving (Fig. 4).

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FIG. 3. Core presence.

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Presence and emotion: an important but neglected link

Emotional engagement and presence are oftenconfused, as if they were the same thing. As indi-cated above, we consider that emotion and pres-ence are intimately related, but not identical; we canfeel emotional engagement without feeling muchpresence, and vice versa. So what exactly is the linkbetween presence and emotions? According to ourmodel, emotional processes directly influence twoof the three layers of presence: core presence andextended presence.

One of the main activities of the self is to trackchanges in core affect (feeling good or bad, ener-gized or enervated), according to their rapidity andextent. When this happens, it is critical for the selfto focus on its sensorial experience by leaving inthe background the remaining neural processes. Inthis sense, a change in the level of core affect acti-vates a higher level of core presence, needed to sep-arate between reality and fiction. As underlined byRussell,25 core affect is not dependent by any realityjudgment: it responds to the contents of conscious-ness whether based on reality or fiction. It is corepresence that allows the organism to make this es-sential distinction.

For extended presence, too, the link with emo-tions is critical. As we have seen, core affect can existwithout being labeled, interpreted, or attributed toany cause. One of the main activities of the extendedself is the perception of affective qualities. But ac-tivity of the extended self does not always result inhigh extended presence; a focus on the externalworld is also needed. The extended self is, in gen-eral, as concerned with the imaginary as with thereal. When in a state of high presence, the extendedself is preoccupied with the present external situa-tion. But at many other times, imagined and re-called events and information (which often includea self-conscious focus on the idea of self) occupy theself, and this will be indicated by low extendedpresence. In this sense, varying levels of extendedpresence also reflect the possibility of separating

the imagined (including ones self-conscious idea ofself) from the real (experienced in relation to its sig-nificance to the self). And this explains why maxi-mal states of presence are associated with a loss ofself-consciousness (in the sense of a focus on theidea of oneself).

In summary, we can expect two levels of influ-ence of emotional processes on the degree of pres-ence: (a) a shift in the level of core affect activates ahigher level of core presence; and (b) an easy attri-bution of the shift results in a higher level of ex-tended presence. If we feel high core presence weare more likely to behave as if events are real, andthis is the mechanism that is to some degree fooledby virtual reality. Positive reality judgments will tendto increase extended presence. When core presenceis not integrated with extended presence, experi-enced presence will be lower than when it is, andwill tend to extend for shorter periods of time. Theways in which the three layers of presence may bemore or less integrated, and the implications of thisfor designing mediated experiences which invokepresence, are the topics for the remaining sectionsof the paper.

FOCUSED PRESENCE: INTEGRATINGTHE THREE LAYERS

In this section, we apply our three-layer theory ofpresence to try to understand how the sense ofpresence varies across different situations, and inparticular the different ways in which aspects ofmediated experience affect presence. From that, weoutline the potential of this view as a tool for de-signing particular types of experience with pre-dictable degrees and types of presence.

Focus, locus, and sensus

Waterworth and Waterworth8 outlined a three-dimensional model of experience in relation to

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presence, consisting of focus, locus, and sensus.Principally, the model was intended to provide adesign space, in which potential and actual interac-tive media applications could be placed, as an aidto both design and evaluation. Focus describes thenature of an observer’s attention, specifically whetherattention is mostly directed towards present events(in the real or a virtual world)—in which case themodels predicts a high degree of presence—or ismostly directed towards internally-generated sce-narios (in imagination) which are not currentlypresent in the world. Waterworth and Waterworth8

referred to this latter, reflective state of mind as ab-sence, corresponding to a low degree of presence.

We can now extend and refine this concept offocus in light of the three levels of presence pro-posed here. Specifically, we suggest that focus canbe seen as the degree to which the three layers ofpresence are integrated towards a particular situa-tion. The more integrated the layers, the higher thedegree of experienced presence. Presence would bemaximized when the contents of extended con-sciousness are closely aligned to those of core con-sciousness and of proto consciousness, which willarise when the three levels are working in concertto produce a strong focus on the present environ-ment. The pivot for this integration is core pres-ence. Absence of mind thus arises when extendedconsciousness is minimally concerned with the cur-rent situation or situations with which core andproto consciousness are involved.

From an evolutionary perspective, the real worldhas priority and is the background against whichmental life is framed. The proto self exists momentby moment through our monitoring of our internaland external environment. To maintain our bodiesin the world we need to know both their internalstate and their precise relations to the world imme-diately around them. Much of this is unconsciousand automatic, we only become specifically awareof processes such as digestion or proprioceptionwhen things do not function normally, within limitsacceptable for the stability of the organism. Thisawareness arises as the events are integrated intocore consciousness, as described earlier.

One of the main reasons for current interest inpresence is that it may be evoked by both the realworld and by media. The locus dimension8 capturesthe extent to which the observer is attending to thereal world or to a world conveyed through media.The biological purpose of presence means that it isdominated by the current state of the body, and per-ceptions of the current state and position of the bodyin relation to the world in which the body is located.Any mediated presence is in competition with pres-

ence in the real world. “Breaks in presence”34 are anexample of rapid shifts of presence between the realand a mediated world. In other words, they seem tobe temporary changes in the locus of experience, al-though Spagnolli and Gamberini35 present evidencethat they are more a temporarily wider distributionof presence over the locus dimension—taking inboth the real and the virtual worlds.

The history of media and their effects is complexand beyond the scope of this paper. We will sim-plify for present purposes by suggesting that sometraditional non-electronic media, such as books,verbal accounts, and letters, principally address ex-tended consciousness. This limited capability wasmirrored later by electronic media such as text doc-uments, e-mails, and telephone calls. All of theseproduce a conceptual model in the reader or hearerthat is usually not closely or immediately related tohis or her current situation in the real world. Inother words, they do not elicit core or proto pres-ence. Because of this, they produce a relatively lowdegree of presence integration and are low on thefocus dimension (and the degree of experiencedpresence is low). Traditional more pictorial mediaforms such as drama, painting and sculpture wereoften successful in evoking a sense of core presenceand sometimes also a sense of extended presencewith which it was integrated to a greater or lesserdegree. Again, this is mirrored by more recent elec-tronic media such as television, computer graphics,and animations. Still, the proto level of presence isnot addressed by such media and, because of thisinherently restricted focus, the degree of experiencedpresence is correspondingly limited.

The third dimension of Waterworth and Water-worth’s8 model, sensus, refers to the level of con-sciousness or attentional arousal of the observer,and we can also interpret its effects on presence interms of our three layers of presence. Arousal willaffect such factors as degree of activity of the organ-ism, and the effect is likely to be passed upwards, tothe core self, which may then become more activelyengaged in the world. Conversely, emotional arousalof the core layer will tend to impact downwards onthe proto self, which will become innervated tocope efficiently with the current situation. At thelevel of extended consciousness, attentional arousalwill tend to be determined by the significance ofwhat is experienced, the meaning of current eventsin terms of interest or emotion.

Mediation and the three layers of presence

Because we are always in the real world, evenwhen engrossed in media or in thought, proto pres-

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ence is probably never totally divorced from thecurrent physical situation and state in which wefind ourselves. Most mediated experiences do notattempt to address the individual at the level ofproto consciousness, since the technical demandsof eliciting presence are less the higher the layer in-voked. As already stated, absence of mind ariseswhen extended consciousness is minimally con-cerned with the current situation, or situations,with which the other two layers are involved. Awell-written novel can readily engage extended con-sciousness, while core consciousness will be verylittle affected, and proto consciousness not at all.Overall, presence will not be focused, and the de-gree of experienced presence will be relatively low.Some researchers suggest that a novel may providethe technological minimum for presence in media.36

Since we view presence as a solution to the prob-lem of determining what is happening to the self atthe present time, we suggest that extended pres-ence does not exist without core consciousness. Coreconsciousness drives the problem solution; the moreit is able to integrate the three layers, the more con-vincing the answer to the problem.

As we move down from extended consciousnessto core consciousness, the technological demandson the medium increase. Whereas conceptual mod-eling can be relatively slow, perceptual models andthe predictions they provide must be created fast,since this core level is evolutionarily designed tosupport what may need to be very rapid interac-tions with the real world. To mimic this natural in-teractivity involves rapid response times between amedium and its user, and often involves detailedinspectability of aspects of any displayed informa-tion. More generally, information must be displayedin concrete forms that can be accepted by core con-sciousness as realistic. Proto presence has the mostdemanding technological requirements, and was thelast of the three layers to be addressed throughmedia. It functions at the level of proprioception,spatial and internal monitoring, which may reflectthe primal role of these processes in the evolutionof consciousness.37 As yet, our ability to simulatethe demands of this layer is far from complete, butthe development of partial simulations—such as cur-rent virtual reality—implementations—is the reasonfor the current interest in presence. This is becauseinclusion of the proto layer generates a quantumleap in mediated presence.

Proto presence is based on proprioception andother ways of knowing bodily orientation in theworld. In a virtual world this is sometimes knownas “spatial presence” and requires the tracking ofbody parts and appropriate updating of displays.

Core presence is based largely on vividness of per-ceptible displays. This is equivalent to “sensorypresence” (e.g., in non-immersive VR) and requiresgood quality, preferably stereographic, graphics andother displays. As already stated, core conscious-ness is the pivot for judgments that something fromthe world outside is impacting on the self, on thelife of the organism. As with the extended presencelayer, if proto consciousness is integrated with coreconsciousness, proto presence will be involved inthe feeling of presence, thus strengthening the over-all sense of presence. The extent to which these twolevels are integrated produces what is usually calleddegree of immersion. Extended presence requiresintellectually and/or emotionally significant con-tent. Integrating the three layers amounts to foolingthe system into a conviction that something signifi-cant is happening to the self in the here and now.

The different layers of presence may be less thanperfectly integrated in several ways, including thefollowing:

• If you experience a VR without a tracking sys-tem, you can have high level of core presence(vividness), a high level of extended presence(engagement), but no proto presence (spatialpresence).

• If you read a good book while sitting in a com-fortable, safe place, extended consciousness willbe engaged by media (engagement), but the otherlayers will not be involved.

• If you are in an immersive VR, but are pre-occupied with personal worries (perhaps becausethe mediated content is not very engaging),proto (spatial) and core presence (vividness) willbe invoked by the medium, but not extendedpresence.

• The same situation with particularly uninterest-ing content of the VR but no dominating per-sonal worries (low engagement) may tend toproduce frequent “breaks in presence” (a changeor spreading of position on the locus dimension).

We can see changes in the locus of presence, suchas Slater’s11 “breaks in presence,” as illustratinghow core consciousness attempts to integrate thethree levels. Content entering core consciousnesswill remain there for as long as it can be integratedwith the content of the other layers. If competingcontents appear at either of the other two layers, achange in locus is possible. The probability and du-ration of such changes depend on extended con-sciousness; attention is likely to be captured bywhatever is most relevant to the goals of the ex-tended self, whether this is a stimulus from the real

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world or a mental event such as a sudden thought.Even the occurrence of a new vivid stimulus, suchas a loud sound (attracting core presence), or a breakin bodily continuity such as a cable obstructingmovement in a VR (attracting proto presence) willonly have temporary effects. Once extended con-sciousness has judged the event as no longer rele-vant, the self will revert to the previous content ofcore consciousness.35

OPTIMIZING PRESENCE

We have suggested that presence should be con-sidered a layered experience, created by the evolu-tion of the central nervous system in its attempt toembed the sensory-referred properties into an in-ternal functional space. However, if presence is reallyan evolved psychological mechanism, it shouldexist independently of a given medium. More inparticular, it cannot be considered as a simple re-sponse to media. This approach has three impor-tant corollaries:

• In the real world the level of presence is not thesame in all the situations. For instance, if I’m at-tending a lesson in university, my level of pres-ence can be lower or higher in relation to theinterest I have in the topic discussed.

• There are exceptional situations in real life thathave an optimal level of presence. In these situa-tions all the three layers are activated giving tothe subject a full sense of control and immersion.

• It should be possible to design mediated situa-tions that elicit exceptionally high presence.

Are these corollaries true? If in general mostpresence researchers agree that in real life the levelof absorption and attention is not the same in allthe situations, it is more difficult to accept the sec-ond point. However, some suggestions about thecharacteristics of this higher level of presence comefrom recent researches into the concept of flow,which we outline in the next section. This is fol-lowed by a description of the potential for excep-tional presence through mediated experience.

Optimal presence and the concept of flow

Csikszentmihalyi38,39 defined “flow” as an opti-mal state of consciousness characterized by a stateof concentration so focused that it amounts to ab-solute absorption in an activity. According to Csik-szentmihalyi,40 when people are in a flow state,“[they] shift into a common mode of experience

when they become absorbed in their activity. Thismode is characterized by a narrowing of the focusof awareness, so that irrelevant perceptions andthoughts are filtered out; by loss of self-conscious-ness; by a responsiveness to clear goals and unam-biguous feedback; and by a sense of control overthe environment . . . it is this common flow experi-ence that people adduce as the main reason for per-forming the activity.”

Starting from this definition, different authorshave tried to define flow in an operational way. ForGhani and Deshpande,41 the two key characteristicsof flow are (a) total concentration in an activity and(b) the enjoyment which one derives from an activity.Moreover, these authors identified two other factorsaffecting the experience of flow: a sense of controlover one’s environment and the level of challengerelative to a certain skill level. In Hoffman andNovak,42 flow is defined in terms of the experience offlow (intrinsic enjoyment, loss of self-consciousness),behavioral properties of the flow activity (seamlesssequence of responses and self-reinforcement), andits antecedents (skill/challenge balance, focused at-tention, and telepresence). If we compare these defi-nitions with our three layer model of presence, wecan find many interesting similarities.

Our three-layer, evolutionary model of presencesuggests that maximal presence arises when protoconsciousness, core consciousness and extendedconsciousness are focused on the same external sit-uation or activity. Maximal presence thus resultsfrom the combination of all three layers with an ab-normally tight focus on the same content (Fig. 5), sothat attention is directed exclusively towards thecurrent external situation. We suggest that this iscompatible with the flow concept, and indicates oneapproach to designing mediated experiences of ex-ceptional presence.

Normal, everyday levels of presence arise from asplit of attentional resources between layers of dif-fering content, with some attention being directedto the current external situation. Minimal presenceresults from a lack of integration of the three layers,such that attention is mostly directed towards con-tents of extended consciousness that are unrelatedto the present external environment—a psychologi-cal state of absence.8

Designing optimal presence

For us, optimal presence in a mediated experi-ence arises from an optimal combination of formand content. The form must provide the means fora convincing perceptual illusion, but the contentshould be integrated with (and so attract attention

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to) the form for the illusion to happen convincingly.We suggest that proto presence is determined onlyby form, core presence by both form and content,and extended presence only by content. The inte-gration of presence can occur in either the real or avirtual world. In the case of a virtual world, weneed to provide both appropriate form and mean-ingful content. Presence in the real world dependsonly on content, on what we experience as happen-ing to us in the here and now, since the form is pro-vided and is always appropriate.

To optimize experienced presence in virtual envi-ronments we must design in a way that allows inte-gration of the three layers (Fig. 1). As we have said,this is technically demanding at the lower levels.We need to provide as much immersion as possible,integrating proto (spatial) and core (sensory) pres-ence. To integrate extended presence, the events andentities experienced in the virtual environment musthave significance for the participant. For us then,maximal presence arises from an optimal combina-tion of form and content. The form must providethe means for a convincing bodily and perceptualillusion, but the content should be integrated with(and so attract attention to) the form for the illusionof mediated presence to happen convincingly. Wedo not think we always feel presence when attend-ing to something, internal or external, nor that theinternal and external are always competitive inproducing presence. On the contrary, the internal,“imaginal” content (of extended consciousness) may

either enhance or detract from the overall sense ofpresence. An example of enhancement is a typicalcomputer game, where game designers strive toensure that content and form are well integrated.Optimal presence arises when the contents of ex-tended consciousness are aligned with the otherlayers of the self, and attention is directed to a cur-rently present external world.

We can identify at least three ways of approach-ing the design of optimal mediated presence: digitalparticipation, mediated flow, and embodied immer-sion. In these situations, the organism responds asif what happens in a mediated environment is real,in the fullest sense, and of immediate significance.

Digital participation can arise if we design a rolefor the participant as a performer in an interactivedrama43 see from a first person perspective. If theperformer becomes emotionally and intellectuallyengaged by the events in an appropriately immer-sive environment, extremely high levels of presencecan be achieved.44 A feature of this state of partici-pation is a corresponding loss of self-consciousness:not that the self is not present—it is maximally so—but that an internal model of the self is not thefocus of extended consciousness. In this respect,digital participation resembles the flow state andduring which extended consciousness is also notpreoccupied with the idea of self.

Trevino and Webster were the first authors tostudy mediated flow.45 According to them, this rep-resents the extent to which (a) the user perceives a

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FIG. 5. Layers, media, and mental states.

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sense of control over the computer interaction, (b)the user perceives that his or her attention is focusedon the interaction, (c) the user’s curiosity is arousedduring the interaction, and (d) the user finds the in-teraction intrinsically interesting. As with digitalparticipation, events are experienced from a firstperson perspective.45

Embodied immersion is our term for a style of in-teraction that uses bodily movements not only forconsciously-monitored control over the environ-ment, as in standard computer interactions, but alsofor more direct, automatised inputs from the im-mersant. The pioneering work in this area was car-ried out by Char Davies in the mid-nineties.46 InOsmose, for example, breath and balance are usedto control navigation, while in Ephémère visuallydwelling on a portrayed “organic” form causes it toage before the eyes of the immersant. As with theexamples digital participation and mediated flow,this style of first-person mediated experience re-sults in a loss of self-consciousness and, as with theothers, we see this as an approach to eliciting maxi-mal levels of presence.

Petranker47 distinguishes between “narratives,”which are usually expressed in the third personand which we tell or are told to us, and “stories,”which we inhabit from a frist person perspective.For us, maximal presence arises when we fully “in-habit” the “story” of what is happening to us rightnow. Narrative, by its nature, is a distancing fromthe present. To design for maximal presence is tocreate stories we can inhabit as fully as possible.These stories are located in immersive environ-ments and elicit embodied, unselfconscious and en-gaged participation from all three layers of the self.

CONCLUSION

In its earliest evolutionary form, presence wasthe sense that something was happening outsidethe organism in the here and now, something thatcould affect the organism, as opposed to being partof the organism. Initially, this may have been basedin sensation (in proto consciousness) of somethingacting on the organism’s boundary with the envi-ronment.48 Later on in evolutionary (and neurologi-cal) terms, sensation led to perception, and presenceemerged as the feeling (in core consciousness) ofbeing in an external, perceptible world in whichthings happen in relation to the organism. Laterstill, internal modeling (in extended consciousness)allowed attention to be directed towards non-present,imagined worlds, experienced as being inside theorganism (specifically, in the head).49 To be useful

in assessing possible scenarios, presumably theirmain evolutionary purpose, these imagined eventsevoke similar emotional responses as external eventswould, but not the same feeling of presence.

Once we could imagine situations and events, itbecame advantageous to discriminate imagined,internal, hypothetical worlds from perceived eventsin the physical, external world—a discriminationthat we suggest is based on the evolved form ofpresence. It is interesting to note that there mayhave been an intermediate period when this dis-crimination was not reliably made in this way50

and when internal thoughts were perceived as thecommands of Gods. But as consciousness extendedto encompass both the outside world and an evolv-ing internal, conceptual world, the survival advan-tages for organisms still reliably able to make thisdiscrimination are obvious, and presence emergedin its current, evolved form. (In abnormal cases, asDamasio12 points out, a reversion to something likethis state indicates serious pathology: “It is as if,without the sense of self in the act of knowing, thethoughts one generates go unclaimed because theirrightful owner is missing. The self-impoverishedorganism is at a loss as to whom those thoughtsbelong.”130)

By this evolutionary view, presence does notdiscriminate between the real and the virtual, butbetween the internal and the external. Clearly, evo-lution could not have equipped us to feel the differ-ence between what is really present externally andwhat we perceive as present because of technologi-cal mediation. We can mostly tell the difference withexisting virtual environments because of technical,or formal, limitations in the way the environment iscoupled to the organism. But still, virtual realitiesdo attempt to engage the organism in the sameways that the real world does, and they are more orless successful in this. The extent to which theyevoke presence is to a large degree the extent towhich they succeed. But this is not only a matter ofemotional or intellectual engagement—which canalso be stimulated by imagined situations. We maycome to confuse a virtual experience with a real onebecause they are, in principle and as far as the or-ganism is concerned, the same. They both evokepresence, the perception of a world surroundingthe organism.

We have suggested that the purpose of presenceis to provide a basis for the organism to separateevents that occur only within the self from externalevents that may act on the self. Presence is experi-enced as a unitary feeling, a feeling of being in aworld that exists outside of the self but in which theself is situated. We have suggested that contribu-

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tions to the intensity of this feeling can come fromthree layers of the self, and we refer to these asproto presence, core presence and extended pres-ence. The more the three layers are integrated (fo-cused on the same events) the stronger the intensityof the presence feeling. The difference in presenceexperienced through different media can be ex-plained by the fact that many media influence onlya limited number of layers. In a compelling bookreading only extended consciousness is involved,and with a movie experience we can modify bothcore presence and extended presence but not protopresence. Only in immersive virtual reality are allthe three layers of consciousness modified by themedia experience, and immersive environments areunique amongst media in their ability to produce asense of presence as high as the maximal levels ex-perienced in the physical world. And this is whyvirtual reality may be more effective in psychother-apy than purely imaginal techniques, at least forcertain conditions. But, as in the physical world,immersion does not guarantee high presence.

To optimize experienced presence in virtual envi-ronments we must design in a way that integratesthe three layers of presence. As we have seen, this istechnically demanding at the lower levels. We needto provide as much immersion as possible, inte-grating proto (spatial) and core (sensory) presence.But if what is happening is not of interest or impor-tance to the individual, the layers of presence willnot be integrated and presence will be relativelyweak. To integrate extended presence with the otherlayers, the situations experienced in the virtual en-vironment must have immediate significance forthe participant. We have suggested three designroutes to achieving this: digital participation, medi-ated flow, and embodied immersion.

It might appear paradoxical that the focusing ofself that underlies maximal presence also implies aloss of self-consciousness. But in optimal presence,biologically and culturally determined cognitive pro-cesses are working in harmony to focus all levels ofthe self on events unfolding in the present situationin which the organism is situated. This does not in-clude experiencing the internal construction—theidea of self—that we sometimes call self-conscious-ness. To be oneself is to lose sight of the idea of oneself.

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