Blakemore and Cooper's study Storyboard
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- Aim: To investigate the visual development of kittens who were allowed to move freely but raised in an exclusively vertical or horizontal environment
- - Method: Laboratory experiment- Design: Independent measures design
- Procedure:- Kittens were housed in a dark room when they were born. - From 2 weeks onwards, they were put into cylindrical apparatus for 5 hours/day: they stood on a glass platform where they could see a curved surface with black and white stripes (either vertical or horizontal); there were no corners.- Kittens were fitted with collars to prevent them from viewing their body contours.- 5 months old: kitten were moved to a room with tables and chairs: their visuomotor behavior was observed -> This was repeated for several hours each week.- 7.5 months old: one kitten from horizontal condition + one from vertical condition were anesthetized for single cell recordings of their neuronal activity.
- Behavioral results: - Kittens in both horizontal + vertical condition showed signs of extreme visual impairment.- They didn't show visual placing when brought on a table top (but did show normal pupillary responses). They failed to show startle response when an object was thrusted towards them- They were frightened when they reached the edge of the surface -> researchers described them as having 'behavioral blindness' as they couldn't detect edges perpendicular to the environment they were raised in.- Only those in the vertical condition could visually track a rod held vertically + only those in a horizontal condition could visually track a rod held horizontally.
- Neurophysiological results: - Kittens showed no evidence of severe astigmatism (which could have explained their unusual behavior) + 75% of cells in both kittens' visual cortices were binocular (like a normal kitten)- For vertical condition kittens, horizontal plane recognition cells didn't fire in response to objects with horizontal edges + For horizontal condition kittens, vertical plane recognition cells didn't fire in response to objects with vertical edges.
- Neurophysiological results: - The distribution of preferred cell orientations was abnormal -> no neurons had their optimal orientation within 20 degrees perpendicular to their environment condition (vertical or horizontal); only 12 neurons were within 45 degrees of this -> Anisotropy (directional dependence) was found to be significant. - No obvious large regions of 'silent' cortex were found -> neuroplasticity accounts for the lack of cells preferring orientations within 20 degrees of perpendicular axis
- Conclusions:- Visual experiences in the early life of kittens can modify their brains and affect their perceptions and behaviors.- During maturation, a kitten's visual cortex changes to adapt to the nature of its visual experience.- Brain development is determined by their functional demands made upon it, rather then pre-programmed genetic factors.- Neurodegeneration couldn't account for changes in the kittens' visuomotor behavior.
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