Visual cliff

{{{DevPsy}}

The visual cliff is a piece of experimental apparatus designed to evaluate depth perception.

It consists of a box with a heavy glass top and a narow board across the centre. On one side of the board there appears to be a large drop {the visual cliff), while on the other it appears shallower.

The subject (most commonly an infant) is placed over the cliff and if the move quickly to the shallower end this is taken as evidence that they can perceive depth.

Most species that are active at birth show an immediate avoidance of the cliff. Human infants cannot move away from the cliff for some monthes. But newborns placed over the cliff show increased distress showing that they do perceive the threat.