Biopsychology- Split-brain Research Into Hemispheric Lateralisation Flashcards
Hemispheric lateralisation -
The idea that the two halves (hemispheres) of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other, as in the example of language (which is localised as well as lateralised).
Split-brain research -
A series of studies which began in the 1960s (and are still ongoing) involving epileptic people who had experienced a surgical separation of the hemispheres of the brain. This allowed researchers to investigate the extent to which brain function is lateralised.
What is hemispheric lateralisation?
It is the concept that certain mental processes, such as language, are controlled by one hemisphere of the brain rather than both.
What did Roger Sperry’s split-brain research investigate?
Whether other neural processes, aside from language, are organised in one hemisphere and how the hemispheres function independently.
What surgical procedure was performed on split-brain individuals?
A commissurotomy, where the corpus callosum and other tissues connecting the hemispheres were severed to control epileptic seizures.
What was the main communication impact of the commissurotomy?
It prevented the two hemispheres from sharing information, allowing researchers to study their independent functions.
Describe the basic procedure used in Sperry’s split-brain research.
An image or word was projected to one visual field (right or left), with the corresponding hemisphere processing it. Split-brain individuals could not transfer this information to the other hemisphere.
What did Sperry find about describing objects in split-brain individuals?
When an object was shown to the right visual field (left hemisphere), participants could describe it. When shown to the left visual field (right hemisphere), they could not.
Q: Why couldn’t split-brain individuals describe objects seen in their left visual field?
A: The right hemisphere lacks language centers, and information could not be transferred to the left hemisphere.
Q: How were split-brain individuals able to recognise objects by touch?
A: They could use their left hand (controlled by the right hemisphere) to select matching objects or related items without verbal identification.
Q: What happened when two words were presented simultaneously in split-brain studies?
A: The word in the right visual field (processed by the left hemisphere) could be spoken, while the object in the left visual field (processed by the right hemisphere) could be selected by the left hand.
Q: How did the right hemisphere perform in recognising faces?
A: It was dominant in matching faces and selecting pictures, while the left hemisphere struggled with this task.
Q: What are the strengths of Sperry’s methodology?
A: The use of highly specialised and standardised procedures ensured precise control and reliable results by isolating information to one hemisphere.
Q: What theoretical debate did Sperry’s work prompt?
A: Whether the two hemispheres are functionally distinct and operate as “two minds” or if they work as an integrated system.
Q: What is a limitation of Sperry’s research sample?
A: The findings were based on a small and unique group of 11 individuals with epilepsy, which may not generalise to the wider population.
Q: Why might differences in hemispheric function be overstated?
A: In the normal brain, the hemispheres constantly communicate, and many functions associated with one hemisphere can be performed by the other when necessary.
Q: What is one legacy of Sperry’s work that is criticised?
A: The oversimplification and exaggeration of functional differences between the hemispheres in pop psychology.
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What did Sperry find about describing objects in split-brain individuals?
When an object was shown to the right visual field (left hemisphere), participants could describe it. When shown to the left visual field (right hemisphere), they could not.
Why couldn’t split-brain individuals describe objects seen in their left visual field?
The right hemisphere lacks language centers, and information could not be transferred to the left hemisphere.
How were split-brain individuals able to recognise objects by touch?
They could use their left hand (controlled by the right hemisphere) to select matching objects or related items without verbal identification.
What happened when two words were presented simultaneously in split-brain studies?
The word in the right visual field (processed by the left hemisphere) could be spoken, while the object in the left visual field (processed by the right hemisphere) could be selected by the left hand.
How did the right hemisphere perform in recognising faces?
It was dominant in matching faces and selecting pictures, while the left hemisphere struggled with this task.
What are the strengths of Sperry’s methodology?
The use of highly specialised and standardised procedures ensured precise control and reliable results by isolating information to one hemisphere.
What theoretical debate did Sperry’s work prompt?
Whether the two hemispheres are functionally distinct and operate as “two minds” or if they work as an integrated system.
Why might differences in hemispheric function be overstated?
In the normal brain, the hemispheres constantly communicate, and many functions associated with one hemisphere can be performed by the other when necessary.
What is a limitation of Sperry’s research sample?
The findings were based on a small and unique group of 11 individuals with epilepsy, which may not generalise to the wider population.
What is one legacy of Sperry’s work that is criticised?
The oversimplification and exaggeration of functional differences between the hemispheres in pop psychology
