Sperry Flashcards
What is the background of Sperry’s study
Epilepsy is brought on by abnormal electrical impulses within the brain that disrupt normal patterns
In 1940s split brain surgery was used to prevent abnormal electrical impulses from spreading
Sperry thought the patients who had undergone the surgery would perfect participants to find out what part of the brain completes what function
What is lateralisation of function
One side of the brain has a different role from the other
What is the corpus callosum
Fibres that carry the majority of information between the two hemispheres of the brain
What is contra lateral control
Each side of the body is controlled by the other side of the brain
What is a commissurotomy
Surgical operation to sever the corpus callosum
What was Sperrys aim
To study the functions of separated and independent hemispheres
What sample was used
Epileptic - 11 patients who had undergone a commissurotomy as a treatment for epilepsy. They were obtained from a surgery in America
Non-epileptic - compared with a group of people who had not undergone surgery
Why did Sperry select the sample that he did
He was able to test hemispheres independently as they would have been separated in surgery
Weaknesses of the sample
Too small
2 people had surgery 4-5 years ago so may have recovered/adapted
Can’t be generalised
Ethnocentric
What controls were used in the study
Objects & images used
Time images shown for (1/10 second)
Fixation point
Hands being out of view
One eye covered
What happened when objects were flashed in the right visual field
Information goes to the right hemisphere
They are able to say what the object is
What happens when an object is flashed in the left visual field
Information passes to the right hemisphere
They can draw the object with their left hand
They cannot say what the object is
What happens when different stimuli are presented in each visual field
(Eg key in right / apple in left)
Key information passes to left hemisphere
Apple information passes to right hemisphere
They can say that they saw a key and draw an apple with their left hand
They cannot say why they have drawn an apple
What happens when simple maths problems are presented in the left visual field
The information goes to the right hemisphere
They can write the answer with their left hand
What happens when a photo of a nude pin up is presented in the left visual field
The information is passed into the right hemisphere
They can laugh or look embarrassed
They cannot say what they have seen
What happens when they feel objects with their right hand only (unseen)
Information goes to the left hemisphere
They can say what they are holding
What happens when objects are felt by the left hand only (unseen)
Information passes to the right hemisphere
They can pick up object again and draw it with their left hand
They cannot say what they are holding
What conclusions were found
The left hemisphere has language ability (written and verbal) and controls right hand side of the body
The right hemisphere only communicates non-verbally and controls the left hand side of the body
What ethics were kept in which were broken?
Informed consent, confidentiality and deception were kept
Protection from harm was broken
In what ways was the ethnocentric?
The sample was obtained from a hospital in America, but the roles of each brain hemisphere should be universal so perhaps it doesn’t matter
How was it internally reliable?
The procedure was very standardised and easy to replicate due to the amount of controls for example the images were only shown for one 10th of a second
How was it externally reliable?
The sample was only 11 split brain patients and therefore perhaps not large enough to establish a consistent effect. Although perhaps biologically as we are all the same same it might not matter.
How was it internally valid?
Perhaps a behaviour can be explained as result of their epilepsy not surgery
How is it externally valid? (Population validity)
The sample was very specific, so perhaps not generalisable but doesn’t matter due to it being based on natural biology
How is it externally leave valid? (Ecological validity)
The Taki scope procedure was not very realistic as we see things for more than one 10th the second so our brain could adapt
Feeling around and not being able to see your hands is relatively normal
How does Sperry study linked to psychology being a science?
It is falsifiable and replicable as could be repeated again in lab conditions proving false. The data is very objective based on the participant abilities.
How do you Sperry study linked to the nature versus nurture debate?
Nature is prominent as it investigates natural brain abilities rather than influence by experiences
How does Sperry study linked to the reductionism versus holism debate?
It is reductionist as it only takes into consideration biological explanations of behaviour
How does Sperry study linked to usefulness?
It might be useful when identifying capabilities for those with brain damage
