hemispheric lateralistaion

Question 1

what is hemispheric lateralisation?

Answer 1

the idea that the two halves of the brain are functionally different and each hemisphere has functional specialisations e.g. the left is dominant in language and the right excel is at visual motor tasks

Question 2

what are the left hemispheres functions?

Answer 2

• dominant in language
• controls right hand/foot
• receives info from right visual field

Question 3

what are the right hemispheres functions?

Answer 3

• dominant in visual motor tasks
• controls left hand/foot
• receives info from left visual field

Question 4

how are the two hemispheres connected?

Answer 4

they are connected through nerve fibres called the corpus callosum which facilitate interhemispheric communication allowing the left and right hemispheres to talk to each other

Question 5

what are split brain patients?

Answer 5

their two hemispheres no longer communicate - undergone a commissurotomy

Question 6

who studied hemispheric lateralisation?

Answer 6

Sperry and Gazzaniga

Question 7

what was the aim of their research?

Answer 7

to investigate the functions of the left and right hemispheres and how specialised each hemisphere is to certain tasks

Question 8

what was their procedure?

Answer 8

3 tasks
1. image was projected to the right visual field (processed by left) or left visual field (processed by right)
2. draw an image with left hand (processed by right) or right hand (processed by left)

Question 9

what were their findings?

Answer 9

describe what you see task - participant could easily describe what they saw when image was projected to right visual field, compared to left visual field - as language is dominant in the left hemisphere
drawing task - all participants do better images with their left hand even if they were originally right-handed as the right hemisphere is dominant in visual motor tasks

Question 10

What was their conclusion?

Answer 10

The findings highlight the key differences between the two hemispheres

Question 11

evaluation point one

Answer 11

• small sample
• sample of just 11 people with history of epileptic seizures (lacks population validity)
• may have caused unique changes to the brain which could have influenced findings
• general laws about lateralisation cannot be established (nomothetic) and findings cannot be generalised to normal brains and the rest of society

Question 12

evaluation point two

Answer 12

• methodological issues
• sperrys experiment was somewhat artificial for example an image being protected onto a screen lacks mundane realism - doesn’t reflect every day situations
• therefore cannot be generalised to daytoday life
• however split brain research is very scientific objective as a standardised procedure is used

Question 13

evaluation point 3

Answer 13

• started a debate on the nature of the brain
• sperry’s work triggered a theoretical and physiological debate on the degree of communication between the two hemispheres
• pucetti believed that two hemispheres was so different they represented a form of duality within the brain whereas others believed they were more integrated
• the value of sperrys work is in promoting this complex debate

Question 14

evaluation point 4

Answer 14

• individual differences
• all 11 participants had varying degrees of connection and length of drug therapies prior to their procedures
• therefore putting them all into one category is assuming that all exactly the same
• so drawing conclusions about lateralisation as if they are one group of participants is misleading