Blakemore & Cooper (1970)
Key terms
Visual cortex
The part of the brain that receives and processes sensory nerve impulses from the eyes
Startle response
Visual placing
When a cat puts its feet out to meet the edge of a surface
The ‘backing off’ reaction of a cat when an object is moved quickly towards their face
Overal aims
The aim was to investigate how being raised in a visually restrictive environment would affect the visual brain development of cats
- Compare the behavioural consequences of raising kittens seeing only horizontal or vertical stripes
- Investigate the neuropsychological effect on neurons in kittens’ visual cortex
Sample
2 kittens from birth until around 1 year of age
Procedure
What was the environment for the first two weeks of the kittens’ lives?
The newborn kittens were kept in a completely dark room for the first 2 weeks of their life
What was the environment from two weeks until 5 months?
Kittens were put internet a striped cylinder for 5 hours a day. They wore a black collar so were only able to see vertical/horizontal stripes
What happened to the kittens when they were 5 months old?
The kitten was taken into a well-lit room with furniture to test their behaviour
What was the IV in the study?
The orientation of the stripes within the cylinder (horizontal or vertical)
Controls
Black collar
Five hours a day in cylinder
2 weeks in darkness
Conclusions
The difference between the kittens suggests thats neurons can change their preferred ori according to the stimulation they receive, matching the ability of the brain to respond to the features in its visual input
How the study links to psychological debates
Nature/nurture: Nurture as the brain can change in response to the visual environment
Psychology as a science: Replicable, objective, and falsifiable as very controlled, used quantitative measures and can be replicated to see if it is false
Individual/situational: Behaviour dependent on situation of cylinder orientation
Reliability
Internal reliability (is the procedure standardised and replicable?)
Highly standardised and replicable due to the high level of controls
External reliability
Is the sample large enough for results to show a consistent effect?
Only 2 kittens were used in this study but perhaps this doesn’t matter as we are investigating biological concepts
Validity
Internal validity (was it an accurate test of brain plasticity?)
Seemed to be a good test of brain plasticity as the only difference in the procedure for the kittens was the direction of the stripes
External reliability
Population validity (is the sample diverse enough to be representative?)
Possible problem with generalising beyond the species of kittens
Ecological validity (were the tasks measuring behaviour in a way that is true to life?
Not a realistic scenario as the environment was so visually restricted.
Concurrent validity
Cats showed the same deficits in 2 seperate tests to check their perception of the other orientation
Ethnocentrism
Not relevant here. We are looking at biological fators and the environment the kittens were in were not culturally biased
Ethics
In what ways can this study be defended?
Replacement: There was no alternative replacement to animals within this research
Reduction: They reduced the impact to the minimum amount of cats
Refinement: They refined the procedure by only having the cat in the cylinder for 5 hours a day
In what ways can this study be criticised?
There are not many practical applications of the research and therefore perhaps was not worth harming the kittens for
Results- behavioural findings
Initial reactions
Navigated around the room by touch
Clumsy
No startle response
Normal pupillary reflexes
Background
.Blakemore & Cooper were inspired by the work of Hirsch and Spinelli. They were interested in neurons in the visual cortex of the brain.
They found they could change the way neurons in the visual cortex aligned themselves by controlling what kittens could see as they grew up
Kittens raised could only see vertical stripes in one eye and horizontal stripes in the other eye.
When the cats were released into an everyday environment, the researchers found that they had visual impairments.
Experimental design
As each kitten was exposed to a different cylinder, independent measure
After 10 hours of exposure to well-lit surroundings what changed and what deficits did the kittens still show?
deficits they recovered from
visual placing returned to normal
startle response returned to normal
Deficits that remained
still clumsy in following moving objects
still bumped into objects/furniture
results- neurophysiological findings
Results from scans showed the visual neurons within the visual cortex had aligned themselves to match the environment the kitten was brought up in. There were little to no neurons aligned to the opposite direction.
This is because the cats had no need for neurons in the other direction and therefore these were moved elsewhere
How did the horizontally and vertically raised cats differ?
The cats were described as 'virtually blind' to the opposite orientation to their upbringing
They found this by experimenters shaking a rod in front of the cat and seeing if they responded. The cat only responded if the rod was shaken in the same orientation as they had seen in the cylinder
After 10 hours of exposure to well-lit surroundings
Deficits they quickly recovered from
Visual placing returned to normal
No visual placing
Startle response returned to normal
Deficits that remained
Still clumsy
Still bumped into objects
Background
Brain plasticity is where your brain adapts and changes according to whay you do in your life
Blakemore and Cooper were inspired by the work of Hirsch and Spinelli. They were interested in neurons in the visual context of the brain
They found they could change the way neurons in the visual context alligned themselves by controlling what kittens could see as they grew up
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