PY Two :- Gibson and Walk (1960) The "Visual Cliff"

Gibson and Walk (1960) – The “Visual Cliff”

Context

     Depth perception refers to our ability to comprehend that some objects are more distant than others. It is just one element of our visual capabilities, but it is an essential perceptual ability to have as we have to negotiate our way around the world.

     Nativists believe we are born with the capacity to perceive depth. Their abilities may not all be functioning properly when we are born, but the process of maturation rather than learning determines development.

     Empiricists believe that the ability to perceive depth is acquired through experiences.

    Interactionalists believe our abilities to perceive depth is a product of both innate abilities interacting with environmental factors.     

     If depth perception is innate, we would expect it to be apparent by the time a young animal is mobile, because this would be adaptive. A young animal which does not have this ability at this critical time is less likely to survive, and therefore an innate ability to perceive depth would be adaptive.

  Lashley and Russell :- Reared rats in the dark and found that they could still jump the correct distance on a platform, which would suggest that depth perception is innate. However, the researchers had trained the rats to jump onto the platform. This study proves that there is an aspect of “nurtured” behaviour.

Aims

     Gibson and Walk aimed to investigate if the ability to perceive depth is innate or learned through experience. They argue that if depth perception is innate, then it should be apparent by the time infants are able to move independently. If it is a learned ability, mobile infants may not be able to perceive depth.

      As humans are not mobile until about 6 months old, only using infants would mean that the results would be inconclusive.

     Gibson and Walk therefore decided to also test the depth perception of a range of non-human animals, such as kids, lambs and turtles. They would be able to investigate if depth perception was evident from the time such young animals were mobile. This would then provide more evidence about whether depth perception is innate.

Procedures

Participants

      The human participants were 36 babies aged between 6 and 14 months. There were also chicks, lambs and kids who were one day old, rats and kittens who were four weeks old and rats and kittens who were raised in the dark and were four weeks old. There were also turtles who were tested.

Method

     All of the babies in the study were able to crawl. Each child was placed in the centre of the visual cliff on a centreboard. Their mothers then called for them from the cliff side and the shallow side. The idea was to see whether they would be less inclined to crawl across the “cliff”, this would suggest that their depth perception was intact as soon as they could crawl. This would in turn suggest that…