Biopsychology - Split Brain Research Into Hemispheric Lateralisation Flashcards
What does hemispheric lateralisation suggest about language processing?
Hemispheric lateralisation suggests that for the majority of us, language is subject to the left hemisphere. It proposes that the left hemisphere is more associated with analytic and verbal tasks, whereas the right is more geared toward rudimentary words and phrases but contributes nonverbal and contextual elements to language.
What was Sperry’s split-brain research focused on?
Sperry’s research focused on investigating how the brain processes information when the main communication link between the two hemispheres, the corpus callosum, is severed. This allowed him to study whether the hemispheres performed tasks independently of one another.
What surgical procedure did Sperry’s participants undergo, and what was its purpose?
Participants underwent a procedure called a commissurotomy, where the corpus callosum and other tissues connecting the two hemispheres were cut down the middle. This was done to control severe epilepsy and meant the two hemispheres could no longer communicate directly.
Describe the general procedure used by Sperry in his experiments.
Sperry presented information to one hemisphere at a time using a visual field setup. For example, an image or word could be projected to an individual’s right visual field (processed by the left hemisphere) or the left visual field (processed by the right hemisphere). In a normal brain, the corpus callosum would transfer this information between hemispheres. However, in split-brain individuals, this communication was not possible, so the information stayed in one hemisphere.
What was the significance of Sperry’s procedure for studying hemispheric functions?
Sperry’s procedure ensured that only one hemisphere was receiving information at a time, allowing for highly controlled and specific investigation of lateralisation in the brain.
What were the key findings regarding describing what you see?
If an object was shown to the right visual field, individuals could easily describe what they saw. However, if the object was shown to the left visual field, individuals often reported nothing was there. This is because language centres are located in the left hemisphere.
What were the key findings regarding recognition by touch?
While individuals could not describe objects presented to their left visual field, they could select a matching object with their left hand. For example, if a cigarette was shown to the left visual field, the left hand could retrieve a related object, showing the right hemisphere’s ability to process visual information.
What findings emerged about composite words and faces?
When two words were presented simultaneously, one to each hemisphere, participants could write the word shown to their left visual field (right hemisphere) with their left hand and say the word shown to their right visual field (left hemisphere). The right hemisphere was found superior in drawing tasks, and it was also dominant in recognizing faces.
What is one evaluation point about the findings on lateralised brain functions?
Sperry’s work demonstrated that the left hemisphere is the “analyst” (focusing on language and verbal tasks), while the right hemisphere is the “synthesiser” (handling spatial and holistic tasks). This has been a key contribution to understanding brain function.
What is one evaluation point about the strengths of Sperry’s methodology?
Sperry’s experiments were highly controlled, ensuring that only one hemisphere was receiving information at a time. This allowed for the development of a very useful and well-controlled procedure.
What is one evaluation point about theoretical contributions from Sperry’s research?
Sperry’s work sparked debate about the extent of communication between hemispheres in everyday functioning. Some researchers argue that the hemispheres are so functionally different that they represent a form of duality in the brain, almost like two minds.
What is one evaluation point about generalising Sperry’s findings?
Critics have argued that Sperry’s findings may not be widely applicable because split-brain individuals are an unusual group. Only 11 participants were studied, all of whom had a history of severe epilepsy, which could have influenced the results.
