Blakemore and Cooper

• Brain Plasticity 


  The ability for the brain to change shape and distribution to accommodate new information
• Aim


  To limit visual experiences of kittens to one orientation and to look at the behavioural consequence of this restriction
• Background

  Hubel and Wiesel - total visual deprivation in kittens cause neurons in the brain associated with the deprived eye to decline in number
• Sample


  2 lab raised kittens that were kept in complete darkness for two weeks

  Their visual experience was manipulated by exposing them to a completely horizontal or vertical environment
• Research method

  Lab experiment
• Research design 


  Independent measures
• Description of the cylinder 


  The cylinder was decorated with white and black horizontal or vertical stripes varying in different lengths as far as they could see

  There was a clear glass platform half way up which the kitten was placed on

  The cylinder was 46cm in diameter and 2m high
• Procedure 


  From 2 weeks to the age of 5 months each kitten spend on average 5 hours a day in the visual display apparatus

  They wore a black collar so they could not see their own bodies and limited their vision to 130 degrees

  The stripes were illuminated by a spotlight beneath the top cover

  This routine stopped at 5 months old

  The kittens were taken into a small room for several hours each week and this was fitted with tables and chairs

  visual reactions were observed and recorded

  At 7.5 months two were anaesthetised so their neurophysiology could be measured.
• Dependent variables

  Ability to move around and respond to objects

  Ability to jump from a chair to the floor

  Ability to follow a moving object

  Ability to judge the distance of objects to touch them

  Their startle response

  Their response to a rod held vertically or horizontally
• Results

  Kittens were visually impaired

  no startle response

  guided themselves by touch

  showed behavioural blindness horizontally raised kittens could not detect vertical objects and vise versa

  Permanent damage - always followed moving objects in a clumsy way and jerky head movements

  Neurophysiological - orientation sensitivities were abnormal. for horizontally raised cats the neurons fired around the vertical axis and vise versa.
• Conclusions

  Visual experiences in early life of kittens can modify their brains and have profound perceptual consequences

  Brain development is determined by the functional demands made on it

  A kitten's nervous system adapts to match the features of its visual input