The Zulus were less susceptible to the Miller-Lyer illusion than the urban South Africans- a large proportion of them identified the lines as being the same length. Segall et al believed this was because they were less familiar with an environment made heavily from straight lines (e.g. their huts was circular) so didn’t apply size constancy in the same way as the urban South Africans. This meant that they didn’t perceive any difference in the length of the lines. Segall et al saw this cross-cultural difference in perception as evidence that perceptual abilities are developed in response to the environment. In other words, perception is the result of nurture.
b) Some psychologists believe that the development of perceptual abilities such as depth perception and visual constancies are the result of the nature- they’re innate abilities. Others believe that they are the result of nurture – we learn them through interaction with our environment. There are studies to support both sides of this debate.
For example, Gibson and Walk (1960) investigated the development of depth perception in babies. They created a `visual cliff` and investigated whether six month old babies would crawl over the `deep` side. They found that babies were reluctant to crawl over the deep side, and concluded that babies could perceive this as a drop. From this, they concluded that depth perception is the result of nature. However, the babies that Gibson and Walk tested were 6 months old so could have learnt depth perception by this age.
Campos (1970) addressed this problem by using a different measure of depth perception. He measured the heart rate of babies who could and couldn’t crawl didn’t change on either side of the cliff. He found that the heart rate of babies who couldn’t crawl didn’t change on either side of the cliff, suggesting that they are not aware of the depth. However, the heart rate of babies who could crawl dropped on the deep side, suggesting that older babies are aware of the change in depth. Campos concluded that as only the older babies appeared to be aware of depth this shows that depth perception is learned and therefore down to nurture.
The conflicting findings of these studies and many more (e.g. Segall et al (1966) suggests perceptual development is the result of the nurture, Bower (1985) suggests it’s the result of nature) mean that no conclusion can yet be drawn on whether perceptual development is the result of nature or nurture. In fact, many psychologists now believe that perceptual abilities could come about by a combination of the two.
by
thenainoji (student)
