The document discusses hemispheric specialization, where each hemisphere has specialized functions - the left hemisphere specializes in verbal and analytical functions while the right hemisphere specializes in non-verbal, spatial, and visual functions. Research has provided evidence for this through studying patients with brain damage, those who underwent split brain surgery to disconnect the hemispheres, and tests on intact brains like the Wada test.
2. Hemispheric
Specialisation
This is the idea that one hemisphere has
specialised functions, or that it exerts
greater control over a particular function. It
is also known as hemispheric dominance
and hemispheric lateralisation.
In reality both the left and right
hemispheres are involved in nearly all
functions.
3. The Left Hemisphere
The left hemisphere specialises in verbal and
analytical functions.
Verbal functions involve the use or recognition of
words eg. reading, writing, speaking and
understanding speech.
Analytical functions involve breaking down a task
into its key parts and approaching it in a sequential ,
‘step by step’ way, as is required when using logical
reasoning to interpret and apply a formula to solve a
maths problem.
4. The right Hemisphere
The right hemisphere specialises in non-
verbal functions that are not dependent on
language skills eg. Spatial and visual
thinking such as completing a jigsaw
puzzle, reading a map, recognising faces
and tunes; appreciating music and
artworks; creativity; and fantasy eg
daydreaming.
6. ACTIVITY
Identify the cerebral hemisphere (left or
right) that specialises in the following
cognitive and behavioural functions
1.Appreciating the beauty of a forest
2.Judging whether a car will fit into a
parking bay.
3.Listening to someone speak
4. Kicking a football with your left foot
7. Research on hemispheric
specialisation
There are three main approaches to
conducting research on hemispheric
specialisation.
•Studying people with brain damage
•Studying people after a split brain operation
•Studying people with intact brains
8. Brain Damage Paitents
• Provided evidence of localisation of
language skills (Broca’s and Wernicke’s
areas)
• Neglect syndrome, a disorder caused by
damage to the right hemisphere.
9. Neglect Syndrome
• Neglect syndrome is
a result of brain
damage to the right
areas of the right
cerebral hemisphere
• Patient believes the
left side of their
world does not exist
10. Split Brain Surgery
Patients who have undergone a procedure
called a split-brain operation have their
corpus callosum surgically cut, which is a
bundle of nerve fibres that connect the two
hemispheres thereby disconnecting one
hemisphere from the other. This procedure
was first used in the 1940’s to stop recurring
seizures in severe cases of epilepsy.
• http://www.youtube.com/watch?
v=SpBc5Y0ES2s
11. Roger Sperry
• In the 1960’s Roger Sperry conducted a
series of tests which involved patients
viewing visual information being
presented to only one hemispheres
• Information presented to the left visual
field only (to the left side of patients
vision) was sent to the right hemisphere
of the brain and information presented
to the right visual field only was sent to
the left hemisphere.
12. Split brain studies reveal:
• Ability to verbally name and
identify words and objects flashed
to the left hemisphere.
• Inability to verbalise words or
name objects visually flashed to
the right hemisphere; patients can
identify these objects by touch
alone using their left hand (ie.
Controlled by the right
hemisphere)
• Spatial puzzles are solved better
using the left hand.
16. Wada Test
• Some of the best evidence relating to hemispheric
specialization comes from the Wada test—a procedure
carried out before brain surgery.
• In the Wada test each hemisphere is put to sleep at
different times by injecting anesthetic into a major
artery that leads only to that hemisphere. While one
hemisphere is anesthetized, the other remains awake
and conscious. Once half the brain is anesthetized,
doctors can interview the other half (if the patient is
capable of talking) or give instructions to perform
simple tasks. This helps to determine what skills or
abilities might be confined to one hemisphere.
17.
18. Tachistoscope
• What is it?
• How has it helped show evidence for
hemispheric specialisation
19. Revision
1. List three hemispheric specialisations of
each of the left and right hemispheres.
2. Describe neglect syndrome. What causes
it?
3. Explain how split brain surgery has
contributed to evidence to support
hemispheric specialisation.
