Describe and Evaluate Hemisphere Lateralisation
DesDeD
AO1: KNOWLEDGE & UNDERSTANDING:
Idea that certain processes or behaviours are controlled by one hemisphere rather than the other.
Left- Analyser as identifies logic and language.
Right- Synthesiser as emotion and face recognition, assembling information together.
Motor/Sensory Areas- Not lateralised but they are cross wired- Contralateral (LH control RB, RH control LB)
Visual Cortex- Is Contralateral (opposite side control) and Ipsilateral (same-sided).
Right hemisphere process’ left visual field form both eyes.
Left hemisphere process’ right visual field from both eyes.
AO3: EVALUATION AND ANALYSIS
‘Thorough, effective and focused’. Elaborate with evidence and explain why it is a strength or weakness.
Point Evidence & Explain
1. Even in connected brains the hemispheres process information differently. Gereon Fink
Lateralisation in Connected 1996 used PET scans during visual processing tasks. When asked to focus on the picture as
Brain a whole the right brain was more active, when asked to focus on elements of the image,
the left brain was active. Suggests lateralisation is a feature of whole and split brains.
2. One limitation is that the idea that LH is analyser and RH is synthesiser. Jared Nielsen 2013
One Brain analysed brain scans from over 1000 7-29yr olds and found people did use certain
hemispheres for certain tasks. However, there was no evidence of a dominant side.
Suggests notion of right/left brain is wrong.
3. Lateralisation is adaptive as it enables 2 tasks to be performed simulations with efficiency.
Lateralisation v Plasticity Lesley Rogers 2004 showed that lateralised chickens could find food while watching for
predators but normal chickens couldn’t. Neural plasticity could also be seen as adaptive.
Following damage through illness or trauma, some functions can be taken over by non-
specialised areas in the opposite hemisphere. Language can switch sides, Holland 1996.
, Describe and Evaluate Split-Brain Research
DesDeD
A unique group of patients who had Commissurotomy- where the Corpus Collosum is severed so that the 2 hemispheres
can no longer communicate. Done to control frequent and severe epileptics. KEY STUDY- Sperry 1968, Studied split brain
patients and compared them to control.
Procedure- Word was placed in the left or right visual field. Optic chiasm is still connected so information can go through to
opposite sides, this is then dealt with independently by LH/RH but info isn’t shared as corpus collosum is severed. Tactile
tasks were carried out with their hands underneath an opaque screen. Used sense only.
Findings of Sight- Right- When a picture was shown, the right visual field was able to describe it better. Left- When it was
presented to the left field, they could not describe it and often reported no object.
Findings of Touch- Left- If patients are shown an object in their LVF they can pick up the object (from behind a screen) with
their left hand but could not verbalise what their selecting. The left hand was also able to select an object most closely
associated with the first object due to its analysis and logic. Different- If two different objects are placed in the hands then
put in the unseen pile. Both hands will search for their OWN object and reject the other hands object as their not
communicating.
Findings of Drawing- A picture is shown to the left or right visual field and the patients draw it. They were consistently
better when drawn by left hand (right hemisphere). This was despite being right-handed. This suggest the right hemisphere
is better at drawing.
Conclusion- It seems that in these patients the hemispheres process info separately and have different functions. Sperry’s
research seems to support lateralisation. LH- More Verbal. RH- More Emotional
AO3: EVALUATION AND ANALYSIS
‘Thorough, effective and focused’. Elaborate with evidence and explain why it is a strength or weakness.
Point Evidence & Explain
1. Michael Gazzaniga 1989 showed split-brain ppts. Perform better than normal on certain
Split-Brain Research tasks. Faster at finding the odd one out in an array of similar objects than normal ppts.
Kingstone 1995 says the LH’s better cognition is ‘watered down’ by the inferior RH.
Supports Sperry’s earlier findings that LH and RH are distinct.
2. Casual relationships are hard to establish. Participants were compared to a neurotypical
Generalisation Issues control group but none of them had epilepsy and the whole experimental group did. This is
a major cofounding variable as any difference may be due to epilepsy. Although Fink’s
research supports the conclusions.
3. Split-brain as not performed for the purpose of the research (quasi-experiment). All
Ethics procedures were explained beforehand and fully informed consent. Trauma of the
(Counterpoint) operation may only be revealed later and the numerous tests over sometimes years may
have been stressful.
DesDeD
AO1: KNOWLEDGE & UNDERSTANDING:
Idea that certain processes or behaviours are controlled by one hemisphere rather than the other.
Left- Analyser as identifies logic and language.
Right- Synthesiser as emotion and face recognition, assembling information together.
Motor/Sensory Areas- Not lateralised but they are cross wired- Contralateral (LH control RB, RH control LB)
Visual Cortex- Is Contralateral (opposite side control) and Ipsilateral (same-sided).
Right hemisphere process’ left visual field form both eyes.
Left hemisphere process’ right visual field from both eyes.
AO3: EVALUATION AND ANALYSIS
‘Thorough, effective and focused’. Elaborate with evidence and explain why it is a strength or weakness.
Point Evidence & Explain
1. Even in connected brains the hemispheres process information differently. Gereon Fink
Lateralisation in Connected 1996 used PET scans during visual processing tasks. When asked to focus on the picture as
Brain a whole the right brain was more active, when asked to focus on elements of the image,
the left brain was active. Suggests lateralisation is a feature of whole and split brains.
2. One limitation is that the idea that LH is analyser and RH is synthesiser. Jared Nielsen 2013
One Brain analysed brain scans from over 1000 7-29yr olds and found people did use certain
hemispheres for certain tasks. However, there was no evidence of a dominant side.
Suggests notion of right/left brain is wrong.
3. Lateralisation is adaptive as it enables 2 tasks to be performed simulations with efficiency.
Lateralisation v Plasticity Lesley Rogers 2004 showed that lateralised chickens could find food while watching for
predators but normal chickens couldn’t. Neural plasticity could also be seen as adaptive.
Following damage through illness or trauma, some functions can be taken over by non-
specialised areas in the opposite hemisphere. Language can switch sides, Holland 1996.
, Describe and Evaluate Split-Brain Research
DesDeD
A unique group of patients who had Commissurotomy- where the Corpus Collosum is severed so that the 2 hemispheres
can no longer communicate. Done to control frequent and severe epileptics. KEY STUDY- Sperry 1968, Studied split brain
patients and compared them to control.
Procedure- Word was placed in the left or right visual field. Optic chiasm is still connected so information can go through to
opposite sides, this is then dealt with independently by LH/RH but info isn’t shared as corpus collosum is severed. Tactile
tasks were carried out with their hands underneath an opaque screen. Used sense only.
Findings of Sight- Right- When a picture was shown, the right visual field was able to describe it better. Left- When it was
presented to the left field, they could not describe it and often reported no object.
Findings of Touch- Left- If patients are shown an object in their LVF they can pick up the object (from behind a screen) with
their left hand but could not verbalise what their selecting. The left hand was also able to select an object most closely
associated with the first object due to its analysis and logic. Different- If two different objects are placed in the hands then
put in the unseen pile. Both hands will search for their OWN object and reject the other hands object as their not
communicating.
Findings of Drawing- A picture is shown to the left or right visual field and the patients draw it. They were consistently
better when drawn by left hand (right hemisphere). This was despite being right-handed. This suggest the right hemisphere
is better at drawing.
Conclusion- It seems that in these patients the hemispheres process info separately and have different functions. Sperry’s
research seems to support lateralisation. LH- More Verbal. RH- More Emotional
AO3: EVALUATION AND ANALYSIS
‘Thorough, effective and focused’. Elaborate with evidence and explain why it is a strength or weakness.
Point Evidence & Explain
1. Michael Gazzaniga 1989 showed split-brain ppts. Perform better than normal on certain
Split-Brain Research tasks. Faster at finding the odd one out in an array of similar objects than normal ppts.
Kingstone 1995 says the LH’s better cognition is ‘watered down’ by the inferior RH.
Supports Sperry’s earlier findings that LH and RH are distinct.
2. Casual relationships are hard to establish. Participants were compared to a neurotypical
Generalisation Issues control group but none of them had epilepsy and the whole experimental group did. This is
a major cofounding variable as any difference may be due to epilepsy. Although Fink’s
research supports the conclusions.
3. Split-brain as not performed for the purpose of the research (quasi-experiment). All
Ethics procedures were explained beforehand and fully informed consent. Trauma of the
(Counterpoint) operation may only be revealed later and the numerous tests over sometimes years may
have been stressful.
