Blakemore and Cooper
Aim
Conclusions
Sample
Research Method
Behavioural observations
Results of the observation
Results of the neurophysiological examination
Results of the observation pt 2
To investigate the development of the primary visual cortex and to find out if some of its properties such as orientation selectivity are innate or learned.
Lab experiment using independent measures design
IV: Whether the kittens were reared in a horizontal or a vertical environment
DV: The cats visuomotor behaviour once they are placed in an illuminated environment
Measured: 1) Their behaviour was observed in a normal environment, 2) Neurological investigation of the direction of orientation-specific neutrons in the visual cortex
Kittens(from birth-7.5 months) were randomly allocated to one of two conditions
Two of the kittens (one horizontal and one vertical) were used to study neurological effects
Procedure
1) The ability to move around and respond to objects
2)Ability to jump from chair to the floor
3) Ability to follow a moving object
4)Ability to judge the distance of objects to touch them
5) Their startle response and visual placing
6)Their responses to a rod held vertically or horizontally
Kittens were housed from birth in completely dark room. From 2 weeks were put in special apparatus for 5 hours per day, tall cylinder with horizontal or vertical stripes and glass bottom. Kitten wore a wide black collar and this routine stopped with kittens were 5 months old
Kittens were then taken for several hours from dark cage to a small, well lit room, furnished with tables and chairs. Visual reactions were observed.
Visual experiences in the early life of the kittens can modify their brains and have profound perceptual consequences
Brain development is determined by the functional demands made upon it, rather than pre-programmed genetic factors;thus demonstrating brain plasticity
A kittens visual cortex may adjust itself during maturation to the nature of its visual experience.
The environment can determine perception at both a behavioural and physiological level- in cats. Questionable to whether results can be generalised to humans.
At 7.5 months, two kittens were anaesthetised so their neurophysiology could be examined. The cats were presented with bright slits or edges of light while psychologists took recording from individual neurons. Recordings were taken from 125 neurons from to kittens.
Kittens were initially extremely visually impaired
Their pupillary reflexes were normal but they showed no visual placing when brought up to a table and no startle response
They guided themselves mainly by touch
They showed behavioural blindness in the the kittens raised in the horizontal environment could not detect vertically aligned objects and vice versa.
The kittens quickly recovered from many of the deficiencies, within 10 hours of normal vision they showed startled responses and visual placing
Some defects were permanent:
-They always followed moving objects with clumsy, jerky head movements
-Often tried to touch things well beyond their reach
No evidence of severe astigmatism (no eyesight problems)
Horizontal plane recognition cells did not fire off in the kitten from the vertical environment and vice versa so there was a distinct orientation selectivity , showing they suffered from physical blindness
However, certain neutrons had not simply 'died off', as there were no obvious large regions of 'silent' cortex, they were simply not functioning