Gibson And Walk Flashcards
Context and aims of Gibson and Walk
Nativism and Empiricism
In psychology there is a debate between nature and nurture, those who believe that we acquire behaviours due to nature are called nativists and those who believe that we learn and develop behaviours are called empiricists.
Lashley and Russell conducted a study on rats reared in the dark, could jump a correct distance however they were taught to jump from a platform in the light and could have learnt depth perception in the training rather than it being innate.
Gibson and Walk noted that human infants would avoid certain depths after learning to crawl and wanted to determine whether this was an innate characteristic or a developed characteristic.
Because it takes a couple of months for human infants to gage the ability of crawling, Gibson and Walk used other non-human neonites to determine whether depth perception is an innate or acquired ability, for example through Chicks, Puppies and Kittens who have the ability to walk within 24 hours of life.
The aim was to discover whether depth perception is down to nature or nurture.
Procedure of Gibson and Walk
Gibson and Walk used 36 human infants from the age of 6-14months, all with the ability to crawl.
The method was a laboratory experiment, where participants were placed on a centre board of a Visual Cliff, which was a glass surface supported above the floor with a checkered pattern, one side lays just underneath the board perceived as ‘shallow’ where the material on the other side was much lower to give a ‘deep’ effect. The centreboard which the infants were placed on acted as a control, it had no depth and therefore infants could determine a difference between each depth.
The mothers of the infants called to them for two minutes from each side, this was done to see if the infants would perceive the depth of the cliff side and crawl over regardless or go to the shallow side. GIBSON AND WALK wanted to observe whether the infants would be less likely to cross the ‘cliff’ side than the ‘shallow’ side.
Neonates used in the experiment included, puppies, kittens, turtles, rats, kids and lambs, they were placed on the centreboard to see which side they would move to.
Gibson and Walk created a variation in which the material was changed from the checkered pattern to a plain pattern to see if the animals could still perceive the depths.
Findings of Gibson and Walk
27 out of 36 infant participants crawled onto the ‘shallow’ side at least once, where 3/36 infants attempted to crawl onto the ‘cliff’ side. Infants often crawled away from their mothers when she called from the ‘cliff’ side and cried when they couldn’t reach her on the cliff side.
All animals 24hours after their births showed a preference to the shallow side. Kids and Lambs never stepped onto the cliff side, where rats who depended on their whiskers showed no preference to any side, once Gibson and Walk cut off their whiskers they preferred the shallow side.
Kittens froze when placed on the cliff side, at 4 weeks they use their sight for walking and therefore preferred the shallow side. 76% of turtles showed a preference to the shallow side although it was hypothesised that they would go to the deep side as it resembled water.
In non human neonates depth perception is innate as there was no time for them to learn it as they were only a day old.
Whereas human infants had time to acquire depth perception.
From the variation which included the change of pattern, it was observed that the participants showed no preference when there was a plain pattern, in conclusion that patterns are used in cues of depth perception.
Evaluation of Gibson and Walk
Laboratory study, control for example where the mother stood and where the infants were placed on the centreboard.
The control of extraneous variables meant that Gibson and Walk could establish cause and effect to why the infants moved from each side, for example the temperature inside of the lab, meaning the infants did not move to the shallow side because it was warmer than the cliff side.
Another strength is the design of the visual cliff which had a centreboard with two sides of glass to ensure that the infants decision was based on vision.
Ethical issues
Harm to participants, the infants were distressed because their mothers were calling to them to cross the perceived ‘dangerous’ cliff side
Kittens, kids and lambs were visually distressed by being placed on the cliff side and this breaches the protection to ppts ethical guideline.
The mothers of the infants provided informed consent on behalf of their infants who were too young to understand the experiment and purpose.
The infants could not withdraw as they were not able to communicate their feelings as they were so young, so did not have choice and also breaches the ethical guideline of the right to withdraw.
The design of the cliff meant that it was safe for the infants to use and the physical harm to participants guideline was not breached.
Validity. The study Lacks ecological validity because the experiment is not true to real life, it is not usual for infants to perceive depth perception on a visual cliff.
The standardised procedure of the experiment means that it could be replicated, Campos replicated the study and found results to support Gibson and Walk, this shows reliability of the methodology.
Weakness of validity, the age of the infant participants meant that they could have learned depth perception before the experiment, however Gibson and walk counteracted this by using neonates who were less than a day old. Showing that depth perception was innate in some species.
Strength of the validity, the participants all showed similar reactions at the cliff side, where they were all afraid of crossing over the cliff side this means the behaviours are a true measure of depth perception.
Alternative evidence of Gibson and Walk
Campos by using a heart rate monitor, he analysed how the fear changed the heart rates of infants of varying ages, this was both an empiricist and nativist study, as he developed it to see how both perspectives are influences on the depth perception of human infants, finding that it can develop as we increase our experiences.
Suggestion of depth perception as innate but fear is learnt, as the younger infants had a slower heart rate than the older infants.
Tondel and Candy (2007) showed infants between 2-5 months old an image of a moving clown, they found that the infants were able to track the clown even when it was moving 50cm/second. Suggests that the ability to track moving objects is innate, as the infants were so young.
Pei, Pettet and Norcia (2007) found contradictory evidence to Gibson and Walk, this was regarding patterns and textures rather than the checkered pattern of Gibson and walk, it became clear that they notice simple patterns rather than complex textures suggesting that some basic perceptual characteristics are innate, where other more complex have to be developed such as texture gradient
