In our conscious life, we think of ourselves as entities distinct from our bodies, and even from our brains, although we all know now that the brain is the control centre of the body. We think and talk about using our hands, using our eyes, using our brains. The philosopher Daniel Dennett calls this the gbenign user illusionh. Dennett is a leading figure in the philosophy of consciousness, and his book gConsciousness Explainedh (1991, Penguin edition 1993) is a classic.
We might naïvely think that the brain, or some part of the brain, is a gcontrol roomh in which our consciousness resides, receiving messages from the sense organs and sending out signals to the muscles in response to the messages. Dennett calls this control room the gCartesian Theatreh, after the philosopher René Descartes, who came to the conclusion that the pineal gland was gthe seat of the soulh. Descartes was not being entirely fanciful: the pineal gland is a unique object situated right in between the two hemispheres of the brain. The function of this gland is not entirely clear: there is an interesting Wikipedia article about it at http://en.wikipedia.org/wiki/Pineal_gland.
It certainly cannot be the case that the Cartesian Theatre contains a ghomunculush, a tiny version of oneself which studies the monitors and presses the appropriate buttons. In that case the homunculus itself would also have a brain with a Cartesian Theatre inside it, and we would be off on a vicious regress. Even so, there might be a Theatre with something taking charge inside.
Dennett presents various arguments as to why this cannot be the case. An interesting one involves what is known as the gphi phenomenonh, which is related to the illusion that underlies the cinema. At the cinema, at least in the old days, the film consisted of a series of still images which was passed rapidly through the projector. This produces the illusion of continuous movement on the screen.
The cinema illusion is called gbeta movementh, and is apparently distinct from the phi phenomenon, though quite how is a mystery to me. You can find out more at http://en.wikipedia.org/wiki/Phi_phenomenon. Anyway, the phi phenomenon is the one we need to examine. A white flash appears briefly at one point on a screen, and a short time later another white flash appears at a different point. If the interval and the distance apart are not too great, most observers have the illusion of a white spot moving from one place to the other. This was first investigated by the psychologist Max Wertheimer, who published his results in 1912.
Rather surprisingly, it was not until around 1976 that the philosopher Nelson Goodman asked what would happen if the two flashes were of different colours. Two psychologists, Paul Kolers and Michael von Grünau did the appropriate experiment. A flash of one colour was shown first, followed by one of a different colour. Suppose they were red followed by green. Most observers in that case report seeing a moving red spot which suddenly changes to green half way between the two places. There is another Wikipedia article about this, http://en.wikipedia.org/wiki/Color_Phi_phenomenon, which gives a link to http://www.philosophy.uncc.edu/faculty/phi/Phi_Color2.html, where there is supposed to be a Java applet in which you can see the phenomenon for yourself. But be careful - every time I've tried the link recently my Firefox browser has gone into a deep sleep from which it can only be aroused by switching off and starting again. In any case, I didnft find that demonstration so convincing even when it was working, I think because the background was white rather than black, and couldn't be changed. Some years ago I came across a site where the background was black, and the phenomenon was really startling, but I canft find it any more. The only link anywhere seems to be the browser anaesthetic one above. Please let me know if you find something better!
Anyway, the significance of the phenomenon is that the illusion must be constructed by the brain. It is not subject to conscious control, because we canft decide not to be fooled by it. The illusion must be put together after the green flash has occurred, because there is no indication of the second colour until then. Our brains try to make a coherent story out of the sense data we receive, and in this case the brain decides that a moving coloured spot that changes colour half way is the best explanation of what is seen.
Most such illusions seem to be visual, but there is at least one which is tactile - the so-called "cutaneous rabbit". There is a Wikipedia article about that too - http://en.wikipedia.org/wiki/Cutaneous_rabbit_illusion. The observer's arm rests out of sight on a cushion, and a machine delivers a number of rapid taps to the wrist, followed shortly afterwards by more taps further up the arm, at the elbow, and maybe more on the upper arm. The observer has the illusion that a small animal has hopped along the arm, hence the expression "cutaneous rabbit", though maybe "cutaneous baby frog" would be more descriptive. (In class I suggested "cutaneous mouse", but it seems that the sensation is definitely one of hopping rather than running.)
Although such phenomena show that different parts of our brains may work independently, they do not prove that there is no central controller, only that the control is rather incomplete. However, it is easier to hypothesise that there is no central control at all: different parts of the brain may take charge depending on the circumstances.
I've already used the words "conscious" and "consciousness" several times, and of course the kind of consciousness I'm thinking of is "self-awareness". But with Dennett, we might wonder why we have such self-awareness. What is its purpose? Perhaps an example will make the point clearer. Suppose at some time you suddenly feel very thirsty. That sensation will of course be registered in your brain, and parts of your brain will get to work on solving the problem. Relevant memories will be activated. Perhaps there is a memory of a vending machine nearby, so part of your brain sends out the necessary instructions to the muscles to set about walking to it. At the machine your eyes register what drinks are available, how much they cost, and so on and so on. Eventually the coordination between your senses, your brain and your muscles will obtain a drink and your thirst will be quenched. You will be aware of what you are doing as well, but why should this be necessary? Surely your brain and body could carry out the whole process without any extra awareness of it as well?
Dennett suggests that the reason for such consciousness is unique to humans, and arises because we often have to explain our actions to others. For instance, in the example above, someone might ask you, "Where are you going?" As a result of the question, some part of your brain monitors what is happening in other parts, and the result is turned into language - "I'm thirsty, so I'm going to get a drink from the machine over there." Such monitoring is what constitutes self-awareness, or consciousness.
Dennett's theory makes consciousness very much dependent on language. Childhood memories provide quite good evidence of this. Many people like myself have a few very early memories which are entirely visual, like a blurred still photograph of a scene. I have a distinct one of lying on my back and looking up at a blue sky and the side of our house. Very likely I was in a pram and my mother had left me outside for some fresh air. Other people have mainly auditory memories of occasional events in their early lives. Our proper connected memories do not seem to come until we are about four or five years old, which of course is when children have mastered the basics of their native language. My first memories of that sort involve a visit to London with my parents - I distinctly remember seeing an underground train for the first time, and feeding bits of bread to some ducks and swans. Probably the visit took place during the Great Exhibition in 1951, when I was just about five years old. Many people start school at around that age, and their first memories often involve their first days there.
Such narrative memory is very important to humans, for we often have to explain to others just what we did at some particular time in our past, and we are expected to remember our life histories in some detail. But just as in the case of the phi phenomenon or the cutaneous rabbit, parts of our brains may be working on their independent versions of our narrative history, and revising them in the light of other stories, memories, or new sense data. Dennett calls this gthe multiple drafts modelh. It is rather as we may write successive drafts of an essay, maybe deleting earlier drafts as we go. One particular draft, continuously updated, will be the narrative draft of onefs own history. We are all aware of how, for instance, different eyewitnesses of a street accident may give the police conflicting narratives of what actually happened. They do not have to be lying - different people get a different set of sense impressions of some event, and their brains try to put together some coherent story based on those impressions. Different witnesses end up with different stories.
Given the potential confusion of different drafts in our brains, we need to form a strong sense of "I", the one entity which ties all the stories together. The gbenign user illusion" may be a necessity, as well as just benign.
If Dennett is right, then animals other than humans do not have such self-awareness at all, since they have no language. Many observations of our cats suggest to me that that is correct. They do not have narrative memory, nor do they need any. Roo, for instance, remembers that, if she jumps on my desk while I am working there, she will almost certainly receive a welcome and be allowed to stay. So when she feels like some company and affection, she jumps on my desk. She does not need to remember any details of previous times when she did that, and she certainly will never be asked about them in a way she could understand! Remembering just that certain things are associated is quite enough to make her behave as she does.
You will see that I definitely agree with Dennett's ideas in this area. I'd like to know how you feel in your next assignment. If you agree with Dennett too, then try to restate the theory in your own way with your own examples. If you disagree, then state why, and give reasons. Maybe you have observed something about a pet's behaviour that suggests a high degree of self-awareness. Or maybe you have some idea of human behaviour that indicates that there really is some central controller, some kind of "soul" that directs the body, including the brain. Whatever your ideas on the subject are, I'd like to know!