Monday, 27 November 2017

Blakemoor + Cooper's brain plasticity study (1970)


Context/Background

Biological workings in the brain influence behaviour in humans + animals

In the visual cortex of the brain, orientation-specific cells change the kind of stimulus they respond to, depending on an animal's early visual environment

This study shows the plasticity of a kitten's brain, as neurones originally conditioned to respond to horizontal or vertical orientation can switch when required

Physical structure of human and cat brains are similar, and their brains have a control of visual stimuli correlated to changes in RNA structures

Neurones of the visual cortex are selective for the orientation of lines and edges in the visual field


Aim

To investigate development of primary visual cortex and to find out if some of it's properties are innate or learned


Method

Lab experiment, independent measures

Iv= whether kittens were reared in horizontal or vertical environment
Dv= visuomotor behaviour once placed in an illuminated environment


Procedure

Kittens studied from birth and randomly allocated to 2 conditions, 1 from each condition were housed in completely different dark rooms, for 2 weeks and put into a stripy cylinder for 5 hours a day

The cylinder consisted of a clear glass platform inside a cylinder, where the inner walls were black and white stripes, either vertical or horizontal

Kittens were not upset and they sat calmly inspecting the walls in the tube.
The routine stopped at 5 months and they were taken for several hours a day into a small, well-lit furnished room and they were observed and recorded

At 7.5 months, 2 of them were anaesthetised so their neurophysiology could be examined


Findings

Both kittens were initially visually impaired and showed no startled response when an object was thrust at them 

Pupil responses were normal when reacting to light intensity

They guided themselves by touch and got scared when reaching edges of tables

The kittens raised in horizontal environments could not detect vertically aligned objects, and vice versa

Kittens recovered normal vision in 10 hours but always tried to touch things beyond their reach = impaired depth perception

They suffered from 'physical blindness'


Conclusions

Visual experiences in early life of kittens = modify brains = profound perceptual consequences

Visual cortex = part of the ocipital lobe at the back of the brain

visual cortex adjusts itself during maturation

Nervous system adapts to match probability of occurrence of features of visual experience

Brain development is determined by functional demands rather than pre-programmed genetic factors


Evaluation

Research method- Lab experiment = scientific apparatus (cylinder) and high control, hard to generalise to humans but cats do have similar vision to us

Data type- qual and quant

Ethics- Some pain and distress for the cats as well as mother seperation

validity- standardised procedures = high reliability and low ecological validity

Reliability- highly replicable and only 2 kittens = limits reliability 

sample bias = 2 kittens so a small sample, they could've been abnormal reducing validity and reliability 
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