Flashcards in Sperry, 1968 (Split Brain) Deck (23):
What is epilepsy?
A collection of disorders that are associated with uncontrollable seizures and electrical impulses.
What is the main bundle of nerve fibres that joins the two hemispheres called?
Corpus callosum (thick body).
What animals had Sperry performed the split brain technique on?
Cats and monkeys.
What is the left hemisphere connected to?
Right side of the body and right visual field.
What is the right hemisphere connected to?
Left side of the body and left visual field.
Which of the two hemispheres are connected to language?
What is the aim of study?
To investigate the psychological effects of hemisphere deconnection (in split brain patients) and the lateralisation of function.
What is the method of the study?
Quasi Experiment/Case Study
Describe the participants.
-11 'split-brain patients'
-Undergone hemisphere deconnection due to epilepsy which could not be treated by medication.
Describe the procedure.
The participant had one eye covered and was asked to gaze at a fixed point in the centre of a projector screen. Visual stimuli were back projected onto the screen either to the right or left at a very high speed (one picture every 0.1 second or less). This meant that the eye only had time to access the image in the visual field where it was placed. Below the screen was a gap so the participants could reach objects but not see his or her hands.
What was the visual investigation?
It involved flashing one stimuli at a time to one visual field or two stimuli simultaneously to different fields and participants were asked to identify what they saw through speech, writing or drawing.
What was the tactile investigations?
It involved placing an object in one hand, or the other, or both hands simultaneously without the participant being able to see what they were holding and then asking them to identify what they had been holding through speech, writing and drawing or manual selection from various objects.
What is the IV in the study?
If they were a split brain patient or not.
What is the DV in the study?
P's performance on the tests.
What are the results?
-A picture shown in one visual field is only recognised again if it appears in that visual field.
-Items presented in the right visual field (left hemisphere) could be described as speech and written.
-If the same items are then projected to the left visual field (RH) the participants says he did not see anything.
-If you then ask the participant to use his left hand (RH) to point to a matching picture or object in collection of pictures/objects, then he points to the item he has just said he couldn't see.
What can the right hemisphere do in split brain patients? (7)
-Human mental capacities
-Understanding of general categories
-Simple arithmetic problems
-Responding to spoken cues
What does the study show?
Patients acts as if they have two minds in one body. He established that the left hemisphere has language and the brain shows lateralisation of function. He acknowledges that there are individual differences between patients.
What were the strengths of the method used?
-Quasi experiment: allowed researchers to investigate variables that they are not able to investigate in a lab experiment.
-Can be seen as a collection of detailed case studies conducted in highly controlled and objective laboratory equipment and procedures (reliable).
What are the weaknesses of the methods used?
-No full control over IV.
-Low ecological validity (tests are not like real life).
-Test is artificial.
How representative was the sample of participants?
-Small sample so lacks generisability but all Ps experienced similar effects.
-It may have been the epilepsy that had caused their brain functioning differently (hard to draw out conclusions).
What type of data was collected?
-Quantitative: If something could be identified or not. (Data about different functioning of the two hemispheres.)
-Qualitative: Experiences of "split brain" patients. (Giggling at pin up pictures without knowing why they giggled.)
Define: Lateralisation of function
How the two hemispheres have different functions.