The child is placed on the raised area on a sheet of glass which covers the black and white squares. On one half of the area, the black and white squares are not immediately below the glass, but about one meter below. Six-month old babies were very reluctant to crawl over the 'cliff' even when their mothers encouraged them to do so. Because a six-month old human may already have learnt depth perception, the experiment was tried with animals such as chicks, kids and lambs which can walk as soon as they are born. They too refused to cross the cliff.
Size constancy Try the exercise on the right.
You should have found that the size of the after-image varies in proportion to the distance from the eye. If the distance from the eye to the paper was 20 cm and the distance to the wall 100 cm, the after-image on the wall will be five times bigger than that on the paper. We have referred to these functions as hard-wired. In fact, it is very difficult to know what functions of perception are innate, what mature after birth and what are learned. Of possibly more interest for Communication, Cultural and Media Studies are those which are learned - and that's what we'll take a look at in the following sections.