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Gibson And Walk (1960)

Gibson And Walk (1960). The Visual Cliff. Context. Nativist view- innate ability to perceive the world. Opposed to learning through experience. Lashley and Russell (1934)- rats reared in dark could still jump correct distance to platform.

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Gibson And Walk (1960)

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  1. Gibson And Walk (1960) The Visual Cliff

  2. Context • Nativist view- innate ability to perceive the world. Opposed to learning through experience. • Lashley and Russell (1934)- rats reared in dark could still jump correct distance to platform. • Criticism: Invalid- rats could have learnt to judge distance through training.

  3. Aim • Investigate whether depth perception is innate or learned. • Will mobile infants avoid a visual drop?

  4. Procedure: Sample • 36 human infants aged 6-14 months and their mothers. • Must be mobile- able to crawl. • Followed by trials with animal young, e.g chicks, kids, lambs, rats, puppies and kittens. • Another trial used only kids (goats) and lambs because they could be tested within 24 hrs of birth. • No opportunity to learn to perceive depth.

  5. Procedure: Equipment • The Visual Cliff • Surface usually in a check pattern (to show clear depth cues) and a drop covered by a glass floor. • The glass floor controls for other non-visual cues.

  6. Procedure- Method • Child is placed in centre of visual cliff. • Mother beckons child towards her from both sides (shallow and visual cliff) to test if the infant is less inclined to cross a visual cliff. • Animal trials were used to reduce the chance of pre-crawl learning. • Animals were placed in the centre and the direction in which they moved was tested (towards or away from the visual cliff) • Kids and lambs were then placed on a surface, which could be lowered to create a visual cliff, to test their response to visual cues suggesting the floor was moving further away.

  7. Procedure- Method cont. • In another condition the check surface was replaced by a uniformly grey one to ensure the validity of the measure. • Was it the depth cues, which are eliminated by the grey surface, causing the participant’s reactions?

  8. Results • 27/32 infants moved off the centreboard. • All 27 crawled onto the shallow surface. • Only 3 ventured on to the visual cliff. • Many infants moved away from their mother if she was beckoning them towards the visual cliff.

  9. Results cont. • No lambs, kids or chicks ventured onto the visual cliff. • When placed on the visual cliff they froze. • In the adjustable cliff condition all animals froze when the visual cliff dropped more that 12 inches. • They did not adapt after multiple trials. • In the uniform grey condition animals showed no preference for either side of the surface.

  10. Conclusions • All animals, including humans, had intact depth perception by the time they could move. • In animals this occured within 24hrs of birth, suggesting depth perception is innate. • Thus, the nativist position is supported. • The grey condition showed the innate mechanism for depth perception involves interpreting changes in patterns.

  11. Evaluation- strengths • The visual cliff is a safe and easily identifiable measure. • Visual cliff procedure controlled for extraneous variables, such as touch perception. Improved validity. • Tested on a range of species. • Straightforward procedure. • Easily replicable- good external reliability. • Participants all had a very similar experience- good internal validity.

  12. Evaluation- weaknesses • Small sample. • Large age range of infants. Infants have time to learn depth perception. • Conclusions are justified by trials with other species. • Behavioural measure- could not test infant’s or animal’s reasons for moving away from the visual cliff. Issue of validity. • Ethics- causing distress to infants and animals. Cannot be asked for consent directly. Unable to withdraw.

  13. Alternative Evidence- Supporting • Tondel and Candy (2007) • Method: Presented infants aged 5-7mnths with image of fast-moving clown. • Conclusion: Infants were able to track clown even at speeds of 50cm/sec. Visual tracking is innate. • Sinai, Ooi, and Hi (1998) • Method: Adults ability to judge distance up to 7m. • Conclusion: When the ground was even, texture was used as a cue, and judgements of distance were more accurate. When the pattern was obscured, e.g. By a ditch, accuracy declined. Supports that pattern is an important depth cue, as in Gibson and Walk’s grey condition.

  14. Alternate Evidence- Opposing • Pei, Pettet, and Norcia (2007) • Whilst some basic perceptual processes are innate, they develop through experience. • Carried out experiments using a range of patterns and shapes, demonstrating that infants could not recognise the more subtle differences in texture that adults can.

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