Split-Brain Research into Hemispheric Lateralisation Flashcards
Explain what’s meant by hemispheric lateralisation
The two halves of the brain are functionally different -certain mental processes and behaviours are controlled by one hemisphere rather than the other
Give an example of a function that we know is subject to hemispheric lateralisation
Language is controlled by the left hemisphere only
Outline the key study done by Sperry (1968). Including the aim, procedure and findings in your answer
Studied a group of patients who’d had their corpus callosum (bit that connects the two halves of the brain) severed bc of epileptic fits etc. This allowed Sperry to investigate if each side of the brain was specialized for certain functions.
Had a + in centre of screen – patients told to look at this so info only went to one eye or other.
Images or words projected into either the left or right visual field - Images presented in the left field could not be described bc went to RH – language is in LH -Images could be identified with touch by both left and right hand
Composite words - PPTs would use their left hand to write the word – controlled by RH – which receives info from LVF, but would say the word presented to the right visual field – controlled by LH – which receives info from the RVF – RH better at drawing and spatial stuff than left
Matching face - the right hemisphere seems to be dominate in facial recognition – presented with 2 faces to match to another – one in LVF – RH – consistently chosen – when 2 faces mixed – RH dominated recognition
What is split-brain research?
A series of studies which began in the 1960s involving epileptic patients who had experienced surgical separation of the hemispheres of the brain. This allowed researchers to investigate the extent to which brain function is lateralised.
Briefly evaluate the methodology in split-brain research (Eval +)
Standard procedure - only showed the images for one tenth of a second. Patients didn’t have time to use both eyes to view the image
Why are there issues with generalizability in Sperry’s research? (Eval -)
Only 11 PPTs took part in the study, all had epilepsy - may have impacted the brains and the findings. The level of disconnections between the two hemispheres of the brain was different for all PPT. The control group didn’t have epilepsy, this was inappropriate as they’re different from the experimental group in two ways, a control group who had epilepsy would’ve been better.
Explain why the difference in functions may be overstated (Eval -)
While the verbal and non-verbal descriptions of the left and right hemispheres may be useful in reality the distinction is less clear cut. In a normal brain the two hemispheres are in constant communication. Many behaviours associated with one hemisphere can be carried out by the other if it’s needed.
