Biopsychology : Split Brain Research Into Hemispheric Lateralisation Flashcards
What is hemispheric lateralisation
The idea that the two hemispheres of the brain are functionally different + that certain mental processes + behaviours are Mainly controlled by one hemisphere
What is split brain research
- series of studies involving epileptic people who had experienced a surgical separation of the hemispheres of the brain
- allowed researchers to investigate the extent to which brain function is lateralised
Outline sperrys sample in his research into split brain research
- all studies involved a unique group of individuals whom had all undergone the Same surgical procedure where the corpus callosum was severed in order to separate the two hemispheres + control epileptic seizures
- so the communication line between both hemispheres for these individuals was removed
- so Perry + colleagues could view the extent to which the 2 hemispheres were specialised for certain functions
Outline sperrys procedure in his research into split brain research
- an image/word was projected to the individuals right visual field (processed by left hemisphere)
- the same/different image was protected to the left visual field
- in the normal brains, the colours callosum would share the information to create a complete picture
- this did not occur in sperrys sample
What were the four topics studied by sperry in his research into split brain research
- describing what you see
- recognition by touch
- composite words
- matching faces
Outline the results of sperrys study for ‘describing what you see’
- when a picture was shown to an individuals right visual field they could describe what was seen
- when it was presented to their left visual field they could not describe what was seen + reported their wa nothing there
- language is processed in the left hemisphere so the individuals inability to describe objects in the left visual field was because there was no language centre in the right hemisphere
Outline the results of sperrys study for ‘recognition by touch’
- individuals could not attach verbal labels to objects projected in the left visual field but they were able to select a matching object from a bag of different objects using their left hand
- so the individuals were not able to verbally identify what they had seen but could ‘understand’ what the object was
Outline the results of sperrys study for ‘composite words’
- if two words were presented simultaneously, one on either side of the visual field
- e.g. a key on the left and a ring on the right
- the individual would select the key with their left hand and say the word ‘ring’
Outline the results of sperrys study for ‘matching faces’
- the right hemisphere appeared dominant in recognising faces
- when asked to match a face from a series of other faces, the picture processed by the right hemisphere was consistently selected.
- the picture presented to the left hemisphere was consistently ignored
What are the three evaluation points for split brain research into hemispheric lateralisation
- research support for lateralised brain functions
- strengths of the methodology
- the approach has a theoretical basis
Outline ‘research support for lateralised brain functions’ as an evaluation point for split brain research into hemispheric laterisation
- Sperry (and gazzaniga’s) work into the split brain theory has produced impressive research findings
- the main conclusion drawn is that the left hemisphere is geared towards analytical and verbal tasks and the right is better at performing spatial tasks and music
- left hemisphere = the analyser
- right hemisphere = the synthesiser
Outline ‘strengths of the methodology ’ as an evaluation point for split brain research into hemispheric lateralisation
- experiments involving split brain individuals made use of highly specialised + standardised procedures
- in Sperry’s study, participants would be asked to stare at a given point, the ‘fixation point’
- the image projected would flash up for 1/10th of a second
- this allowed Sperry to vary aspects of the basic procedure and ensured only 1 hemisphere was receiving info at a time
Outline ‘the approach has a theoretical basis ’ as an evaluation point for split brain research into hemispheric lateralisation
- sperrys worked promoted a theoretical and philosophical debate about the degree of communication between the 2 hemispheres
- some theorists (Pucetti) have suggested that the 2 hemispheres are so functionally different they represent a form of duality in the brain. - that in effect, we are all 2 minds
