Depth perception

Accretion

the gradual reappearance of a moving object as it emerges from behind another object

Ames room

a specially constructed room where two people of the same size standing in the two back corners will look very different in height

Atmospheric perspective

a pictorial depth cue that arises from the fact that objects in the distance appear blurred and tinged with blue

Binocular cells

cells with two receptive fields, one for each eye; their main function is to match the images coming to each eye

Binocular disparity

a binocular depth cue because our two eyes are in different locations in our head and therefore have slightly different views of the world

Correspondence problem (depth perception)

the problem of determining which image in one eye matches the correct image in the other eye

Corresponding points

refers to a situation in which a point on the left retina and a point on the right retina would coincide if the two retinae were superimposed

Crossed disparity

the direction of disparity for objects closer to the viewer than the horopter (the image in the left eye is to the right of the image of the object in the right eye)

Cue approach to depth perception

the system whereby depth perception results from three sources of information, monocular cues to depth present in the image, binocular cues from the comparison of images in each eye, and cues from focusing the eyes, such as vergence and accommodation

Deletion

the gradual occlusion of a moving object as it passes behind another object

Diplopia

double images, or seeing two copies of the same image; usually results from the images of an object having too much disparity to lead to fusion

Familiar size

the cue whereby knowing the retinal size of a familiar object at a familiar distance allows us to use that retinal size to infer distance

Horopter

the region in space where the two images from an object fall on corresponding locations on the two retinae

Interocular velocity differences

the depth cue that arises when the retinal image moves faster in one eye than the other, which allows us to tell not only depth but direction

Linear perspective

the pictorial depth cue that arises from the fact that parallel lines appear to converge as they recede into the distance

Monocular depth cues

depth cues that require only one eye

Moon illusion

the illusion where the moon looks larger when it is near the horizon than it does when overhead

Motion parallax

a monocular depth cue arising from the relative velocities of objects moving across the retinae of a moving person

Motion-based cues

cues about depth that can be seen with a single eye in which the inference of distance comes from motion

Müller–Lyer illusion

the illusion where a line that has two lines going away at an angle looks longer than a line of the same length but the end lines angle back across the main line

Noncorresponding points

refers to a situation in which a point on the left retina and a point on the right retina would not coincide if the two retinae were superimposed

Occlusion

a visual cue that occurs when one object partially hides or obstructs the view of a second object; we infer that the hidden object is farther away from us than the object that obstructs it

Optic flow

a motion depth cue that involves the relative motion of objects as an observer moves forward or backward in a scene

Panum’s area of fusion

the region of small disparity around the horopter where the two images can be fused into a single perception

Pictorial cues

information about depth that can be inferred from a static picture

Ponzo illusion

illusion in which two identical objects are placed with one on top of the other. the top object looks further and larger while the bottom image looks closer yet smaller

Random-dot stereograms

stereograms in which the images consist of a randomly arranged set of black and white dots, with the left-eye and right-eye images arranged identically except that some of the dots are moved to the left or the right in one of the images, creating either a crossed or an uncrossed disparity

Relative height

a visual cue in which objects closer to the horizon are seen as more distant

Relative size

the fact that the more distant an object is, the smaller the image will be on the retina

Shadows

a depth cue arising because an object is in front of its shadow; the angle of the shadow can provide information about how far the object is in front of the background

Size constancy

the perception of an object as having a fixed size, despite the change in the size of the visual angle that accompanies changes in distance

Size–distance invariance

the relation between perceived size and perceived distance, whereby the perceived size of an object depends on its perceived distance, and the perceived distance of an object may depend on its perceived size

Stereopsis

the sense of depth we perceive from the visual system’s processing of the comparison of the two different images from each retina

Texture gradient

a monocular depth cue that occurs because textures become finer as they recede in the distance

Uncrossed disparity

the direction of disparity for objects that are farther from the viewer than the horopter (the image of the object in the left eye is to the left of the position of the image of the object in the right eye)

Vergence

the inward bending of the eyes when looking at closer objects

Visual angle

the angle of an object relative to the observer’s eye

Zero disparity

the situation in which retinal images fall along corresponding points, which means that the object is along the horopter

Absolute distance judgment

egocentric localization; distance between self and the object

Relative distance judgment

object-relative localization; distance between one object to the next

Accommodation

crystalline lens changes shape to focus on objects

Eye elevation hypothesis

moving eyes upwards makes objects appear similar

Emmert’s Law

perceived size of an object having a constant visual angle is proportional to the perceived distance of the object

Human factors and ergonomics

area of psychology related to the design and engineering of equipment and systems that people use, intentionally taking into account information about how people perceive, think, and behave