From Wikipedia, the free encyclopedia.
Consciousness is the mental state of being aware of oneself and one's environment.
Many important questions in philosophy center on consciousness. The term has many competing definitions, but it is generally regarded to comprise qualities such as self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment. Most people regard human consciousness as self-evident. However, consciousness has been a great problem for scientists and philosophers. In particular, philosophers have asked "How do we know we are conscious?" and "How do we know other people are conscious?". It turns out that these are difficult questions, both to formulate accurately, and to answer.
Another question is to what extent other animals have consciousness. Some believe that humans are the onlyconscious beings, while others assert that other animals are more or less conscious. These issues are of great interest and controversy not only to scientists and philosophers, but also to those concerned with animal rights.
Informally, consciousness denotes being awake and responsive to one's environment; what some call reactivity. This might contrast to being asleep or being in a coma.
Many cultures and religious traditions place the seat of consciousness in a soul separate of the body. Today, many scientists consider consciousness to be a function of the brain, based on the observation that chemicals and events that affect the brain can affect consciousness.
In psychology, human behavior is seen as being driven by a combination of conscious and unconscious processes.
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Consciousness and language
Because humans can express themselves using language, it is tempting to equate language abilities and consciousness. There are, however, speechless humans (infants, Kaspar Hauser, accident victims), to whom consciousness is attributed despite language lost or not yet acquired. Also, consciousness does not change by the acquisition of a new language. Consciousness is therefore one of the conditions for the language acquisition; missing language ability is, however, no reference to missing consciousness.
Language is the substantial means of humans to give expression to the experience of consciousness. Other forms are artistic, such as music, dance, painting and sculpture.
A thing that is conscious uses the pronoun I to refer to itself.
Loss of consciousness
Several studies point to common mechanisms in different clinical conditions that lead to loss of consciousness.Persistent vegetative state (PVS) is a condition in which a person loses the higher cerebral powers of the brain, but maintains sleep-wake cycles with full or partial autonomic functions. Studies comparing PVS with healthy, awake subjects consistently demonstrate an impaired connectivity between the deeper (brainstem and thalamic) and the upper (cortical) areas of the brain. In addition, it is agreed that the general brain activity in the cortex is lower in the PVS state.
Loss of consciousness also occurs in other conditions, such as general (tonic-clonic) epileptic seizures, in general anaesthesia, maybe even in deep (slow wave) sleep. The currently best supported hypotheses about such cases of loss of consciousness focus on the need for 1) a widespread cortical network, including particularly the frontal, parietal and temporal cortices, and 2) cooperation between the deep layers of the brain, especially the thalamus, and the upper layers; the cortex. Such hypotheses go under the common term "globalist theories" of consciousness, due to the claim for a widespread, global network necessary for consciousness to exist in the first place.
Consciousness and memory
Consciousness is closely connected with the ability of memory, since even after temporary consciousness loss the identity of the individual remains.
The science of consciousness
Though some believe that consciousness is beyond science, many scientists, both materialist and otherwise, believe that science can explain the function of the brain in giving rise to consciousness.
Chemistry
Brain chemistry affects human consciousness. Sleeping drugs (such as Midazolam = Dormicum) can bring the brain from the awake condition (conscious) to the sleep (unconscious). Wake-up drugs such as Anexate reverse this process. Many other drugs (such as heroin, cocaine, LSD, MDMA) have a consciousness-changing effect.
It is generally believed that general anaesthetics work by suppressing consciousness.
Physics
Physicists have tried to explain consciousness by the action of even smaller phenomena than chemical reactions. A controversial book by Roger Penrose, The Emperor's New Mind, suggests that non-local quantum mechanical effects constitutes the function of the mind. He also suggested that we need to deepen our knowledge of fundamental physicsto properly explain consciousness.
Consciousness and philosophy
Philosophers distinguish between phenomenal consciousness and psychological consciousness. Some suggest that consciousness resists or even defies definition.
Phenomenal consciousness
There is, in the view of very many philosophers, one mental function that accompanies some, or perhaps all, mental events, namely, consciousness. In a philosophical context, the word "consciousness" means something like awareness, or that a mind is directed at something. (That sounds more like a definition of that philosophical term "intentionality" often referred to with the layman's term "aboutness".) So when we perceive, we are conscious of what we perceive; when we introspect, we are conscious of our thoughts; when we remember, we are conscious of something thathappened in the past, or of some piece of information that we learned; and so on.
In this philosophical sense of the word "conscious", we are conscious even when we are dreaming; we are conscious of what's happening in the dream. But sleep researchers believe there is a sleep stage that happens, called "deep sleep", in which apparently we are not conscious of anything in any sense. No mental processes that involve consciousness in an ordinary or in a philosophical sense are going on. So dreamless deep sleep is an instance in which one is alive and one's brain is functioning, but there are no mental events occurring in which there is any element of consciousness.
Modern investigations into and discoveries about consciousness are based on psychological statistical studies and case studies of consciousness states and the deficits caused by lesions, stroke, injury, or surgery that disrupt the normal functioning of human senses and cognition. These discoveries suggest that the mind is a complex structure of various localized functions held together by a unitary awareness.
There has been some debate about the following question: Must one be conscious, in the philosophical sense, whenever a mental event occurs? For example, is it possible to have a pain that one does not feel? Some people think not; they think that in order for something to be a pain, one has to feel it and hence be aware of it. Similarly, if anything is a thought, then one has to be aware of that of which one is thinking (indeed, that seems nearly atautology); if there is no consciousness, then one is not thinking. This raises these questions: do mental eventsnecessarily involve consciousness? What about functioning of the brain of which we are unaware?
Suppose we answer "No." Then, of course, what we'd be saying is that there are some mental events that do not include an element of consciousness. These events are going on even though we aren't aware of them. In other words, part of the mind is unconscious. Cognitive scientists believe that many cognitive processes are unconscious in this manner; we are aware of only some of the events that are occurring in our minds.
Some view consciousness as an emergent phenomenon, somehow arising from a hierarchy of unconscious processes. These are fairly recent views, made popular only after Freud.
Psychological consciousness
Psychological consciousness refers to a closely interrelated set of features. Julian Jaynes lists these features as:
1. spatialization - having an internal mental 'space' in which hypothetical events can 'happen'. It is impossible to think of any events occurring in time without spatializing them, usually on a timeline running from left to right. People who are not conscious (eg, in a hypnotic state) are incapable of thinking about time or putting things in a time-ordered sequence.
2. analog I - being able to see 'in' one's spatialized mind what one would 'see' if one were in a certain situation. For example, if a person comes to a fork while walking through a forest, they can 'see' 'in' their mind what they would through their eyes if they took either of the paths. It's based on this information that they can decide to take one path (perhaps more scenic) over the other.
3. analog Me - the 'I' is the subject performing actions, through whose eyes we 'see'. The 'Me' is an object 'seen' in its entirety. The 'I' is the first-person view in computer games while the 'Me' is the third-person view, behind the main character. One can often 'see' oneself performing actions 'in one's mind' as if one were 'outside' of one's own body.
4. excerption - the taking of a small aspect of something to stand for that whole thing. No one thinks of their city by imagining every house, every street corner and every sewer. One takes something, perhaps the skyline or city hall, and lets it stand for the whole thing. The same occurs for everything. Recalling one excerption after another by a chain of associations is what constitutes 'reminiscence'.
5. conciliation - something similar to assimilation of knowledge to fit a schema but done 'in' a conscious mind.
6. narratization - the constant unnoticed activity of thinking of one's life in terms of stories, in which one is the star character.
See also
- Artificial consciousness
- Altered state of consciousness
- Attention
- Cognitive science
- Consciousness-only
- Daniel Dennett and his book Consciousness Explained
- Gerald Edelman
- John Searle
- Neural Darwinism theory
- Psychology
- Qualia
- Quantum mind
- Reality
- Society of Mind theory
- unconscious mind
- Vedanta
- Vedic science
- Yogacara
Further reading
- How the Mind Works, Stephen Pinker.
- Consciousness Explained, Daniel Dennett 1991
- Consciousness: An Introduction, Susan J. Blackmore, 2003.
- The Alex Studies: Cognitive and Communicative Abilities of Grey Parrots, Irene M. Pepperberg, 1999.
- The Feeling of What Happens, Antonio Damasio, 1999
- The Emperor's New Mind, Roger Penrose
- Elements of a Science of Consciousness, Charles Fox, 2004. Online MSc thesis.