Psychology -> Hemispheric specialisation
Findings of research of people who have intact brains and those with brain damage
Evidence of this hemispheric specialisation has come from cases where people have had brain damage. Brain damage to the left side of the brain, Broca's area, results in problems with the production of speech. Damage to Wernicke's area, found in the temporal lobe of the left hemisphere, usually leads to problems in comprehending language.
To further investigate the special abilities of the two cerebral hemispheres, researchers have worked with people who have had a rare type of surgery where their corpus callosum is cut to control severe epilepsy. After the 'split-brain' operation, it is as if the person has two brains. Each hemisphere seems to have its own consciousness, sensations, perceptions and behaviours.
Studies of people with intact brains also reveals hemispheric specialisation. When verbal stimuli are presented to the left hemisphere via the right eye or ear, they are processed more quickly and more accurately than when they are presented to the right hemisphere via the left eye or ear. Conversely, the right hemisphere appears to process visual-spatial tasks, such as recognising a face, more quickly.