PSYC 3040 - Chapter 10

Cue Approach to Depth Perception

an approach focused on identifying information in the retinal image that is correlated with depth in a scene

Oculomotor Cues

Depth perception cues created by convergence and accommodation, related to the physical movement of the eyes

Vergence

inward movement of the eyes that occurs when we look at a nearby object

Accommodation

the change in shape of the lens of the eyes when we focus on objects at various distances

Monocular Cues

Depth perception cues that work with under one eye

Pictorial Cues

sources of depth information that can be depicted as a picture

Occlusion

a cue that tells us one object is partially covered by another, indicating the partially covered object is further away

Relative Height

a cue that tells us objects higher in the field of view and with their bases closer to the horizon are more distant

Familiar Size

a cue that tells us one object is more distant than another based on our prior knowledge of the sizes of the objects

Relative Size

a cue that tells us when we have two objects known to be equal in size, the one that is further away will take up less of our field of view than the one that is closer

Perspective Convergence

a cue that tells us lines, like railroad track lines, convergence in the distance, so objects further along them must be further away

Atmospheric Perspective

a cue that tells us the farther away an object is, the more air and dust particles we have to look through to see them, causing further objects to appear less sharp and slightly blue tinted

Texture Gradient

a cue that tells us when similar objects are equally spaced throughout a scene, they form a pattern, and elements appear to be spaced more closely together if they are further

Shadows

decreases in light intensity caused by the blockage of light; they help enhance the three-dimensionality of objects

Motion Parallax

a cue that occurs when we are moving and nearby objects appear to move by us much more quickly than further objects

Deletion

a cue that occurs when we move our head to the side and become unable to see an object

Accretion

a cue that occurs when we move our head to the side and become able to see an object

Stereoscopic Vision

refers to your brain's ability to combine two different retinal images (from your left and right eyes) into a single, 3D perspective

Strabismus

a misalignment of the eyes that causes people to only see out of one eye at a time, since the visual system suppresses the vision in one eye to prevent double vision

Binocular Disparity

the difference in the images on the left and right retinas; the basis for stereoscopic vision

Corresponding Retinal Points

points on the retina that would overlap if the eyes were superimposed on each other

Horopter

the curve of all points in space that fall on corresponding points of the two retinas (almost like your field of vision)

Noncorresponding Points

the images of objects that are not on the horopter, and thus do not fall on places on the retina that would overlap if the eyes were superimposed

Absolute Disparity

the degree to which an image deviates from falling on a corresponding point

Angle of Disparity

the angle between a corresponding point on the right eye for the left eye image, and vice versa

Crossed Disparity

occurs when an object is closer to you than where you're looking, causing a pattern of disparity where your left eye sees an object to the right of your fixation point, and your right eye sees an object to the left of your fixation point

Uncrossed Disparity

occurs when an object is further than where you're looking, causing a pattern of disparity where your left eye sees an object to the left of your fixation point, and your right eye sees an object to the right of your fixation point

Stereopsis

the impression of depth that results from information provided by binocular disparity; in other words our ability for depth perception

Random Dot Stereogram

a stimulus that contains no pictorial cues; it is a pair of random dot patterns in which one pattern is a duplicate of another, with a small square of dots shifted ever so slightly the side

Stereoscope

a device that uses two lenses to focus the left image on the left eye and the right image on the right eye, allowing you to see the shifted area in a random dot stereogram as a small square floating above the background

Binocular Depth Cells

neurons that signal different amounts of binocular disparity

Frontal Eyes

eyes animals have to allow for overlapping visual fields, affording binocular disparity for stereopsis at the cost of a narrower field of view

Lateral Eyes

eyes animals have to maximize field of view, affording a greater sense of surroundings at the cost of overlapping visual fields for stereopsis

Visual Angle

the angle of an object relative to an observer's eye; the amount of circumference an object takes up on a viewer's retina based on the object's size and its distance from the viewer

Size Constancy

refers to the fact that our perception of an object's size remains relatively constant even when viewing it from different distances

Size-Distance Scaling

a formula to calculate an object's perceived size (S) based on the size of its image on the retina (R), its perceived distance (D), and a constant K: S = K × (R × D)

Emmert's Law

states that the perceived size of an afterimage is determined by the surface against which the afterimage is viewed; the farther away an afterimage appears, the larger it will be

Müller-Lyer Illusion

a size illusion in which two lines are presented side-by-side, one with arrows pointing inward and the other with arrows pointing outward; both lines are the same length although the one with arrows outward initially seems longer

Misapplied Size Constancy Scaling

a theory stating that the same mechanisms that help us maintain stable size perceptions in the 3D world sometimes create illusions when applied to 2D objects

Conflicting Cues Theory

states that our perception of line length depends on two cues, which conflict with each other to form a compromise on perception of length: (1) the actual length of the vertical lines, (2) the overall length of the figure

The Ponzo Illusion

also known as the railroad track illusion, in which two animals of equal size are on a railroad track that converges into the horizon, such that we perceive the further animal as larger

The Ames Room

a visual illusion physically constructed such that the room's right side is twice as distant from the observer as the room's left side, and the observer can only see the room through a peephole; as a result, the perceived distance from the observer to each person is the same, but one person in the room's retinal image is larger, making them seem bigger to the observer

The Moon Illusion

refers to the visual illusion in which the moon appears larger on the horizon than when it is high in the sky

Apparent Distance Theory

states that the moon on the horizon appears larger because it is viewed across terrain, which contains depth information, as opposed to the sky which does not (people report the sky looking closer to them than the horizon)

Angular-Size Contrast Theory

states that the moon in the sky appears smaller because it is surrounded by a large expanse of sky, making it seem smaller by comparison, as opposed to the moon on the horizon which is surrounded by more objects

Autostereograms

a single two-dimensional (2D) image that tricks the human brain into seeing a hidden three-dimensional (3D) object or scene of depth without needing a stereoscope or special glasses, due to repeating patterns