Right hemisphere -Dominant for non verbal info
Left hemisphere - Dominant for language and speech
Brain functions are localised in one hemispere
Brain lateralisation means two halves of the brain are not exactly alike
Paul Broca - damage in area of left brain led to language loss, but damage to same are of right brain did not have the same consequence
Two hemispheres connected
The ability of the two hemispheres investigated when surgeons cut nerve fibres from corpus callosum in treatment for epilepsy.
Connected by corpus callosum
People with their two hemispheres disconnected are called split brain patients
Split brain patients
The conclusion was that the left hemisphere was responsible for language and speech.
Right hemisphere specialises in visual-spatial processing and face recognition
Sperry and Gazzaniga (1967) studied split brain patients
Stimuli was presented to one hemisphere and pps were asked to respond
Stimuli presented to the right hemisphere did not produce a verbal response
Limitations of split brain research
Patients with split brain are rarely encountered in sufficient numbers to be used for research.
Slit brain procedure rarely carried out now.
Andrewes (2001) argues conclusions are drawn from studies with very few pps.
Language may not be restricted to the left hemisphere
Gazzaniga (1998) recent discoveries have disconfirmed earlier discoveries. Left hemisphere language
Case studies (J.W.) - He developed the capacity to speak out of his right hemisphere.
J.W. can now speak about info presented to the left tor right brain
Advantages of hemispheric lateralisation
Rogers' findings on chickens provides evidences that brain lateralisation enhances brain efficiency in cognitive tasks
This demands the simultaneous but different use of both hemispheres
Lateralisation and immune system functoning
Architects and mathematically gifted people tend to have superior right-hemispheric skills
They are more likely to suffer high rates of allergies and problems with the immune system
Tonnessen (1993) found small but significant relationship between handedness and immune disorders
Lateralisation changes with age
It appears to not stay exactly the same throughout a persons lifetime
Szaflarski found that language became more lateralised to the left hemisphere with increasing age, but after the age 25, lateralisation decreased with each decade of life