Sensation & Perception - Lecture 5

Question 1

S-cone

Answer 1

A cone cell specialized in detecting short wavelength, commonly referred to as the “blu cone”

Question 2

M-cone

Answer 2

A cone cell specialized in detecting middle wavelength, commonly referred to as the “green cone”

Question 3

L-cone

Answer 3

A cone cell specialized in detecting long wavelength, commonly referred to as the “red cone”

Question 4

Spectral sensitivity

Answer 4

The sensitivity of a cell or a device to different wavelengths on the electromagnetic spectrum

Question 5

Photopic

Answer 5

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 6

Scotopic

Answer 6

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

Question 7

Three steps to color perception.

Answer 7

1. Detection.
2. Discrimination.
3. Appearance

Question 8

Principle of univariance

Answer 8

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 9

Trichromacy or Trichromatic theory of color vision

Answer 9

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.

Question 10

Metamers

Answer 10

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

Question 11

Additive color mixture

Answer 11

A misture 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 12

Subtractive color mixture

Answer 12

A misture 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.

Question 13

Cone-opponent cell

Answer 13

A cell type that, in effect, subtracts one type of cone input from another.

Question 14

Lateral geniculate nucleus (LGN)

Answer 14

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 15

Koniocellular

Answer 15

Referring to cells in the koniocellular layer of the LGN of the thalamus.

Question 16

Parvocellular

Answer 16

Referring to cells in the parvocellular layers of the LGN of the thalamus.

Question 17

Equiluminant

Answer 17

Referring to stimuli that vary in color but not in luminance.

Question 18

Mesopic

Answer 18

Referring to the middle range of light intensities.

Question 19

Color Spaze

Answer 19

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 20

Opponent color theory

Answer 20

The theory that perception of color is based om the output of three mechanisme, each of them resulting from an opponency between two colors.

Question 21

Achromatopsia

Answer 21

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

Question 22

Deuteranope

Answer 22

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

Question 23

Protanope

Answer 23

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

Question 24

Tritanope

Answer 24

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

Question 25

Cone monochromat

Answer 25

An individual with only one cone type

Question 26

Rod monochromat

Answer 26

An individual with no cones of any type. Are badly visually impaired in bright light.

Question 27

Agnosia

Answer 27

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

Question 28

Anomia

Answer 28

An inability to name object in spite of the ability to see and recognize them.

Question 29

Synesthesia

Answer 29

The perceptual experience elicited by a stimulus that does not typically produce that experience, while the stimulus that does normally produce the experience is absent.

Question 30

Color contrast

Answer 30

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

Question 31

Color assimilation

Answer 31

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

Question 32

Related color

Answer 32

A color such as brown or gray, that is seen only in relation to other colors.

Question 33

Negative afterimage

Answer 33

A negative afterimage occurs when the original stimulus’s polarity is reversed, resulting in a dark afterimage for a light stimulus, with complementary colors.

Question 34

Adapting stimulus

Answer 34

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

Question 35

Neutral point

Answer 35

At the neutral point of opponent color mechanisms, where red-green and blue-yellow are balanced, stimuli appear achromatic, devoid of color signals.

Question 36

Color constancy

Answer 36

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

Question 37

Illuminant

Answer 37

The light that illuminates a surface.

Question 38

Spectral reflectance function

Answer 38

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

Question 39

Spectral power distribution

Answer 39

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

Question 40

Reflectance

Answer 40

The percentage of light hitting a surface that is reflected and not absorbed into the surface.