Split-brain research into hemispheric lateralisation

Question 1

What is hemispheric lateralisation?

Answer 1

The idea that specific functions are reserved to & controlled by one of the 2 hemispheres

Question 2

What is split-brain research?

Answer 2

A series of experiments that investigate whether other neural processes (like language) are lateralised

Question 3

What did Sperry’s 1968 studies involve?

Answer 3

• A group of individuals that had all undergone the same surgical procedure called commissurotomy (corpus callosum cut to separate hemispheres)
• The pps main communication line had been removed which allowed Sperry to test to which extent the 2 hemispheres were specialised for certain functions

Question 4

What was Sperry’s general procedure to carry out split-brain research?

Answer 4

• image projected to individual’s RVF and the same or different image projected to LVF
• in ‘normal’ brain the corpus callosum would share info across hemispheres giving complete picture
• presenting image to split-brain individual meant info couldn’t be shared across hemispheres

Question 5

Evaluation: Strengths of methodology

Answer 5

• hemispheric lateralisation uses standardised & specialised procedures
• as part of Sperry’s research pps would stare at a given point and then an image would flash on the screen for 1/10th of a second
• this meant pps couldn’t move their eyes across the image and share info
• this ensured only 1 hemisphere was receiving information and allowed well-controlled procedure

Question 6

Evaluation: Issues with generalisation

Answer 6

• Sperry’s research only involved 11 pps taking part in all procedures and all who had a history of epileptic seizures
• it has been argued this may have caused unique changes in the brain and influenced findings
• some pps had experienced more of a disconnection between hemispheres than others

Question 7

Evaluation: Demonstrated lateralised brain functions

Answer 7

• Sperry’s work into split-brain produced a lot of impressive findings
• main conclusion found is is LH is more geared towards analytic & verbal tasks whilst RH contributes to emotional content to language
• research says LH is analyser & RH is synthesizer which is a key contribution to understanding our brain processes

Question 8

Evaluation: Theoretical basis

Answer 8

• Sperry’s work prompted theoretical & philosophical debate about degree of communication between hemispheres in everyday functioning
• some theorists (Roland Pucetti) suggested that the 2 hemispheres are so functionally different that they represent a form of duality in the brain (idea of 2 minds emphasised rather than created more in a split-brain person)