Hemispheric Lateralisation

Question 1

What is hemispheric lateralisation?

Answer 1

The idea that two halves (hemispheres) are functionally different

Question 2

What is the left hemisphere for?

Answer 2

It is lateralised for language comprehension (Brocas and Wernickes on left side)

Question 3

What is the right hemisphere for?

Answer 3

Visual motor tasks/ spatial skills

Question 4

How are the hemispheres connected?

Answer 4

By the corpus callosum, which is nerve fibres that allow the hemispheres to communicate with eachother by sending nerve impulses

Question 5

How is the brain contralateral?

Answer 5

The LH controls movement, vision and touch of the right side of the body by sending
The RH controls movement, vision and touch of the left side of the body

Question 6

What are split brain patients?

Answer 6

People who have had their corpus callosum cut, causing their hemispheres to be split from eachother. This is done to reduce epilepsy

Question 7

What is the purpose of split brain research?

Answer 7

It studies how the hemispheres function when they cant communicate with eachother

Question 8

What was Sperry’s research?

Answer 8

• Aim: study how 2 separated hemispheres deal with, for example, speech and vision
• 11 people with split brains were studied with a special setup where an image would be projected to their RVF (processed by LH) and vice versa.
• A normal brain would have the corpus callosum share info between both hemispheres but cannot occur with split brain patients

Question 9

What were Sperry’s findings?

Answer 9

• When a picture of an object was shown to the RVF, they can describe what they saw, but couldn’t with LVF as they said there was nothing there
• In connected brain, messages of RH are relayed to language centres of LH, not possible in split brain.
• However, they could select a matching object out of side with left hand (Linked to RH)
• CONCLUSION: Observations show how functions are lateralised in the brain. LH - verbal. RH - silent but emotional.

Question 10

AO3: Limitation of split- brain research

Answer 10

• Those who have undergone split-brain surgery are very rare
• Means there is a very small sample of people
• Lack generalisability

Question 11

AO3: Limitation of split-brain research

Answer 11

• Sperry’s research - causal relationships hard to establish
• Behaviour of split-brain patients compared to a neurotypical control group
• None of the people in the control group had epilepsy - cofounding variable
• Differences observed between 2 groups may be result of epilepsy than split brain

Question 12

AO3: Strength of split-brain research

Answer 12

• Michael Gazzaniga showed split-brain patients perform better than connected on certain tasks
• Faster at identifying the odd one out in an array of similar objects
• In normal brain, LH’s better cognitive strategies are ‘watered down’ by inferior Rh
• Increases validity

Question 13

AO3: Strength of hemispheric lateralisation

Answer 13

• Research shows even in connected brains, 2 hemispheres process info differently
• Gereon Fink et al. used PET scans to identify which areas of a brain were active during visual processing task
• Connected brain ppts asked to look at a whole forest, regions of RH were active. When told to focus on finer details such as individual trees, areas of LH dominated
• Hemispheric lateralisation is a feature of the connected and split brain