Presence and the Self: a cognitive neuroscience approach

This paper proposes a neurobiology-based theory of presence based on four different positions related to the role and structure of presence, as follows. First, presence is a defining feature of self and it is related to the evolution of a key feature of any central nervous system: the embedding of sensory-referred properties into an internal functional space. Without the emergence of the sense of presence it is impossible for the nervous system to identify the separation between an external world and the internal one. Second, even if the experience of the sense of presence is an unitary feeling, conceptually it can be divided in three different layers, phylogenetically different and strictly related to the three levels of self identified by Damasio (Damasio, 1999). In particular we can make conceptual distinctions between proto presence, core presence, and extended presence. Third, given that each layer of presence solves a particular facet of the internal/external world separation, it is characterized by specific properties. Finally, in humans the sense of presence is a direct function of these three layers: the more they are able to differentiate the self from the external world, and the more they are integrated, the more we experience a sense of presence.

Riva, G and Waterworth, J A (2003).Presence and the Self: a cognitive neuroscience approach. Presence-Connect, 3 (3), posted 07-04-2003.

1 The Biological Purpose of Presence
1.1 The emergence of extended consciousness

For organisms in a natural environment, it is vital to pay attention and respond rapidly to present threats and opportunities. Our emotional and cognitive life is built on this evolutionary substrate. But as our self evolved, imagined situations became increasingly important to survival and biological success. In his Brainstorms (Dennett, 1978) book, Dennett suggested the existence of an important difference between self and point of view:

“Point of view clearly had something to do with personal location, but it was itself an unclear notion. It was obvious that the content of one's point of view was not the same as or determined by the content of one's beliefs or thoughts. For example, what should we say about the point of view of the Cinerama viewer who shrieks and twists in his seat as the roller-coaster footage overcomes his psychic distancing? Has he forgotten that he is safely seated in the theater? Here I was inclined to say that the person is experiencing an illusory shift in point of view. In other cases, my inclination to call such shifts illusory was less strong. 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 that is crisper and more pronounced than anything Cinerama can provoke.” (p. 314-315, Italics added)

As noted by IJsselsteijn and Riva (IJsselsteijn & Riva, 2003), what Dennett calls “an illusory shift in point of view” conceptualizes well the concept of presence. The question is, how our mind can say that this shift in the point of view is illusory? How is it possible to differentiate between a real and an imagined situation?

According to recent psychological theory, perceptions are guesses of what is out there now and predictions of what is about to happen. A way to put this is that perceptions are rather like hypotheses of science - predictions of unsensed features of objects, and of futures that may not happen (Gregory, 1998b). They are never certainly true and often wrong. Yet the guesses of hypotheses are the nearest we ever get to reality. If perceptions are internal predictions, how can we differentiate them from other internal processes, such as conceptual modeling?

According to current neurobiological work, evolution created two different levels of consciousness to solve this problem (Damasio, 1999): core consciousness and extended consciousness. Core consciousness is what we share with some nonhuman animals - a simple biological phenomenon, the scope of which is the Here and Now. This basic, integrated representation of one moment and one place is independent of language, reasoning and memory (Metzinger, 1999).

When we imagine, think, plan and generally deal with information that does not only constitute our experience of things and events in the currently present external situation we are exercising extended consciousness: “Extended consciousness has to do with making the organism aware of the largest possible compass of knowledge.” (p. 198). According to Damasio, extended consciousness emerges from:

· The gradual build-up of memories of the organism’s biography (the experiences of the “core-self”). Each autobiographical memory then becomes an object, which takes part in inducing and enhancing core consciousness;

· The ability to hold active, simultaneously and for an extended period of time, many images that collectively define the autobiographical self and the object it is interacting with.

It is extended consciousness that allows us to create an internal world in which we may suspend disbelief, as compared to a perceptual world experienced as outside the self. Extended consciousness relies on working memory (Damasio, 1999), which can be seen as the “active scratchpad” of mental life (Baars, 1988). It is in working memory that the internal world we are currently experiencing is largely created. Its main function is to allow us to consider possibilities not present in the current external situation. In contrast, core consciousness is directed exclusively to the here and now – the present – and is what we share with all conscious animals.

Extended consciousness gives us obvious advantages over organisms without it, such as the ability to plan and generally enact in the imagination possible scenarios in the future, as well as to increase the sophistication of learning from the past. Language depends on it, because we must retain linear sequences of symbols in working memory if we are to understand utterances, whether spoken or written.

The advantages of extended consciousness depend on the fact that we can distinguish between the experience of the external word and experience of internal worlds, both remembered and imagined. Confusions of the two indicate serious psychological problems, problems which, until recent times, would have prevented survival and the passing on of this condition. As noted by Waterworth and Waterworth (Waterworth & Waterworth, 2003): “if we react as if the external world is only imaginary we will not survive long (think of this the next time you cross a busy street). And if we think that what we are merely imagining is actually happening, we may omit to carry out basic activities on which our survival depends. We are suggesting that presence is the feeling that evolution has given us to make this vital distinction.” (p. 2)
1.2 The presence of self

According to this view, what is the role of self? Damasio proposes important conceptual distinctions between a preconscious precedent of self and two distinct notions of self-consciousness (Damasio, 1999; Dolan, 1999):

  • the proto self: a coherent collection of neural patterns that map, moment by moment, the physical state of the organism;
  • the core self: a transient entity which is continuously generated through encounters with objects;
  • the autobiographical self: a systematic record of the more invariant properties that the organism has discovered about itself.

In this vision, the basis for a conscious self is a feeling state that arises when organisms represent a non-conscious proto-self in the process of being modified by objects. In essence, the sense of self depends on the creation of a second-order mapping, in certain brain regions (brainstem nuclei, hypothalamus, medial forebrain and insular and somatosensory cortices), of how the proto-self has been altered (Dolan, 1999).

However, it is only the autobiographical self that generates the subjective experience of possessing a transtemporal identity. The presence of the autobiographical self centers the flow of our interactions with perceptual objects on itself, thereby making them our own experiences. In summary, the presence of you is the feeling of what happens when your being is modified by the acts of apprehending something (Metzinger, 1999).
1.3 The brain mapping

As we have just seen, core self and core consciousness have their origins in a mapping of body states and are about two facts: the organism relating to sensory streams and the fact that this relation causes a change in the organism. It follows that a key starting point for a theory of presence is description of how the brain maps its sensorial inputs, and, most importantly, the dynamics of their relationship.

Damasio tries to answer this question by adding two more components to his model:

· Autobiographical Memory: the organized record of the main aspects of our biographies;

· Dispositions: records, which are dormant in our memory until activated by a similar or related experience.

To understand how these components are related we can use an example: the way our self experiences the first view of the Colosseum in Rome. We receive sensory signals from our eyes, ears, nose and sense of touch that are mapped by the proto self. Some microseconds later, this activity is monitored by the core self and becomes the content of core consciousness. A few microseconds more are required for the activation of extended consciousness. Some milliseconds later, it adds dispositional records of that place (or similar places) coming from autobiographical memory. We may recognize the place because we studied it in architectural history; and we may have emotional ties because we associate the place with special memories (our most recent experience of the Colosseum was while watching a preferred movie: “Gladiator”). The result is a single conscious experience integrating perceptions, emotions and feeling. Once the event has ended, it is restored in dispositional space with new data about our most recent experience.

2 The Three Layers of Presence

One of the main ideas expressed in this paper is the link between presence and self. More in detail, we suppose that presence is the result of the evolution of the central nervous system in its attempt to embed the sensory-referred properties into an internal functional space (Llinás, 2001). As noted by Waterworth and Waterworth (Waterworth & Waterworth, 2003), the appearance of the sense of presence allows the nervous system to solve a key problem for its survival: how to differentiate between internal and external states.

We hypothesize that it is possible to associate a specific layer of presence with each of the three levels of self identified by Damasio. Further, given that each layer of presence solves a peculiar facet of the internal/external world separation, it is characterized by specific properties.
2.1 The first layer: proto presence

As we have seen, the main activity of the proto self is a non-conscious mapping of the physical state of the organism. What is the evolutionary goal of the proto self? To predict the characteristics of the external world as it is experienced through sensorial inputs.

As suggested by Llinás this can be done even by a lamprey (Llinás, 2001). How? The steps identify by the latest neurobiological studies are (pp. 23-24):

· the comparison of the sensory referred properties of the external world with a separate internal sensorimotor representation of those properties;

· the transformation/utilization of this premotor solution into finely timed and executed movements.

In this process movement plays a key role. On one side, an adaptive movement is the evolutionary goal of the proto self. On the other side, it is through motility that it can embed the propriety of the external world in its sensorimotor representation. These properties are the constraints generated by the coordinate systems that describe the body: in an evolutionary process that required millions of years the proto self experienced, through movement, these constraints and used them to model the external world. In this vision how can we define proto presence? Tentatively we can say that the more the proto self is in the body, the more it is different from the external world. More precisely we can define proto presence as an embodied presence related to the level of perception-action coupling: the more the organism is able to couple correctly perceptions and movements, the more it differentiates itself from the external world, thus increasing its probability of surviving.
2.2 The second layer: core presence

In Damasio's model, the second level of self is the core self, a transient entity, ceaselessly re-created for each and every object with which the brain interacts. What is the evolutionary goal of the core self? It is the integration of specific sensory occurrences into single percepts.

According to Gregory (Gregory, 1998b) this is done through a coherent world-model that evolves in real time according to its own internal logic. In such a vision, perception depends very largely on knowledge derived from past experience of the individual and from evolutionary experience.

During waking consciousness, this model is modulated by the senses, but it persists even when sensory input is temporarily cut off: close your eyes and you'll still be keenly aware that the Colosseum is in front of you. As far as your inner model is concerned, the Colosseum is still there; and as that inner model is used to generate motor commands, any movements you choose to make (such as searching for a taxi) will be adjusted to take the Colosseum’s presence into account. As suggested by Farber, the core self has two functional states (Farber, 2001): while 'online' — actively synchronized with the external world — it can be used to predict what will happen next or what the likely outcomes of different actions will be, and while 'offline', it can model scenarios from memory or imagination, or generate the realistic (if disordered) worlds of our dreams. However, this model works if the nervous system is able to differentiate between the two states. In fact, recognizing the present is essential for survival in the here and now.

Gregory underlined (Gregory, 1998a): “As perception depends on rich knowledge from the past stored in the brain, there must be a problem in identifying the present moment from past memories, and also from anticipations running into the future. The present is signaled by real time stimuli from the senses; but as perceptions are 90% or more stored knowledge, the present moment needs to be identified for behavior to be appropriate to what is happening out there now.” (p. 1694, italics added)

How is this done? Neurobiological research suggests the existence of two specific processes: cognitive binding and temporal coherence: In Llinás' approach (Llinás, 2001) cognitive binding is done by the core self through the temporal linking of the independently operating neural mechanism included in the proto self. By inducing temporal coherence to different neural structures, the core self is able to produce a shift in attentional focus. This shift is also able to differentiate between dreaming and waking: in dreaming the intrinsic activity of the proto self does not correlate sensory inputs with ongoing thalamocortical activity (thalamocortical system is considered the site of the core self) making them invisible to the core self (Llinás & Pare, 1991).

In these processes what is the role of core presence? Core presence is the activity of selective attention made by the self on perceptions: the more the organism is able to focus on its sensorial experience by leaving in the background the remaining neural processes, the more it is able to identify the present moment and its current tasks, increasing its probability of surviving.
2.3 The third layer: extended presence

The higher level of self in Damasio's theory is the autobiographical self. Autobiographical self is based both on memory and on anticipations of the future, and integrates memories of past experiences, learned ideas, beliefs and skills, and hopes for the future into present experience. As detailed by Damasio (Damasio, 1999), “autobiographical self depends on systematized memories of situations in which core consciousness was involved in the knowing of the most invariant characteristics of an organism's life - who you were born to, where, when, your likes and dislikes, the way you usually react to a problem or a conflict, your name, and so on.” (p. 86)

This involves the use of the centers of higher thought in the cortex and the widely distributed faculty of memory. In fact, it develops gradually throughout life and is largely the product of adding abilities, reasoning and memories of all the richness of experience to core consciousness.

The possibility of defining internal goals and tracking their achievement is the element that allows the final shift in the evolution of the self: from meaning-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 value or worth of the event for us (Janoff-Bulman & Frantz, 1997). In this vision, the role of extended presence is to verify the significance of the experience for the self. The more the self is present in significant experiences, the more it will be able to reach its goals, increasing its possibility of surviving.
3 Focused Presence: integrating the three layers
3.1 Focus, locus and sensus

Waterworth and Waterworth (Waterworth & Waterworth, 2001) outlined a three-dimensional model of experience in relation to presence, consisting of focus, locus and sensus. Principally, the model was intended to provide a possible design space, in which potential and actual interactive media applications could be placed, as an aid to both design and evaluation. Focus described the nature of an observer’s attention, specifically whether attention is mostly directed towards present events (in the real or a virtual world) – in which case the models predicts a high degree of presence – or is mostly directed towards internally-generated information which is not currently present in the world. The former can be characterised as perceptual (or concrete) processing, the latter as conceptual (or more abstract) processing. Waterworth and Waterworth (Waterworth & Waterworth, 2001) referred to this latter, reflective state of mind as absence, corresponding to a low degree of presence, and suggested that position on the focus dimension determines the degree of experienced presence.

We can now extend and refine this concept of focus in light of the three levels of presence proposed earlier in the paper. Specifically, we suggest that focus can be seen as the degree to which the three layers of presence are integrated towards a particular situation. The more integrated the layers, the higher the degree of experienced presence. Presence would be maximized when the contents of extended consciousness are closely aligned to those of core consciousness and of proto consciousness, when the three levels are working in concert to produce a strong focus on the present environment. The pivot for this integration is core presence. Absence of mind thus arises when extended consciousness is minimally concerned with the current situation, or situations, with which core consciousness is involved.

From a biological, survival perspective, the real world has priority and is the background against which mental life is framed. The proto self exists moment by moment through our monitoring of our internal and external environment. To maintain our bodies in the world we need to know both their internal state and their precise relations to the world immediately around them. Much of this is unconscious and automatic, we only become specifically aware of processes such as digestion or proprioception when things do not function normally, within limits acceptable for the stability of the organism. This awareness arises as the events are integrated into core consciousness, as described earlier.

One of the main reasons for current interest in presence is that it may be evoked by both the real world and by media. The locus dimension (Waterworth & Waterworth, 2001) captures the extent to which the observer is attending to the real world or to a world conveyed through media. The biological purpose of presence means that it is dominated by the current state of the body, and perceptions of the current state and position of the body in relation to the world in which the body is located. Any mediated presence is in competition with presence in the real world. "Breaks in presence" (Slater & Steed, 2000) are an example of rapid shifts of presence between the real and a mediated world. In other words, they seem to be temporary changes in the locus of experience, although Spagnolli and Gamberini (2002) present evidence that they are more a temporarily wider distribution of presence over the locus dimension – taking in both the real and the virtual worlds.

The history of media and their effects is complex and beyond the scope of this paper. We will simplify for present purposes by suggesting that some traditional non-electronic media, such as books, verbal accounts, and letters, address extended consciousness. This limited capability was mirrored later by electronic media such as text documents, e-mails and telephone calls. All of these produce a conceptual model in the reader or hearer that is usually not closely or immediately related to his or her current situation in the real world. In other words, they do not elicit core or proto presence. Because of this, they produce a relatively low degree of presence integration and are low on the focus dimension. Traditional pictorial media forms such as drama, painting and sculpture were often successful in evoking a sense of core presence and sometimes also a sense of extended presence with which it was integrated to a greater or lesser degree. Again, this is mirrored by more recent electronic media such as television, computer graphics, and animations. Still, not all levels of presence are addressed by such media and, because of this inherently restricted focus, the degree of experienced presence is correspondingly limited.

The third dimension of Waterworth and Waterworth’s (Waterworth & Waterworth, 2001) model, sensus, refers to the level of consciousness or attentional arousal of the observer, and we can also interpret its effects on presence in terms of our three layers of presence. Arousal will affect such factors as degree of activity of the organism, and the effect is likely to be passed upwards, to the core self, which may then become more actively engaged in the world. Conversely, arousal of the core layer will tend to impact downwards on the proto self, which will become innervated to cope efficiently with the current situation. At the level of extended consciousness, attentional arousal will tend to be determined by the significance of what is experienced, the meaning of current events.
3.2 Presence in media: limitations and potentials of designed presence

In this section, we apply our three-layer theory of presence to try to understand the different ways in which aspects of mediated experience impact on presence. From that, we outline the potential of this view as a tool for designing particular types of experience with predictable degrees and types of presence.

Because we are always in the real world, even when engrossed in media or in thought, proto presence is probably never totally divorced from the current physical situation and state in which we find ourselves. Most mediated experiences do not attempt to address the individual at the level of proto consciousness, since the technical demands of eliciting presence are less the higher the layer invoked. As already stated, absence of mind arises when extended consciousness is minimally concerned with the current situation, or situations, with which the other two layers are involved. A well-written novel can readily engage extended consciousness, while core consciousness will be little affected, and proto consciousness not at all. Overall, presence is not focused, and the degree of reported presence will be relatively low. Some researchers suggest that a novel may provide the technological minimum for presence in media (e.g. Slater, 2003). Since we view presence as a solution to the problem of determining what is happening to the self at the present time, we suggest that extended presence does not exist without core consciousness. Core consciousness drives the problem solution; the more it is able to integrate the three layers, the more convincing the answer to the problem.

Moving down from extended to core consciousness, the technological demands on the medium increase. Whereas the machinery of conceptual modeling is abstract and relatively slow, perceptual models and the predictions they provide must be created fast, since this core level is evolutionarily designed to support what may be very rapid interactions with the real world. To mimic this natural interactivity involves rapid response times between a medium and its user, and often involves detailed inspectability of aspects of any displayed information. More generally, information must be displayed in concrete forms that can be accepted by core consciousness as realistic. Proto presence has the most demanding technological requirements, and is the last of the three layers to be addressed through media. It functions at the level of proprioception, spatial and internal monitoring, which may reflect the primal role of these processes in the evolution of consciousness (e.g. Sheets-Johnstone, 1998). As yet, our ability to simulate the demands of this layer is far from complete.

Proto presence is based on proprioception and other ways of knowing bodily orientation in the world. In a virtual world this is sometimes known as "spatial presence" and requires the tracking of body parts and appropriate updating of displays. Core presence is based largely on vividness of perceptible displays. This is equivalent to "sensory presence" (e.g. in non-immersive VR) and requires good quality, preferably stereographic, graphics and other displays. As already stated, core consciousness is the pivot for judgements that something from the world outside is impacting on the self, on the life of the organism. As with the extended presence layer, if proto consciousness is integrated with core consciousness, proto presence will be involved and this layer will strengthen the overall sense of presence. The extent to which these two levels are integrated produces what is usually called degree of immersion. Extended presence requires intellectually and/or emotionally significant content. Integrating the three layers amounts to fooling the system into a conviction that something is happening to the self in the here and now.

The different layers of presence may be less than perfectly integrated in several ways, including the following:

· If you experience a VR without a tracking system you can have high level of core presence (vividness), a high level of extended presence (engagement) but no proto presence (spatial presence).

· If you read a good book while sitting in an comfortable, safe place, extended consciousness will be engaged by media (engagement) but the other layers will not be involved.

· If you are in an immersive VR, but are pre-occupied with personal worries, proto (spatial) and core presence (vividness) will be invoked, but not extended presence.

· The same situation, with particularly uninteresting content of the VR but no dominating personal worries (low engagement) may tend to produce frequent "breaks in presence" (a change or spreading of position on the locus dimension).

We see changes in the locus of presence, such as Slater's (Slater, 2002) "breaks in presence", as illustrating how core consciousness attempts to integrate the three levels. Content entering core consciousness will remain there for as long as it can be integrated with the content of the other layers. If competing contents appear at either of the other two layers, a change in presence locus is possible. The probability and duration of such changes depend on extended consciousness; attention is likely to be captured by whatever is most relevant to the goals of the extended self, whether this is a stimulus from the real world or a mental event such as a sudden thought. Even the occurrence of a new vivid stimulus, such as a loud sound (attracting core presence), or a break in bodily continuity such as a cable obstructing movement in a VR (attracting proto presence) will only have temporary effects. Once extended consciousness has judged the event as no longer relevant, the self will revert to the previous content of core consciousness (Spagnolli & Gamberini, 2002).

Recently, Slater (2003) has claimed that presence is determined only by form, but our three-layer model of presence suggests that this is an oversimplification. We suggest that proto presence is determined only by form, core presence by both form and content, and extended presence only by content. The integration of presence can occur in either the real or a virtual world. In the case of a virtual world, we need to provide both appropriate form and meaningful content. Presence in the real world depends only on content, on what we experience as happening to us in the here and now, since the form is provided and is always appropriate.

To maximize experienced presence in virtual environments we must design in a way that allows integration of the three layers. As we have seen, this is technically demanding at the lower levels. We need to provide as much immersion as possible, integrating proto (spatial) and core (sensory) presence. To integrate extended presence, the events and entities experienced in the virtual environment must have significance for the participant. One promising approach is to design a role for the participant as a performer in a drama (Nath, 2001). It appears that if the performer becomes emotionally or intellectually engaged by the events in an appropriately immersive environment, high levels of presence can be achieved (Waterworth et al., 2002). In this situation, the organism responds as if what happens in a mediated environment is real, in the fullest sense. Because of this, an immersive VR with appropriately engaging content may be a uniquely effective means of addressing personal dispositions of real significance for the individual concerned.
4 Conclusions

The purpose of presence is to provide a basis for the organism to separate events that occur only within the self from external events that may act on the self. Presence is experienced as a unitary feeling, a feeling of being in a world that exists outside of the self. We have suggested that contributions to the intensity of this feeling can come from three layers of the self, and we refer to these as proto presence, core presence and extended presence. The more the three layers are integrated (focused on the same events) the stronger the intensity of the presence feeling.

The difference in presence experienced through different media can be explained by the fact that many media influence only a limited number of layers. In a compelling book reading only extended consciousness is involved, and with a movie experience we can modify both core presence and extended presence but not proto presence. Only in immersive virtual reality are all the three layers of consciousness modified by the media experience. We suggest that this gives immersive VR a privileged status as a medium for meaningful experiences.

Appropriate form is needed for high presence, but reality judgement is not only a matter of form. We are more likely to attend to and assess information that has significance for us. At the same time, our model allows presence to be differentiated from emotional or intellectual engagement and, because of that, from consciousness in general.
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Giuseppe Riva , Eva & John Waterworth