Hemispheric
Specialisation
The cognitive and behavioural functions of the right
and left hemispheres
The non-verbal vs verbal and analytical functions
The findings of research on intact brains
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.

Both the left and right hemispheres are
involved in nearly all functions.
LEFT HEMISPHERE
SPECIALISATIONS



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.
RIGHT HEMISPHERE
SPECIALISATIONS

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.
LEFT HEMISPHERE
• Focus is on small details,
zooms in on specifics and is
local. Processes information
logically, sequentially and
analytically.
• Receives sensations from
the right side of the body.
• Motor functions include:
Controls voluntary bodily
movements on the right
side of the body and the
production of speech.
• Perceptual functions
include: Comprehension of
language
• Cognitive functions:
Reading, writing, analytical
thinking, sequential
processing, logical
reasoning and mathematics.
RIGHT HEMISPHERE
• Focus is on a wide-angle
view, assembling pieces of
the world into a coherent
picture and is global.
Processes information
intuitively (ie. less logically)
and holistically (whole
patterns simultaneously).
• Receives sensations from the
left side of the body
• Motor functions include:
Controls voluntary bodily
movements on the left side of
the body.
• Perceptual functions include:
Recognition of faces and
patterns.
• Cognitive functions: Musical
ability, spatial ability-design,
movement, dance, emotional
expression and detection of
emotion.
Left versus right
Is it as simple as this?
Another way of looking at it…
RESEARCH ON HEMISPHERIC
SPECIALISATION
There are 3 main approaches to conducting
research on hemispheric specialisation. They
are:
1. Studying people with brain damage
2. Studying people who have had a split-brain
operation
3. Studying people with intact , undamaged
brains.
BRAIN DAMAGE RESEARCH
●




Injuries, stroke or lesions reveal:
Left hemisphere damage is associated with language disorders
(eg aphasias)
Right hemisphere damage is associated with visual-spatial
disorders(eg. difficulty recognising faces) called facial agnosia or
prosopagnosia, also neglect syndrome and spatial disorientation.
Damage to the Broca’s area in the frontal lobe of the left cerebral
hemisphere is associated with the production of fluent speech. It
produces speech that is very deliberate, consisting of a few words
with very simple grammatical structure, such as “Mother went
shop” instead of “My mother went to the shop”. The damage
rarely results in the total loss of speech.
Damage to Wernicke’s area in the temporal lobe of the left
hemisphere results in people producing meaningless speech that
is not considered to be understandable language.
Neglect Syndrome: A disorder caused by damage
to the right hemisphere
• Someone with this
disorder behaves as
if the LEFT side of
their world does not
exist. For instance,
if asked to copy a
picture of a house
they will only draw
the right side of it.
SPLIT BRAIN OPERATIONS
 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.
 In the 1960’s Roger Sperry conducted a series of tests
on split-brain patients which involved the participants
viewing visual information being presented to only one
hemisphere.
 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.
Sperry’s split-brain research

1.
2.
3.
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.
Sperry’s split-brain research


cont…
When Sperry flashed objects in the left visual field (and these
were sent to the right hemisphere) his patient only known as
N.G. could not say what she saw (because the area of the brain
responsible for speech is in the left hemisphere). To check that
she did actually see an object when presented in the left visual
field Sperry asked N.G. to use her left hand to reach under the
partition for the object. N.G. could correctly do this because her
left hand was controlled by the right hemisphere that also saw
the image of the object.
The message from the primary motor cortex in the right
hemisphere for the left hand to move does not use the corpus
callosum.
Research findings on intact brains
Research in this area has concentrated on two
sensory systems- vision and hearing.
Psychologist’s can easily measure participants’
responses using these senses
A tachistoscope is a type of projector that can be
used to present visual information to each visual
field and therefore each hemisphere
independently. A participant fixates on a centre
point marked by a dot or a cross.
When non-verbal information is presented to the
right hemisphere (and projected to the
participants left visual field) it is recognised faster
than when presented to the left hemisphere
(projected to participants right visual field) since
processing of non-verbal information is
dominated by the right hemisphere.
Research findings on intact
brains…cont
People recognise verbal information faster when these are
presented to the left hemisphere than when they are
presented to the right hemisphere.
That is, people identify verbal stimuli, words more quickly
when flashed to the right visual field only.
Evidence for hemispheric specialisation is provided by brain
imaging techniques that capture images of activity during
certain types of tasks.
Recordings of the neural activity in the brain on people with
intact brains reveal that there is greater brain wave (EEG)
activity in the left hemisphere with verbal tasks and greater
activity in the right hemisphere with spatial tasks.
Psychologists refer to the brain’s “plasticity”, which is the
brain’s capacity for an entire function to relocate to the
opposite hemisphere if injury, disease or surgery destroy
the part of the hemisphere where the function is mainly
located.
THE END
References:
Grivas,J., Down, R. & Carter, L. (2004).
Psychology: VCE Units 3& 4. (3rd ed.)(8593). Melbourne: Macmillan Education.
Milesi, P. & Vainer, L. (2005) Psych Notes
Unit 3. 2nd Ed. Victoria: A+ Publishing.
Van lersel, Bradley, Coon, Houlihan, Koerner,
Montalto, Rossborough & Stone. (2005)
Nelson Psychology VCE Units 3 and 4.
Melbourne: Thomson Nelson.