Understanding Consciousness
stevet@sussex.ac.uk
The following is a draft chapter for a forthcoming introductory undergraduate textbook on Psychology. The book is edited by Patrick McGhee and is to be published by Palgrave/Macmillan in 2003.
But
what I'd like to know
Is could a place like this exist so beautiful
Or do we have to find our wings and fly
away
To the vision in our mind?
Stevie Wonder,
'Visions', in Innervisions, Motown Record Corporation, 1973.
Without
consciousness the mind-body problem would be much less interesting. With
consciousness it seems hopeless.
Thomas Nagel, What is it like to be a bat?, The Philosophical Review, 83, October 1974. p. 436.
Contents:
Overview
Key concepts used in chapter
Specific aims of the chapter
A What is consciousness?
Access
and phenomenal consciousness; self-consciousness
PAUSE FOR THOUGHT BOX
- A practical exercise
CRITICAL
THINKING BOX - Psychology and the study of consciousness: some key issues.
Consciousness and unconsciousness
Computers
- mind without consciousness?
Experimental
investigations of deep (?) unconscious cognition
PAUSE FOR THOUGHT BOX - Consciousness, non-humans and moral concern.
B Special states of
consciousness
'Special'
states of consciousness: (1) sleep and dreaming.
'Special'
states of consciousness: (2) hypnosis .
'Special'
states of consciousness: (3) mind-altering drugs, meditation.
PAUSE FOR THOUGHT BOX: The ethics of drug research.
C Consciousness and brain
processes: a puzzling relation
History:
behaviorism versus introspectionism
Searching
for the neural correlates of consciousness
Crick and
Watson: Neural Oscillations
Edelman: Neural Darwinism.
Penrose and Hameroff: Quantum events in
microtubules.
Can consciousness be equated with states of the brain?
PAUSE FOR THOUGHT BOX: Problems with the identity theory of consciousness
Functionalism: another physicalist
account of consciousness.
A
functionalist example: global workspace theory.
CRITICAL THINKING BOX: What functions does consciousness perform?
Problems with functionalist theories
Can
there be a scientific theory of why we are conscious at all?
CRITICAL THINKING BOX - The zombie scenario
Study questions
Further reading
Relevant web sites
References cited in chapter
Overview of chapter
In this chapter we will see how the psychological study of consciousness has veered between two extremes over the last hundred years. As the twentieth century began, conscious experience was seen as at the centre of concern of the professional psychological researcher. Following the start of the behaviourist revolution (Watson,1913), consciousness was dropped from psychology: the idea that psychologists could study anything so subjectively uncertain as individual episodes of awareness, was condemned as anti-scientific nonsense. The idea that psychology only studied behaviour dominated until recently.
But there has been a slow revival of interest in 'internal' states. Progress in neuroscience the scientific study of the structure and functioning of the brain - offered a new direction for research, with the development of theories explaining many types of mental processes in terms of brain-structures. Meanwhile, the development of cognitive or 'functionalist' theories of mind allowed a different kind of way back in to the 'interior', beyond the behavioural barrier, by stressing the more abstract, organisational roles that might be played by conscious awareness within the mental economy. Both these approaches paved the way for the return of consciousness to the stage.
Both neurally-based and functionally-based methods have been popular as ways to explain the facts of conscious awareness. But while such approaches help shed light on how consciousness arises in the brain and on the ways it may play a part in mental organisation, there seems to be an 'explanatory gap' (Levine 1983, 1993) here. For it's not clear why such neural or functional mechanisms should produce conscious awareness at all.
Why, for instance is it the case that there is a distinctive subjective quality to the experiences one has when playing pool, and a different subjective quality to the experience of, say, inspecting someones hair for lice? Conceivably, robots could one day engage in highly complex and human-like forms of motor or perceptual processing without any conscious awareness being present. (For instance, a robot has already been built that plays pool: it is unlikely that its builders could convincingly claim that it has any subjective experiences of its actions when it plays.) So why did our evolutionary history involve the emergence of this inner experiential life, over and above the mechanisms in themselves? What adaptive purpose did consciousness evolve to meet?
In the last ten years or so there has been an increasing recognition of the need to study consciousness head-on. Now, within the growing interdisciplinary field of 'consciousness studies', workers in many fields are collaborating. There are both empirical questions: What are the mechanisms that are in fact closely linked to consciousness? There are also philosophical and methodological questions - for example: Can consciousness be identified with physical properties of an organism, or is it perhaps a special, non-physical, kind of property? Is consciousness amenable to scientific study at all? Does our talk of 'subjective experience' just express a host of shifting, mutually contradictory myths or linguistic half-truths? How do unconscious states, or so-called 'altered states' of consciousness fit in the picture. These are some of the issues we will look at in this chapter.
Key concepts used in this chapter (in alphabetical order)
access-consciousness
altered states of consciousness
animal consciousness
artificial consciousness
artificial intelligence
behaviourism
blindsight
computational theories of consciousness
deep unconscious
dreaming/REM states
dualism
epiphenomenalism
evolution/selective advantage of consciousness
explanatory gap
first-person/third-person
fringe consciousness
functionalism
global workspace theory
'hard problem' of consciousness
hypnosis
identity theory of mind
intentionality
introspection/introspectionism
materialism/physicalism
meditation
mental productivity (cognitive 'work)
microtubules/quantum effects
mind-body problem
neural correlates of consciousness
neural Darwinism
neural oscillations
phenomenal consciousness
phenomenology
privacy
psychoactive drugs
psychoanalysis
self-consciousness
sleep
stream of consciousness
subjective/objective
unconscious mental states
zombie scenario
Specific Aims
of this Chapter
(a) to give some preliminary definitions of 'consciousness', and related concepts;
(b) to discuss various kinds of 'altered' states of consciousness, such as dreaming, hypnosis and drug-induced states;
(c) to survey how consciousness has been approached over the last hundred years;
(d) to examine
whether conscious states can be equated with physiological states of the brain,
or with functional or 'software' states.
A What is consciousness?
Everyone knows what it is to be conscious. But it's very difficult to put in words what exactly we understand by the term. It's not even clear that the term names just one single type of process. For instance we often use the term to refer to processes that occur in our minds during normal, waking life. However it may be thought that dreaming is a kind of consciousness, even though it occurs during sleep. Again hallucinations, drug-induced states, or heightened experiences such as religious ecstasy may be thought to depart considerably from cases of normal waking conscious awareness.
Even limiting our scope of inquiry for now to the normal experiences of (reasonably) everyday life, it's hard to get a clear idea of what is included under 'consciousness' and what is not. Perhaps the best way to get at it is through some examples.
Picture in your mind the sensation of walking barefoot over a thick wool-fibre carpet and suddenly stepping on the point of a drawing pin hidden in the deep pile. Think of the distinctive quality of what it would be like for you to be in that situation. (Not very pleasant!)
Think of that luxurious feeling as you slip into a warm bath after a really stressful day. Think of what it feels like to get a stitch while running; to see a mass of riotous colors; to sit through a boring lecture or meeting longing for the tea-break; to learn of the death of a close relative or friend; to witness a brilliant performance by a symphony orchestra or a rock band; to be beside yourself with rage; to gaze over a breathtaking landscape overcome by a feeling of calm.
These are just some of the many sorts of experiences which make up the rich, varied texture of our everyday conscious life. When we talk of consciousness, we are referring to the state of being on the 'inside' of these different situations, of 'what it is like' (Sprigge 1971, Nagel 1974) to be directly experiencing them. William James put forward (1910) some basic principles about everyday conscious awareness (in a set of lectures originally given in 1892). These include the following:
Every thought or state of mind that one has appears to be 'part of a personal consciousness' - they are thoughts of 'mine'
Within this personal consciousness there is constant change between successive states;
Despite these changes, our consciousness appears to us as a continuous flow or stream; and our attention is continually hovering and shifting from one object or content to another: 'Like a bird's life, [consciousness] seems to be an alternation of flights and perchings.'
Other things that people have said about consciousness include:
Conscious thoughts are 'private' or 'first-person' - I can't have direct access to your states, nor you to mine,
But we can have indirect, 'third-person' access to other people's conscious states via listening to their verbal reports, or via certain sorts of behavioural tests or brain-imaging technologies, etc.;
Conscious states are 'ineffable' or 'incommunicable', in the sense that, if I try to describe verbally what it is like to experience the colour blue, I will not be able to convey it to someone who has been blind from birth, or who is an achromat (a sighted person who has no visual experiences of colour);
Conscious states have a special kind of 'content' or 'object' - consciousness is always 'of' something. (This property is often known as intentionality.)
Some
philosophers and psychologists say that there are several different kinds or
levels of consciousness. For example, as well as the ordinary consciousness of
everyday waking existence, there is the kind of conscious state that we are in
when we dream. There are also, seemingly, other forms of consciousness, - such
as states induced by psychoactive chemicals, or states of 'heightened'
awareness gained through meditation, etc.
Access and phenomenal consciousness; self-consciousness
Many
theorists have suggested that there is a distinction to be made between
'informational' and 'qualititative' aspects of consciousness - that is, between
the factual knowledge of the content of a conscious experience, and what it is
like to experience that content.
BOX: Pause for Thought: A Practical Exercise
In order to get clearer on the distinction between these two aspects, try the following simple thought-experiment. Imagine each of the following sounds: try and 'play each of them in your mind' in turn:
· the clanking of an iron bar as it hits a concrete floor;
· the thwack of a tennis ball as it is served;
· the ripping sound of piece of cotton material being torn
Try to ascertain how, in your imagined awareness, each of those sounds carries both of the following elements:
(a) informational or representational content: that is what would enable you to pick it out as the sound it was;
and
(b) a particular qualitative character - how the sound sounds to you. (For someone other than you it might have a different qualitative character, but what matters for you is how it is for you).
End of Box
Theorists
have used a number of terms to distinguish between these two apparent
properties of an experience, that is the factual knowledge of the identity or
nature of an experience (e.g. its a clanking rather
than a ripping sound), and the subjective quality of the experience in itself.
For example they talk of the first as the representational or intentional
content of the experience, and of the second as its phenomenal or
phenomenological content.
Ned Block (1995, Young and Block, 1996) has used the terms 'access consciousness' and 'phenomenal consciousness' to mark these two aspects of conscious awareness (A- and P-consciousness for short). A mental state is access-conscious if you can think about it, describe it in some way, and use it to guide action - for example when your conscious visual tracking of the relative positions of a piece of cotton and a needle eye help you thread the cotton through the needle.
On the other hand the term phenomenal consciousness refers to the qualititative character of the experience in itself - its 'what-it's-like' quality. (Cf Jackendoff 1987).
Another type of consciousness is self-consciousness. Imagine again you're threading a needle. In one sense you will be fully conscious of - fully intent in - what you are doing. But in another sense you may be 'lost' in the activity: just doing it in a way that Hubert Dreyfus (2000) describes as 'absorbed coping'. You may be A- and P-conscious but perhaps not self-conscious of your activity. However if your attention shifted from the activity to yourself as the author of that activity, your state would change to self-consciousness (and maybe your performance of the act itself would degrade).
According to Young and Block (1996), self-consciousness involves having a concept of a self, which suggests that it is perhaps more akin to A- than to P-consciousness. You can probably switch into a state of self-consciousness quite easily - for example by reading the nonsense-word at the end of this sentence, bagiupemiscerous. Because you have suddenly stopped taking the process of reading for granted, you are likely to be aware now of yourself reading, instead of just doing the activity in an 'absorbed' way.
It is
worth noting that self-consciousness, as defined, may not be attributible to
infants, because they may lack the concept of themselves. Likewise, people with
Alzheimer's disease and other degenerative states may lose the ability to be
self-conscious, while still retaining access and phenomenal forms of
consciousness - albeit pershaps in a modified or restricted form. Some people
have also suggested that practiced meditators also lose a concept of self, and
acquire an awareness of 'pure being'.
Critical Thinking Box: Psychology and the study of consciousness - some key issues.
Let us now look at some of the problems that are encountered in the study of consciousness. Consider each of these questions in turn. As you review the list now, write down any ideas you may have, however vague and uncertain, about what the right answers to them might be. This list is far from exhaustive. Some of the questions are dealt with at some length in this chapter; others are touched on only in passing. At the end of your reading of this chapter you might perhaps wish to go back to this list, and see if you have any clearer answers to any of the questions.
· How does consciousness relate to other mental processes, such as thinking, perception, volition, emotion, etc.?
We will try to provide the reader with some tools to help inform their further reflection on these issues, and with guides to some of the key concepts and writings in this fast-developing area.
END OF BOX
Consciousness and unconsciousness
Some psychologists think that the most significant things in the mind are happening down below the threshold of consciousness. On this picture of the mind a lot of hidden 'machinery' is needed - complex unconscious linguistic or visual processes, for example - to enable us to use our mind or act consciously. On an alternative version of this picture, derived from Freud, a subject's actions and experiences through life are strongly conditioned by hidden emotional currents that are buried from view because they are too painful or socially unacceptable to be revealed.
From a quite different perspective, some theorists assume that mental activity is primarily conscious in nature, and that those aspects of thinking that occur below the threshold of awareness are mental only in some derivative sense. For such people - John Searle being an example (1992) - mental processing is always at least potentially conscious, even if much of it in fact is not experienced consciously. But some, like William James (1983, pp. 162ff., quoted in Baars and McGovern, 1996, p. 66), believe that indeed there are no such things as (actually or potentially) unconscious mental processes.
Could there be mind without consciousness, without even the capacity for consciousness? Some people claim that computers can have genuine mental capacities - such as abilities to make intelligent judgments, etc. - while not possessing consciousness. But this is highly controversial. Is 'consciousness' just another name for 'mind'? Most people today would say that there are many things that happen 'within' our mind, or which we do with our mind, of which we are not conscious. Some of these are perhaps processes that we can relatively readily bring into conscious awareness, but which seem to be taking place anyway irrespective of our whether we are currently attending to them or not.
For example when sitting down to eat a meal or working at a computer screen, many things occur on the 'fringe' of our awareness - such as the noise of traffic or trees rustling outside, or the feel of the pressure of one's feet against the floor. Yet it is easy to become aware of those things, to bring them 'into the spotlight' of consciousness. Again, you are likely to have had the experience, while reading, of suddenly realizing that, for the last few seconds or minutes, your mind has completely wandered off the text, even though you've been dutifully scanning the words. Other unconscious processes are perhaps not so easy to bring into awareness - and with some it is perhaps in principle impossible to do so.
Some writers reject the idea of mental processes that cannot be brought to consciousness even in principle. Searle (1992) uses the term deep unconscious to characterise this supposed kind of unconsciousness. He argues that no such deep unconscious mental events ever do occur - that all mental events must be either actually conscious or at least accessible to consciousness in principle. In his view the repressed unconscious wishes and intentions of Freudian theory can exist: they are not instances of 'deep unconscious' states, he says, because they are supposedly accessible in principle (if with great difficulty) under psychoanalysis, and so may be sensibly held to be part of the mental realm. However many functional processes postulated in the models of cognitive psychologists and artificial intelligence researchers - for example in attempts to explain vision-processing or language-understanding - seem to take place completely outside the range of conscious awareness, to be beyond conscious access even in principle. Rather, their existence is inferred on the basis of complex theories which often involve highly sophisticated comparisons between brains and computational systems. Such processes, Searle says, do count as deep unconscious, and in his view, they could not exist or at least could not be considered to be mental in nature. This means that Searle is going against a lot of currently fashionable theory within psychology and cognitive science particularly those theorists who look with favour on computer-based models of cognitive processing.
Computers - mind without consciousness?
According to computational views of mind, mentality relates to the brain rather in the way that computer software relates to the electronic hardware on which it runs. Consider such mental abilities as planning actions, understanding or producing sentences, or recognizing objects from patterns input to our visual organs. Many psychologists, impressed by computer simulations within artificial intelligence (AI), have sought to explain such abilities as they are found in humans or other animals, in terms of complex models based on the details of such AI simulations.
People who favour this approach say that if a computer can simulate visual recognition, however imperfectly for now, then our abilities to do so are likely to based on similar kinds of processes. But such a view does indeed seem to suppose deep unconscious kinds of cognitive processing, as Searle suggests. Clearly such processes are not conscious within the electronic hardware of computers because nothing is (or is that an assumption too easily granted?) In AI-inspired psychological models, the procedures are often thought not to be consciously observable, even in principle. Rather they are inferred entities, like electrons, quarks, and so on, are inferred to exist within physical theory.
According to Searle such inferred processes cannot be thought of as mental because they lack an important feature that all mental events must possess. Searle calls this feature 'aspectual shape' (1992: 156ff.). When I experience or think of something, I think of it 'under a certain aspect'. For example I may be currently conscious of my pet cat under the aspect 'warm cuddly furry creature'. But my neighbour, who has just seen the cat attack a bird in her garden, may experience the cat under the aspect 'hateful scourge of winged creatures in the vicinity'. For Searle, all mental states must possess aspectual shape. But, he says, something can have aspectual shape in this way only if it is capable of being consciously experienced. From this the conclusion is drawn that deep unconscious states cannot be mental states .
The statement that only conscious experiences can have aspectual shape is a conceptual claim on Searles part: it is not based on empirical evidence. Searle would not regard this proposition as the sort that could be disproved experimentally. That may be a weakness in his argument, but perhaps it can be shown to be one only by designing a suitable experiment not necessarily an easy task. But in any case, supporters of computational models of mind who defend the existence of such deep unconsious mental mechanisms may respond to Searle as follows. The notion of mind may be thought of as the exercise of what might, in a very broad sense, be mental productivity'. In order to grasp this notion of mental productivity consider, for example, computers that play chess. There are many chess-playing machines, some of which will beat all but the most skillful of players. Indeed in 1997 the IBM computer company were able to get their program Deep Blue to beat the then reigning world chess champion, Gary Kasparov, in a 6-game match. This caused a big flurry of comment in the press at the time. Was this the final demonstration that machines could think? Now few people would want to assert seriously that Deep Blue was even potentially capable of being conscious of its mental processes. Nevertheless it seems not unreasonable to see it the machine as performing mental operations of a sort - engaging in 'cognitive work', or mental productivity. There are many other similar examples of cognitive work or productivity that one can attribute to computers today, and these will become more common as technology develops for example programs that control robots in factories, or which check a loan applicants credit-worthiness. Productivity is the achievement of the kind of results that we achieve with our minds.
The suggestion is that such productivity has to be considered as mental in the broadest sense, even though it has no necessary connection with consciousness. Computers (if running programs of the right sort) have mental productivity of this kind, even if they are not even potentially capable of consciousness. The deep unconscious cognitive processes that are described in theories of visual perception and other cognitive theories may perhaps be mental in this wider sense. Indeed the actions of ordinary computers and even calculators may be mental in this sense, even though quite unconscious - such mechanisms engage in 'cognitive work' which produce results fit for purpose, even though the mechanisms have no way of themselves consciously benefiting from or making sense of those results. (See Torrance, 1989, n2000a).
Experimental investigations of deep (?) unconscious cognition
Whatever the rights or wrongs of this issue, there do seem to be examples of processes that, on independent grounds one might wish to call mental or cognitive, but which do not seem accessible directly to consciousness, and so may be deep unconscious in Searle's sense. Such processes seem to be amenable to straightforward experimental verification, rather than to be inferences based on broad theoretical models. For example, experiments by Marcel (1983) and others have suggested that there is a process of unconscious 'stimulus coding'. Subjects were shown rapid displays of word stimuli followed by a visual masking pattern, in such a way that they failed to register conscious awareness of the stimuli. They were then shown additional stimuli, and were were found to react more rapidly to the second stimuli when the initial stimulus 'primed' the subsequent one - for instance where the first, masked, stimulus was 'money', and the second one was the word 'bank'.
Another example is the phenomenon of 'blindsight' (Weiskrantz, 1986, Young and de Haan, 1993). Patients with certain types of damage to their primary visual cortex claim that they have no conscious discrimination in some regions of their visual field. Nevertheless, if asked to make a guess about an object placed in the 'blind' region, their success in identifying the object will be well above chance. This seems to indicate that cognitive processing with respect to the blindsighted region is occurring, even though the visual awareness is lost. It seems that the blindsighted patients possess a kind of knowledge of which they can have no direct awareness.
Such
experimental results are controversial, but they do provide accumulating
evidence that 'mental' processes which are not conscious, and which cannot be
brought to consciousness in any straightforward way, even in principle, have to
be acknowledged as occurring - so the mental is not exhausted by the conscious.
PAUSE FOR THOUGHT BOX
Consciousness, non-humans and moral concern.
Let us ask at this stage to what extent consciousness might be attributible to non-human subjects? Many people would be prepared to accept that certain kinds of conscious awareness are to be found elsewhere in the animal kingdom. Perhaps animals, like infants, lack the necessary conceptual capacities to enable them to be subjects of states of self-consciousness.
The case of access-consciousness is more problematic, perhaps. Creatures without language will be unable to report or reflect on their mental states, but they can and do engage in the kinds of deliberate, guided action - such as when stalking prey - that is a mark of access-consciousness. Moroever, few would deny that at least higher animals can experience various kinds of sentient states, and some would insist - for example on the basis of neuroanatomical properties - that there is strong evidence of phenomenal consciousness extending even down to quite primitive kinds of creature.
The question of the attribution of conscious states of different kinds to biological creatures raises some key ethical issues such as beneficence, cruelty, praise, blame, etc. Most people would agree that it would be irrational to feel resentment or ethical concern towards tables or cars or computers (as currently designed, at least). Our sense of the irrationality of such feelings is closely bound up with an intuition that these are not the kinds of object that have sentient states. So there is, perhaps, a close association between having phenomenal consciousness and being a fit subject of moral concern. And only creatures with phenomenal consciousness appear to be capable of experiencing suffering or states of positive affect.
Some would argue that creatures that lack self-consciousness do not really suffer in a morally significant way, and hence cannot be subject to cruelty in the way that humans can. On that view, it could be permissible to slaughter such animals because they are unable to anticipate or reflect on themselves as the subjects as suffering. But if such creatures have phenomenal consciousness, surely they do experience pain, fear, etc., and therefore do suffer. It is left to you to work out your own position on these matters.
What
about artificial consciousness in future machines? In the film The Bicentennial Man, based on a novel
by Isaac Asimov and Robert Silverberg (1993), the main character, Andrew
Martin, is a robot with an electronic brain, which equips him with a very high
level of cognitive and bodily performance capabilities, which are at near human
levels, and in many respects - e.g running speed, manual dexterity - well above
human levels. Andrew Martin is depicted as fulfilling all the standard conditions
for self-consciousness and access-consciousness, while the question is left
wide open as to whether he possesses sentient, or phenomenal, awareness. Could
it be that possessing these cognitive forms of consciousness alone without phenomenal consciousness might
qualify a being as a suitable subject of moral concern? Or would we be wasting
our time feeling any kind of empathy towards such a being if they did not have
any phenomenal awareness? This sort of case, while fictional and speculative,
may help to refine our ideas of the moral status of attributions of
consciousness. (See
END OF BOX
B Special states of consciousness
'Special' states of consciousness: (1) sleep and dreaming.
'Our normal waking consciousness, rational consciousness as we call it, is but one special type of consciousness, while all about it, parted from it by the flimsiest of screens, there lie potential forms of consciousness entirely different.No account of the universe in its totality can be final which leaves these other forms of consciousness quite disregarded.' (James,1958, 378-9)
While most psychological and philosophical investigation of our conscious mental life has focused upon waking consciousness, no study of consciousness can be complete without paying some attention to 'non-standard' or 'altered' states. The distinction between standard and 'altered' states is a rather blurd one. Psychology textbooks usually consider dreaming, drug-induced states, meditative or contemplative states and hypnosis under this heading. Yet there are many other types of situations where one might be thought to be in an 'altered' state: for example during the two or three-minute journey on a white-knuckle ride in a theme park, or in states of extreme emotional arousal such as fear, elation, etc.
Also,
during our 'waking' life it appears that we spend a large amount of time 'lost'
in daydreams or fantasies. Studies of college students in
The most familiar 'altered state' is dreaming. Most humans sleep a third of the day, and roughly a third of this time we dream. There are different brain-wave patterns associated with four or five levels of sleep. Four or five times a night most of us ascend to a shallow level, and this is when dreams occur. A characteristically energetic saw-toothed EEG pattern is recorded, and a rapid eye-movement (REM) accompanies the dreaming. REM sleep was discovered in the 50s by a researcher who measured his small son's eyes shifting periodically during sleep with an EEG machine he was repairing at home (Seligman and Yellen, 1987). Large numbers of subjects have now been tested by being asked to report their experiences during different states of sleep, and reports of dreaming correlate with REM states. In addition to dream-like states during sleep, many people report dream-like states while going into sleep states (hypnogogia) and while waking up (hypnopompia). Memories of the content and existence of these states recede rapidly on regaining normal waking. But if asked to report very soon after dreaming, subjects will often describe very vivid experiences - hence they seem to be forms of consciousness rather than unconsciousness.
Why do we dream? Do we need to? According to Freudian theory (1900), dreams have a manifest content - the narrative or thought-sequences that the dreamer remembers, and a latent content, which is the 'censored' significance of the dream. Freud maintained that the latent content of dreams relates to powerful, but socially unacceptable, wishes or libidinal drives, usually of an erotic nature. Freud believed the function of dreaming is to allow these sexual desires to have some kind of expression, albeit often heavily disguised, so as to free people from having these hidden wishes and fantasies cause overt behaviour that would unduly disrupt normal, 'civilized' society.
Much twentieth-century literature and art - for example the painting of Salvador Dali or Marc Chagall - has been influenced by Freudian psychoanalytic interpretations of dreams and other aspects of mental life. Nevertheless many contemporary critics of Freud are sceptical of this 'safety-valve' account of dreaming. On one alternative theory, dreaming performs a sort of consolidation function, by allowing the brain to 'digest' intensive informational or emotional inputs that have occurred in recent previous waking time. Studies have shown that when deprived of REM sleep we perform less well on memory-conservation tasks (Empson & Clarke, 1970, Karni & Sagi, 1994).
Most researchers agree that we need to dream. Subjects who are deprived of REM-sleep and of the associated dreaming include much more REM-periods in their sleep when allowed to catch up. REM sleep has been observed in most other mammals (but not fish, for example). Dreaming is thus likely to meet a deep function, but there is no consensus on what that function is. However it seems likely that, even if Freud over-stated his case, the activity and content of dreams have helped to condition many aspects of cultural creativity and of our response to such products.
William
Dement is a sleep researcher whose work stretches over four decades. He has
documented the numerous ways that sleep deficit can threaten physical health
and psychological and well-being. His recent book (Dement and Vaughan 2000)
offers a powerful argument to the effect that poor sleep patterns is one of the
key problems of contemporary technological civilization. A useful technical
review of the nature and functions of sleep and dreaming, sleep disorders, etc.
is to be found in Moorcroft (1993). Sleeping and dreaming are also important
topics in Buddhism and other eastern spiritual practices: these subjects formed
the focus of one of a regular series of biennial meetings between the Dalai
Lama and western scientists and philosophers (Dalai Lama, Varela, et al., 1997)
'Special' states of consciousness: (2) hypnosis .
Hypnosis
is another generally acknowledged 'altered state' of consciousness. However,
while a great many people claim to have been successfully hypnotized, many
psychologists challenge the view that there is any special state at all, suggesting rather that it is a social construct. Modern
reports of the practice date from the 18th century physician Anton Mesmer, who
worked in
One highly sceptical view of hypnosis is that people who display bizarre effects in hypnotic situations are highly compliant types of individual who want to believe in hypnosis, and that the phenomenon of hypnosis is a social construction. They are 'buying in', in other words. A contrasting view (Hilgard 1986), based on 'disassociation', is more positive about the status of hypnotism as an altered state of consciousness. On this view hypnosis involves the simultaneous action of two or more cognitive control subsystems in a subject, with separate inputs and outputs, each subsystem operating without reference to the other(s). This may explain why a hypnotic subject can perform acts which they claim later they are unaware of having done. According to Hilgard hypnotic suggestion has activated one control subsystem while other subsystems operate independently, and while the overall monitoring function has been diverted or suppressed.
A
striking effect observed under hypnosis is the disappearance of anxiety about
pain - apparently hypnotically induced analgesia. Some patients have been able
under hypnosis to undergo surgical procedures without anaesthetic. A classic
experiment by Hilgard involves having subject immerse an arm in iced water long
enough to cause intense pain-reactions normally. Hypnotized subjects report
feeling no pain; but if they are asked to press a button with their
non-immersed hand to indicate that they did feel pain in some part of them, the
button is often pressed. Hilgard believes that there is a 'hidden
consciousness' operating in such cases, and that this suggests that hypnosis is
a special state of consciousness, rather than just an amalgam of more everyday
effects.
'Special' states of consciousness: (3) mind-altering drugs, meditation.
Much
work on special states of consciousness concentrates on the effects of
chemicals in altering awareness. Many writers have reported a sense of viewing
a 'deeper', more 'real' level of existence when influenced by certain
mind-altering drugs. For some, but not all, such users, this sense wears off as
the drug's influence wanes. Certain researchers - for example those who have
investigated the use of the drug Ayahuasca in upper Amazonian tribal cultures -
believe that there may be important insights into the nature of mental reality to
be gained from the study of the social rituals surrounding the use of this
drug, and from experience of the drug itself (Shanon, 2000, Luna and White
(eds) 2000)
PAUSE FOR THOUGHT BOX: The ethics of drug research.
Research on mind-altering drugs - particularly its participant aspects - raises important ethical and methodological problems. How should we view the supposed scientific findings of a researcher who is reporting the personal experiences of psychoactive drugs? How objective are they likely to be in evaluating this experience, if the drug has, as one of its effects, to induce a strongly enhanced sense of significance? On the other hand are people who have had no such experiences qualified to judge claims made by such researchers? After all would we trust the judgment of a completely tone-deaf person conducting scientific research on musical experience or activity?
End of box.
There
are at least three basic types of mind-altering, or psychoactive, drugs. Depressants
slow down neural/bodily activity; stimulants
excite it; and hallucinogens induce
distorted perceptual or sensory impressions. Depressants include alcohol (taken
in large amounts), barbiturates and opiates (including morphine and heroin).
Such substances inhibit neural functioning, and effects include a pleasurable
lethargy and a release from anxiety or pain. Stimulants include cocaine and
amphetamines, as well as the more widely used caffeine and nicotine. Effects
include feelings of elation and increased energy, but such feelings may be
accompanied by increased anxiety and bodily arousal. Hallucinogenic drugs (also
called psychodelics) include marijuana and LSD (Lysergic Acid Diethalamide), as
well as ayahuasca mentioned earlier. Such drugs produce distorted percepts
(e.g. seeing a skeleton when looking in a mirror), inappropriate feelings of
power (e.g. thinking one can fly), apparent deep philosophical insights, and
dream-experiences that seem real. Emotional effects may vary from extreme
euphoria to panic.
In the case of almost all of these drugs, tests have shown that the experiences that users report and exhibit are to some extent influenced by social expectations - as appears the case for hypnosis. However, unlike with hypnosis, no one would seriously claim that the effects of psychoactive drugs are primarily social constructions.
All of the drugs mentioned above, and others like them, have marked negative effects or risks. Some, like heroin and cocaine, have unpleasant withdrawal symptoms; some - the hallucinogens - may induce life-threatening delusional states; some, such as alcohol, produce depression, memory loss, impaired reactions, and so on. Clearly, first-hand investigation of these various drugs is hampered by the evident dangers surrounding their use, and by the legal prohibitions on possessing most of them. Paradoxically, because of the fact that many of them are in widespread use notwithstanding the legal restrictions, it is relatively easy to find willing (anonymous) participants for studies of users' descriptions of their experiences.
The term 'altered state of consciousness' covers a heterogenous collection of different kinds of phenomenon, some banal and some less so. The cases we have been looking at all help to widen our picture of what might be understood by that elusive term 'consciousness'. This is true whether we take the states to be different variations of a single, broad phenomenon of consciousness, or rather to be distinctive phenomena in their own right.
There are, of course, other kinds of 'altered state' for example various forms of religious experience, including meditation, or mystical or religious rapture, etc., as well as heightened aesthetic experiences such as are reported by some musicians, actors, and so on. There are also special kinds of dream experiences, such as lucid dreaming (LaBerge, 1998), or anomalous states such as out-of-body or near-death experiences. Some of these examples appear to go together with belief-systems that conflict with certain principles - such as objectivity, material causation, etc. - that seem to be built into the scientific worldview shared by most working psychologists. They (and the other examples of altered states discussed above) also raise interesting puzzles relating to our earlier distinctions between phenomenal, aspect- and self-consciousness. How far do such states neatly respect these conceptual categories? However, as we shall see, the case of consciousness raises a wide range of fundamental philosophical challenges for psychologists. To these we now turn.
C Consciousness and brain-processes: a puzzling
relation
History: behaviorism versus introspectionism
Within the last fifteen years or so, there has been a remarkable outpouring of articles and books from psychologists and neuroscientists discussing a great many aspects of consciousness. An interdisciplinary community has grown up, dedicated to understanding the nature of consciousness. While psychologists, cognitive scientists and neuroscientists are at the heart of this community, they have joined with philosophers, computer scientists, biologists, quantum physicists, and others.
Yet this buzz of investigative energy over the topic of consciousness is a relatively new phenomenon within the scientific community. There is a strong consensus today that consciousness can fruitfully be studied via scientific methods, and via other methods as well - for example through meditation or phenomenological reflection. But it was not always so. For most of the twentieth century, the term 'consciousness' was considered to be off-limits as far as science was concerned; the domain of mystics and loonies rather than of serious investigators.
The view which prevailed in psychology through much of the century is that science can deal only with publicly observable phenomena. It was thought that for psychology to be a science, it must limit itself to investigating behavioural responses of human or animal subjects, under carefully controlled stimuli in a laboratory setting; or alternatively to tracing the structures and functions of the brain and central nervous system. The scientific approaches of behaviorism and of neuroscience thus rejected the 'first-person' data of introspective observation, in favour of 'third-person' behavioral or neural data.
In a famous paper John B. Watson (1913) set the scene for the age of behaviorism:
'Psychology as the behaviorist views it is a purely objective experimental branch of natural science. Its theoretical goal is the prediction and control of behavior. Introspection forms no essential part of its methods, nor is the scientific value of its data dependent upon the readiness with which they lend themselves to interpretation in terms of consciousness.'
Watson was contrasting his behaviouristic techniques with the 'introspective' methods of investigation that dominated psychology at the time he was working. One of Watson's most celebrated intellectual adversaries was William James (1890/1983), who saw psychology as aiming to provide a painstaking description of the contents of conscious processes as they appeared to the attentive subject reflecting inwardly on the processes of his or her own inner experience. James amassed a large number of observations about the character of the inner world of consciousness, on the basis of inner reflection upon his own consciousness, and of reports by others about their conscious experiences.
But Watson regarded all such investigations of the 'inner' nature of consciousness to be scientifically worthless. Psychology hitherto, he wrote, 'has failed signally in the fifty-odd years of its existence as an experimental discipline to make its place in the world as an undisputed natural science'. The method of introspection was, Watson claimed, incapable of being properly repeatable in the way that science demands. If two introspective psychologists disagree on what particular finding is revealed through introspection, what are we to conclude? Each can claim that the other has not been properly trained in introspective technique, or that they had misobserved or misdescribed the results of introspection. But who is to know? The possibility of public, undisputed, objective evidence or data seems, he thought, to have gone out of the window.
Searching for the neural correlates of consciousness
The tradition of behaviourism has dominated twentieth-century psychology and philosophy of mind. However it is now somewhat in eclipse. Of the many other approaches which now at the forefront in psychology, two stand out as particularly influential in the present day - the neuroscientific approach, and the approach of cognitive psychology. Each of these address an important drawback of the behaviorist tradition in psychology. The first drawback was this. It may be appropriate to investigate outward behavioural patterns in subjects, and the perceptual stimuli that conditioned such behavior. Nevertheless it seems very limiting to assume (as behaviourists seem to) that psychologists could have nothing to say about the highly complex mechanisms in the brain itself.
Surely, then, the neurophysiological processes which occur between the perceptual 'inputs' impinging on a subject and the behavioural 'outputs' emanating from the subject are relevant to explaining the psychological state of that subject. Certainly those who actively examine the structure and function of the brain believe this is the case. The gradual growth of neuroscience over the last six or seven decades has taken that discipline from a somewhat shadowy, speculative area, to a firmly established body of scientific knowledge, which is now expanding very rapidly indeed. Neuroscientists have put forward a variety of views about how the brain supports consciousness.
Crick and Watson: Neural Oscillations.
One currently influential view on the 'neural correlates of consciousness', has been offered by Francis Crick and Christof Koch (1990; see also Crick, 1994). Crick and Koch are interested in how consciousness seems, as we saw William James observe, to involve a paradoxical of unity and diversity: at one time we are conscious of many things bound together in a single perception. How does the brain manage to link the various particular perceptions into a unified whole? Crick and Koch believe that if neuroscience can solve the binding problem, as this is called, then this is likely to provide a solution to the puzzle of how the brain generates consciousness. Their solution draws on recent work (see Singer,1995, cited in Searle, 1998, p. 34), which measures the rate of firing of groups of neurons, and which has discovered that different groups in separate parts of the brain appear to fire in harmony. Crick and Koch suggest that neural synchrony in the range of 35 to 70 hertz (times per second) is what produces consciousness in the brain.
Edelman: Neural Darwinism.
Another influential neurophysiological account of how consciousness arises comes from Gerald Edelman (like Crick, a Nobel Laureate). Edelman draws strong parallels between the ways brains develop and Darwinian natural selection theory (Edelman, 1989, 2000). Edelman's 'Neural Darwinism' suggests that brain development follows competitive selectional mechanisms very similar to evolution in natural species - except that the competition in the brain is between neuronal groups rather than between members of a population of organisms. Edelman calls these neuronal groups 'maps' because they are connected in systematic ways to external receptor cells such are found in the retina, or to other maps inside the brain. An important feature of these maps is that the connections are 're-entrant' - that is that one map will connect to other maps that have connections which eventually connect back to the original map. It is this cyclical form of interrelation between that is a key to consciousness for Edelman, which he sees as a dynamic, distributed global activity of linked elements in the brain.
Penrose and Hameroff: Quantum events in microtubules.
Most influential theories of how consciousness arises in the brain see the relevant activity as happening at the level of neurons. A very different sort of theory locates the causation of consciousness at a much smaller scale. Stuart Hameroff has investigated the properties of microtubules - parts of neural protein structure found at the region of the synapse. He has proposed (1994) that certain effects that occur in these structures are so microscopic that classical physics can no longer be used to describe them, and it is necessary to resort to quantum-level explanations. Hameroff, a neurophysiologist, works closely with Sir Roger Penrose, a mathematical physicist. Penrose has proposed a new form of quantum physical theory which, he thinks, is confirmed by research in the properties of synaptic microtubules. Penrose argues (1994a, 1994b) that the quantum effects observed explain how it is that humans can (with their brains) perform mathematical tasks that conventional computers cannot perform, namely recognize special forms of proof called incompleteness proofs (such as the one famously offered by Kurt Gödel in 1933). Humans can understand such proofs, says Penrose, because their consciousness allows them to perform intuitive, non-formal, jumps of understanding that computers, which always, at root, work in terms of formally specifiable steps, cannot achieve. The quantum effects found in microtubules can, say Hameroff and Penrose, provide an explanation for such conscious activity. (For criticisms, see Churchland and Grush, 1995.)
Here,
then, are three of the currently most well-known accounts of how processes in
the brain may cause the occurrence of conscious experience. All of these
theories are highly speculative, but each of them has a chance of being true.
There are many other theories. Other recent accounts of how the study of the
brain may enable us to understand consciousness are to be found in Damasio
(2000) and in
Suppose,
now, that one of these neurophysiological accounts (or a combination of them)
does turn out to provide the true explanation of how consciousness arises in
us. What would that theory have accomplished? It would have explained what
neural (or sub-neural) processes accompany
consciousness. But would it have explained why
consciousness results from those neural processes? And is it the case that the
neural processes are one thing and the conscious experiences are another,
different, thing that the neural processes bring into being? Or are the
conscious experiences the same as the
neural processes? In other words is this an identity
or merely a correlation?
Can consciousness be equated with states of the brain?
We have now now come to one of the most central and elusive questions within modern psychology and the philosophy of mind. Are mental states (and conscious states in particular) identical with brain states? Could it be that the pain I experience when I step on a pin just is a certain set of neural activations (or certain quantum effects in microtubules in my synapses)? Or is consciousness something quite separate from mere neural events?
If
consciousness really did have some other kind of physical existence over and above neural processes, it's difficult
to see what it could be. If it were some physical process apart from the brain,
it would surely have to be some other sort of process in the body - but what? And if not in the body, then where? So could consciousness
be a non-physical process, which
somehow interacts with the brain? That would seem to offend a basic scientific
belief in materialism or physicalism - the belief that everything
in the natural world (including our mental states) must be constituted from
physical events. Most modern psychologists and neurophysiologists assume that
some version of physicalism is true. Classic philosophical defences of
physicalism are to be found in Place,1956 and Smart,
1959 (both reprinted in
Many eminent psychologists - for example Sperry, Libet, Eccles and others, have favoured the non-physicalist alternative - often known as dualism. The classical version of this view is often called substance-dualism, and its most famous exponent was the seventeenth century French philosopher Réné Descartes. The clearest account of Descartes' view is in his Meditations on First Philosophy - first published in 1641 (see Anscombe and Geach, 1964). According to Descartes, the universe is divided into two different kinds of substances: res extensa - the (spatially extended) world of physical objects, known only indirectly via sense-perception; and res cogitans - the world of thoughts, which do not exist in space and which are directly accessible to consciousness. A more modern exponent of this view in psychology is Sir John Eccles, working in collaboration with the philosopher of science Sir Karl Popper. (Eccles, 1980,1987; Popper and Eccles, 1977.) On this view conscious states are special processes, that exist alongside physical processes, and which interact with the latter via certain groups of neurons in the brain, but which are not physical in themselves. There are major philosophical difficulties with this view, which are resolutely tackled by Eccles and Popper.
A more popular version of dualism - property-dualism - says that mental states like consciousness are not in themselves non-physical processes or part of a non-physical substance, but are rather non-physical properties of the physical brain (Sperry, 1985, Libet 1996). Property-dualism is closer to the modern scientific world-view, since it allows conscious processes to be tied more closely to brain-processes - indeed to be properties of the brain (non-physical ones) that emerge as a result of certain physical events. Also perhaps it allows consciousness to be explained as part of natural scientific theory. However we would have to stretch our conception of science so that it included these non-physical properties in addition to the physical properties of the world.
One problem with property-dualism is that it makes it hard to see how conscious processes could themselves have any causal influence on the physical processes in the brain (or in the wider bodily system). For if consciousness were non-physical, how could it affect the brain (or anything else in the physical world) in any way at all? According to this picture, known as epiphenomenalism, consciousness would be like car exhaust smoke - caused by the engine's operation but having no causal influence on that operation.
So property-dualism seems to imply this one-way view of the causal relation between brain and consciousness. But it's hardly inviting. If I accidentally press my hand on a hot radiator, my consciousness of the pain felt in in my hand will - it appears - cause me to move the hand rapidly away (or cause my brain to activate the relevant motor mechanisms). This, and a thousand similar examples, suggest that causation must go both ways - from consciousness to brain as well as from brain to consciousness.
To summarize:
(1) If we suppose conscious processes aren't physical, then we would seem to be pushed towards dualism, and thus to a strange picture of conscious states having no causal influence on physical processes in our brains and bodies.
(2) But if we insist conscious processes are physical, then how else can we explain their nature other than by saying that they're identical with brain processes?
PAUSE FOR THOUGHT BOX: Problems with the Identity Theory
It may seem to be common sense (informed by scientific awareness) to insist that conscious states can straightforwardly be equated with processes in the brain. This view is known as the 'identity' theory. But there are a number of problems with this kind of view, if taken seriously. First, there is what is called the 'knowledge' argument. (Jackson, 1982; see van Gulick 1993 for critical discussion). Think back to the examples of auditory experience given earlier - the clang of an iron bar hitting concrete, the sound of a tennis ball being hit, etc. Think again of what you 'know' in knowing what it's like to hear sounds like. It seems to be a very different kind of knowledge from the sort of knowledge a scientist might gain by finding out about the how auditory perceptions are implemented in the brain. Imagine a neuroscientist who had the most detailed knowledge possible about the neural basis of audition but who had no experience of hearing (because, we suppose, she was born deaf). Now her deafness is suddenly removed, and at last she hears sounds first-hand. Surely what she is gaining is some new piece of knowledge: not just a new way to identify something she already knew all about. This suggests that the experiences themselves can't be directly identified with the neural processes. Consider your own reactions to this example.
There is a second kind of problem for identity theories. Suppose this time that there's a hypothetical world where there are conscious beings, that look and behave very much like humans, but who don't have brains that are physically made up in the way our brains are. Suppose the biology on this world is very different from our own - based on silicon chemistry, say, rather than on carbon chemistry. Imagine one of these human-like creatures - let us call her Jane - leaning against a hot radiator, and withdrawing her hand rapidly, uttering words very like 'Ouch, that was painful', and so on.
Surely it's at least conceivable that Jane is genuinely in pain, or in some unpleasant conscious state very similar to pain. Yet if pains are specifically identified with the neuronal processes that occur in biological systems like ours, then there can can't be pains in this alternative biology. Surely we don't want to have to say that creatures without terrestrial biologies (and who knows what kinds of alternative biologies exist on other planets?) can't have pains or other conscious feelings. Yet that is what the identity theory seems to be forcing us to do. Because according to that view, pains, etc., are literally identical to certain kinds of processes occurring only in brains which are made up according to our biology.
Is there a way of rescuing the 'spirit' of physicalism as a theory of mental states, which allows you an acceptable escape-route from each of these difficulties?
END OF BOX
Functionalism: another physicalist account of consciousness.
We saw, in our discussion of dualist views above, that refusing to equate conscious states with brain states seems to have unpalatable consequences - we find ourselves admitting questionable sorts of non-physical processes. The nature of these non-physical processes seems difficult to explain. It also seems hard to see how such non-physical processes can interact with physical processes, such as those going on inside the brain.
However accepting the equation "conscious processes = brain processes" (as identity-theory does) seems to have its own awkward problems. One very basic problem with admitting that conscious states really are identical with brain states, is simply that they appear to be so different. Certainly, people can be aware of pains and other conscious feelings without any knowledge of neuroscience - and have done for most of the history of human life. There's a real mystery about how the richness of first-person experience could actually be equated with any process in the brain. As Colin McGinn has famously put it: 'How can technicolour phenomenology arise from soggy gray matter?' (McGinn, 1989, 349).
There are other problems with the identity theory (see Pause for Thought box). However we will now briefly consider an alternative kind of theory which still allows conscious states to be physical properties. This kind of theory is often called 'functionalism'. Put very simply functionalism says that conscious states, like pain, and so on, are to be identified by their causal role, rather than by their underlying physical make-up. (But such states can still be physical, just as the software states on a computer are physical even though they aren't identical with the computer's hardware.)
The notion of function, or causal role, that is operating here, is one which can be understood independently of any particular way in which it is implemented or realized. This idea is commonly referred to as implementation-neutrality, a notion in fact familiar to us within everyday life. For example, a journey between London and Edinburgh could be taken by train, by coach or by car. These three methods of transport are three alternative ways of implementing the plan of getting from London to Edinburgh. Again, a football game can be seen by watching TV or by going to the stadium. Similarly one could use a brush and pan or a vacuum cleaner to clear up sugar spilt on the kitchen floor. In each case there is a common function (end), and there are different implementations (means).
Computer technology illustrates implementation-neutrality to perfection: the same software - a particular make of web-browsing program, for example - can run on different brands of computer, with different kinds of processor inside, where each computer will perform identical (very similar) operations and display similar things on its screen in similar situations while the program is running on its hardware. So we identify the software by its functions rather than the physical mechanism that happens to be realizing those functions. (For presentations of types of functionalism that lean heavily on parallels with computational processes, see Turing, 1950, and the extensive writings of Daniel Dennett, particularly his 1991 and 1998. Critiques of computational functionalism by John Searle are widely published. See, for example, his 1980 and 1998.)
In a
similar way we can talk of the functional role of conscious states. For
example, as a crude approximation, one might say that the 'functional role' of
pain is to act as a signal of danger to the body, by activating various other
causal processes that instigate necessary motor outputs. On this functional
account pain is a sort of causal intermediary that plays its role along with
other states, so as to enable the organism to maximize survival and well-being.
(For broader philosophical accounts of functionalism see Sober, 1990, Fodor,
1982.)
A functionalist example: global workspace theory.
The functionalist approach within psychology has led to a number of distinctive kinds of theory of consciousness. In contrast to neuropsychological theories, these theories talk less about neural implementation, and more about the abstract, or high-level roles that consciousness plays in the overall psychological economy.
One
well-known example of a functional theory of consciousness is the 'global workspace' theory of Bernard
Baars (1997; Baars and McGovern, 1996). According to Baars, consciousness has a
variety of different functions (see box).
CRITICAL THINKING BOX: What functions does consciousness perform?
Here are some functions of consciousness proposed by Bernard Baars. Check through this list. Do you agree that all these are functions that consciousness performs? Are there any functions that are left out of this list, in your view?
Proposed functions performed by consciousness (Paraphrased from Baars and McGovern, p 91-92.)
· it allows an organism to resolve ambiguities in perceptual inputs, by setting a context;
END OF BOX
Baars's
Global Workspace (GW) theory contains a number of elements.
First there is the idea that our actvity is managed by a very large number of specialized processing subsystems that work unconsciously - for example groups of cells in the cortex that control various linguistic production or recognition functions, or vision neurons that are activated by line-orientations.
Second the theory supposes that there is, within the brain a capacity for broadcasting 'messages' which these specialized unconscious 'experts' can send to one another. Baars uses different metaphors for this - sometimes a blackboard with notes posted on it; sometimes a spotlight trained to different parts of a darkened stage. Baars understands this blackboard or stage in terms of the concept of 'working memory' as used widely by cognitive psychologists.
Third, there are contexts. These are coalitions between the unconscious experts that are set up during the life-time of the organism behind the scenes of consciousness - they can be short-lived or very long lasting. Baars gives the example of the word 'set' - which will be interpreted one way in the context of playing tennis and another way in the context of watching the sun go down.
An
illustration of how GW theory works is as follows (ibid p. 91). Consider a
smoker who is just about to light up another cigarette. She catches sight of
the health warning on the packet, which brings the act of lighting up into the
conscious spotlight, which sends a contextualizing message to a
'long-term-survival' coalition that (with luck) halts the act of smoking.
Problems with functionalist theories
Supporters of functional (or 'cognitive') theories of consciousness, like Baars, regard themselves as explaining organizational roles that are implemented at a lower level by neural hardware or 'wetware'. But their theory looks at the higher, organizational level rather than at the hardware itself. For this reason their theories do not suffer from objections to do with alternative biological implementations (see pause for thought box, above). So a hypothetical being with an alternative biological makeup could, in principle, be conscious on Baars' theory, so long as their hardware did implement the various elements of a GW system.
But
although such theories do an admirable job of explaining how consciousness fits
into a wider mental organization, do they actually explain why conscious
experiences have to feel the way they do, or why they have to feel like
anything? Could it not be possible to build a very complicated robot that
implements all the various features of GW theory, but which was completely
unconscious? The objection to functional theories of consciousness is, then,
that such theories don't really do what they set out to do. They aim to explain
why phenomenal consciousness occurs. But all they do is give a detailed account
of the organizational structures that creatures with phenomenal consciousness
must have. So the theories exhibit an 'explanatory gap', in Joseph Levine's
phrase (1983, 1993). If there wasn't such a gap then when we understood the GW
theory (or some theory like it) we would understand why it was that any being
exemplifying the account just had to be conscious, that it was unthinkable that
they were not. But this doesn't seem to be the case: it looks as though one
could build an artificial model that had all the functional features of the GW
theory, but which wasn't actually conscious.
Can there be a scientific theory of why we are conscious at all?
We are left somewhat with a dilemma. Current psychological theories of consciousness seem to be of two main sorts. One type concentrates on the neural hardware that realizes consciousness. Another type concentrates at a more abstract level of functional organization. Both types of theory seem to be telling us part of the complete story of consciousness. The first tells us about the varying causal roles played by conscious processes in a wider mental economy. The second tells us how these causal roles are implemented in actual neuronal (or sub-neuronal) structures. But neither type of theory seems to be giving us a crucial part of the explanation - namely why these functional or neuronal processes have to have any kind of phenomenal 'feel' at all. Why couldn't the physiological states or the functional roles have occurred without anything phenomenal going on at all? David Chalmers has called this, in a couple of influential articles (1995, 1997), the 'Hard problem of consciousness'.
According
to Chalmers, any neurophysiological or functional explanation of consciousness
will always suffer from a severe limitation. Any such theory is taken by its
supporters to be physicalist in character, in the way that was explained above.
That is, the theory is designed to supply a physical mechanism which is
intended to provide just the right reason why consciousness arises in us. But,
Chalmers says, we can surely imagine a hypothetical universe, just like ours,
in which all the same physical events occur, but in which consciousness is
missing. This is the so-called zombie scenario (see box). If this argument is
correct, then any attempt to explain consciousness in terms of a set of purely
physical causes - whether neurophysiological or functional or what - must be
doomed. Consciousness must have either a non-physical explanation or no
explanation at all (at least not one we can rationally grasp).
CRITICAL THINKING BOX - The zombie scenario
The philosopher David Chalmers writes that we can imagine an exact physical replica of our universe, exact down to the last electron,existing somewhere far away from us in its own space and time locality. Because it duplicates (within its locality) all the physical properties of our universe, it will necessarily implement all the functional properties. So therefore the same conscious states ought necessarily to arise in this duplicate universe, if the physical nature of events in our really do provide an explanation of consciousness. It should be necessarily implied by the very thought of such a physically identical universe, that all the same conscious events will be present in that one as are present in ours.
The underlying reasoning for this is the following general principle:
If there is a purely physical explanation of phenomenon Y, and X is the physical process that explains Y, then whenever X occurs (including in any imaginary but logically possible universe), Y must necessarily occur also.
But, Chalmers argues, this supposition can be shown to fall victim to the following zombie scenario. Theres no self-contradiction in supposing that the inhabitants of this universe, despite their functional and physical similarities to us, are zombies that is, that although they appear to be intelligent and sentient beings, they in fact have no (phenomenal) conscious states at all. If such a zombie universe is describable without contradiction, then it looks as if no theory of a physicalist kind could explain how consciousness arises. Here would be a case where the same physical processes (X) must occur (because the universe has a totality of physical events identical to ours) but the conscious phenomena (Y) do not occur. (See Chalmers, 1996, especially ch. 3)
Chalmers thinks that instead we should be looking for a non-physicalist explanation for consciousness: that we should accept, in other words, a dualist view, according to which conscious states are not reducible to physical processes at all, but have their own special kind of - extraphysical - existence. Chalmers is confident that there could be a scientific theory of consciousness, but that we will have to extend the bounds of scientific theory to include non-physical processes as well as physical ones. (See Chalmers, 1995, 1996, ch. 4, and 1997; also the numerous other papers of his on his website, cited at the end of the chapter.)
You might wish to take a moment to try to imagine the kind of zombie universe Chalmers is describing. A depressing kind of place. All the bustle and vigour of our own world universe, but no phenomenal awareness present. But unpleasantness apart, is such a universe 'logically' absurd? For that to be the case there would have to be some kind of logical self-contradiction (like trying to imagine a 5-sided square: a figure that has exactly 4 sides - that follows from the definition of being a square - but that also has 5 sides, not 4 sides!).
Can you find a self-contradiction like that in the description of the zombie universe. If not, it would be harder to conclude that Chalmers is wrong. Also, consider if you agree that it would indeed follow from Chalmers' argument that consciousness must be understood to be a non-physical process?
END OF BOX
Not everyone agrees with Chalmers argument. Some people argue that the zombie scenario he describes is indeed self-contradictory, or is at least conceptually incoherent in some deep sense. If that were so, then perhaps some form of physicalist explanation could be saved after all (see, for example, Nagel, 1998).
Some writers - for example Colin McGinn have drawn rather pessimistic conclusions from such reflections on the difficulties of explaining consciousness. They are called 'mysterians'. They say that how consciousness comes to be present in our neuronal structures is something which we could have no understanding of. McGinn agrees that there must be some reason why our brains must necessarily be conscious in the way they are. But, he says, our brains may not themselves be able to understand how that necessity comes about - the reasons for consciousness might be ones to which we are 'cognitively closed', just as chickens are cognitively closed to understanding chess.
So we are left with our earlier question: could phenomenal consciousness be explained within a scientific theory at all? Perhaps science will one day show how phenomenal states are correlated with various neural processes. Maybe there could be a fully-developed theory of functional organisation, along the lines proposed by Baars or some variant theory. But such accounts may just have to leave it as a brute fact, inexplicable by scientific theory that such neural or functional processes do generate conscious experience. Certainly there is a challenge here that no-one studying consciousness can afford to take lightly. But researchers are coming up a variety of responses to the challenge. And this is making the study of consciousness one of the liveliest areas of debate within modern science.
Future directions
As stated earlier, consciousness research is now a lively area of interdisciplinary cooperation. A lot of work is being done to establish the neural correlates of consciousness. Much work is based on perfecting neural imaging technologies such as Computer-Assisted Tomography (CAT) and Magnetic Resonance Imagery (MRI) in order to extend the empirical base of this knowledge. Functional theories such as that of Baars, are being progressively extended and brought into closer harmony with work on neural implementation. One of the key issues on which researchers are collaborating is the so-called 'binding problem' - how is it that our conscious experience succeeds in integrating the various disparate elements that seem to be processed by physically distinct subsystems in the brain? Another key theoretical issue is how consciousness evolved - what adaptive function can it be shown to have played in evolutionary selection? This is linked to another question about evolution: how phylogenetically recent or ancient a phenomenon is consciousness? Various researchers continue to build computer or robotic models that, they claim, display prototypical conscious properties, but such claims are highly disputed (as is more or less every claim made in consciousness research). Computer models are becoming a lot more sophisticated, bringing in concepts from evolutionary biology, dynamical systems in physics, and other theoretical approaches to complex systems.
There is also growing emphasis on what are called 'first-person' methods. These involve careful reflexion on the structure and content of conscious experience itself, using methods based on European phenomenology and meditative techniques. (Varela & Shear, 1999, Thompson, 1999). Other theorists are looking more and more deeply into the possibilities of quantum physics for showing how consciousness comes to be present in the physical universe; and many are exploring a view of the universe, inspired by the uncertainty principle in quantum physics, that suggests that consciousness may be a fundamental aspect of all physical systems (panpsychism).
All of these themes are likely to be pursued over the next ten years, making it certain that consciousness will become one of the liveliest branches of scientific psychology. But what is very unlikely to happen in that time-frame is that a widely-agreed answer will be given to the really 'Hard Problem' of consciousness, that is the question of whether consciousness can be fully explained in terms of any physical process at all, and if so, how.
Summary of chapter
We have seen that consciousness raises great puzzles. Everyone can recognize it in themselves, yet it is difficult to pin down in a theoretically rigorous way. Can we even be sure that others besides ourselves our conscious, given that we can apparently only engage with their consciousness in an external, third-person way, rather than in the direct, first-person way that we encounter our own experience? We have distinguished between access-consciousness and phenomenal-consciousness. The first relates to the way consciousness is part of the way our mind performs tasks (for example, its via our awareness of a grating noise that we distinguish that sound from others). The second, on the other hand, concerns the experienced quality itself what it is like to hear that noise. We also discussed self-consciousness, and we looked at theories of the unconscious. Are all mental events at least potentially conscious, or can there be kinds of mental process which are not even in principle accompanied by a consciousness of their occurrence.
Could there be computers or robots with genuine mental states, for instance that do not have the capacity for phenomenal consciousness? The creation of artificially intelligent beings, with mind but no experience, might raise moral questions; but the creation of fully blown artificial consciousness would raise even deeper ones. This suggests that there is a close relation between consciousness and ethical matters; debates about animal consciousness confirm such a relation.
We examined special states of consciousness, such as sleep and dreaming, hypnosis, mind-altering drugs and meditation. Such states suggest that any full theory of consciousness will have to be complex indeed to take proper account of all such phenomena. They also raise deep questions of whether our normal, everyday levels of waking awareness represent a gold standard by which to judge other states, or just a level of impoverished humdrum banality to which most of us are condemned but which a fortunate few are able to transcend.
There have been a number of influential theories within psychology and within philosophy relevant to consciousness. The introspective method favoured by William James and others saw conscious experience as at the heart of the mental or psychological domain. Behaviourists like Watson banished experience to the anti-scientific fringe. Only in recent decades have psychologists and philosophers started to look once again at inner processes. The progress of the brain sciences has led to a flowering of neurophysiological theories of consciousness. But the idea that consciousness can just be thought of as identical with particular neuronal processes raises many philosophical difficulties. We examined contrasting functional theories of consciousness for example the global workspace theory - which seek to explain consciousness in terms of higher level causal roles in an organisms mental economy. We saw that any attempt to explain how consciousness arises in us in purely physical terms is open to philosophical challenge.
Some people for example David Chalmers have argued that the only way forward is to assume that consciousness is a non-physical phenomenon. According to his view it may still be accounted for scientifically, but we would have to broaden our conception of science to include non-physical as well as physical processes. Such a view is not widely shared, but it has been part of a new recent ferment of discussion which has seen consciousness regain its position as a serious topic of scientific inquiry.
Some study questions
Further reading on consciousness
Note: The following items (some of which are also cited in the references to the chapter, see below) are highly selective. There is now an enormous wealth of published books, collections and journal articles on the wide range of issues in the study of consciousness, with more being published every month.
Collections:
Blakemore, C. and Greenfield, S. (eds). (1987). Mindwaves: Thoughts on Intelligence, Identity and Consciousness. Oxford: Basil Blackwell.
Block, N., Flanagan, O. and Güzeldere, G. (eds.) (1997). The Nature of Consciousness: Philosophical Debates, Cambridge, MA: MIT Press.
Davies, M. and Humphreys, G. (eds.) (1993). Consciousness: Psychological and Philosophical Essays. Oxford: Blackwell.
D. Dennett, Brainchildren, Essays on Designing Minds, London: Penguin Books
Edelman, G. and Tononi, G. (2000), Consciousness: How Matter Becomes Imagination London: Allen Lane..
Greenfield, S. (2000) Brain Story. London: BBC Publications.
Metzinger, T (ed) (2000) Neural Correlates of Consciousness: Empirical and Conceptual Questions. Cambridge, MA: MIT Press.
Searle, J. (1992). The Rediscovery of the Mind. Cambridge, MA: MIT Press.
Searle, J. (1998). The Mystery of Consciousness. London: Granta Books.
Shear, J. () Explaining Consciousness: The Hard Problem,
Varela, F. and Shear, J., eds., (1999). The View Within: First-person approaches to the study of consciousness. Special issue of the Journal of Consciousness Studies, vol 6, (Feb/March)
Velmans, M. (ed.) (1996). The Science of Consciousness: Psychological, Neurophsychological and Clinical Reviews. London: Routledge.
Velmans, M. (ed.) (2000) Investigating Phenomenal Consciousness: New Methodologies and Maps, Amsterdam: John Benjamins (due around October)
Books:
Chalmers, D. (1996) The Conscious Mind: In Search of a Fundamental Theory, NY: Oxford University Press.
Crick, F. (1994). The Astonishing Hypothesis. The Scientific Search for the Soul. London: Simon and Schuster.
Damasio, A. (2000). The feeling of what happens: body and emotion in the making of consciousness. London: Heinemann.
Dennett, D. (1991). Consciousness Explained. London: Penguin Books..
Levine, J. (2001) Purple Haze: The Puzzle of Consciousness. New York: Oxford University Press.
Varela F., Rosch, E., Thompson, E. (1991) The Embodied Mind: Cognitive Science and Human Experience. Cambridge, MA: MIT Press.
Velmans,
M. (2000) Understanding Consciousness,
London: Routledge.
Journals
Journal of Consciousness Studies.
A major interdisciplinary journal on all aspects of consciousness that has helped to shape the field. Website:http://www.imprint.co.uk/
Consciousness and cognition.
A journal of the Association for the Scientific Study of Consciousness. Website: http://www.apnet.com/www/journal/cc.htm
Psyche.
An
online journal of the Association for the Scientific Study of Consciousness.
Website: http://psyche.cs.monash.edu.au/
Relevant web sites
http://www.consciousness.arizona.edu/
Center for Consciousness Studies in Tucson, Arizona - a major world centre for research in consciousness. The home of the conferences on 'Toward a Science of Consciousness', which have been held in Tucson every other year since 1994.
http://www.u.arizona.edu/~chalmers/index.html
The home page of David Chalmers, one of the major philosophical researchers on consciousness. A number of his key papers are available to be read online. The website has a comprehensive set of links to many resources, including online papers by many others in the field, a comprehensive bibliography, a miscellany of websites that will be of interest to researchers on consciousness, and much else.
Web site of the Association for the Scientific Study of Consciousness: the main world-wide organization for scientific research in this area. It has organized an annual conference since 1997, and has also links to several electronic seminars on topics in the psychology and neuroscience of consciousness.
Comprehensive Cognitive Science online archive compiled by Stevan Harnad, of the University of Southampton. A compilation of online papers on psychology, neuroscience, philosophy and artificial intelligence, with a large number of entries on consciousness
http://www.gold.ac.uk/academic/ps/velmans.htm
The website of Max Velmans, Goldsmiths College. Velmans is one of the foremost UK psychologists researching into consciousness.
http://mind.phil.vt.edu/www/mind.html
Mind-brain resources, from Valerie Gray Hardcastle at Virginia Tech. An website packed with an extensive set of resources. Some are from her own institution, but there are many links to other interesting material all over the web relevant to consciousness, the mind and related matters.
http://www.consciousness.arizona.edu/pcs/pcs.html
Phenomenology and the Cognitive sciences - a project linking studies in psychology, neuroscience and the philosophy of consciousness with intellectual currents in continental phenomenology as found in the writings of Edmund Husserl, Maurice Merleau-Ponty, etc.
The
Brain Project - an Australian website that has some interesting historical
material, plus interviews with some important consciousness researchers.
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