blakemore and cooper

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aim?
to investigate the development of the primary visual cortex (in cats) and to find out if some of its properties, such as orientation selectivity, are innate (as suggested by Hubel and Wiesel) or learned
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sample?
Kittens, raised in the dark from birth, were randomly allocated to conditions. Two of the kittens (one reared in a horizontal and one in a vertical environment) were used to study neuro-physiological effects by implanting electrodes in Visual cortex
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research methods?
lab experiment with independant measures design.
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IV and DV?
V: Whether the kittens were reared in a horizontal or a vertical environment. -DV: Visuo-motor behaviour at 5mnths onwards, once they were placed in a ‘normal’ environment-whether the horizontally raised kittens could detect vertically aligned object
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materials 1?
Kitten stood on clear glass platform, halfway up a cylindrical container: entire inner surface is covered in either vertical or horizontal, black-and-white stripes, lit by spotlight at top.
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materials 2?
Top and bottom edges of the barrel are outside kitten’s field of vision. Kitten wears collar so it can’t see its own body.
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procedure?
Kittens were mainly raised in the dark, until 5 months, but at 2 weeks they began to spend 5 hours a day in a horizontal or vertical environment. Their behaviour was then observed at 5 months in a furnished, well-lit room
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what was the first orintation selecivity task?
A sheet of thick Perspex with thick black and white lines, either horizontal or vertical in orientation, was thrust towards the kitten, to see whether the kitten showed a startle response, indicating they perceived it.
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what was the second orintation selecivity task?
a stick was shaken in front of the kitten, either held horizontally or vertically, to see if the kitten tried to catch and chase it, demonstrating they’d perceived it.
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what was changed at 7 1/2 months?
At 7 ½ months, one kitten from each condition was anaesthetised and electrodes implanted in V1 to measure activity of neurons in response to presenting vertical or horizontal bars of light.
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behavioural finding 1?
No startle response: when object thrust towards them
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behavioural finding 2?
No visual placing: the cats did not put their legs out when they were held towards the edge of the table. Kittens started recovering from visuo-motor deficits in hours, so they were likely due to a lack of experience with visual stimuli.
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results of the two conditions? 1
Horizontally-raised kittens didn’t startle when vertical lines were thrust towards them, and vertically-raised kittens didn’t startle when horizontal lines were thrust towards them.
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results from two conditions? 2
Horizontally-raised kittens didn’t try to catch/chase/reach for the stick when it was shaken vertically, and vertically-raised kittens didn’t try to catch/chase/reach for the stick when it was shaken horizontally.
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neurophysiological findings 1?
the Horizontally-raised kitten had neurons which selectively responded to horizontal orientations. The Vertically-raised kitten has neurons which selectively responded to vertical orientations
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neurophysiological findings 2?
There was no region of silent neurons found (neurons which showed no response to any visual stimuli) so it seems that the stimuli which would usually respond to the other orientation in normal cats adapted to all respond to the same orientation.
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conclusions 1?
) Early perceptual experience influences perception (nurture). Horizontal or Vertical lines can only be perceived if experienced. Neurons in V1 only respond to the orientation experienced.
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conclusions 2?
This can only occur within a sensitive period- up to 5 months- as ability to perceive certain orientations did not improve when kittens were raised in normal environments after 5 months
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sample?

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Kittens, raised in the dark from birth, were randomly allocated to conditions. Two of the kittens (one reared in a horizontal and one in a vertical environment) were used to study neuro-physiological effects by implanting electrodes in Visual cortex

Card 3

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research methods?

Back

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Card 4

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IV and DV?

Back

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Card 5

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materials 1?

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