Research Into Lateralisation Flashcards
What is hemispheric lateralisation?
The idea that the two halves of the brain are functionally different.
What is split brain research?
A series of studies which involved people with epilepsy who had experienced a surgical separation of the hemispheres.
What is the corpus collosum?
What connects the left and right hemispheres of the brain.
How are sensory and motor control processed?
Contralaterally
What does contralaterally mean?
Opposite side
damage to the left hemisphere will affect the right side of the body, (vis versa)
What is the procedure called when they cut the corpus collosum?
Hemispheric disconnection.
What side of the brain is the left visual field connected to?
Right hemisphere.
What side of the brain is the right visual field connected to?
Left hemisphere.
What year was Roger Sperry’s research done in?
1968
What was Sperry’s method?
An image/ word is projected to either visual field and processed by the certain hemisphere
What did Sperry find?
That information presented to one hemisphere in split brain patients, it is not transferred to the other hemisphere.
What were the 3 tasks Sperry and Gazzaniga tested in split brain patients?
1) describe what you see
2) tactile test
3) drawing task
What did the do in the describe what you see task?
An image was presented to either the left or right visual field and they had to describe what they saw.
What did they do in the tactile test task?
An object was placed in the patients left or right hand and they had to describe what they felt or select a similar object from a series.
What did they do in the drawing task?
Participants were presented with an picture in either their left or right visual field, and they had to draw what they see
Describe what you see findings?
When picture was presented to the LVF they could describe what they saw, but when it was presented to the RVF they could not describe what they saw.
Tactile test findings?
When object was placed in right hand (LH) they could describe what they felt, but when the object was put in their left hand (RH) they could not describe what they felt
Drawing task findings?
When the picture was presented to the right visual field (LH) the picture they drew was never clear, but when the picture was presented to the left visual field (RH) they drew much clearer and better pictures.
What is the left hemisphere dominant in?
Speech and language.
What is the right hemisphere dominant in?
Visual-motor tasks.
What year was Sperry and Gazzaniga research done in?
1967
How many patients were in Sperry’s study?
11
Strength - Chicken study + counterpoint
- it is assumed that lateralisation increases neural processing capacity
- Rogers et al found in domestic chickens that brain lateralisation enhanced the ability to perform two task simultaneously
- can enhance brain efficiency
- (C) study was on animals not humans + not many split brain patients
Weakness - age
- research shows that lateralisation changed with age
- Szaflarki et al (2006) found that language became more lateralised to the LH with age, but after 25 lateralisation decreased
- this raises questions, like whether everyone has a hemisphere more dominant and whether this changes with age
Critisism - language may not be restricted to LH
- Turk et al (2002) discovered a patient who damaged LH, but developed the capacity to speak in the RH
- this suggest that lateralisation may not be fixed but that the brain can adapt following damage.
Limitation - split brain procedure is rarely carried out nowadays + counterargument
- Andrews points out that there are not many participants, patients may have other confounding physical disorders, or have less sectioning than originally believed
- (C) despite small sample size, studies are in a lot of detail, allows researcher to investigate in a lot more detail
Lateralisation meaning?
One hemisphere of the brain being responsible for particular physical and psychological functions.
