Unit 2 - Classic Biological Core Studies Flashcards
Summarise the background of Sperry’s study
- brain has 2 symmetrical hemispheres, connected by the corpus callosum
- brain has contralateral control
- the brain has localized function = left side control speech and writing and the right side controls emotion and spatial awareness
- each eye has two contralateral visual fields
- a ‘commissurotomy’ can cure extreme epilepsy and limit side effects by reducing the electrical activity
What is contralateral control?
the opposite sides control
What is a commissurotomy?
a split-brain operation that cuts out the corpus callosum
What was Sperry’s aim?
To study the functions of separated and independent hemispheres and to map the lateralization of brain functions
What was Sperry’s sample?
11 split-brain patients - all had a commissurotomy - all had severe epilepsy with no drug response 2/11 had surgery a while before study 9/11 had surgery recently
What is this sampling method by Sperry?
Opportunistic
What is a unity of consciousness?
Where the corpus callosum is able to pass information across between the two hemispheres
What was the equipment Sperry used?
A tachistoscope
- screen in front of subject
- hands hidden
- unable to see tactile objects
What happened when Sperry presented an object in the right visual field?
- Info to left hemisphere - language
2. Able to see, identify and find with right hand
What happened when Sperry presented an object in the left visual field?
- Info to right hemisphere - spatial awareness
- Able to draw and find with left hand
- Unable to see and identify
What happened when Sperry presented an apple to the left and a key to the right visual fields?
- Apple to right hemisphere, key to left hemisphere
- Able to draw apple and identify/see key
- Unable to identify seen an apple
What happened when Sperry presented maths problems to left visual field?
- Info to right hemisphere - maths
2. Able to carry out maths problems
What happened when Sperry presented a nude picture to the left visual field?
- Info to right hemisphere - not language
- Able to laugh and react
- Unable to identify what seen
What happened when Sperry presented an object to the right hand?
- Info to left hemisphere - language and process
2. Able to identify and point with same hand
What happened when Sperry presented an object to left hand?
- Info to right hemisphere - spatial awareness
- Able to find with left hand
- Unable to have an conscious awareness of it
How did Sperry carry out the visual tasks for 1 eye?
- Cover one eye
- Look at central fixation point
- Image projected for 1/10 second
How did Sperry carry out the visual tasks for both eyes?
- Watch fixation point
2. Flash two images either side simultaneously for 1/10 second
How did Sperry carry out right hemisphere tests?
- LVF shown object on screen, pick out object from touch in an array
- LVF shown simple maths ie. sort objects by shape, size, texture with left hand
- LVF and RVF shown geometric shapes with nude in LVF and RH responds non-verbally
How did Sperry carry out the tactile tasks for 1 hand?
- Subjects hands hidden behind screen
- Find object responding to what saw
or - Object placed in hand
- Asked what given and/or asked to point to what given
How did Sperry carry out the tactile tasks for both hands?
- 2 objects given in each hand
- Find objects by touch from array
- Asked to say what held
What did Sperry conclude about his study?
- Supports that brain consists of 2 independent hemispheres, each with own consciousness
- Dominant side = left (speech)
What ethics did Sperry uphold?
conducted ethically
Did Sperry’s study have internal reliability?
highly controlled lab experiment
Did Sperry’s study have external reliability?
- quite small but general trends found
- some ‘outright exceptions’ challenge reliability
Did Sperry’s study have construct validity?
- understanding
- not looking at central point
- Brain surgery timing
Did Sperry’s study have population validity?
all split brain patients who had extreme epilepsy
Did Sperry’s study have ecological validity?
Visual - no as you look with both eyes
Tactile - more valid (ie. feeling for change in pocket)
Was Sperry’s study ethnocentric?
no - investigating a species-specific behaviour (lateralization affected by anatomy and physiognomy of brain)
- some showed exceptions (environmental and cultural influences?)
- without cross - cultural examination, hard to confirm if a non - westerner would produce same results
What debates does Sperry link to?
- Psychology as a science
- Usefulness of research
- Freewill - determinism debate
How does Sperry link to the Psychology as a science debate?
- controlled lab experiment that fits scientific criteria
- would be possible to replicate and falsify with a fresh sample (may not be easy)
How does Sperry link to the Usefulness of research debate?
- groundbreaking, beginning to understand physiognomy of brain
- revealed importance of corpus callosum for internal communication
How does Sperry link to the Freewill - determinism debate ?
- biological determinism, inability for commissurotomy determined by physiological factors
How does Sperry relate to the biological area?
- investigates regions of the brain and lateralization of function
- demonstrates how corpus callosum might determine our behaviour
How does Sperry relate to the key theme of regions of the brain?
- sheds light on right and left hemispheres
- info on role of corpus callosum, as used to think no role
Summarise the background of Blakemoore and Cooper’s study
Based on research done by Hirsch and Spinelli at Stanford
- researched reared kittens with one eye vertical stripes and other horizontal stripes
- found most neurons of visual cortex were monocurly driven and preferred orientation of neurons reflected pattern exposed in that way
- suggests the neurons of the visual cortex showed plasticity in that they developed according to environment experienced
What does monocurlarly driven mean?
driven by one eye
What does visual placing mean?
does not move feet out to meet table or ledge when placed on it
What were the aims of Blakemoore and Cooper’s study?
- To investigate the visual experience of kittens to one orientation and to compare the behavioural consequences of this restricted environment on kittens
- To investigate the neurophysiological effects on the neurons in the kittens visual cortex which investigates the responses of brain development to environment and brain plasticity in developing visual scene
What was Blakemoore and Cooper’s procedure for the first two weeks of their lives?
housed in a completely dark room
What was Blakemoore and Cooper’s procedure from two weeks to five months old?
- exposing the kittens to either vertical or horizontal lines
- spending 5 hours a day inside apparatus
What was Blakemoore and Cooper’s procedure from 5 months old?
- exposure to stripes stopped as kittens had passed through sensitive/critical period for visual development
- taken to a well - lit room for several hours a week to see behavioral consequences of restricted visual experience
Explain the apparatus Blakemoore and Cooper used?
- cylinder with vertical or horizontal stripes on walls
- glass platform
- lid with a spotlight illuminating
- kitten wore a wide collar to stop seeing itself
- 2m by 46cm
What were the initial behavioral results when the kittens were taken to a well - lit room in Blakemoore and Cooper’s study?
- showed visual deficiencies:
1. normal pupillary reflexes but no startle response
2. no visual placing until touched
3. navigated room b y touch
4. fear of response when reached edge of surface walking on
What were the behavioral results after 10 hours of exposure to well - lit surroundings in Blakemoore and Cooper’s study?
- deficiencies disappeared:
1. began to show visual placing
2. startle responses
3. would jump easily from a surface to floor - some deficiencies remained:
1. visual tracking of moving objects was with clumsy, jerky head movements
2. often tried to reach for moving objects way out of reach
3. often bumped into things
How did the horizontally and vertically raised kittens differ in the behavioral results in Blakemoore and Cooper’s study?
blind for contours perpendicular to the orientation they had experienced
What were the two experiments in Blakemoore and Cooper’s study to prove the kittens were blind to the perpendicular stripe?
- sheet of Perspex with thick black and white lines presented to kittens. No reaction if ‘wrong’ orientation but a startle response if ‘right’ orientation
- rod shaken in front of kittens. If shaken in ‘right’ orientation, kitten would respond (chase and try to catch) if ‘wrong’ orientation kittens would ignore
Outline the procedure for the neurophysiological tests in Blakemoore and Cooper’s study
2 cats (7.5 months) were anesthetised and paralysed and eyes opened. Electrodes inserted into primary visual cortex to take electrical readings from neurons. Neuron activity recorded to show optimal orientation for each neuron when shown bright slits of light. 125 neurons recorded in total - 52 from horizontal and 72 from vertical
What were the results for the neurophysiological tests in Blakemoore and Cooper’s study?
- in normal cat neurons would be balanced (circle)
- in horizontally raised kitten, no neurons in the vertical orientation and vice versa
What did Blakemoore and Cooper conclude from their study?
- visual experience in early life has modified their brains and there are profound perceptual consequences
- this brain plasticity demonstrates role of nurture in development of vision (in cats)
What ethics did Blakemoore and Cooper uphold?
Protection from harm - cats had no long-lasting damage and conducted with strict ethical guidelines laid down by Home Office for studies carried out on animals
What ethics did Blakemoore and Cooper break?
- Integrity - no idea if relates to humans and does not outweigh costs to benefits for animals
- Protection from harm - “the cats did not seem upset by their surroundings” - subjective, does not prove cats were not distressed
Did Blakemoore and Cooper have internal reliability?
- controlled lab experiment with detailed descriptions of procedure (easily repeatable)
Did Blakemoore and Cooper have external reliability?
- does not explicitly state sample size
- ideally need a larger sample
Did Blakemoore and Cooper have construct validity?
- high design validity (findings caused by the restricted environment)
Did Blakemoore and Cooper have concurrent validity?
- behavioral and neurophysiological measures showed evidence that results were true
this supports claim brains influenced by environment
Did Blakemoore and Cooper have ecological validity?
No - cats nor humans brought up in that environment
Did Blakemoore and Cooper have population validity?
generalised to cats and not humans as far as we know
Is Blakemoore and Cooper ethnocentric?
not relevant when discussing cats
What debates does Blakemoore and Cooper link to?
- Nature/ nurture debate
2. Psychology as a science
How does Blakemoore and Cooper relate to the nature/nurture debate?
- development of visual orientation in cats was a product of nature and nurture:
nature = provided kittens with neurons with a preferred orientation
nurture = restricted visual environment which had a strong affect on brain development
How does Blakemoore and Cooper relate to the psychology as a science debate?
- controlled lab experiment, fulfills scientific criteria
- possible to falsify
How does Blakemoore and Cooper relate to the biological area?
- investigates effect on environment on developing brain in cats
- demonstrated plasticity of kittens brains, preferred orientation can switch
How does Blakemoore and Cooper relate to the key theme of brain plasticity?
- visual neurons will change preferred orientation
ie. horizontally raised will develop horizontal vision
