This is a mini-paper in which I discuss first my general approach to the study of consciousness, and then some of the specific ideas that this has resulted in.
We will know for sure the correct approach to studying the problems of consciousness when we have finally solved them. Any given approach means making some assumptions in advance about what the answers are likely to be. So I will not attempt to prove that my approach is the correct one, rather I will just state it and let the reader decide if they think that my way is a good way to proceed.
There are three major aspects of consciousness that any complete theory must deal with:
I believe that eventually we will be able not only to describe the three aspects separately, but also to describe the precise relationship between them. My approach is unashamedly materialistic and Darwinistic. But even within the framework of Darwinistic materialism (or is it materialistic Darwinism?) there is room for variation. So I will state a further assumption:
A) Consciousness is a definite entity which has a specific function and specific physiology to support that function.
Among other things, this is an explicit rejection of Eliminativism, the idea that consciousness does not really exist, and Epiphenomenalism, the idea that it does exist, but that it does not really do anything. To prove that consciousness does exist and does actually do something, consider that there are some situations which can only be dealt with effectively in a conscious manner, for example any situation which is too complicated or novel to handle "non- consciously" (I will follow this idea up in more detail later on).
Another idea that this also contradicts, but more subtly, is that of Emergence. The idea of Emergence is that if you have enough of something, then consciousness appears as a result. The exact thing that there has to be enough of varies somewhat (among different proponents of the concept), but it can be enough neurons connected together, or enough information being processed, or enough knowledge stored and used. In all cases Emergence allows for consciousness to have a function, but denies the existence of any specific physiological implementation. It is difficult to prove that Emergence is wrong, but I would note that usually when a given system implements a given functionality there is some specific hardware (or maybe software) that explicitly implements that functionality. To give a silly example -- one might observe that large cars tend to have power steering, but power steering does not just "emerge" from the largeness of the car.
It could be argued at this point that scientists have looked for a specific "consciousness module" in the brain and failed to find it, and that this is precisely why Emergence, Epiphenomalism and even Eliminativism are given serious consideration. But returning to the three aspects, I would note that it is a little bit dangerous to decide that we cannot find any specific physiological implemenation of consciousness, i.e. aspect 3, when we are not even clear about what it is that consciousness does or what it is for, i.e. aspect 2. It could be that when we have a clear idea about what consciousness does, we will be able to pinpoint its location and physiological implementation, and it will turn out to be some aspect of the brain's physiology that was already known about but whose purpose was not well understood.
A more detailed objection to the idea of conscious modules is that there are specific brain modules that are responsible for specific types of information processing, e.g. understanding visual images, or coordinating specific programs of muscular activity, but these modules are active whether the information processing in question is conscious or not conscious. My reply is that either there is some specific conscious module, and it is one which is connected to all the other modules, or, there is some physiological implementation of consciousness that is spread out among all the modules, or some mixture of both. To give a concrete possibility, there may be some group of neurons which emit a special neurotransmitter and which transmit it to large areas of the brain, and this group specifically implements some aspect of consciousness, and at the same time the receptors for that neurotransmitter are necessarily distributed over a large area, and they too can be considered to be part of the implementation of consciousness.
The concepts of input and output are central to understanding information processing. In most if not all cases the behaviour of any information processing system can be described in terms of three things -- (1) input, (2) internal state, (3) output. The output of the system at any time depends on its input at that time and its internal state, and the internal state at any time depends on its previous input and its previous internal state. The description of the internal state can often usefully be divided into two components: short-term state reflecting the production of output information as a function of input (over the short term), and long-term state representing the "learning" or "memory" of the system.
All theories and observations about how the brain and nervous system work can be described in terms of input/output and, where necessary, internal state.
As I remarked above, it is observed that there are many types of information processing that occur in the brain, which can occur either with consciousness or without consciousness. If we believe that consciousness is a definite something with a definite purpose, then the implication is that information processing in which consciousness is involved is different in some way, and that the involvement of consciousness helps to solve the processing problem.
We therefore want to know: what is this extra something that consciousness adds to information processing? A good starting point is to refer to our own experience of those information processing activities which sometimes occur consciously and sometimes occur non-consciously, and ask -- When is it that consciousness is required and when is it not required?
Two classical examples often given in this sort of discussion are driving a car and playing the piano. The general conclusion in both cases is that the task can be performed with less or even no involvement of consciousness if the performer is well-practiced, and if the current situation in which the task is being performed is not out of the ordinary. The beginner will have to perform the task consciously, and even the practiced expert will bring consciousness into it if something new or difficult comes up (driving is perhaps more subject to unexpected difficulties than piano playing).
The observation that we need consciousness to deal with the unfamiliar and the difficult is not new. We can also observe that consciousness is in some sense a limited resource. We can only be conscious of one thing at a time. The more things that we can be well-practised in and deal with as familiar, the better, and conversely too much newness and unfamiliar difficulty will overwhelm our ability to respond to situations in an effective and timely manner.
Knowing that we need consciousness for the unfamiliar and the difficult does not tell us what benefit consciousness actually confers in such situations. So now I will spell out my theory as to what consciousness actually does -
And how does it modulate normal information processing?
I hypothesise that consciousness changes information processing in the following way -
In 1, Benjamin Libet observes that the formulation of intended response occurs before conscious awareness, but that conscious awareness of the intention precedes final activation of the response, allowing for consciousness to play a veto/confirm role.
I have looked at what the physiological correlates of consciousness might be assuming this theory to be true. The various diffuse modulatory systems seem the most likely candidates -- (1) because they have connections to large areas of the brain, and (2) because drugs that are known to act on these systems are in one way or another "consciousness-altering".
The first such diffuse modulatory system is the noradrenergic system consisting of the small body called the locus coeruleus which projects onto many different parts of the brain. The locus coeruleus appears to react most strongly to novel and non-painful stimuli. This is the nearest thing that I am aware of to a "non-routineness detector". I therefore propose that the action of the locus coeruleus represents the first stage of conscious information processing.
Another diffuse neurotransmitter is dopamine. The action of dopamine appears to divide approximately into two systems. One is the mesocorticolimbic system which apparently forms a reward system. Rewards (and punishments) certainly play an indirect role in the operation of consciousness and I will discuss them more later. The other dopaminergic system is that which projects onto the striatum, and whose action is primarily correlated with the performance of voluntary muscular behaviours. This seems to match up with the final confirmation that I propose occurs as the last stage in conscious information processing.
What goes on in between is more difficult to discern. From the work of Damasio et al.2, which shows the importance of emotion in decision-making, I must presume that the emotional areas perform a major role providing input to the final decision to confirm or not to confirm.
There is indirect evidence that serotonin plays a role in dealing with potential objections to putative conscious responses. Serotonin agonists such as fluoxetine (Prozac) are effective in treating disorders of both depression and anxiety, and both of these conditions can be understood as ones in which the patient has difficulty ignoring objections to proposed courses of behaviour. In the case of anxiety the objections relate to the cause of the anxiety, in the case of depression they arise from a general pessimism about the outcome of any course of action. The implication is that serotonin takes part in the process by allowing objections to be ignored or overridden, and also perhaps by recording the fact that objections were overridden so that the strategies that caused them to be overridden can be held accountable should it later turn out that the objections were valid.
The other well known diffuse modulatory system involves acetylcholine, but I have no evidence as to what role if any it plays in consciousness.
Free will and determinism have been discussed and argued about for centuries. The discussion centres around a number of questions -
In terms of my three aspects of consciousness, we can see that much of this discussion centres round the subjective aspects and physiological aspects of free will.
The subjective experience of free will is enough to convince many that it really does exist and that it really is in some sense unpredictable.
The apparent conflict between deterministic physical law and non-deterministic free will has given rise to speculation about the physical basis of free will. (Those of a non-materialistic bent like to regard free will as proof that there is more to life and reality that physics.) The discovery of non-deterministic quantum mechanics seemed to provide a possible answer.
Investigation of chaotic dynamics suggested that even classical physics is -- for practical purposes -- non-deterministic, because arbitrarily small initial perturbations of a dynamic system cause large variations in its state at some later time. Some have followed this idea and suggested that the brain may operate chaotically. It is important to remember that even very simple systems can behave chaotically. It is thus possible that, even if the brain does behave chaotically, the basic components of the brain are essentially non-chaotic, and that it is only the highest level of organisation and connection between different modules that results in chaotic behaviour.
Less effort seems to have been spent on investigating the functional aspect of free will. If there is such a thing as free will, what is it for? What does it achieve? For the religious thinkers who think about the concept the answer is fairly obvious. Free will is something that defines responsibility, and it is used to resist temptation. Life is a battle in which free will struggles against temptation. It's good if free will wins, bad if it loses.
Within the framework of Darwinism we also see that life is a battle, but it is a battle won by the most successful reproducer. When free will struggles against temptation, it may be that sometimes reproduction is most successful if free will wins, and sometimes it is more successful if temptation wins.
To get a better idea of what free will might be for, we can consider what behaviour would be determined by if free will did not exist. The most common presumption relates to the aforementioned idea of free will against temptation -- if there was no free will, then temptation would determine behaviour. To translate that into more biological language, instincts would directly control our behaviour.
The Behaviourist theory of operant conditioning more or less said precisely that, that the learning of behaviour was controlled in a precise way by reward and punishment, reward and punishment being defined in terms of the satisfaction or otherwise of biological drives. Behaviourism was thus seen by many as a direct denial of the existence of free will (and therefore much despised).
If free will does exist, then this implies that behaviour is not directly controlled by expectation of reward and punishment. A simple and popular proof of this is the observation that one can choose to do something that would generally be regarded as unrewarding, for example to pinch oneself very hard, or to miss a couple of meals.
Yet even those who insist that free will exists will admit the existence of a tendency for behaviour to be controlled by reward and punishment. In fact this is what temptation is all about. One way to measure this tendency is statistically -- for example not everyone goes to the beach when it is sunny, and some individuals may decide not to (just to demonstrate their decision-making ability, or because they don't like going to the beach at all), but it is very likely that many more people will go to the beach when the weather is warmer and sunnier.
I will now consider three plausible hypotheses as to the function of a free will which is non-deterministic and which in particular reduces the extent to which behaviour is determined by biological drives:
Hypothesis 1 does not require the basic mechanism of free will to be anything more than simple randomness, but it does not explain all the features of free will, especially major resistance to temptation. It also fails to explain the idea that there is some essential "I" which acts when free will influences behaviour.
Hypothesis 2 is to some extent orthogonal to the question of non-determinism. Drives may be culturally acquired, but whether they are or not is independent of whether or not drives directly control behaviour.
Hypothesis 3 seems the most paradoxical, but the paradox can be reconciled if we allow that free will is a system for ignoring or resisting biological drives in the short term in order to satisfy them better in the long term.
I have discovered a simple metaphor which may explain how this can come about. Consider a manager running a business. In the long term businesses tend to seek increased profits. Yet in the short term the person in charge of the business can take actions which are not profitable. Sometimes it is necessary to take actions which are not profitable in the short term in order to increase profit in the long term. But they cannot persistently take unprofitable actions because if they do then they will run out of money. The possibility of bankruptcy is the constraint that forces a business to take at least some account of profit in the long term. A second constraint also acts on a business in a competitive economy -- there can be no straightforward way of making a guaranteed level of profits indefinitely, because if there was, then other businesses would take advantage of the same opportunity, and the competition would raise input prices and lower output prices until the profit disappeared.
I propose that some similar constraints act on human free will. Free will can resist temptation in the short term, but it cannot ignore it persistently unless there is some compensating benefit that results. There must be some state of mind that corresponds to "bankruptcy". The best candidate seems to be depression, since this is a state in which the ability to take actions which do not result in immediate benefits is severely reduced. The connection between depression and serotonin mentioned above suggests that serotonin may be some sort of "currency".
I believe that there also exists a process whose effect is similar to that of competition on a business, i.e. it prevents the permanent existence of any steady source of profit. Rather than introduce competition, this process adjusts the effects of reward and punishment on free will so that only the difference between actual and expected rewards and punishments has an effect. In the long term, as our expectations are altered by experience, expected rewards and punishments will tend to match actual rewards and punishments, reducing the difference and therefore the effect to zero. A prediction that this makes is that it is possible for the non-occurrence of reward or punishment to have a strong subjectively observed effect, if the non-occurrence in question is unexpected. This is indeed the case, and we call these effects disappointment and relief respectively. Not only are they subjectively felt, but disappointment increases depression and relief reduces it.
I have discussed consciousness as a system that deals with non- routineness by (1) recognising non-routine situations, (2) provoking a putative response, (3) considering objections, and finally (4) confirming or vetoing. I have discussed free will as a system which disconnects behaviour from reward and punishment in the short term. To form a complete theory it will be necessary to link these two sub-theories. As suggested by the serotonin connection, it is the strategies that determine whether or not to confirm putative responses (guided by emotional feelings), which must be the strategies that are held to account in the long term by the action of rewards and punishments, and it is these strategies that control "free will". They represent the essential "I".
Another major aspect of consciousness that must be dealt with is attention. Attention is something that determines, at least to some extent, what it is that comes into conscious awareness, i.e. the input to consciousness. Attention is also something that can be under voluntary control. Thus consciousness has the means to control its own input. This much we can know from our subjective experience of attention.
As I mentioned before, consciousness is a limited resource, in that we can only consciously perform one task at a time. The importance of attention is therefore to have a means of directing consciousness where it is most needed.
A rough description of attention is that we become aware of stimuli that we pay attention to. But two qualifications must be applied to this statement. One is that attention only partly controls awareness. If some stimulus outside what is being attended to is sufficiently strong or unexpected or important, then we will become aware of it anyway. The second is that attention must be paid before a stimulus occurs, if attention is to cause that stimulus to enter conscious awareness. Thus attention must necessarily be directed at some particular class of stimuli rather than some specific stimulus, because the direction of attention has to be determined before the specific stimulus occurs.
These considerations suggest the following model of how attention works:
If we allow that attention and awareness are distinct although related features of consciousness, then it is possible to give an explanation for the phenomenon sometimes observed where the solution to a problem which has previously been thought about will suddenly present itself.
When trying to solve some problem P, a person will pay attention to the possible appearance of some solution S with required property X. We can suppose that the conscious direction of attention has a residual effect, in which responsiveness to the property X is maintained at a higher level, even when consciously controlled attention has moved onto other things. At some later time an idea I presents itself and happens to have property X. The residual heightened responsiveness towards X is enough for the observation that idea I has property X to come into conscious awareness, restarting the train of thought involved in the attempted solution of P.
This is somewhat different to the usual proposed explanation of this phenomenon, which states that a concealed non-conscious thought process carries on independently of conscious thought processes, only coming into awareness when the solution is found.
Qualia are considered by some to be one of the great mysteries of consciousness. How can one explain the blueness of blue? asks the philosopher, mystified by the blueness of his own experience of blue. The person that he asks understands the question, because they have their own experience of the blueness of blue. It is possible that an alien intelligence might find the question somewhat incomprehensible. (We don't know, because we have never met an alien intelligence.) Because the blueness of blue seems to be a purely subjective phenomenon, it is difficult to see how one could ever answer the question in a satisfactory manner.
There are however a few clues. One is synesthesia, which seems to be a disorder of qualia, where the synesthete perceives the same qualia attached to what are normally regarded as distinct perceptions. This implies that perceptions have qualia independently of their meanings.
Another is the observation that some perceptions are more qualia-ish than others. Popular examples include colors, smells and emotions. Examples of un-qualia-ish perceptions are words and to some extent shapes.
This suggests that being a qualia is a special property of some perceptions, and not others, and that the distinction between qualia and non-qualia has some functional consequence.
Qualia perceptions are perceptions that impose themselves strongly on consciousness.
Recall my theory outlined above, that consciousness is a process for dealing with non-routine situations, i.e. situations in which it may be difficult to apply past experience. I propose that qualia are attached to special perceptions whose significance is either independent of context, or dependent on context in a straightforward manner. They are thus more valuable when dealing with situations different to any situation previously encountered, because the conclusions that can be deduced from them are more robust.
For a concrete example, consider the word "kerosene" (either spoken or written) and the smell of kerosene. The significance of the word can be highly varied depending on what sort of sentence it appears in. The sentence might be discussing some kerosene nearby, or some kerosene far away, or kerosene in a general sense, or a request for kerosene that someone wants, etc. On the other hand, if you smell kerosene, there is only one possible conclusion, independent of any other aspect of the current situation, which is that there is some kerosene nearby (and it is not in a sealed container).
With colors this independence of context is less obvious. However we must remember that most of the different colors that we see nowadays are artificial. If we consider a color like bright yellow, there are only a limited number of natural objects which are bright yellow. Those that come to mind are: various species of bird, flowers, lemons, bananas, sulfur and the sun. Once the bright yellowness was perceived, there would usually be very little difficulty in determining from other perceptual clues the identify of the object or substance that was bright yellow.
Emotional qualia play an important role in deciding the best course of action to take. Color and smell provide information about the outside world. But the problem that consciousness must solve is the satisfaction of biological drives. It is therefore important for consciousness to have information about the current status of biological drives. This information helps consciousness to calculate what course of action will result in reward or punishment in any particular situation. For example if you feel angry, then all things being equal, you can expect to be internally rewarded (at least in the short term) if you attack or break something. Similarly, the qualia of being hungry communicates to consciousness the important fact that eating would make you feel better.
With regard to the physiological aspect of qualia, my prediction is that the areas of the brain that deal with qualia perceptions will be found to have some special direct connection to those areas that are involved in calculating the final confirmation or veto of putative responses to non-routine situations.
 Benjamin Libet "Neural processes in the production of conscious experience", The Science of Consciousness, edited by Max Velmans, Routledge 1996.
 Damasio, Bechara, Damasio & Tranel, "Deciding Advantageously Before Knowing the Advantageous Strategy", Science, Feb 28, 1997.