PSYC 1000 - Chapter 5c: Vision

Comprehensive vocabulary flashcards covering Gestalt principles, depth perception, monocular and binocular cues, perceptual constancies, and visual illusions from Chapter 5 (Vision).

Gestalt

A German word meaning "form" or "whole," referring to the psychological view that the brain perceives sensory input in a holistic manner by imposing meaningful patterns, such that the whole is greater than the sum of its parts.

Top-Down Processing

A perceptual process in which the brain applies stored organizing principles, expectations, and past experiences to construct meaningful gestalts from raw sensory experience.

Necker Cube

A visual stimulus that demonstrates Gestalt grouping and top-down processing by causing the brain to perceive a three-dimensional cube with nonexistent lines and depth rather than a simple collection of partial circles or two-dimensional shapes.

Figure Ground

A Gestalt organizational law describing the perceptual tendency to divide a visual scene into a central focused object (the figure) and its surrounding backdrop (the background).

Bi-stable (Reversible) Images

Ambiguous visual displays in which figure and ground compete and alternate over time, demonstrating how perception is influenced by expectations and past experience.

Law of Proximity

A Gestalt grouping principle stating that visual stimuli that are physically close together tend to be grouped together perceptually into a unified set.

Law of Similarity

A Gestalt grouping principle stating that stimuli sharing similar physical properties (such as color, shape, or orientation) are perceived as belonging together.

Law of Continuity

A Gestalt principle stating that visual elements positioned along a smooth, continuous line or contour are perceived as a single uninterrupted pattern.

Law of Closure

A Gestalt principle describing the perceptual tendency to fill in gaps and perceive a complete, finished unit from an incomplete sensory stimulus.

Impossible Figures

Two-dimensional drawings designed such that the brain persistently tries to organize them into a coherent three-dimensional gestalt, even though the depicted object is physically impossible.

Depth Perception

The ability to perceive the world in three dimensions and estimate the distance and size of objects, which is partly innate and develops in human infants by $6\text{--}14\text{ months}$ of age.

Visual Cliff

A laboratory apparatus consisting of an elevated glass platform with a shallow and deep side, used to demonstrate that depth perception develops early and is partly innate in human infants and newborn animals.

Binocular Cues

Visual depth cues that require the coordinated use of both eyes to construct a $3\text{D}$ representation from flat, $2\text{D}$ retinal images.

Monocular Cues

Depth cues that require only one eye to perceive distance; often termed pictorial cues because they can be captured in photographs and two-dimensional paintings.

Convergence

A binocular neuromuscular cue in which the eyes rotate inward to fixate on nearby objects; the brain uses the increased tension in the eye muscles to infer that an object is close.

Retinal Disparity

A binocular cue based on the slight difference between the horizontal positions of images cast on the two retinas; the brain compares this disparity to judge depth, where greater disparity indicates closer distance.

Interposition

A monocular depth cue occurring when one object partially blocks the view of another, leading the viewer to perceive the occluded object as being farther away.

Relative Height (Elevation)

A monocular cue where objects situated higher in the lower half of the visual field are perceived as more distant, whereas objects located lower in the upper half of the visual field appear farther away.

Texture Gradient

A monocular cue where a coarse, distinct texture indicates close proximity, while a finer, more densely packed and less detailed texture indicates greater distance.

Linear Perspective

A monocular depth cue wherein parallel lines appear to converge as they recede into the distance; greater convergence corresponds to greater perceived distance.

Light and Shadow

A monocular cue where nearby objects reflect more light to the eye (appearing brighter), and shading patterns generate depth based on the brain's default assumption that illumination comes from above.

Clarity or Aerial Perspective

A monocular depth cue where distant objects appear hazier, fuzzier, or less clear due to atmospheric scattering compared to sharper, nearby objects.

Relative Size

A monocular cue based on the principle that if two objects are assumed to be of similar physical size, the one projecting a smaller retinal image will be perceived as farther away.

Familiar Size

A monocular cue where preexisting knowledge of an object's real dimensions allows the brain to infer its distance based on the size of the image it casts on the retina.

Motion Parallax (Relative Motion)

A monocular depth cue experienced by a moving observer, where nearby objects appear to sweep past in the opposite direction rapidly, while distant objects appear to move more slowly or remain stationary.

Perceptual Constancy

The top-down visual ability to perceive familiar objects as unchanging in shape, color, brightness, and size despite continuous variations in the sensory stimuli reaching the retina.

Shape Constancy

The tendency to perceive the true shape of a familiar object as stable and unchanging, even when changes in viewing angle alter the geometry of its retinal image (e.g., viewing an opening door).

Colour (Brightness) Constancy

The perception that an object maintains consistent luminance and reflectance even when lighting conditions and the amount of illumination falling on it change substantially.

Size Constancy

The perception that an object retains its actual physical dimensions regardless of changes in viewing distance and corresponding fluctuations in retinal image size.

Size-Distance Relationship

The perceptual principle specifying that perceived distance determines perceived size; if two stimuli cast identical retinal images, the stimulus judged to be more distant is perceived as larger.

Ponzo Illusion

A geometric-optical illusion where two identical horizontal lines placed between converging linear perspective cues are perceived as different lengths because the upper bar is judged to be farther away.

Moon Illusion

A visual illusion where the full moon appears significantly larger on the horizon than at the zenith due to the "flattened sky" effect, which causes the horizon moon to be perceived as farther away despite casting the same retinal image.

Ames' Room Illusion

A distorted trapezoidal room designed to appear cubic through a peephole, causing two people of equal height standing at different corners to appear radically different in size due to incorrect distance assumptions.

Motion Perception

Motion toward and away: as objects retreat from us, size of retinal image shrinks; as they approach, image gets larger. Size constancy leads to perception of motion and distance (rather than a change in size).

Stroboscopic Movement

The perception of continuous visual motion created by presenting a rapid succession of slightly different stationary frames rather than continuous physical movement.

Critical Flicker Fusion Frequency

The display threshold rate (approximately $24\text{ frames per second}$) at which the brain fuses discrete, flashing images into a seamless perception of continuous movement.

Phi Phenomenon

An illusion of movement that occurs when adjacent stationary lights turn on and off in rapid alternation, leading observers to perceive a single light moving back and forth.