Biopsych: Lateralisation and split-brain research Flashcards
What’s hemispheric lateralisation
The idea that the two hemispheres of the brain are functionally different and that certain mental processes are mainly controlled by one hemisphere.
The two hemispheres are connected by the corpus callosum (a bundle of nerve fibres) which allows info from one hemisphere to be sent to another.
What are the 3 roles of the left hemisphere?
the language centre, it controls the right side of the body (e.g., right hand) and receives info from the right visual field.
What are 3 roles of the right hemisphere?
it forces visuo-spatial tasks, it controls the left side of the body and receives info from the left visual field.
Who conducted Split-brain research?
Sperry and Gazzaniga (1967) —> the first to study the capabilities of split-brain patients.
What’s the aim of Sperry and Gazzaniga’s research?
to test the capabilities of separated hemispheres in split-brain research.
What’s the procedure of Sperry and Gazzaniga’s research?
an image or word was projected to a patient’s right visual field (processed by the left hemispheres) for 1/10th of a second and the same or different image was projected to the left visual field. The patient would then be asked to make a response with their left hand, right hand or verbally.
What were the findings of Sperry and Gazzaniga’s research?
(sight)
when a picture of an object was shown to a patients right visual field they could easily describe what was seen because the right visual is processed by the left hemisphere and the left hemisphere has a language centre. When a picture was presented to the left visual field the patient couldn’t describe what was seen and often reported that there was nothing present because the right hemisphere doesn’t have a language centre so can’t respond verbally.
What were the findings of Sperry and Gazzaniga’s research?
(touch)
when the object was placed in the right hand and processed by the left hemisphere the patient described verbally what they felt. Or they could identify the test object presented in the right hand by selecting a similar appropriate object, from a series of alternative objects. When the object was placed in the left hand and processed by the right hemisphere the patient couldn’t describe what they felt or could only make a wild guess. However, the left could identify a test object presented in the left hand, by selecting a similar or appropriate object from a series of alternate objects.
What’s the conclusion of Sperry and Gazzaniga’s research?
the left hemisphere is broadly responsible for speech and language. The right hemisphere is responsible for visual-spatial processing and facial recognition. Doesn’t show how the brain is organised into discrete regions with specific sections responsible for specific functions. Instead suggests that connectivity between different regions is as important as the operation of the different parts.
What are the 4 AO3 points for lateralisation and split-brain research
+Methodology
+/-Hemispheric lateralisation
-Generalisation
-Brain plasticity reduces the credibility of hemispheric lateralisation
(+AO3) Why is the methodology a strength?
Precise standardised procedure – presenting visual info to one hemispheric field at a time. Patients stared at a fixed point with one eye, image flashed up for 0.1 seconds. There was no time for the patients to move their eyes over the image to spread to other visual fields. Thus making the study well controlled, easy to replicate and so, has high internal validity and reliability.
(+/-AO3) +/- of hemispheric lateralisation
If each hemisphere can preform different tasks simultaneously, it might improve the efficiency of our brains (explains multi-tasking) but there’s limited empirical evidence for this.
(-AO3) How is lateralisation and split-brain research a generalisation?
Small, unusual sample: 11 patients with a history of seizures which may have caused unique changed to the brain, influencing the findings. Thus, making it difficult to generalise the findings of the study to normal brains and reducing population validity.
(-AO3) How does brain plasticity reduces the credibility of hemispheric lateralisation
Suggests other areas of the brain can compensate for the damage of a specific region and carry out said function. ‘Independent’ functions may not be so clear cut. Sperry and Gazzangia may have over-simplified findings.
