‘Consciousness’, a topic raised right from the first 2003 Reith Lecture, is a particularly intriguing phenomenon, not least because it is unclear exactly why we have the experience of being conscious. A very simple animal, such as an amoeba, presumably has no such experience, since it has no nervous system (let alone a brain) with which to generate consciousness. Nevertheless, it survives very well, and can respond appropriately to its environment, as when it envelops food particles.
In a similar way, we humans can also respond automatically and unconsciously. For example, there are short links of nerves connecting pain receptors to muscles. As a result, if we touch a hot surface the muscles quickly snatch the hand away, long before the brain has recognised what happened and we become consciously aware of the event. Even more complex activity, which does involve the brain, can occur without consciousness. This often happens when the complicated actions have been very well practised, such as the movements needed to control a car. While learning to drive we are painfully conscious of every little detail of the different activities that have to be co-ordinated, but ask experienced drivers whereabouts on a familiar journey they made small adjustments to accelerator pedal pressure and they will have no idea.
If we can function without conscious awareness, why should consciousness be there at all? Scientists have suggested two possible approaches to this question. One proposes that consciousness is just an accidental by-product of having a large brain: when there are so many neurons (we have of the order of one hundred million million) the brain becomes able to monitor its own activity. The alternative approach suggests that consciousness is no accident, but developed through evolution, because creatures with consciousness had a better chance of survival.
It is possible to think of a number of reasons why consciousness has survival value, but I want to explore just one; it concerns imagination. It is a valuable ability to be able to imagine events and scenarios, either things past, or possible futures. It makes it possible to plan, and to pose ‘What if?’ questions. To be able to visualise and reflect upon scenarios generated from within, the brain requires brain structures that can do this, and if those have evolved they will also be available to reflect upon real information from the outside world. In other words, to be able to imagine also means that we will be conscious of reality. Importantly, the brain is usually able to distinguish between the imaginary and the real, although we must all have had the experience of not being sure whether we carried out some action, such as locking the door, or merely thought about doing it.
Sometimes the brain makes large mistakes about reality. It is often possible to deduce something about the workings of a system by observing the errors that result when the system goes wrong. Professor Ramachandran mentions a number of such illuminating problems, such as feeling a limb that is not actually there (phantom limb pain, following amputation). Here the brain is unable to ‘believe’ in the reality. At the opposite extreme is the case of ‘Blindsight’. Sufferers can be shown to respond to visual information, but are completely unaware of it at the conscious level, just as if they are blind. In this case the brain is behaving more like that of a far simpler animal that does not have conscious awareness.
Problems like these are the result of injury, generally to the brain itself, so cannot be produced to order; a researcher has to wait for the right kind of patient to come along. My own area of research is in hypnosis, and this has the advantage that it is possible to produce some of the same effects, without causing any permanent change to the brain. Hypnosis is often referred to as an altered state of consciousness, and I believe that many of the phenomena it can produce result from the brain ceasing to use the mechanism that distinguishes between the imaginary and the real. As a result, imagined scenarios can be experienced as vividly realistic hallucinations.
Hypnosis can mimic many of the effects described in the Reith Lectures, including pain asymbolia, the ability to be aware of a painful stimulus, without actually being distressed by the pain. In contrast, it has also been used to remove phantom limb pain, by enabling the sufferer to ‘see’ the non-existent limb. I am currently working with Professor Larry Weiskrantz of Oxford University, the researcher who first reported on blindsight and indeed coined the term. We are trying to produce equivalent effects in hypnosis and then to explore the neural processes involved.
Many of these themes are taken up in Open University courses. Our course on Cognitive Psychology has large sections devoted to consciousness and neuropsychology. Biological Psychology: Exploring the Brain, offers a more integrated, interdisciplinary approach to the brain, behavioural and psychological sciences. Another course, Signals and Perception: the Science of the Senses, touches on some of these issues and, at the Masters degree level, Exploring Cognition: Damaged Brains and Neural Networks goes further into the idea that we can learn how the brain works by looking at the nature of the problems that arise when it fails to work.
To find out more, explore Vilanyanur S Ramachandra's lectures.