Blakemore and Cooper (biological)

• Name of study?

  • “development of the brain depends of the visual environment“
• Aims of study?

  • to compare the behavioural consequences of exposing kittens to one orientation
  • to investigate the neuropsychological effects on the neurones in the visual cortex
• method?


  • lab experiment
  • independent measures
  • highly controlled environment
• IV?


  • whether the kittens were raised in a horizontal or vertical environment
• DV?


  • what was their visuomotor behaviour once they were places in an illuminated environment - (e.g could horizontally raised kittens detect vertically aligned objects?)
• CV?


  • time in cage
  • collar
• participants?


  • kittens (don‘t know how many)
  • 2 of them were used for the second part of the study (neuropsychological effects) - reducing animal use with only 2 kittens
• procedure?


  • from birth, kittens were housed in complete darkness
  • from the age of 2 weeks, they were put in a special apparatus for 5 hours a day
  • apparatus = clear glass cylinder with vertical or horizontal black and white stripes
  • wore a black collar to restrict visual field to 130 degrees
  • routine stopped when kittens were 5 months old
  • at 5 months they were taken out of dark cage and into a well-lit room with tables and chairs for several hours each week
  • their visual reactions were observed
• What was the neuropsychological effects procedure?

  • at 7.5. months, 2 kittens (1 reared in horizontal and 1 reared in vertical)
  • they were anaesthised so their neurophysiology was examined (reducing and refining pain)
• results from first part?

  • initially extremely visually impaired
  • had no startle/flinch response
  • guided themselves mainly by touch
  • were frightened when they reached the edge of surface
  • showed ‘behavioural blindness’ (those raised in horizontal couldn’t detect vertically aligned objects)
  • eyes of kittens raised in vertical, followed a vertical rod and vice versa
  • kittens quickly recovered and within 10 hours their startle response came back
• which defects were permanent?

  • jerky head movements
  • tried to touch things out of their reach
• neurophysiological examination results?


  • no evidence of severe astigmatism -( may have explained behavioural responses)
  • horizontal plane recognition cells didn‘t ‘fire-off” in vertical kitten so there was a distinct orientation selectivity showing kittens suffered from physical blindness (vice versa)
  • about 75% of cells in both cats were clearly binocular in almost every wat the responses were like a normal kitten
  • there was a critical period where kittens couldn’t use pathways (neurones must be stimulated within 3 months)
  • shows part of our vision isn’t completely innate
• How were the distributions of preferred orientation abnormal?

  • not one neurone had its optimal orientation within 20 degrees of the axis, and only 12 were within 45 degrees of it
  • this anisotropy (property of being directionally dependent), was significant as p greater than and equal to 0.00001 chi squared test
• What can modify the brains of kittens during early life?

  Visual experiences
• How does a kitten's visual cortex adjust during maturation?

  It adjusts to the nature of its visual experience
• How does a kitten's nervous system adapt to visual input?

  It matches the probability of occurrence of features
• What determines brain development according to the study material?

  Functional demands made upon it
• At what levels can the environment determine perception in cats?

  Behavioural and psychological levels
• Is it questionable whether findings in cats are generalizable to humans?

  Yes, it is questionable
• data?


  • qualitative (detailed description of response to effects)
  • quantitative (statistical testing)
• ethics?


  • used reduce and refine by only using 2 kittens fro second part
  • used anaesthetic to reduce pain but kittens may have been distressed
• validity?


  • ecologically valid - humans visual cortex are similar
  • high population validity
  • not representative (2 kittens selected may have been atypical)
• reliability?


  • standardised to ensure replicability
  • only 2 kittens did the neurophysiology test so limits reliability
• sample?


  • small sample (2 kittens) isn’t generalisable
  • cats. visual cortex isn’t extremely different to humans
• nature vs nurture?


  • showed development in visual orientation in cats was a product of both nature and nurture
• ethnocentrism?


  • no relevance as wasn’t tested on humans
• psychology as a science?

  • the experiment followed the scientific criteria of theory (aims, controls, variables etc)