The visual ability to distinguish the world in three dimensions, tied with the ability to measure how far away an object is called depth perception. A monocular cue is any inducements related to depth perception that can be perceived through the use of one eye alone that is in contrast to binocular cues, which require the use of both eyes to perceive depth. The monocular depth cue in which an object, that is blocking another object, is perceived as closer is called overlap (interposition). It forms the appearance that the object that is being covered, or overlapped, is the one that is further away.