Split- brain research into hemispheric lateralisation

Question 1

What was the procedure of the split-brain study?

Answer 1

• a group of people had a procedure to cut their corpus collision in order to separate their two hemispheres to prevent epileptic fits -they were then studied to see if their hemispheres could perform tasks independently
• an image would be projected to a patients right visual fiend which would be assessed by the right hemisphere in a normal brain this information would be shared between both hemispheres
• this was tested in 4 ways:

Question 2

What results came from describing what you see in the split-brain study?

Answer 2

-when a picture is shown to the right visual field the participant had no problem describing what they saw however if an image was shown to the left visual field the would not be able to describe it because there are no language centers in the right hemisphere

Question 3

What results came from recognition by touch in the split-brain study?

Answer 3

-whether an image was shown to the left or right visual field they were able to select a matching object from a grab bag behind a screen

Question 4

What results came from composite words in the split-brain study?

Answer 4

• if two words were presented simultaneously on either side of the visual field the patient could write with their left hand the word key and say the word ring
• different shapes were splashed to both the right and left visual field the left hand could draw it better than the right hand despite the right hand being the preferred hand for all the patients

Question 5

What results came from matching faces in the split-brain study?

Answer 5

• the right hemisphere also appeared dominant in terms of recognising faces
• when asked to match a face from a series of other faces, the picture seen in the left visual was consistently selected, whilst the picture in the right visual was consistently ignored
• when a picture made up of two different halves of a face was presented - one half to each hemisphere - the left hemisphere dominated in terms of verbal description whereas the right hemisphere dominated in terms of selecting a matching picture

Question 6

What are the evaluation points of split-brain research into hemispheric lateralisation?

Answer 6

+helps us understand how the brain works: left = language
+standardized procedures: reliable and high internal validity
+encouraged theoretical discussion: two brains or two hemispheres working together
-lacks generalisability: small sample or OCD sufferers

Question 7

How do demonstrated lateralised brain functions support split-brain research into hemispheric lateralisation?

Answer 7

• Sperry’s and later Gazzaniga’s pioneering work into the split-brain phenomenon has produced an impressive and sizeable body of research findings, the main conclusion of which appears to be that the left hemisphere is more is more geared towards analytic and verbal tasks whilst the right is more adept at performing spatial tasks and music
• the right hemisphere can only produce rudimentary words and phrases but contributes emotional and holistic content to language
• research suggests that the left hemisphere is the analyser whilst the right hemisphere is the synthesiser - a key contribution to our understanding of brain processes

Question 8

How is using standardized procedures a strength?

Answer 8

• the experiments involving split-brain patients made use of highly specialised and standardised procedures
• Sperry’s method of presenting visual information to one hemisphere field at a time was quite ingenious
• typical, participants would be asked to stare at a given point, the fixation point, whilst one eye was blindfolded
• the image projected would be flashed up for one-tenth of a second, meaning the split-brain patient would not have time to move their eye across the image and so spread the information across both sides of the visual field and subsequently both sides of the brain
• this allowed Sperry to vary aspects of t5he basic procedure and ensured that only one hemisphere was receiving information at a time
• thus he developed a very useful and well-controlled procedures

Question 9

How is theoretical basis a strength of split-brain research into hemispheric liberalization?

Answer 9

• Sperry’s work prompted a theoretical and philosophical debate about the degree of communication between the two hemispheres in everyday functioning and the nature of consciousness
• some theorists have suggested that the two hemispheres are so functionally different that we have two minds that this is a situation that is only emphasized rather than created in the split-brain patient
• other researchers have argued that the two hemispheres form a highly integrated system and are both involved in most everyday tasks

Question 10

How are methodological problems a weakness of the split brain study?

Answer 10

• Only 11 patients means the sample is unrepresentative of the whole population so it would be hard to make generalizations
• Patients were categorized into one experimental group, but some may have had more or less of the corpus callosum severed
• Experimental group only compared to those without a split-brain not to those who were epileptic without a split-brain