What is meant by the term ‘brain plasticity’?
When experiences reorganize neural pathways in the brain, and the brain changes in order to adapt to the new environment.
What are neurons?
Nerve cells which carry messages (human brain has around 100 billion neurons).
What did Hirsch and Spinelli investigate in 1970?
- Made kittens view vertical stripes with one eye and horizontal stripes with the other eye
- Found that the eye that received vertical stripes looked more at vertical images (same pattern for horizontal eye)
- Suggest that neurons in the brain developed certain pathways to adapt to the environment
Describe the dual cortex system.
- Light reflected off things enters the eye
- Light converted into electrical signals which are sent through neural pathway
- Signals travel along optic nerve, cross over at optic chasm, and enter left/right hemisphere
- Visual cortex located in the occipital lobe (back of head)
- Visual cortex processes the information
What are simple cells?
Cell that responds to oriented edges and gratings.
What is the independent variable in Blakemore and Cooper’s study?
Whether the kittens were reared in vertical or horizontal environment.
What was the aim of the study?
To investigate the biological and behavioral effects of a restricted visual experience and whether brain plasticity occurs due to nurture.
What was the research method used in this study?
Laboratory experiment.
What was the sample used?
Kittens from birth to roughly 1 year old.
Outline the procedure of the study (what did they do to the kittens)?
- Kittens housed in dark room from birth
- From age of about 2 weeks, kittens exposed to either horizontal or vertical strips by putting them in cylinders with a horizontal or vertical pattern on the walls
- Stripes were black and white and a variety of widths and covered the whole wall
- Kittens randomly allocated to one of the two conditions and were placed in the cylinder for 5 hours per day
How did Blakemore and Cooper restrict the kittens visions so they only saw the stripes?
Kittens wore a collar which limited their vision to about 130 degrees.
How was the kittens ability to move around affected?
They often bumped into things.
How was the kittens startle response affected?
Kittens showed no startle response when object or hand was thrust towards them.
How was the kittens visual placing affected?
They didn’t stretch out paws when they were held out to be put down on a table - only did when they felt the table
How was the kittens navigation affected?
They moved around the room using touch and showed fear when they reached an edge.
How long did it take for most effects to disappear?
About 10 hours.
How did kittens respond when a rod was shaken in front of them in each orientation?
- If rod was presented horizontally, only horizontally raised kitten would respond to it.
- And vice versa
How did the kittens respond when a sheet of Perspex with lines was presented to them?
- No reaction when shown to them in the ‘wrong’ orientation
- Startled if shown to them in ‘right’ orientation
How were 2 of the kittens brains analysed?
They had an electrode inserted into their visual cortex to measure neural activity.
What did they find when they looked at the kittens neural activity?
- Appeared to suffer from ‘physical blindness’
- Found kittens would show patterns of neurons in the same orientation as their reared environment
- Showed little activity when shown images opposite to their original environment
What are the main conclusions of the study?
- Early visual experiences can modify a kittens perception
- Brain plasticity does occur as a result of experience
- Brain development can be affected by nurture
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Loftus and Palmer (1974)16
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Grant et al. (1998)10
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Moray (1959)14
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Simons and Chabris (1999)11
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Milgram (1963)12
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Piliavin et al. (1969)13
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Levine et al. (2001)14
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Bocchiaro et al. (2012)14
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Bandura et al. (1961)17
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Chaney et al. (2004)11
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Lee et al. (1997)20
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Kohlberg (1968)18
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Freud (1909)22
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Baron-Cohen et al. (1997)19
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Gould (1982)22
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Hancock et al. (2011)23
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Casey et al. (2011)22
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Blakemore and Cooper (1970)21
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Sperry (1968)18
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Maguire et al. (2000)18
