Gibson and Walk PY2.

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  • Created by: bananaaar
  • Created on: 31-03-14 19:58
Aims and context 1?
Increasing interest in evolutionary psychology - 'Is depth perception innate or learned?' Nativists & Empiricists.
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What do Nativists believe?
claimed that depth perception is inborn, even through it only appears as person matures. The survival of humans and animals depends on having depth perception from birth (e.g. babies need to avoid top of stairs, animals avoid cliff edges.)
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What do empiricists believe?
Claim that depth perception was learned through experience.
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Walk Aims and context 2?
Yerkes (1904), compared aquatic and land turtles' depth perception by placing them on a raised board. Found aquatic turtles stepped off more than land turtles, presumable because turtles cannot fall in natural habitat so have evolved without.
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Walk aims and context 3?
Lashley compared rats ability to jump across gaps, half raised in light, half in dark. Founf both rats could jump equally well, which suggests depth perception is innate (however he did train rats to jump)
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G&W Aim 1?
Find out if depth perception is innate or learned though experience, believing that if it was innate it should be apparent when intact has independent locomotion.
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G&W Aim 2?
To investigate depth perception in both human infants and young animals in order to demonstrate that it was innate from independent locomotion across different species.
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G&W research Method?
Laboratory experiment at Cornell University.
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Sample size (human)
36 human infants aged 6-14 months (all with independent locomotion)
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Sample size (animals)
1 day old chicks lambs & goats, 4 week old kittens (as well as some in light/dark), 4 week old rats (some with hoods so used whiskers). Also other rats raised in dark. Pigs, dogs and aquatic turtles also used.
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G&W Research involved 1?
The visual cliff which consisted of a large glass sheet that was supported 30cm above the floor. On one side a sheet of patterned material was placed directly under glass (shallow side) and other side pattern was on floor, giving illusion of a drop.
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Research involved 2? G&W
Placing an infant on the centre board to see if it would crawl to its mother who was calling from the 'shallow side' and then from the 'deep side'.
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Research Involved 3? G&W
Placing the young animal on the centre board to see whether it moved on to the shallow/deep side.
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Research Involved 4?
Controlling confounding variables such as reflections from the glass by lighting the visual cliff from below the glass.
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Ethical issues addressed by G&W?
Using a glass shelf to create the illusion of a cliff. This ensured the pps safety even on the 'deep side', i.e. they were protected from harm.
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G&W Findings with human infants? 1
27/36 infants moved off the centre board (9 infants didn't move at all)
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G&W Findings with human infants? 2
All 27 that moved crawled to the shallow side to their mother.
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G&W Findings with human infants? 3
Only 3 infants tried to crawl onto 'deep side'.
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G&W Findings with human infants? 4
Several infants patted the glass on the 'deep side' but still would not cross to that side.
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G&W Findings with human infants? 5
Many infants crawled away from their mother when she called them from the deep side.
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G&W Findings with human infants? 6
Other infants cried when their mother called from the deep side because they could not get to her without going over the 'cliff'.
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G&W findings with non-human animals: 1
Chicks, kids and lambs hopped off the centre board onto the shallow side and never onto the deep side.
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G&W findings with non-human animals: 2
If kids/lambs were placed on deep side they froze in a posture of defence.
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G&W findings with non-human animals: 3
The normal 4 week old kittens preferred the shallow side and froze and circled back to the centre when placed on the 'deep side'
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G&W findings with non-human animals: 4
Kittens reared in the dark for 27 days crawled onto both sides equally and did not freeze on the deep side - however 1 week later in the light they avoided deep side.
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G&W findings with non-human animals: 5
24% aquatic turtles crawled onto deep side (perhaps because they cannot fall in their natural habitat?)
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G&W findings with non-human animals: 6
The hooded rats were content to explore both the 'shallow' and the 'deep' side equally as they could use their whisks not their sight - however when centreboard was raised they nearly always crawled onto shallow side (95-100% of the time)
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G&W conclusion 1?
Human infants have depth perception as soon as they can move on their own.
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G&W conclusion 2?
Their evidence does not prove that human depth perception is innate - although it does support the nativist view.
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G&W conclusion 3?
Young animals have depth perception from birth which is consistent with evolutionary theory.
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Reliability?
Strong - standardised procedure, same visual cliff for animals and babies, all pps subject to same test so high in consistency/reliability.
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Sample?
Problematic - Sample used for animals was very large so animals could be compared and predictions could be made. However human sample was small (36 babies) so data inaccurately generalises based on small sample.
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Validity?
Problematic, lab experiment so setting is artificial/lacks mundane realism (babies not usually placed on 'cliff). However strong as cliff was made to replicate real life (e.g. baby falling down stairs) so had internal validity as it proved its aims.
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Data?
Strong- both types of data (quantitative, 24% aquatic turtles crawled onto deep side) and qualitative (reactions of kittens when placed on deep side) so added depth could be included.
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Ethics?
Problematic. Strong - ops protected from actual physical harm by using visual cliff. Weak - animals such as kittens may become distressed being placed on deep side so weren't protected from psychological harm. TST breaks ethical guidelines.
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Alternative Evidence's for G&W?
Lashley, Yerkes and Campos.
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Alternative Evidence G&W 1?
Lashley supports as he found ability to hum gaps with rats was the same for rats reared in dark, suggesting innate perceptual skills. G&W also found that distance perception is innate, supporting evolution theory.
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Alternative Evidence G&W 1 which is better?
Lashley support is limited by the fact that lushly trained the 'dark' rats before testing, so blurred nature nurture line?
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Alternative Evidence G&W 2?
Yerkes supports as he found that depth perception in land turtles is better than aquatic ones as they have evolved without it, suggesting its innate. Supports G&W as turtles had worst depth perception (24%deep side).
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Alternative Evidence G&W 2 which is better?
G&W is more reliable as they used a range of ops including different animals/humand whereas Yerkes only used turtles.
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Alternative Evidence G&W 3?
Campos found that older infants showed more fear of cliff than younger infants, suggesting depth perception is learned. Also said infants are more likely to go on deep side if facial expression was welcoming by mother. Rejects G&W -says its leaned.
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Alternative Evidence G&W 3 which is better?
G&W is more reliable than campos as G&W used a wider range of ops, which made it a fairer test, whereas Campos only used human infants.
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Card 2

Front

What do Nativists believe?

Back

claimed that depth perception is inborn, even through it only appears as person matures. The survival of humans and animals depends on having depth perception from birth (e.g. babies need to avoid top of stairs, animals avoid cliff edges.)

Card 3

Front

What do empiricists believe?

Back

Preview of the front of card 3

Card 4

Front

Walk Aims and context 2?

Back

Preview of the front of card 4

Card 5

Front

Walk aims and context 3?

Back

Preview of the front of card 5
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