Sperry - Biological area Flashcards
What did Sperry’s other research on humans and monkeys who had a split-brain show?
BACKGROUND
Animals/Humans who had undergone surgical section of the corpus callosum suggested the behaviour effects of this surgery may be less severe than other forms of cerebral surgery e.g frontal lobotomy
Are the right and left hemisphere mirror images of each other
THEORIES
Yes
BUT there are distinct areas dealing with speech production and comprehension
(Broca’s area and Wernicke’s area, respectively) showing their functional localisation
What are Broca’s area and Wernicke’s area? (2)
THEORIES
- Wernicke’s area is the region of the brain that is important for language development
- Broca’s area is related to the production of speech.
What is functional lateralisation
THEORIES
The view that functions are performed by distinct regions of the brain
What side of the brain are Broca’s area and Wernicke’s area found in?
THEORIES
The left hemisphere
Where do areas in the right hemisphere receive information from?
THEORIES
The left side of the body
What is the right hemisphere concerned with?
THEORIES
activities in the left side of the body and vice versa
Where would information received by the Right visual field go to? which hemisphere and what side of the body? (3)
THEORIES
- RVF
- LH
- Right hand/body
What was the aim of Sperry’s study?
He set out in his study___
Each ____ possesses
Has____
- Sperry set out in this study, using split brain patients to show that
- Each hemisphere possesses an independent stream of conscious awareness
- Has its own separate chain of memories that are inaccessible to the other
What was the hypothesis?
The hypothesis is that split brain patients perform differently from individuals without a split brain
What was the experimental method?
RESEARCH METHOD
Quasi experiment
What did this controlled observation allow researcher’s to investigate?
RESEARCH METHOD
Controlled observation of split-brain patients to investigate behavioural symptoms resulting from hemisphere deconnection
Was this study a snapshot or longitudinal study?
RESEARCH METHOD
Snapshot study
What could this study also be classed as?
RESEARCH METHOD
A series of clinical case studies
What was the IV?
RESEARCH METHOD
Presence or absence of Split brain
What was the DV?
RESEARCH METHOD
The participants performance on various visual and tactile tasks
How many patients were used?
SAMPLE
11 split brain patients
What had these patients undergone
SAMPLE
Undergone ‘an extensive midline section of the cerebral commissures to control severe epileptic convulsions not controlled by medication’
Where were they from?
SAMPLE
LA, America
What were the patients experiencing before the surgery? (2)
SAMPLE
Experienced severe epileptic seizures
that could not be controlled by medication
What is a split-brain operation (commissurotomy)? (4) what is the result?
SAMPLE
- It is a possible remedy for severe epilepsy
- It involves cutting through the most of or all of the cerebral commissures that connect the left and right hemisphere of the brain
- (corpus callosum and some other structures)
- Result = no communication is possible between the left and right hemisphere
Who was the first patient? (2)
SAMPLE
- Male
- Had his surgery more than 5 and a half years before the study was conducted
Who was the second patient? (3)
SAMPLE
- Mother
- 30 yr old
- Surgery more than 4yrs before
Who were the other patients? (2)
SAMPLE
- 9 other patients
- They had their surgery at varying times but not long before the study was conducted
What is a tachistoscope?
How was it used to display images? (2)
MATERIALS AND APPARATUS
- A device that displays an image for a specific amount of time
- flashes images at 1/10 of a second
How were images shown? (2)
MATERIALS AND APPARATUS
- Images projected to the screen
- Images were projected to the right or left visual field of each eye
If an image is projected to the right visual field - what happens?
MATERIALS AND APPARATUS
Images projected to the RVF are processed by the LH of the brain
What did patients wear over their eye?
MATERIALS AND APPARATUS
Eye patch
What happened in the visual task? (4)
VISUAL TASK - PROCEDURE
- One eye closed (eyepatch)
- Patient centres gaze on a fixed point in the centre of an upright translucent screen
- Visual stimuli on 35-millimetre transparencies were arranged in a standard projector
- then back-projected at 1/10 of a second or less (too fast for eye movements to get the information into the wrong visual field.
If everything was projected to the left of the central meridian of the screen, where did the image go to? (2)
VISUAL TASK - PROCEDURE
- Everything projected to the left of the central meridian of the screen is passed via the LVF to the RH and vice versa
- Regardless of which eye is used
How did participants reach objects?
TACTILE TASK - PROCEDURE
Below the translucent screen, there was a gap so that participants could reach objects but not see their hands
Where are the objects placed? (in hands)
TACTILE TASK - PROCEDURE
Objects were placed in either the participants right or left hand or both hands
How is the information processed when objects are placed in the left hand?
TACTILE TASK - PROCEDURE
Objects placed in the left hand is processed by the right hemisphere and vice versa
What else did Sperry do?
TACTILE TASK - PROCEDURE
Sperry also conducted a variety of other tests which highlighted the lateralisation of brain function
Could information that was shown and responded to in one visual field only be recognised if it was shown to the same VF? (2)
VISUAL TASK - RESULTS
- Yes
- Information shown and responded to in one visual field could only be recognised again if shown to the same visual field.
What happened when information was presented to the RVF?
VISUAL TASK - RESULTS
Info presented to the RVF (LH system of a typical right-handed patient) could be described in speech and writing (with the right hand)
What happened if the same information was presented to the LVF after info was presented to the RVF? (3)
VISUAL TASK - RESULTS
- Patients insisted he either did not see anything or that there was only a flash of light on the left side
- the info could not be described in speech or writing
- Patient could point with his left hand (RH) to a matching picture/object presented among a collection of pictures /objects
What happened when different figures ($ and ?) were presented simultaneously to different visual fields? (2)
VISUAL TASK - RESULTS
$ sign to the LVF
? to the RVF
- Patient could draw the $ sign with his left hand
- But then reported that he had seen a ?
If objects were placed in the right hand what happened? (LH) (2)
TACTILE TASK - RESULTS
- Patients could describe the objects in speech or in writing
- With the right hand
What happened if the same objects were placed in the left hand? (RH) (2)
TACTILE TASK - RESULTS
- Participants could only make wild guesses
- Often seemed unaware that they were holding anything
When two objects were placed simultaneously in each hand and then hidden in a pile of objects?
TACTILE TASK - RESULTS
Both hands selected their own object and ignored the other hand’s object
Give a conclusion about the worlds of each hemisphere
CONCLUSION
People with split brains have two separate visual inner worlds, each with its own train of visual images
Give a conclusion about the streams of consciousness
CONCLUSION
Split brain patients seem to have two independent streams of consciousness, each with its own memories, perceptions and impulses i.e two minds in one body
