Paper 2 - Blakemore and Cooper on Early Visual Experience

Question 1

What is the visual cortex

Answer 1

the eye recieves visual information which is then processed by the visual cortex, this is located at the back of the brain. There are cells which respond to different orientations of a line. These are grouped together and build up an image

Question 2

what does pasticity mean

Answer 2

viusal cortex changes depending on experience.

Question 3

what is the aim of this study ?

Answer 3

to look at the physiological and behavioural effects of restricted early visual experience on the development of cells in the visual cortex.
Also to consider if brain plasticity is due to nature ot nurture.

Question 4

What was the design of this study

Answer 4

a labatory experiment with independent measures desin.
IV = whether the kittens early experience was a totally horizontal or a vertical environment
DV= behavioural differences and neurophysiological differences.

Question 5

what is the sample of this study

Answer 5

2 cats

Question 6

what was the materials of this study ?

Answer 6

a cylinder with a glass platform and the entire cyclider was covere in black and white stripes which were either horizontal or vertical. There was no corners.
The kitten wore a black collar to prevent it being able to see its own body.

Question 7

what was the procedure of this study ?

Answer 7

For the first 2 weeks they were in a completely dark room.
At 2 weeks they were placed in the cyclinder for an average of 5 hours a day. The rest of the time they were in a dark room.
At 5 months the visual deprivation was stopped. The kittens were not cats and their visual systems were fully developed - they passed the critical period where biological chnages take place in the visual system.
For several hours each week the cat was taken from the dark cage to another room which was small and well lit with tables and chairs.
The cats were given artificial lenses to ensure that any visual difficulties were not due to astigmatism.
The cats initial reponse to the new environment was observed over the weeks.
At 7.5 months the cas were put under anaethetsia so that their neurons could be tested using electrodes, measuring the firing of each neuron. The cats’ eyes were shown lines of all orientations.

Question 8

What were the behavioural results of this study

Answer 8

some cats reflexes were normal such as reaction to light.
They had no visual placing reflex however within 10 hours the reflex had recovered.
No depth perception - The cats often reacjed out to touch something that was usually quite far away, this was a permanent effect.
When shown a long black rod help vertically/horizontally only rhe cat raised with vertical/horizontal environment could play with it.

Question 9

what are the neurological results

Answer 9

75% of the cells were binocular and mainly responded as normal as any animal would
The horizontal/vertical cat - cells did not respond to lines within 20 degrees of vertical/horizontal orientation.
The horizontal/vertical cat - 12/52 neuron responded within 45 degrees of the vertical/horizontal orientation

Question 10

What are the conclusions of this study

Answer 10

Nature ( the brain ) is modified by nurture (experience) so that the biological system fits into the demands of the environment.
The unused parts of the innate nervous system adapt to match the visual input experiences
this demonstrates brain plasticity.

Question 11

evaluate the method of this study

Answer 11

lab envrionment controlled extraneous variables so that nothing else affected the visual cortex. This increases internal validity.However there is low ecological validity
Independent measures design allows for no order effects. However the cats may have individual differences.

Question 12

Evaluate the ethics of this study

Answer 12

minimal numbers of cats were used so less animals were put under possible harm.
However there were permanent affects on the cats - no depth perception.

Question 13

Evaluate the reliability in this study

Answer 13

only 2 cats were used so the experiment was not replicated. however the cats acted identically showing consistency.

Question 14

evaluate validity in this study

Answer 14

external validity - Banks found that children with squnits responded well to early surgery, supporting theory of critical period for brain plasicity for visual skills.
Lacks ecological validity

Question 15

Evaluate the sample and ethnocentrism

Answer 15

Humans and cats have a common ancestor and have similar brains, therefore results can be generalised to humans whilst it cannot be ethically performed on humans

Question 16

evaluate the data

Answer 16

Quantitative data - objective and easy to analyse using statistical tests to make comparisons.
Qualitative - detailed explanations of the cats behaviour.

Question 17

what debates and perspectives does this study relate to

Answer 17

behaviourist - learning and the environment can affect brain structure and function.
nature and nurture - kittens visual cortex neurons are biologically genetically determined but this can be overriden by experience in a restricted environment.
situation - a restricted environement determines the behaviour of the cat.

Question 18

how is this study useful

Answer 18

a better understanding of plasticity could eventually lead to treatments for human visual cortex disorders.