Sperry (1968) Flashcards
Background of the study
-Epilepsy is a brain condition brought on by abnormal electrical impulses discharging within the brain, disrupting brain patterns
-In the 1940s ‘split brain surgery’ was developed as a treatment-the corpus callosum is cut so the EI could not spread throughout the brain
-Sperry thought these patients were perfect for research into what each hemisphere of the brain does
Lateralisation of function
One side of the brain has a different function than the other
Corpus callosum
Fibres that carry the majority of information between the two hemispheres of the brain
Contralateral control
The idea that each side of your body is controlled by the opposite side of your brain
Commissurotomy
Surgical operation to sever the corpus callosum ‘split brain surgery’
Overall aim of the study
To study the functions of separated and independent hemispheres
What was the epileptic sample of the study?
11 patients who had undergone a commissurotomy as a treatment for their epilepsy, they were obtained from a surgery from America
What was the non-epileptic sample of the study?
Epileptic participants were compared with this group of people who had not undergone the surgery and did not have epilepsy
What was the main piece of equipment used?
The tachistoscope
What were the controls of the study?
-Objects
-Fixation point
-Symbols/images displayed for 1/10th of a second
-Hands out of view
-One eye covered
-Tachistoscope
What happened when objects were flashed to the right visual field?
-Information went to left side of the brain
-They could tell you what they had seen
What happened when objects were flashed to the left visual field?
-Information went to the right side of the brain
-They could draw the object they had seen with their left hand
-They could not tell you what they had seen
What happened when an apple was flashed to the LVF whilst a key was flashed to the RVF?
-Apple to right brain hemisphere
-Key to left brain hemisphere
-Could tell you they had seen a key
-Could draw an apple with their left hand
-Could not tell you why they had drawn an apple
What happened when simple maths problems were flashed to the LVF?
-Information went to right brain hemisphere
-Can draw the answer with their left hand
What happened when a photo of a nude pin up was presented to the LVF?
-Laughed, looked embarrassed, turned bright red
-Could not say what they had seen or why they reacted like this
What happened when objects were felt by the right hand only and not seen?
-Information sent to left brain hemisphere
-Could tell you what they had felt
What happened when objects were felt by the left hand only and not seen?
-Information sent to right brain hemisphere
-Could draw the object with their left hand
-Couldn’t tell you want they felt
Conclusions about the left hemisphere of the brain
-Has written and verbal language ability
-Controls the right hand side of the body
Conclusions about the right hemisphere of the brain
-Can only communicate non-verbally
-Controls the left hand side of your body
What ethical guidelines did Sperry uphold?
Confidentiality, informed consent, deception
What ethical guidelines did Sperry break?
Protection from harm
Confidentiality
-No published videos of the study
-Participant details kept confidential
Informed consent
Consented to participate in study after being approached through their hospital
Deception
Participants fully aware of the research
Protection from harm
-Participants frustrated when they couldn’t explain why they were saying/drawing certain things
-Potentially embarrassing to not have full capabilities
Could the study be considered ethnocentric?
-Sample only obtained from a hospital in America
-However not ethnocentric as studying the brain, which is biological so wouldn’t be influenced by culture
Internal reliability
-Participants complete the same tasks
-Easy to replicate due to the high numbers of controls
External reliability
-Only 11 participants, so not large enough to establish a consistent effect
-But may not need as many people as biological
Internal validity
-Participant behaviour may have been caused by their epilepsy rather than their surgery
Population validity
-sample was very specific so potentially not generalisable
-But does it matter due to our natural biology?
Ecological validity of visual tasks
The tachistoscope procedure not very realistic as we see things for more than 1/10th of a second so our brain could adapt
Ecological validity of tactile tasks
Feeling around and not being able to see your hands is relatively normal
What debates does Sperry’s study link to?
-Psychology as a science
-Nature/nurture
-Reductionism/holism
-Usefulness
Psychology as a science
-Falsifiable and replicable as can be repeated again in lab conditions and proven false
-The data is very objective based on the participants abilities
Nature/nurture
Nature as investigates natural brain abilities rather than influenced by experiences
Reductionism/holism
Reductionist as only takes into consideration biological explanations of behaviour
Usefulness
Perhaps useful in identifying capabilities for those with brain damage
