39402347
Description
Mind Map by Darcy Beglan, updated 7 months ago
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Created by Darcy Beglan
7 months ago
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Blakemore and Cooper (1970)
- Participants
- Laboratory-raised kittens
that were housed in
complete darkness until 2
weeks of age.
- Laboratory-raised kittens
that were housed in
complete darkness until 2
weeks of age.
- Aim
- effect on kittens’ visual development of a restricted visual
environment, consisting of either vertical stripes only or
horizontal stripes only, in which the animal could move
freely.
- effect on kittens’ visual development of a restricted visual
environment, consisting of either vertical stripes only or
horizontal stripes only, in which the animal could move
freely.
- Design
- Lab experiment
with an
independent
measures design.
- The kittens were left in the
dark unless they were in the
visual display apparatus or
were being tested.
- The Independent
variable: whether
these stripes were
vertical or
horizontal.
- The dependent variables: the
effects of this rearing. It’s
performance on a number of
visual tests.
- Lab experiment
with an
independent
measures design.
- Procedure
- From 2 weeks old to 5 months of age, each kitten spent on
average 5 hours a day in a visual display unit. This was a
vertical cylinder 46cm in diameter, with a Perspex floor half
way up, on which the kitten could move at will. The kittens
saw no corners, there was no edge to the floor, and as the
cylinder was 2 metres long, the lab floor and ceiling were a
long way away. The entire wall of the cylinder was full of
high-contrasting black and white stripes. For half the kittens
these stripes were vertical, and for the other half horizontal
(IV).
- The dependent variables i.e. the effects of this rearing were measured in several ways. When kittens were
removed from the apparatus at 5 months of age they spent several hours each week in a small well-lit
room containing chairs and tables where their visual reactions were observed. Observations were made of
their ability to move around and respond to objects, to jump from a chair to the floor, to follow a moving
object, to judge distances of objects to touch them, their startle responses and visual placing as well as
their responses to a rod held vertically or horizontally.
- Also, from 7.5 months, biological studies were conducted of
individual neurons in the primary visual cortex of the kittens
to investigate how they respond to lines of orientation and
whether they were monocular or binocular. This was done
by anaesthetising the cat (keeping their eyes open) and
presenting bright slits or edges of light while recording from
individual neurons. Recordings were taken from 125
neurons from two kittens (one horizontal reared and one
vertical reared).
- Also, from 7.5 months, biological studies were conducted of
individual neurons in the primary visual cortex of the kittens
to investigate how they respond to lines of orientation and
whether they were monocular or binocular. This was done
by anaesthetising the cat (keeping their eyes open) and
presenting bright slits or edges of light while recording from
individual neurons. Recordings were taken from 125
neurons from two kittens (one horizontal reared and one
vertical reared).
- The dependent variables i.e. the effects of this rearing were measured in several ways. When kittens were
removed from the apparatus at 5 months of age they spent several hours each week in a small well-lit
room containing chairs and tables where their visual reactions were observed. Observations were made of
their ability to move around and respond to objects, to jump from a chair to the floor, to follow a moving
object, to judge distances of objects to touch them, their startle responses and visual placing as well as
their responses to a rod held vertically or horizontally.
- An example of vertical:
- From 2 weeks old to 5 months of age, each kitten spent on
average 5 hours a day in a visual display unit. This was a
vertical cylinder 46cm in diameter, with a Perspex floor half
way up, on which the kitten could move at will. The kittens
saw no corners, there was no edge to the floor, and as the
cylinder was 2 metres long, the lab floor and ceiling were a
long way away. The entire wall of the cylinder was full of
high-contrasting black and white stripes. For half the kittens
these stripes were vertical, and for the other half horizontal
(IV).
- Evaluation
- Research method: As this was a laboratory
experiment, the kittens’ environments were highly
controlled and therefore causal conclusions can be
made. The study has levels of internal validity - we
can infer that the IV (environment) caused visual
impairment and neurophysiological damage (DV). The
study could also be easily replicated in order to test
the reliability of the findings (although this wasn’t
done).
- Ethical considerations: Exposing
animals to a dark room for two weeks
and then up until 5 months of age a
visually depriving environment, could
be considered to be psychologically
harmful for the kittens. However,
Blakemore and Cooper reported no
distress from the animals. Furthermore,
the study complied with the ethical
guidelines for animal research. It could
also be argued that any harm to the
animals were outweighed by the
usefulness of this research.
- Sampling bias: Blakemore and Cooper would argue that due to
some physiological similarities between cats and humans, we
can generalise results to humans. However, critics would argue
against this due to obvious differences between the species.
Furthermore, as the sample was very small (only 2 cats’
neurophysiology was examined) we may not be even able to
generalise to other cats!
- Research method: As this was a laboratory
experiment, the kittens’ environments were highly
controlled and therefore causal conclusions can be
made. The study has levels of internal validity - we
can infer that the IV (environment) caused visual
impairment and neurophysiological damage (DV). The
study could also be easily replicated in order to test
the reliability of the findings (although this wasn’t
done).
- Conclusion
- Brain development is clearly affected by early experiences and environmental factors rather than just
genetics and there is clear evidence of brain plasticity – ‘the visual experience of these animals had
modified their brain’ and therefore has serious perceptual consequences. The kittens’ visual cortex
adjusts during development as a result of its visual experiences. Evaluation
- Brain development is clearly affected by early experiences and environmental factors rather than just
genetics and there is clear evidence of brain plasticity – ‘the visual experience of these animals had
modified their brain’ and therefore has serious perceptual consequences. The kittens’ visual cortex
adjusts during development as a result of its visual experiences. Evaluation
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