There has been much debate as to whether depth perception is an innate ability, or a learnt one. Gibson and Walk used the visual cliff experiment to answer this question.
The visual cliff consisted of a layer of glass, mounted onto two levels of a checkerboard pattern. The shallow level had the pattern just below the glass, and the deep level had the pattern four feet below. 36 infants of crawling age were placed onto the shallow side and encouraged by their mothers to crawl onto the deep side. Most infants would not crawl on to the deep side of the visual cliff despite their mother’s encouragement. This would suggest that babies can perceive depth, so depth is the result of nature and not nurture.
Gibson and Walk’s research has extremely good face validity, as it provides evidence that the perception of depth and distance is indeed innate. However, the size of this study is too small for the results to be generalised to a wider population. However, the size of the sample can be excused due to the difficulty of obtaining infants at such a young age for the purpose of research. Also, not all the babies showed perception of depth, as some crossed onto the deep end. It cannot therefore be concluded that humans are born with this behaviour. Gibson and Walk’s research was