in progress...

Looking into the physical process of perception,my attention was drawn to a couple of exceptions to the rules which dealt with people with disabilities,difficulties in learning and anomalies.One case really captured my attention and helped me realise that the ways 'normal'(meaning healthy) people perceive things should not be taken for granted. A finding that introduced me to an entirely new ways of perceptional mechanisms was the one of a man with surgically split brain.Having in mind that the brain is a double organ,consisting of left and right hemisphere,and knowing that each hemisphere deals with different communication centers,this case posed the question of the possibility of heaving the two sides of the brain working individually.An extract from Michael S. Gazzaniga's article 'The Split Brain in Man (1967)(Perception:Mechanisms and Models) explains some key experiments carried out with people who undertaken such operation.

'From the beginning the most striking observation was that this procedure did not caused any noticeable changes in the patient's personality,temperament or general intelligence...Close observations revealed some changes in the patient's everyday behaviour. For example,when moving around and responding to sensory stimuli the patient favoured the right side of the body,which is controlled by the dominant left side of the brain...Since the the right side of the visual field is normally projected to the left hemisphere of the brain and the left field to the right hemisphere,one may conclude that in patients with divided brains the right hemisphere is in effect blind.This was no the case.When patients were directed to point to the lights that had flashed in front of them instead of giving a verbal report they were able to tell that a light had been flashed in the left visual field.That meant that the perception of the right and the left visual fields was fairly equal.Clearly,then, the patients' failure to report the right hemisphere's perception verbally was due to the fact that the speech centers of the brain are located in the left hemisphere...We soon realised that each hemisphere receives in addition to the main input from the opposite side of the body,some input from the same side...Tests for motion control revealed that the left hemisphere of the brain exercised normal control over the right hand but had less then full control on the left hand...So how exactly the separation of the two hemispheres affected the mental capabilities of the human brain?...To test this we used two different devices:visual and tactile...When information was presented to the dominant left hemisphere the patient could describe it both orally and in writing.But when presented to the right hemisphere it failed to produce such a response.Evidently the the left hemisphere was completely divorced,in perception and knowledge from the right.Other tests showed that the right hemisphere did have a certain amount of language comprehension.For example when the word ''pencil' was flashed to the right hemisphere,the patients were able to pick out a pencil from a group of unseen objects with the left hand.And when a patient held object with the left hand(out of view),although he could not say the name of it or describe it,he was later able to point to a card with the name of the object written on it...In one particularly interesting test the word 'heart' was flashed across the center of the visual field with the 'he' portion to the left of the center and 'art' to the right.Asked to tell what the word was, the patient would say 'art'-the portion projected to the left brain hemisphere,which is responsible for speech.Curiously,after another flash of the word in the same way,the patient was asked to point ,with the left hand, to one of two cards-'he' and 'art'- to identify the word they had seen.They pointed at 'he'.This experiment shows clearly that both hemispheres had simultaneously observed the portion of the word available to them,and when each hemisphere was given the opportunity to express itself, it prevailed over the other.'

Reading this amazing article,which despite the mainly scientific explanations, made me doubt the universality of the visual language and prompted my research into the ways blind,partially sighted and colour-blind individuals perceive the word around them.

A series of videos by Stanford University on youtube.com has also given me an inside into cases like this and especially one by professor Brian Wandell:
http://www.youtube.com/watch?v=VVgfC_FV2hI
another website worth checking:
http://www.mindhacks.com/