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Transcript:
Knowledge of the physiology of the nervous system tells us a great deal about how information form the senses is transmitted to and from the brain. However, comparatively little is known about how we experience those sensations, and what it is like to feel, think and move. Consciousness is notoriously difficult to define, and explanations of it have tended to be in philosophical, introspective terms. Willian James, a philosopher as well as a pioneering psychologist, coined the phrase 'stream of consciousness' in 1892 to describe the continuous process of thought and perception.
Each of us knows what it is to be conscious, but how do we recognise and measure this in others? They of course can tell us of their experience, but this is as subjective as our own experience. Medical criteria for consciousness are based on responses to sensory stimulus, but tell us nothing of a person's self-awareness. Examination of brain activity in various states of consciousness does, however, provide some clues.