biopsychology - split-brain research n hemispheric lateralisation. Flashcards
What is meant by hemispheric lateralisation?
The idea that the 2 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.
What is an example of hemispheric lateralisation?
How the left hemisphere controls the ability to produce and understand language therefore language is subject to hemispheric lateralisation.
Therefore specialised areas associated with language are found in one hemisphere rather than both.
What is meant by corpus callosum?
Bundle of nerve fibres which allow information received by one hemisphere to be communicated to the other hemisphere.
What is the use of the corpus callosum?
Connects the two hemispheres.
How was the corpus callosum involved in the investigation of the two hemispheres’ abilities?
Surgeons had to cut the bundle of fibres which formed the corpus callosum when treating severe epilepsy.
What was the aim of the investigation involving the corpus callosum?
To prevent the electrical activity that accompanied epileptic seizures crossing from one hemisphere to the other.
What is the aim of the sperry and gazzaniga’s research (1967)?
To investigate the extent to which the two hemispheres were specialised for certain functions and whether the two hemispheres performed tasks independently of one another.
What is the procedure of the sperry and gazzaniga’s research (1967)?
- an image or word was projected to a patient’s visual field (processed by the right hemisphere) or the right visual field (processed by the left hemisphere).
- participants fixate on a dot in the center of the screen and this ensure that information is only presented to the right or left visual field.
- when information is presented to one hemisphere, the information is not transferred to the other hemispheres as the corpus callosum has been cut.
- range of experiments were then conducted including:
- describing what they could see.
- recognition by touch.
- drawing tasks.
- composite words.
- range of experiments were then conducted including:
- when information is presented to one hemisphere, the information is not transferred to the other hemispheres as the corpus callosum has been cut.
- participants fixate on a dot in the center of the screen and this ensure that information is only presented to the right or left visual field.
What occurred in the describe what you see experiment?
- picture was presented in the right visual field and processed by the left hemisphere
↳ patient was able to describe what they saw demonstrating the superiority of the left hemisphere when it comes to language production. - picture was presented in the left visual field and processed by the right hemisphere
↳ patient could not describe what was shown and often reported that there was nothing there.
What occurred in the recognition by touch experiment?
- object was placed in the right hand and processed by the left hemisphere
↳ patient could describe what they felt verbally. - object was placed in the left hand and processed by the right hemisphere
↳ patient could describe what they felt and could only make wild guesses due to no language function in the right hemisphere
➝ left hand could identify an object by selecting a similar appropriate object from a series if objects.
What occurred in the drawing tasks experiment?
- word presented to the right visual field and processed by the left hemisphere
↳ right hand would attempt to draw a picture however it was never as clear as the left one
↳ demonstrates the superiority of the left hemisphere when it comes to language production as the patient was able to say the word presented. - word presented to the left visual field and processed by the right hemisphere
↳ left hand which is controlled by the right hemisphere would constantly draw clearer and better pictures than right hand even though all participants were right-handed.
↳ demonstrates the superiority of the right hemisphere when it comes to visual and motor tasks.
What occurred in the composite words experiment?
- two words were presented simultaneously, either side of the visual field such as key on the left and right on the right
↳ patient would say ring as it is processed by the left hemisphere and they would be able to pick up the key with their left hand as that was processed by the right hemisphere.
What occurred in the face recognition experiment?
- when a composite picture was made up of two different halves of a face was presented
↳ one half to each hemisphere. - left hemisphere dominated in terms of verbal description.
- when asked to match face form a series of other faces the picture processed by the right hemisphere (left visual field) was consistently selected.
What was concluded from sperry and gazzaniga’s research (1967)?
- several difference between the two hemispheres.
- left hemisphere is responsible for speech and language.
- right hemisphere specialises in visual processing and motor tasks.
- research suggests the connection between different regions is just as important as the operation of different parts.
What are the strengths of sperry and gazzaniga’s research (1967)?
- it followed standardised procedures therefore research has high internal validity.
- hemispheric lateralisation enables two tasks to be performed simultaneously with greater efficiency which demonstrates how it can enhance brain efficiency in cognitive tasks.
