A2 perceptual thoeries

However, there are studies which provide evidence that perceptual abilities are due to nurture. A cross cultural study conducted by Segal et al supports this. He used the Muller Lyer illusion with people from African and Filipino cultures. When compared to white South Africans and Americans, the Africans and Filipinos were much less sceptical to the Muller Lyer illusion. This is because people from these cultures live in high open country where vertical objects are important focal points to estimate distance. The White South Americans and Americans, on the other hand, were more sceptical to the Muller Lyer illusion. He therefore concludes that in many cases experience does affect perceptual ability and that perception is related to our experience.



2) To what extent do such studies contribute to the nature-nurture debate in perception? (12 marks)

Some research supports the idea that we are born with the ability to perceive visual information. Many people would agree with this since perception seems so effortless and easy and is not taught or learned. Genes and experience play an important role. Experience begins at birth and gradually develops with age, so the earlier in life a perceptional ability appears, the less likely it will have depended on experience. Researchers

have used many studies to get a better understanding of the nature-nurture debate. Studies on babies confirm that new born babies have some perceptual abilities present at birth and are capable of sensing shapes. Gibson used infants aged 6-14months to conduct a study on depth perception, to find out if babies are capable of perceiving depth. He found that the babies could perceive depth and therefore concluded that depth perception is not always learned. Perceptual development after birth involves a complex interaction between genetic and environmental influences but in reality we do not need years of experience to adapt our perceptions.

One way of doing this is by depriving individuals of experiences they would otherwise of had. Since people can not be used to conduct such studies on due to ethical issues, non-human animals are used unless an individual is deprived because of an accident, disease or other life circumstances. Another way of conducting studies on humans is by altering their experiences, by adding experiences above or below those they would normally have to see whether more experiences will affect the development of their perceptual skills.  

Researchers who performed studies on people using distortion, readjustment and deprivation methods found that human beings are capable of perceiving the world in a different way to normal and can adjust to this altered perception rather quickly and effortlessly, showing that perception can be learned. An example to this is Psychologist, Stratton, who attached a telescope to one eye which resulted in him seeing the world ‘upside down’. But Stratton had not actually learnt to see the world in an ‘upside down’ manor since when he removed the telescope after 8 days he did not see the normal world ‘upside down’. This suggests that the adaptation took the form of learning the appropriate motor responses rather than learning to perceive. Studies of perceptual adaptation/readjustment demonstrate the flexibility of human perception although it is not always clear whether the adaptation is perceptual or motor.

Those who have lack of vision from birth have permanent perception disabilities. The case of a blind man who was blind from birth but later had his vision restored illustrates the difference between what he sensed and how he imagined the world before he could see with what he could see after his blindness. This gives further evidence for the effect of experience on the development of perception, suggesting that perception is based on what we see rather than what we sense.

In conclusion to the nature/nurture argument it is still unclear whether nature or nurture on its own is the solution to how we perceive. After looking at the different studies into perceptual abilities we can state that experience influences and affects perception. However it is almost impossible to know what is genetic and what is acquired through experience. Studying neonates gives the most direct source of evidence but they do not distinguish the effects of maturation and learning. The earlier a particular ability appears, the more likely it is to be under the influence of nature. Therefore the more simple perceptual abilities seem to be controlled by nature and the more complex abilities by nurture.