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Outline and evaluate cross-cultural studies of the development of perceptual abilities
If perceptual abilities are largely innate, then we should expect people living in different
environments to develop in the same way. If they don't then it is clear that perceptual abilities may
be down to both nature and nurture combined.
Hudson (1960) tested depth perception on European, Indian and Bantu children in South Africa using
a set of drawings with an antelope, an elephant and a man with a spear. In each drawing the spear is
pointing at both the antelope and the elephant but depth cues suggest where it is actually pointing.
All children at the beginning of primary school had difficulty using depth cues but by the end of
primary school, nearly all European children could interpret depth cues in drawings. However some
Bantu children still tended to see the pictures as 2d, being unable to interpret depth cues, which
suggest that it is not just an innate process. Page (1970) changed Hudson's question from `which is
nearer to the man, the antelope or elephant?' to `Which is nearer to you, the antelope or the
elephant?' The result was the Zulu participants demonstrated better abilities to perceive depth in
the pictures. We need to be aware that there can be communication difficulty when doing cross
cultural research. We can never be sure that participants and investigators, who rely on translators,
have fully understood each other.
Allport and Pettigrew (1957) tested visual constancies in Zulu people in South Africa with trapezoid
window illusion. Zulus living in rural areas did not have rectangular windows and so it was expected
they would be less likely to experience the illusion, indication shape constancy had not been learned,
exactly what the study found. However with this study we must be careful of imposed etic. For
example peoples lack of ability to see the illusion could be explained by the fact that the means of
testing shape constancy made no sense to them, rather than because they had not learned shape
Gregory claimed that the muller-lyer illusion can be explained in terms of misapplied hypotheses.
Segall et al (1963) supported this with a study involving zulu participants who lived in a circular hut
and not a carpentered world so wouldn't have learned any depth cues. As expected Segall et al
found that the Zulus were less affected by the illusion then were Europeans and Americans. Since
perception is a physical process it might be assumed to be the same across cultures. However the
pigmentation of the retina has been found to vary with skin colour and is linked to difficulties in
perceiving edges of objects. High pigmentation, found in Africans, could explain why they are less
likely to see certain visual illusions. Some evidence has supported this retinal pigmentation
hypothesis, but overall, environmental explanations have been preferred.
However we must always note the problems of doing cross cultural research, groups of participants
may not be representative of that culture, and yet generalisations may be being made about the
whole culture or even the whole country. There is also some anecdotal and poorly controlled
research, natural experiments where it is not reasonable to conclude that the independent variable
(environment) has caused the differences in perceptual abilities but can only conclude that there is an
association between experience and ability.