split brain research into hemispheric lateralisation

Question 1

hemispheric lateralisation

Answer 1

idea that the toe halves of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other

Question 2

split brain studies

Answer 2

Sperry (1968)- studies involved a unique group of individuals all of whom had undergone the same surgical procedure where the two hemispheres of the brain were separated to control frequent and severe epileptic seizures
-for these patients, the main communication line between the two hemispheres was removed

Question 3

procedure

Answer 3

• an image or word would be projected to a patients right visual field (processes by the left hemisphere) and the same or different image would be projected to the left visual field (processed by the right hemisphere)
• in the normal brain the information would be shared between both hemispheres giving a complete picture of the visual world however presenting the image to one hemisphere of a split brain patient meant the information couldn’t be conveyed from one hemisphere to the other

Question 4

key findings (describing what you see/recognition by touch)

Answer 4

describing what you see- when a picture of an object was shown to a patients right visual field they could easily describe what was seen but when shown to the left visual field, the patient couldn’t describe what was seen
recognition by touch- couldn’t attach verbal labels to objects but able to select a matching object from a grab bag of different objects using their left hand (right hem), could understand what the object was using the right hemisphere

Question 5

key findings (composite words/matching faces)

Answer 5

composite words- if two words were presented simultaneously on either side of the visual field eg key on left and ring on right, the patient would write with their left hand (right hem) the word key and say the word ring
matching faces- the right hemisphere also appears dominant in terms of recognising faces, when asked go match a face from a series of other faces, the picture processes by the right hemisphere (left visual field) was consistently selected whilst the picture presented to the left hemisphere was consistently ignored

Question 6

demonstrated lateralised brain functions

Answer 6

Sperrys work has produced an impressive body of research findings, the main conclusion of which appears to be that the left hemisphere is more geared towards analytic and verbal tasks whilst the right better as performing tasks and music
-right hemisphere can only produce rudimentary words and phrases but contributes emotional and holistic content to language

Question 7

strengths

Answer 7

experiments involving split brain patients have highly specialised and standardised procedures

• allowed sperry to vary aspects of the basic procedure and ensured that only one hemisphere was receiving information at a time
• well controlled

Question 8

theoretical basis

Answer 8

sperrys work prompted a theoretical and philosophical debate about the degree of communication between the two hemispheres in everyday functioning and the nature of consciousness

• Pucetti (1977)- suggest the two hemispheres are so functionally different that they represent a form of duality in the brain- that in effect we are all two minds
• others argue that the two hemispheres form a highly integrated system and are both involved in most everyday tasks

Question 9

Issues with generalisation

Answer 9

split brain patients constitute such an unusual sample of people

• only 11 who took part in all variations of the procedure and all had epilepsy
• may have cussed unique changes in the brain