Bio Psych - Laterilisation

Question 1

What is meant by hemispheric lateralisation

Answer 1

Two halves of the brain function differently

Certain mental processes and behaviours are controlled to 1 hemisphere rather than other

Question 2

What is a very significant thing that is subject to lateralisation

Answer 2

Language
Language is strictly just lateralised to the left hemisphere
So damage to left hemisphere - severely impairs peoples language

Question 3

Where are the information from left and right visual processed ?

The right and left side of the body is controlled by what

Answer 3

Idea of the brain being contralateral

Information from right visual field - processed by left hemisphere

Information from left hemisphere - processed by right hemisphere

Right hand side of the body - controlled by left hemisphere
Left hand side of the body - controlled by right hemisphere

Question 4

Explain split Brain research studies

Answer 4

A series of studies which began in the 1960’s involving epileptic patients

had experienced a surgical separation of hemispheres of the brain bu cutting of corpus collosum

. This allowed researchers to investigate the extent to which brain function is lateralised.

Question 5

What does cutting of corpus collosum allow to do

Answer 5

information cannot be passed between the hemispheres.

Question 6

What was general procedure of split brain research studies

Answer 6

Images or words could be projected to right or left visual fields
Normal brain - information immediately shared between both hemisphere
Split brain patient - information not conveyed from one hemisphere to another

Question 7

What were the four findings called of split brain research

Answer 7

Describing what you see
Recognition by touch
Composite words
Recognising faces

Question 8

Explain describing what you see

Answer 8

Speech and language lateralised to left hemisphere
Image shown to right visual field - could easily be described
Info processed in left H which has language centres

Presented to left - couldn’t describe as information processed in right H - no language centres

Question 9

Explain recognition by touch

Answer 9

Object shown in left visual field - cannot describe it verbally
- speech language lateralised to left
hemisphere

However they could select a matching object to the object shown in left visual field by their left hand.

Information from left visual field goes to the right hemisphere which also controls the left hand.

Question 10

Describe composite words

Answer 10

Two words presented on both visual fields
Only able to write the word in left visual field with left hand because both controlled by right hemisphere

Only able to say the word presented to right visual field as info from right goes to left H and language centres are in the left hemisphere

Question 11

What is a strength the of lateralisation (methodology)

Answer 11

Strengths of methodology used to research lateralisation

Eg The experiments had highly standardised procedures.
Patients asked to stare at fixation point whilst one eye was blindfolded.
Only showed images for 1 tenth of a second
Patient would not have time to move their eyes across an image and would not spread across both visual fields

Only one hemisphere receiving information
So sperry developed useful and controlled procedure

Question 12

What is another strength os split brain research (debate)

Answer 12

Sperry’s work has prompted theoretical and philosophical debate.

Pucetti (1977) suggested two hemispheres are so functionally different
Represent a form of duality in the brain (two minds)
Others researchers argued 2 hemispheres form highly integrated system - do not work in isolation

Question 13

What is another limitation of split brain research

Generalisability

Answer 13

Issues with generalisability
Only 11 patients took part in all variations
All had history of epileptic seizures
This may have impacted the Brain and the findings
Level of disconnection was also different in all participants

Limits extent of findings being generalised to normal brains
Lowers validity

Question 14

What is another limitation of split brain research

Over emphasis

Answer 14

Differences in function may be over stated

Verbal and non verbal labels can be useful
But
Distinction between both hemispheres is less clear cut

In normal brain both hemispheres are in constant communication when performing tasks.
If situation called for it - many behaviours associated with one hem can be carried out by either
Shows lateralisation may not be clear or permanent process

Question 15

What is another strength of lateralisation (research to support)

Answer 15

evidence to demonstrate lateralised brain functions.

For example Sperry and Gazzaniga’s pioneering work into split brain research involved them carrying out investigation on patients whose corpus callosum had been cut.

when patients were shown an image to their right visual field, the patient could easily describe what was seen however if the image was shown to the left visual field they couldn’t.

This strengthens the fact that language functions are located only in the left hemisphere. Therefore, each hemisphere controls the visual and motor input of it’s opposite side.

Question 16

Describe matching faces

Answer 16

The right hemisphere is dominant for recognising faces.
When asked to match a face from a series of other faces, the picture processed by the right hemisphere (left visual field) was consistently selected, whilst the picture presented to the left hemisphere was consistently ignored.
When a composite picture made up of two different halves of a face was presented – one to each hemisphere – the left hemisphere dominated in terms of verbal description whereas the right hemisphere dominated in terms of a matching picture.