Chapter 5 Vocab-Color

Question 1

achromatic

Answer 1

Referring to any color that lacks a chromatic (hue) component. Black, white, or gray.

Question 2

achromatopsia

Answer 2

An inability to perceive colors that is caused by damage to the central nervous system.

Question 3

adapting stimulus

Answer 3

A stimulus whose removal produces a change in visual perception or sensitivity.

Question 4

additive color mixture

Answer 4

A mixture of lights. If light A and light B are both reflected from a surface to the eye, in the perception of color the effects of those two lights add together.

Question 5

afterimage

Answer 5

A visual image seen after the stimulus has been removed.

Question 6

agnosia

Answer 6

A failure to recognize objects in spite of the ability to see them, typically due to brain damage.

Question 7

anomia

Answer 7

An inability to name objects in spite of the ability to see and recognize them (as shown by usage), typically due to brain damage.

Question 8

brightness

Answer 8

The perceptual consequence of the physical intensity of a light.

Question 9

color assimilation

Answer 9

A color perception effect in which two colors bleed into each other, each taking on some of the chromatic quality of the other.

Question 10

color constancy

Answer 10

The tendency of a surface to appear the same color under a fairly wide range of illuminants.

Question 11

color contrast

Answer 11

A color perception effect in which the color of one region induces the opponent color in a neighboring region.

Question 12

color space

Answer 12

The three-dimensional space, established because color perception is based on the outputs of three cone types, that describes the set of all colors.

Question 13

color-anomalous

Answer 13

A better term for what is usually called “color-blind.” Most “color-blind” individuals can still make discriminations based on wavelength, but the discriminations are different from the norm.

Question 14

cone monochromat

Answer 14

An individual with only one cone type. Individual is truly color-blind.

Question 15

cone-opponent cell

Answer 15

A cell type—found in the retina, lateral geniculate nucleus, and visual cortex—that, in effect, subtracts one type of cone input from another.

Question 16

cultural relativism

Answer 16

In sensation and perception, the idea that basic perceptual experiences (e.g., color perception) may be determined in part by the cultural environment.

Question 17

deuteranope

Answer 17

An individual who suffers from color blindness that is due to the absence of M-cones.

Question 18

double-opponent cell

Answer 18

A cell type, found in the visual cortex, in which one region is excited by one cone type, combination of cones, or color and inhibited by the opponent cones or color (e.g., R+/G–). Another adjacent region would be inhibited by the first input and excited by the second (thus, in this example, R–/G+).

Question 19

hue

Answer 19

The chromatic (colorful) aspect of color (red, blue, green, yellow, and so on).

Question 20

illuminant

Answer 20

The light that illuminates a surface.

Question 21

L-cone

Answer 21

A cone that is preferentially sensitive to long wavelengths; colloquially (but not entirely accurately) known as a “red cone.”

Question 22

lateral geniculate nucleus (LGN)

Answer 22

A structure in the thalamus, part of the midbrain, that receives input from the retinal ganglion cells and has input and output connections to the visual cortex.

Question 23

M-cone

Answer 23

A cone that is preferentially sensitive to middle wavelengths; colloquially (but not entirely accurately) known as a “green cone.”

Question 24

metamers

Answer 24

Different mixtures of wavelengths that look identical. More generally, any pair of stimuli that are perceived as identical in spite of physical differences.

Question 25

negative afterimage

Answer 25

An afterimage whose polarity is the opposite of the original stimulus. Light stimuli produce dark negative afterimages. Colors are complementary; for example, red produces green, and yellow produces blue.

Question 26

neutral point

Answer 26

The point at which an opponent color mechanism is generating no signal. If red–green and blue–yellow mechanisms are at their neutral points, a stimulus will appear achromatic.

Question 27

opponent color theory

Answer 27

The theory that perception of color is based on the output of three mechanisms, each of them resulting from an opponency between two colors: red-green, blue-yellow, and black-white.

Question 28

photopic

Answer 28

Referring to light intensities that are bright enough to stimulate the cone receptors and bright enough to “saturate” the rod receptors (that is, drive them to their maximum responses).

Question 29

problem of univariance

Answer 29

The fact that an infinite set of different wavelength-intensity combinations can elicit exactly the same response from a single type of photoreceptor. One photoreceptor type cannot make color discriminations based on wavelength.

Question 30

protanope

Answer 30

An individual who suffers from color blindness that is due to the absence of L-cones.

Question 31

reflectance

Answer 31

The percentage of light hitting a surface that is reflected and not absorbed into the surface. Typically reflectance is given as a function of wavelength.

Question 32

related color

Answer 32

A color, such as brown or gray, that is seen only in relation to other colors. For example, a “gray” patch in complete darkness appears white.

Question 33

rod monochromat

Answer 33

An individual with no cones of any type. In addition to being truly color-blind, these individuals are badly visually impaired in bright light.

Question 34

S-cone

Answer 34

A cone that is preferentially sensitive to short wavelengths; colloquially (but not entirely accurately) known as a “blue cone.”

Question 35

saturation

Answer 35

The chromatic strength of a hue. White has zero saturation, pink is more saturated, and red is fully saturated.

Question 36

scotopic

Answer 36

Referring to light intensities that are bright enough to stimulate the rod receptors but too dim to stimulate the cone receptors.

Question 37

single-opponent cell

Answer 37

Another way to refer to cone-opponent cells.

Question 38

spectral power distribution

Answer 38

The physical energy in a light as a function of wavelength.

Question 39

spectral reflectance function

Answer 39

The percentage of a particular wavelength that is reflected from a surface.

Question 40

subtractive color mixture

Answer 40

A mixture of pigments. If pigments A and B mix, some of the light shining on the surface will be absorbed by A, and some by B. Only the remainder contributes to the perception of color.

Question 41

trichromatic theory of color vision (or trichromacy)

Answer 41

The theory that the color of any light is defined in our visual system by the relationships of three numbers—the outputs of three receptor types now known to be the three cones. Also known as the Young-Helmholtz theory.

Question 42

tritanope

Answer 42

An individual who suffers from color blindness that is due to the absence of S-cones.

Question 43

unique hue

Answer 43

Any of four colors that can be described with only a single color term: red, yellow, green, blue. Other colors (e.g., purple or orange) can be described as compounds (reddish blue, reddish yellow).

Question 44

unrelated color

Answer 44

A color that can be experienced in isolation.