Hemispheric lateralisation and split-brain research

Question 1

Hemispheric lateralisation

Answer 1

• 2 hemispheres are functionally different
• Broca’s area and Wernicke’s area show that language is lateralised as they are both in the left hemisphere
• Vision, motor and somatosensory areas are not lateralised as they appear in both hemispheres

Question 2

Split-brain research - overview

Answer 2

• Sperry
• Tested capabilities of separated hemispheres
• LVF to RH to LH
• RVF to LH to RH
• corpus callosum is cut in split-brain patients
• info presented to one hemisphere has no way of getting to other hemisphere and can only be processed in the hemisphere that recieved it

Question 3

Split-brain research - procedure

Answer 3

• patients focus on a dot in the centre of the screen - info presented to either LVF or RVF
• asked to respond with either their left hand (controlled by RH) or right hand (controlled by LH) without being able to see what their hands were doing
• Describe what you see: Image shown to LVF = no - image shown to RVF = yes
• Recognition by touch: LVF and left hand = yes - RVF and right hand = no
• Composite words: can draw with LH if presented to LVF but can’t say it, can say it if presented to RVF but can’t draw it

Question 4

Lateralisation - evaluation - strength

Answer 4

• Research support
• in connected brains the 2 hemispheres process info differently
• researchers used PET scans to identify which brain areas were active during a visual processing task - p’s with connected brains asked to view whole image, regions of RH were more active - when asked to focus on finer detail, areas of LH were more active

Question 5

Lateralisation - evaluation - limitation

Answer 5

• May be different functions but research suggests people don’t have a dominant side of their brain that creates a different personality
• researchers analysed brain scans and did find that people used certain hemispheres for certain tasks but there was no evidence of a dominant side
• suggests notion of right or left brained people is wrong

Question 6

Split-brain research - evaluation - strength

Answer 6

• Research support
• research showed SB p’s actually perform better than connected controls on certain tasks - e.g faster at identifying odd one out
• Supports idea that left brain and right brain are distinct

Question 7

Split-brain research - evaluation - limitation

Answer 7

• Generalisation issues
• SB p’s compared to a control group - but none of the p’s in the control group had epilepsy
• Major confounding variable
• Any differences between the 2 groups may be due to the epilepsy rather than SB