A Theory of Consciousness

A Theory of Consciousness

Giorgio Marchetti
University of Urbino





According to William James’ theory of mind (1890), our conscious mental life flows continuously
like a stream in which “the transition between the thought of one object and the thought of another
is no more a break in the thought than a joint in a bamboo is a break in the wood” (James, 1983, pp.
233-234). For this reason, he adopted the metaphor of “the stream of consciousness”. The stream is
formed by an unbroken series of states of mind, each one of them, however, is different from the
others:

“it is obvious and palpable that our state of mind is never precisely the same. Every thought we have of a given fact is,
strictly speaking, unique, and only bears a resemblance of kind with our other thoughts of the same fact. When the
identical fact recurs, we must think of it in a fresh manner, see it under a somewhat different angle, apprehend it in
different relations from those in which it last appeared. And the thought by which we cognize it is the thought of it-in-
those-relations, a thought suffused with the consciousness of all that dim context” (James, 1983, p. 227).

The difference between each state of mind and the others is highlighted by James also for another
reason. Each state of mind - or “pulse of consciousness” - gives rise to a unitary content, however
complex it may be. If in a precise state of mind we think about, imagine, feel or perceive an object,
we will always have only one thought, image, feeling or perception of that object; we will think
about, imagine, feel or perceive it in a unity, as a whole. “There is no manifold of coexisting ideas;
the notion of such a thing is a chimera. Whatever things are thought in relation are thought from the
outset in a unity, in a single pulse of subjectivity, a single psychosis, feeling, or state of mind”
(James, 1983, p. 268). James reaffirms and refines this hypothesis when dealing with attention:

“The number of things we may attend to is altogether indefinite, depending on the power of the individual intellect, on
the form of the apprehension, and on what the things are. When apprehended conceptually as a connected system, their
number may be very large. But however numerous the things, they can only be known in a single pulse of
consciousness for which they form one complex ‘object’, so that properly speaking there is before the mind at no time a
plurality of ideas, properly so called” (James, 1983, p. 383).


1

---

No doubt James’ description is very realistic and convincing. But how is it possible to conciliate
and explain the apparent contradiction present in the metaphor of the stream of consciousness as
something flowing uninterruptedly, but which is, nevertheless, composed of single pulses of
consciousness? How can we explain the quality of the conscious experience as something
continuous and coherent and, at the same time, made of states of mind each of which is inevitably
unique, different from the others, and characterized by its own qualities? And how can we relate the
properties of consciousness to the way attention works, given that the latter seems to share many
qualities with the former?
A solution to these problems comes from conceiving of the stream of consciousness as the
outcome of a process determined by the continuous interaction of two systems: the perceptual
system and the schema of self.
The perceptual system, principally based on the organ of attention, sense-organs, and
somatosensory organs, enables the organism to be conscious and provides the products that will be
processed by the schema of self and contribute to update and modify it. These products derive from
the operations performed by the perceptual system either on the organism or on the environment.
Conversely, the schema of self, largely based on innate schemas of action, a working memory,
and a long-term memory, provides the rules which make our organism perceive, move, act in
general and interact with other organisms. As a consequence, it provides not only the instructions
for the perceptual system but also the raw material it has to work out: in fact, the actions performed
by the organism can be perceived by the perceptual system (even the very action of perceiving) and
become available under the form of conscious perceptions for the schema of self. The latter in turn
works on the basis of these perceptions to issue a new instruction for the perpetual system and for
the organism.
The uninterrupted interaction of the two systems generates the stream of consciousness; each
interaction between the two systems generates a specific and unique perception. The uniqueness of
each “pulse of consciousness” is determined by the particular instructions that the schema of self
gives each time to the perceptual system. These instructions in turn vary each time because of the
modification of the schema of self by the conscious perceptions. The consistency and coherence of
the stream is ensured by the presence of the schema of self, which tends to run the perceptual
system and the organism in general according to a hierarchy of principles, goals and rules at the top
of which there is one fundamental principle: the principle of survival, which can operationally be
translated into the following imperative “operate in order to continue to operate”.
The perceptual system acts as a monitor that continuously checks what is going on inside and
outside the organism, and informs the schema of self. Without this kind of information, the schema

2

---

of self would be kept in the dark about what has happened or is happening within itself and in the
environment. As we will see, what counts more is that the perceptual system provides the schema of
self with the necessary information for the definition and development of a self, that is, for its
differentiation from the environment.
The fact that the perceptual system monitors the organism implies that the operations and
activities of the organism are consciously perceived only after they have been performed. We
become aware of what we do only after we have done it. Evidence of this is given by our daily
experience: sometimes, we become aware of what we wanted to say only after having said it.
Neurophysiological experiments also prove it. For instance, Libet (1985) shows that a subject
consciously experiences a voluntary act only several hundred ms after his/her brain has initiated it.
The fact that the schema of self is updated and fed by the perceptual system implies that
conscious products play a causal role in human behavior. They not only contribute to modify the
schema of self, but supply the organism with the capacity to act autonomously and voluntarily. As
Cimatti (2000) points out, the only condition necessary for this to happen is that the organism has a
language, and that it uses it not only to communicate its own intentions or the events happening in
the environments to other organisms, as animals do, but also to communicate with itself, directing
its own attention to itself and to its attentional system (and, consequently, to someone else’s
attentional system). In such a way, the organism is able to control its own attention and actions, and
act intentionally. This is what happens when someone says to oneself that it is time to stand up, and
then one stands up. This is also what happens when someone tells someone else to control
him/herself, and the latter acts accordingly. By repeating these kinds of operations, the schema of
self assimilates the notions of autonomy and self-regulation, thus giving the organism the ability to
control and plan its own activities.
Now let us see in detail how the perceptual system and the schema of self function.

The perceptual system

As Mack and Rock (1998) demonstrate, there is no conscious perception without attention. In some
of their experiments, subjects’ attention was engaged by a task (for instance, to report the longer
arm of a cross briefly presented on the screen and centered at about 2 degrees from fixation). After
some trials, an unexpected, unsearched critical stimulus (for example, a black circle) was presented
at fixation, and subjects were asked whether they had seen anything that had not been on the screen
on the earlier trials. Between 60% and 80% of the observers failed to detect the critical stimulus. A
comparison between reports of the critical stimulus on the inattention trials (where subjects were

3

---

told to pay attention to the cross, but were not told that a critical stimulus would appear) and those
on the full attention control (where subjects were told to ignore the cross, and to report only what
else they saw on the screen when the cross was present), confirmed that attention is clearly
implicated in conscious perception. More in general, Mack and Rock’s experiments show that
subjects tend to be blind to a critical stimulus that appears either at or close to fixation when they
are not searching for it, when they are occupied with a task that engages their attention, and when it
is located outside the boundaries of the area to which attention is directed.
These findings do not imply that there is no implicit, unconscious perception, but only that there
is no explicit, conscious perception prior to the engagement of attention. Stimuli to which subjects
are inattentionally blind, can be implicitly, unconsciously perceived. In order to bring them into
consciousness, they must be attentionally processed. Attention represents then the key to conscious
perception and experience: any model that aims at explaining how consciousness works must
necessarily include attention as its most important component.
Given that there is no conscious perception without attention, the question is: how is attention
involved in the formation of conscious perception? What is it that makes attention the key to
conscious experience?
We can start to give an answer to this question by considering what is thought to be one of the
main characteristics of attention: its selective power. By attending to a certain object, we are able to
isolate it from the other objects, so that our conscious mind is completely and exclusively possessed
by it. Apart from the benefits that derive from this characteristic, namely accuracy, speed and
maintenance of mental processing (cf. La Berge, 1995), a full possession of our conscious mind by
the object of attention implies principally the possibility for that object of orientating all the actions
of our organism towards a certain direction instead of towards another one. When we feel pain, for
example, we will do everything to alleviate it: our actions, thoughts and behavior will be directed to
the solution of the problem, and all the different energies of our organism will be absorbed by this
task. This fact exemplifies what represents the most important aspect of consciousness: its power to
drive the organism according to what is taking place in it.
Attention is then responsible for the selective aspect of consciousness, that is, for its capability of
isolating one specific part from the whole, and “filling the mind” (La Berge, 1995) with it.
Therefore, attention provides the mind with the matter that is necessary for it to control and drive
the activity of the organism. It is important to observe that the conscious mind can be filled only by
one attended object per unit of time, however complex it may be. We cannot attend to more than
one thing, or adopt more than one observation level (cf. Negrotti, 1999) per unit of time: we cannot
see the front of something at the same time as we see its back. This derives from a very fundamental

4

---

physical law: if an object occupies a certain place, it cannot occupy another place at the same time;
conversely, a place that is occupied by a certain object, cannot be occupied by another object at the
same time. For this reason, when somebody occupies a certain position, and observes a scene from
that position, they cannot contemporaneously observe the scene from a different position: in order
to look at it from a different position, they will have to change their own position. Strictly speaking,
this rule is valid for all perceptive modalities. The position our body occupies in space and time
equally puts a limit on the working of all our sense-organs and on the form of their products. We
cannot smell something that is miles away from us, or see what is happening overseas (unless, of
course, we watch it on TV). We can see and contemporaneously touch and smell an object,
coordinating the different perceptions and combining them so as to form a single complex object,
but each single complex object so formed cannot have more than one aspect per unit of time.
This limitation has clear adaptive advantages for the formation and development of an organism
as such. It allows the organism to delimit and define itself as an “organism” in a world of
organisms, that is, as something that cannot occupy more than one place per unit of time. The fact
that the organism cannot consciously perceive more than one object per unit of time, implies that
the behavior, the strategies and, in general, the knowledge it will develop, will be consistent with
the limitations imposed on it by a physical world. As I tried to show (Marchetti, 2000), the only
kind of knowledge that such an organism can develop is a procedural one, that is one based on an
orderly, sequential manner of doing things. To put things in order, placing and arranging them in
relation to one another, the organism cannot deal with more than one thing per unit of time. The
organism can achieve this if it is ruled by only one single unit controlling the operations, that is, a
unit working on a single, coherent, specific principle. Should it be more than one unit, they would
work on different principles, unavoidably coming into conflict and originating contradiction and
disorder. Order arises when a unit of control prevails over the others, and rules and coordinates the
organism according to its own principle, thus resolving any conflict. The working of this single unit
is regulated by the organ of attention, which assures that the condition that only one object is
processed per unit of time is fulfilled.
Until now, we have seen that attention is responsible for the selective aspect of consciousness
and for “filling the mind” with the attended object. However, this “filling the mind” has a special
characteristic which deserves and needs to be explained: it is what philosophers call the problem of
qualia (cf. Chalmers, 1996), that is, the fact that when we consciously perceive something, we have
a subjective experience of that something, we feel it, we have some sensations. Any experience has
its own special phenomenal qualities which distinguish it from all other experiences, and which we
cannot avoid feeling directly.

5

---

How does this occur? How can we explain the process of subjectively and directly feeling the
phenomenal qualities of our perceptions? In my opinion, an explanation can be found if we consider
attention as a form of energy, namely the nervous energy that feeds our organism, and the organ of
attention as an organ that supplies this energy. Until now, most models of attention describe it as
something passive. The metaphors used to describe it, whether a filter (Broadbent, 1958), a zoom
lens (Eriksen and St. James, 1986), a spotlight that moves (Tsal, 1983), a gate (Reeves and Sperling,
1986), or a selective, amplifying channel (La Berge, 1995), imply all that it is seen as a privileged
route for events to enter our mind or consciousness, that is, as a kind of mechanism which, letting
information come in and be processed by some other device, plays a marginal, passive role. In such
a way, the core problem of consciousness - how can we explain the fact that we have subjective,
direct experiences of objects? - is devolved to another organ, for example an operating system
(Johnson-Laird, 1983, 1988), a central processor (Umiltà, 1988) or a supervisory system (Shallice,
1988). I think that this way of treating consciousness cannot provide an answer, because there
cannot be a final device towards which information flows, unless we are willing to consider this
final device as a conscious agent itself, or a homunculus, thus entering a vicious circle. In my
opinion, these difficulties arise when a pure information-processing conception of mind is adopted,
whereas a different approach should be assumed to face the problem of qualia. An information-
processing conception of the mind can certainly explain how information is processed, the changes
it undergoes, the time needed to process it, and so on. However, it does not and cannot explain what
a subject feels as it processes information, that is, how its conscious states start forming, develop,
and change as a consequence of what it does. This is because information is made up of ready-made
symbols representing the external world, whose meaning derives not so much from the importance
they have for the subject’s formation and development, but from the importance they have for the
researcher’s investigations. The information-processing approach, in fact, is based on the
assumption that the mind processes representations that already have their own meaning,
independently from the history of the subject, and does not investigate how they acquire a meaning
for the subject, and how the subject builds meaning1. The information-processing level of analysis

1 A similar critique has been addressed to cognitive science by Searle (1980, 1984, 1992). The basic assumption behind
cognitive science is that the brain is a computer and mental processes are computational. According to Searle, this is not
the best way of studying the mind. Describing mental processes by using the metaphor of a computer program, implies
in fact describing them from a pure syntactic and formal level, that is, as operations performed on a set of symbols.
However, a pure syntactic description cannot account for the contents of our mental states, that is, for the meaning that
symbols have for us. As Searle says, syntax is not the same as, nor is it by itself sufficient for, semantics.
Moreover, notions such as computation, algorithm, and program do not name intrinsic physical features of systems;
they must, instead, be assigned to the physics by the researcher. This means not only that it is always possible for us to
characterize a physical system from the outside in various and different ways, according to our own purposes, and that
describing such a system as a computer is only one of many ways of describing it, but also that once we have chosen to
characterize it in this way, we cannot avoid the consequences that this characterization implies: principally, the fact that
if we assign certain properties to the system, we cannot expect that it will develop by itself those properties.

6

---

examines how some parts of a subject’s organism - sense organs, attention, memory, central
processor, an so on - transform information, but does not examine how a sentient subject transforms
itself as it processes information2.
In order to analyze a sentient subject, we must take a different, new perspective, let us call it a
“first-person perspective”, which of course has to presuppose the subject’s existence. Such a subject
can be said to exist and be so when it can delimit and control itself, its operations, movements,
intentions, and actions, according to its sensations and to what it feels. This implies that it is able to
perform a kind of activity that gives it the possibility of directly knowing itself and defining its
limits. The direct experiences it has of itself contribute to form and constitute it: for instance, if it
tries to reach something unsuccessfully, the feeling it has gives it immediately the dimension of its
effort, and the boundaries of its body. We could say that the form it assumes is the outcome of the
activity that produces its experiences: the subject is the result of this activity. It is this activity that
gives it the possibility of existing as a subject, because only by performing it can the subject take a
form and differentiate itself from other subjects and objects. Therefore, describing what a subject
feels and experiences is describing this activity and its course.
How can this activity make a subject have experiences and feelings? I think that an explanation
can be found if we conceive of:

a) the subject as the outcome of a special kind of activity (let us call it attentional activity)
performed by an organism provided with a source of energy (let us call it nervous energy or
attentional energy) capable of directing all the other kinds of energy of the organism;
b) the attentional activity it performs as what makes its state of nervous energy change. This can
happen indirectly, through the action of the organism on the world, and the subsequent re-action
of the world on the organism, or directly, through the action of the organism on itself;
c) the experience it has as the change of its state of energy resulting from performing the attentional
activity.

This is a dynamic and active view of the subject, of course. It implies that the subject as such
emerges from its continuously performing the attentional activity, that is, from its continuously
using and applying its attentional energy; that every time the subject uses its attentional energy, the
action performed affects its source of energy, thus resulting in a possible change of the state of the

The conception of the mind as a computer and mental processes as computational has been criticized also by
neurobiologists and neuroscientists such as Edelman (1989), Reeke and Edelman (1995) and Freeman (1999) on the
grounds that it cannot account for the individual variability of the brain, and the continual modification of the patterns
of neural activity and re-categorization of the world by the brain.
2 For a similar view, see Freeman (1999).

7

---

nervous energy; that the form the subject takes is a result of the way it applies its attentional energy,
that is, of the force with which it applies it and of the specific dimension (whether physical - visual,
tactile, muscular, etc. -, psychological, social, or else) to which it applies it. In this view, a subject’s
feelings and experiences are the direct result of its applying and using its attentional energy. What it
does changes its state of energy, thus immediately affecting itself, its following actions and
behavior.
I then assign attention an active role: following Ceccato’s proposal (1985, 1987)3, I consider the
organ of attention as the source of the organism’s nervous energy. Every time we direct our
attention towards an object, we spend our energy on it. At this point, a change in the state of energy
may occur, thus making us perceive or feel the object. Clear evidence of this can be found in very
common situations. When having certain sensations, our activity tends to be slowed down or
blocked: sensations of sorrow, pain, tiredness, depression, and so on, precisely consist in a
reduction of our general activity, as if they have absorbed our energies completely, or put an
obstacle in the way of our operating. Conversely, sensations of happiness, wellness, freshness, and
so on, consist in a positive stimulation of our activity, as if they have facilitated our operations, or
given us supplementary energy to continue moving and acting. Even less strong kinds of sensation
give us evidence of the change that our state of energy undergoes because of the working of
attention. When we have the intention of perceiving the surface of an object by touching it, we
focus our attention on our fingertips: if a sensation of “hard” arises, we feel that a limitation is
imposed on us, and cannot further expand our movements and energy. On the contrary, when we
have a sensation of “soft”, it is as if we had not yet reached a limit, and could further expand our
energy. Likewise, some colors, forms, smells and sounds excite us, stimulating our organism to
produce more energy, while others calm us, making us reduce our activity.
Following Paul Valéry’s suggestion (1973)4, we can consider sensation as a variation of the state
of energy of a closed system. During the variation, the equilibrium of the system is broken, and the
organism has to spend some energy to reestablish the original conditions. The amount of energy
necessary for the organism to reestablish the equilibrium represents the quantitative aspect of the
sensation. Variation can be positive or negative, the former making the organism more active, the
latter more passive. In both cases, when the organism gets either to the upper threshold of its
capacity or to the lower one, it feels pain. Both an excessive activity requiring too much energy, and

3 According to Ceccato, attention plays this role because besides giving birth to mental life, thought, and mental
categories such as “time”, “space”, and so on, it also regulates the working of our sense organs, and originates emotions
and feelings.
4 Valéry expresses his theory of sensation as follows (I translate from the Italian version): “Sensation does not consist so
much in an introduction of something from the outside, as in an intervention, that is, an inner transformation (of energy)
made possible by an external modification, a variation in a state of a closed system (…) sensation is due to some kind of
disequilibrium (…) sensation is what occurs between two states of equilibrium” (Valéry, 1988, pp. 411-412)

8

---

a slowing down of activity hindering too much our energy, cause pain. An optimal condition of
working makes the organism feel well.
Sensations originating from different perceptual modalities differ qualitatively from each other.
A sensation of “hard” is qualitatively different from a sensation of “red”; sensations pertaining to
different perceptual modalities can usually be correlated and combined, but not confused. We can
account for this fact if we suppose that the organ of attention is divided in as many parts as the
perceptual modalities are. Evidence that, during the perceptual processing stage, attention can be
divided, up to a certain extent, between different perceptual modalities, seems to support this
supposition5. Therefore, we can assume that if we pay attention to a specific perceptual modality, a
specific area of the organ of attention is stimulated, and a specific sensation arises. The specificity
of each area represents the qualitative aspect of sensation.
Let us consider briefly the advantages that an organism has in experiencing directly and
subjectively sensations. An organism (say A) that has the capacity to feel has the capacity to build
and develop its own knowledge. An organism (say B) that cannot feel does not have this capacity.
Let us suppose that B is a robot that was programmed to behave in the same way as A. If it is hot, A
will feel hot, and consequently will exhibit all the signs and behaviors that an organism typically
shows in such a situation: sweat, thirst, tiredness, desire to find a fresh place, and so on. B will
exhibit the same signs and behaviors as A, but it will not feel hot. Until the conditions for which B
was programmed occur, B will behave not only indistinguishably from A, but also will seem to
exhibit a sensible behavior and to act reasonably. Once the conditions have changed (for example, it
may be hot not because of meteorological reasons, but because of a fire), B’s behavior may seem
unpractical, paradoxical or illogical, and even cause its death (drinking water may not be sufficient
to put the fire out or to avoid burning). This is because B has not changed its behavior in spite of the
fact that conditions have changed. A certain kind of knowledge was installed in B, a predetermined
one which is certainly useful on some occasions, but cannot be always suitable. B cannot build and
develop its own knowledge by itself: it is necessary that someone else give it the new instructions to
face the new situation. On the contrary, A builds its knowledge autonomously, because, for it,
knowledge does not corresponds to an explicit, rigid, mediated set of data and procedures, but to an

5 In classical psychological experiments on divided attention, subjects are presented with two tasks that have to be done
concurrently. Usually, each task consists in perceiving a stimulus and making a response. The processing required to
perform a task can be broken into at least three stages: a perceptual processing stage, a response-selection stage, and a
response-execution stage (cf. Posner and Boies, 1971, Allport et al., 1972, McLeod, 1977; for a recent review of the
subject, cf. Styles, 1997). As shown by Fagot and Pashler (1992), a bottleneck occurs at a late stage of the processing
rather than at the perceptual processing stage, namely when the neural machinery, after receiving the critical stimulus
information from perceptual areas, has to retrieve from memory the code for the corresponding action. Therefore, it
seems ascertained that attention can be divided at the perceptual processing stage. On the division of attention, see also
Castiello and Umiltà (1992), who have shown that subjects can split their attention even within the same perceptual
modality, namely the visual one.

9

---

implicit, flexible, direct way of reacting directly to changes and new conditions. To be acquired,
this kind of knowledge need not be formalized, but only experienced. Feelings, emotions,
sensations, and all the other conscious constructs are means of knowing directly, without the need
for external agents to implement and install knowledge.
Further to the foregoing description of the perceptual system, I propose the block diagram of Fig.
1 as the circuit responsible for conscious perception.






Fig 1. Conscious perception


Fig. 1 shows a case of voluntary or endogenous attention. The organism issues instructions to
itself to direct its attention toward a certain somatosensory area or sense-organ. The result of the
activity of the somatosensory system or of the sense-organ (here labeled as “output”) acts directly
on the relevant area of the organ of attention, making the subject have a sensation.
There can also be, of course, cases of captured or exogenous attention. Some objects, such as
one’s own name (Morray, 1959) or other meaningful stimuli (Mack and Rock, 1998), can capture a
subject’s attention even though the subject does not expect them or have any intention toward them.
In these cases, it seems reasonable to think that a signal coming from the somatosensory system or
from the sense-organs has the power to autonomously capture attention and become conscious,
independently of the subject’s intention.
The fact that some objects, such as one’s own name, can become conscious even if the subject
does not pay attention to them, is interpreted by Umiltà (1994) as evidence that attention does not
coincide with consciousness and that they must be considered as independent systems. In these
cases, he argues, the object is perceived consciously in a direct manner, without the intervention of
attention. His argument contrasts with what Mack and Rock (1998) have found. They show that

10

---