Chapter 5- The Perception of Color Flashcards
(45 cards)
S-Cone
A cone that is preferentially sensitive to short wavelengths, colloquially (but not entirely accurately) known as a “blue cone”.
M-Cone
A cone that is preferentially sensitive to middle wavelengths, colloquially (but not entirely accurately) known as a “green cone”.
L-Cone
A cone that is preferentially sensitive to long wavelengths, colloquially (but not entirely accurately) known as a “red cone”.
Spectral Sensitivity
The sensitivity of a cell or a device to different wavelengths on the electromagnetic spectrum.
Photopic
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.
Scotopic
Referring to light intensities that are bright enough to stimulate the rod receptors but too dim to stimulate the cone receptors.
Principle of Univariance
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.
Trichromacy or Trichromatic Theory of Color Vision
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 called the Young-Helmholtz theory.
Metamers
Different mixtures of wavelengths that look identical, or more generally, any pair of stimuli that are perceived as identical in spite of physical differences.
Additive Color Mixture
A mixture of lights. If light A and light B are both the reflected from a surface to the eye, in the perception of color the effects of those two lights add together.
Subtractive Color Mixture
A mixture of pigments. If pigments A and B mix, some of the light shining on the surface will be subtracted by A, and some by B. Only the remainder will contribute to the perception of color.
Lateral Geniculate Nucleus (LGN)
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.
Cone-Opponent Cell
A cell type- found in the retina, lateral geniculate nucleus, and visual cortex- that, in effect, subtracts one type of cone input from another.
Koniocellular
Referring to cells in the koniocellular layer of the lateral geniculate nucleus of the thalamus. Konio from the Greek for “dust”, refers to the appearance of the cells.
Parvocellular
Referring to cells in the parvocellular layers of the lateral geniculate nucleus of the thalamus. Parvo from the Greek for “small” refers to the size of the cells.
Equiluminant
Referring to stimuli that vary in color but not in luminance.
Mesopic
Referring to the middle range of light intensities.
Color Space
The three-dimensional space, established because color perception is based on the outputs of three cone types, that describes the set of all colors.
Opponent Color Theory
The theory that perception of color is based on the output of three mechanisms, each of the resulting from an opponency between two colors: red-green, blue-yellow, and black-white.
Unique Hue
In the context of the opponent color theory, 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 also be described as compounds (reddish blue, reddish yellow).
Achromatopsia
An inability to perceive colors that is caused by damage to the central nervous system.
Basic Color Terms
Color words that are single words (like blue, not sky blue), are used with high frequency, and have meanings that are agreed upon by speakers of a language.
Cultural Relativism
In sensation and perception, the idea that basic perceptual experiences (e.g., color perception) may be determined in part by the cultural environment.
Qualia
In philosophy, private conscious experiences of sensation or perception.
