Consciousness is more than simply being awake. The word is used to describe what people are, their individuality; they are individual, separate consciousnesses.
Consciousness is seen as the domain of the mind but it exists within the context of sensory input to and actions carried out by the body. Shifting levels of arousal are also seen as shifts in the state of consciousness. Thoughts that take place during sleep (dreams) are not under conscious control.
After many decades of investigation, scientists, with the aid of new technological imaging tools, are beginning to develop rational theories of consciousness.
Many of the advances in theory come from a study of defects in the state of consciousness. Damage within the brain causing problems such as Blindsight, can reveal a great deal about consciousness. The effects of blindsight cause a person to be fully able to interact with an object in his/her visual field, yet be totally unaware of its existence. They have no conscious awareness of the object but behave as though they can see it.
Consciousness is a difficult concept to fully understand, yet we do have implicit understanding. Consciousness is something we associate with humans but we may be happy to accept that consciousness is not a thing that can be switched on and off. It is more like a continuum of levels. If this is the case, do any animals other than human beings possess consciousness? This is not the same as asking are any animals intelligent. Do animals have a conscious awareness of themselves?
In this study, it is also interesting to ask the question: Will machines (computers) ever achieve consciousness? If we develop a clear understanding of consciousness, could we then design and install this property in man made machines?
If someone claimed to have developed a machine that was conscious, how could we test the claim? What would we have to do, to prove that the machine was conscious?
Dictionary definitions for consciousness are:
"the waking state of the mind: the knowledge which the mind has of anything that is being experienced; awareness; thought."
"raising development of awareness of one's identity and potential or of (especially public) awareness of social and political issues."
(Chambers dictionary © 1994 by Chambers Harrop Publishers, Ltd.)
There are many theories of consciousness, yet it remains a difficult concept to clearly define and understand. A deep understanding of consciousness is likely to require an understanding of brain function since the brain is the home of the conscious mind.
At one time, it was thought that attention was the same thing as consciousness. Attention is the focusing on one stream of sensor information or thought process to the exclusion of other potentially distracting streams. Many of the things we attend to require conscious thought. However, there are some things that we can attend to that do not require our conscious intervention. One example of this may be an experienced driver carrying out the mechanisms of driving without conscious awareness.
There is a great deal of evidence to support the belief that processing goes on at a sub conscious level. Sometimes we put things out of our mind before an answer emerges later. We may also have experienced the phenomenon of having an answer on the 'tip or our tongue'. In this case it is difficult to bring the answer into conscious awareness although the person knows that it is there, somewhere.
Susan Greenfield (Journey to the centres of the Mind : Freeman 1995 ) develops a well founded argument to support a theory of consciousness based on Neuronal Gestalts. She explains that consciousness has many spatial components but all these exist at one time. In the brain at any one time there will be many groups of neurons paying attention to specific stimuli either from the senses or from thought (internal activity). Some of these groups will be stronger than others but the relative strengths will change over time as new information is made available. The activity of some groups of neurons will fade away over time and new groups will emerge in response to new input. It is suggested that one group of neurons will become dominant and this will be the focus of conscious attention. The other groups will remain active and complete for conscious attention. A change in a situation may switch consciousness from one group of neurons to another.
For Example: Imagine working in an office and your conscious attention is currently on your work. Other groups of neurons are processing other things including the background noise in the office. However, the strongest group is your work. After a little while, one of your colleagues, who is talking to another colleague, quietly mentions your name in the conversation. Immediately, a new group of neurons becomes more active and competes successfully with your work for conscious attention. This may be how consciousness drifts from topic to topic and can sometimes be difficult to control.
Mind and Body
Some believe that there is mind, body and soul. If a person believes in the immortality of the soul, and is happy to accept that the mind resides in the brain then those people must believe that the mind and soul are different. In this case, it is difficult to imagine how the mind and soul interact and what part each plays in our activities.
Within this context, we are only discussing mind. Even this can be a difficult concept. How does the mind relate to consciousness? When we fall asleep, we accept that we temporarily lose our consciousness but not that we lose our minds. It seems that mind is an enduring property of the individual but it is accepted that consciousness is variable and sometimes disappears and then returns. Mind relates to individuality and self.
Note: Handwriting is seen as a reflection of a person's individuality. A person produces the same signature, day after day. Handwriting evolves with the individual. During regression experiments, a persons handwriting also regresses. If a person loses the use of an arm, a signature written with the mouth or feet is still recognisable as that individuals signature. The signature is more than rehearsed muscle movement. This is not proof that handwriting analysis can tell you anything about an individual though. Continuity of individuality is a property of mind that persists through varying levels of consciousness and arousal.
The distinction between mind and body is not as clear as one may think. The body is the only way that the mind can express itself, it is the only source of information for the mind. The well being of the body has a strong influence on the function of the mind. Imagine trying to solve a complex problem or create a work of art if you have a severe toothache. The mind often goes to great lengths to control the outward appearance of the body for many reasons.
Mind and body can be shown to be linked in other ways. Consider the phenomenon of a Phantom Limb: (consider the following conversation)
"See if you can reach out and grab this cup in your right hand. What are you feeling now?"
"I feel my fingers clasping the cup." "Okay try it again." (As the patient tries to reach for the cup, the doctor pulls it farther away)
"Ouch! Why did you do that?"
"It felt like you ripped the cup right out of my fingers."
(James Shreeve, June 1993)
In a normal situation, the patient would have had the cup pulled out of his hand. However, the patient did not have his right arm; he lost it in a storm at sea. Phantom limb and phantom pain sensations can be very vivid.
Changes in levels of arousal may appear similar to the changes in levels of consciousness. At one extreme, arousal prepares the body, in a physical way, for a fight or flight response. At the other extreme, arousal is greatly reduced in sleep. Levels of arousal seem to shift in a similar way to those of consciousness. So is consciousness the same thing as arousal? When we enter a highly aroused state during a fight or flight response, this may not mean that we are any more conscious. When we are in an aroused state during sleep; when we are dreaming, we may not be conscious at all.
Sleep is part of three physically deterministic states. There is wakefulness, non-dreaming sleep and dreaming sleep. Each of these three states is measurably different.
Sleep contains several levels of arousal. In non-dreaming sleep there is a low level of arousal and interestingly enough, it is easier to be woken from this state than from dreaming sleep. Dreaming sleep is accompanied by a higher level of arousal but not by consciousness. Dreaming sleep is often known as rapid eye movement sleep. Dreams can often be vivid.
Some patients who suffer severely from seizure can be in great danger. Uncontrolled activity of the brain spreads throughout the brain and across from one hemisphere to another. An operation that splits the brain in two can alleviate the worst of the symptoms. In such patients, one half of the brain processes information presented to one half of the visual field. In tests, information learned using one half of the brain alone is not useable by the other half. It is as though the patient has never seen or learned the information. However, the half of the brain that did see or learn the task is fully aware.
One case resulted from a patient who was completely blind in the left visual field as a result of brain surgery. Although he could not see any objects on the left of the visual field, he was able to reach out correctly for them when asked to do so. When questioned, the patient said that he was just guessing but when showed video clips of his performance he was amazed. This condition is where a person has no conscious awareness of sight yet certain actions provide evidence that visual experiences are happening at a sub conscious level.
This condition is opposite to blindsight. With this condition, patients are fully aware of visual sensation but cannot recognise objects. For instance, a patient may be able to see a person but completely unable to recognise that person as a life long friend. It seems that there is some sub conscious recognition established from changes in skin conductance etc. but there is no recognition at a conscious level.
A comprehensive treatment of consciousness, leading to the formation of a theory of consciousness can be found in Journey to the centres of the Mind: Susan A. Greenfield: Freeman 1995
Chapter 3 of Cognitive Psychology : Robert J. Sternberg: Harcourt Brace. 1996 also deals with consciousness and attention.