What is depth perception?
Depth perception involves the capacity of perceiving objects as being in front or behind other objects. There are many cues which human observers use to be able to make these judgments. Most depth cues require the use of only one eye and these are called monocular depth cues. Examples of such cues are superposition, perspective, texture gradients, size constancy, shadows and several others. The most powerful monocular depth cue for making relative depth judgments is motion parallax. This is when the eye is moved back and forth laterally when looking at an object. This really improves depth judgments.
The main binocular depth judgment cue is called stereopsis. This is the fact the visual system is capable of using the information from the two eyes, fuse this information, and create a single solid impression of three-dimensional (3D) space. The fact is that because the two eyes are separated from one another, each eye actually has a slightly different two-dimensional (2D) view of the world and we call this difference between the eyes binocular disparity. It is this disparity information that the brain uses to produce stereoscopic vision.
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Jocelyn Faubert, Ph.D.
e-mail: jocelyn.faubert@umontreal.ca