Chapter 3: Sensation and Perception Vocabulary

A complete set of vocabulary flashcards derived from the Chapter 3 lecture notes on Sensation and Perception.

Sensation

The stimulation of sensory receptors and the transmission of sensory information to the central nervous system.

Perception

The process by which sensations are organized into an inner representation of the world.

Absolute Threshold

The minimal amount of energy that can produce a sensation.

Subliminal Stimulation

Sensory stimulation below a person's absolute threshold for conscious perception.

Difference Threshold

The minimal difference in intensity required between two sources of energy so that they will be perceived as being different.

Weber's Constant

The fraction of the intensity by which a source of physical energy must be increased or decreased so that a difference in intensity will be perceived.

Just Noticeable Difference (JND)

The minimal amount by which a source of energy must be increased or decreased so that a difference in intensity will be perceived.

Signal-Detection Theory

The view that the perception of sensory stimuli involves the interaction of physical, biological, and psychological factors.

Feature Detectors

Neurons in the sensory cortex that fire in response to specific features of sensory information such as lines or edges of objects.

Sensory Adaptation

The processes by which organisms become more sensitive to stimuli that are low in magnitude and less sensitive to stimuli that are constant or ongoing in magnitude.

Sensitization

The type of sensory adaptation in which we become more sensitive to stimuli that are low in magnitude; also called positive adaptation.

Desensitization

The type of sensory adaptation in which we become less sensitive to constant stimuli; also called negative adaptation.

Visible Light

The part of the electromagnetic spectrum that stimulates the eye and produces visual sensations.

Hue

The color of light, as determined by its wavelength.

Cornea

Transparent tissue forming the outer surface of the eyeball.

Iris

A muscular membrane whose dilation regulates the amount of light that enters the eye.

Pupil

The black-looking opening in the center of the iris, through which light enters the eye.

Lens

A transparent body behind the iris that focuses an image on the retina.

Photoreceptors

Cells that respond to light.

Rods

Rod-shaped photoreceptors that are sensitive only to the intensity of light.

Cones

Cone-shaped photoreceptors that transmit sensations of color.

Retina

The area of the inner surface of the eye that contains rods and cones.

Bipolar Cells

Neurons that conduct neural impulses from rods and cones to ganglion cells.

Ganglion Cells

Neurons whose axons form the optic nerve.

Optic Nerve

The nerve that transmits sensory information from the eye to the brain.

Fovea

An area near the center of the retina that is dense with cones and where vision is consequently most acute.

Blind Spot

The area of the retina where axons from ganglion cells meet to form the optic nerve.

Visual Acuity

Sharpness of vision, commonly tested using a Snellen chart.

Presbyopia

A condition characterized by brittleness of the lens, causing the lens to stop focusing light correctly on the retina.

Dark Adaptation

The process of adjusting to conditions of lower lighting by increasing the sensitivity of rods and cones.

Value of Color

Refers to the degree of brightness and darkness of a color.

Saturation

Refers to how intense a color appears to us.

Complementary

Descriptive of colors of the spectrum that when combined produce white or nearly white light.

Afterimage

The lingering visual impression made by a stimulus that has been removed.

Trichromatic Theory

The theory that color vision is made possible by three types of cones, some of which respond to red light, some to green, and some to blue.

Opponent-Process Theory

The theory that color vision is made possible by three types of cones, some of which respond to red or green light, some to blue or yellow, and some to the intensity of light.

Trichromat

A person with normal color vision.

Monochromat

A person who is sensitive to black and white only and hence color-blind.

Dichromat

A person who is sensitive to black-white and either red-green or blue-yellow and hence is partially color-blind.

Visual Perception

The process by which we organize or make sense of the sensory impressions caused by the light that strikes our eyes.

Closure

The tendency to perceive a broken figure as being complete or whole.

Perceptual Organization

The tendency to integrate perceptual elements into meaningful patterns.

Proximity

Nearness; the perceptual tendency to group together objects that are near one another.

Similarity

The perceptual tendency to group together objects that are similar in appearance.

Continuity

The tendency to perceive a series of points or lines as having unity.

Common Fate

The tendency to perceive elements that move together as belonging together.

Top-Down Processing

The use of contextual information or knowledge of a pattern in order to organize parts of the pattern.

Bottom-Up Processing

The organization of the parts of a pattern to recognize, or form an image of, the pattern they compose.

Illusions

Sensations that give rise to misperceptions.

Stroboscopic Motion

A visual illusion in which the perception of motion is generated by a series of stationary images that are presented in rapid succession.

Monocular Cues

Stimuli suggestive of depth that can be perceived with only one eye.

Perspective

A monocular cue where distant objects stimulate smaller areas on the retina than nearby ones, causing parallel lines to appear to converge as they recede.

Texture Gradient

A form of monocular cue where closer objects are perceived as having rougher textures and more detail.

Motion Parallax

A monocular cue for depth based on the perception that nearby objects appear to move more rapidly in relation to our own motion.

Binocular Cues

Stimuli suggestive of depth that involve simultaneous perception by both eyes.

Retinal Disparity

A binocular cue for depth based on the difference in the image cast by an object on the retinas of the eyes as the object moves closer or farther away.

Convergence

A binocular cue for depth based on the inward movement of the eyes as they attempt to focus on an object that is drawing nearer.

Size Constancy

The tendency to perceive an object as being the same size even as the size of its retinal image changes according to the object's distance.

Color Constancy

The tendency to perceive objects as retaining their color even though lighting conditions may alter their appearance.

Brightness Constancy

The tendency to perceive an object as being just as bright even though lighting conditions change its intensity.

Shape Constancy

The tendency to perceive objects as maintaining their shape, even if viewed from different angles so that the shape of their image on the retina changes dramatically.

Hering-Helmholtz Illusion

A visual illusion where horizontal lines are straight and parallel, but radiating lines make them appear bent outward near the center.

Müller-Lyer Illusion

A visual illusion where two lines are the same length, but the line with reversed arrowheads appears longer.