Background-Robert M. Yerkes found in 1904 that aquatic turtles have poorer depth-discrimination than land turtles.
Aim = To document if young animals and children were able to perceive depth and know not to walk off a ‘visual’ cliff.
Human study sample = 36 children aged 6 to 14 months. mother was there as well and gave consesnt
laboratory experiment that used a repeated measures design. • (IV) was whether the infant was called by its mother from the cliff side or the shallow side (of the visual cliff apparatus). •(DV) was whether or not the child would crawl to its mother. Other species are quasi experiments.(Iv) naturally occuring- the species (DV) was whether the animal preferred the shallow side or the deep side of the visual cliff apparatus.
Procedure: The apparatus consisted of a board laid across a large sheet of heavy glass which is supported a foot or more above the floor. On one side of the board a sheet of patterned material is placed flush against the under-surface of the glass, giving the glass the appearance as well as the substance of solidity. On the other side a sheet of the same material is laid upon the floor; this side of the board thus becomes the visual cliff
Each child was placed on the centre board, and his mother called him from the cliff side and the shallow side successively. Similarly chicks, turtles, rates, lambs, kids, pigs, kittens and dogs were placed on the visual cliff apparatus and the subsequent behaviour was observed
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Gibson- perception in young children
Findings-
100% of children moved to the shallow side of the cliff to get to their mother.
11% of children moved to the deep side of the cliff to get to their mother.
When the mother called to them from the deep side of the cliff, the most common reaction was to crawl away from the mother. Others would sit and cry on the shallow side.
The chicks would never cross the cliff. Lambs and goats would not cross the deep side.When the cliff drop was made smaller the goats would cross the deep end.
At 4 weeks old the kittens wouldn’t cross the deep end, but raised in darkness would walk on either side.Once exposed to light, these kittens would in a week avoid the deep side.
Conclusions
Most human infants can discriminate depth as soon as they can crawl.
A seeing animal can discriminate depth when its locomotion is adequate, even when locomotion begins at birth.
Depth perception in humans develops before many locomotor abilities.
Depth perception is chicks, kids and goats and kittens manifests itself rapidly.
Hooded rats and kittens use tactile cues from its whiskers to help their depth perception.
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