Chapter 9

Question 1

three functions of color vision

Answer 1

classify and identify colors (ex. red = stop or anger)

facilitates perceptual organization (ex. seeing one object from another)

allows us to survive (ex. recognizing colors of food)

Question 2

what did Isaac Newton propose regarding white light?

Answer 2

white light has a mixture of many colors

Question 3

prism

Answer 3

object that could separate different colors from the white light

Question 4

visual spectrum

Answer 4

colors that humans can perceive (400 - 700 nm)

Question 5

match the wavelengths to the color

Answer 5

blue = short

green = medium

yellow = medium/long

red = long

Question 6

how do wavelengths get processed?

Answer 6

colors of objects are determined by wavelengths that are reflected by light into the eyes

Question 7

chromatic colors

Answer 7

light is able to reflect different wavelengths (e.g., red, green, blue)

Question 8

selective reflection

Answer 8

in chromatic colors, some colors reflect more than others

Question 9

achromatic colors

Answer 9

light reflects equal wavelengths (e.g., white, black, gray)

Question 10

selective transmission

Answer 10

transparent objects (eg., liquids, plastics, glass) allow wavelengths to pass through

Question 11

reflectance and transmission curves

Answer 11

used to plot the percentage of light reflected or transmitted to perceive specific wavelengths

Question 12

two ways to mix color to describe different wavelengths

Answer 12

mixing paints (paint absorbs or takes away colors; short, medium, and long mixed together creates BLACK; SUBTRACTIVE – blue + yellow = green, blue and yellow no longer present)

mixing light (short, medium, and long superimposed or placed over each other creates WHITE; ADDITIVE – green, medium + red, long = yellow, medium-long)

Question 13

three perceptual dimensions of color

Answer 13

hue (color being assessed)

saturation (perceived intensity and pureness of color; how strong it is)

value/lightness (perceived brightness of the color)

Question 14

desaturation

Answer 14

fading of a color due to more white in it

Question 15

trichromatic theory of color vision

Answer 15

three different color mechanisms (for three different wavelengths: short, medium, long) are responsible for color vision

Question 16

color matching experiment

Answer 16

behavioral evidence for trichromatic theory

adjust 3 wavelengths to match the test field of one wavelength

findings:
adjusting 3 wavelengths = possible to match any colors in the test field
adjusting two wavelengths only = cannot match all colors
normal color vision = requires 3 receptors

Question 17

test field

Answer 17

the color light the experimenter wants the observer to match

Question 18

comparison field

Answer 18

observer must manipulate the lighting to match the test field color

Question 19

3 cone pigments in terms of wavelengths

Answer 19

short wavelength, medium, long

Question 20

visual pigment molecule

Answer 20

refers to cones because rods only have short wavelengths

retinal bends from opsin to produce light

Question 21

opsin

Answer 21

protein structure differs representing the three different pigments

Question 22

metamerism

Answer 22

situation in which colors of different wavelengths create an identical color

Question 23

metamers

Answer 23

different wavelengths that come together to make a similar color

Question 24

1 receptor = 1 visual pigment only

Answer 24

wavelengths cannot be identified

color from light looks the same (shades of gray)

Question 25

principle of univariance

Answer 25

when only 1 receptor exists receptors can't detect differences in wavelengths, only the intensity of light

Question 26

2 receptors = 2 visual pigments

Answer 26

ability to identify 2 wavelengths and not just intensity of light

Question 27

3 receptors = 3 visual pigments

Answer 27

ability to identify 3 wavelengths, creating perception of many colors

Question 28

who proposed the two theories of color vision

Answer 28

trichromatic theory of color vision - Helmholtz, Young, and Maxwell opponent-process theory - Hering

Question 29

phenomenological method

Answer 29

describing an observation

Question 30

Hering's color circle experiment

Answer 30

pure colors that cannot be mixed with other colors: red, yellow, green, blue (primary colors or unique hues) opponent colors: blue/yellow, green/red, black/white

Question 31

opponent neurons

Answer 31

located in retina and LGN respond in excitatory manner to one end of the visible spectrum and an inhibitory manner to the other for color pairings

Question 32

trichromatic + opponent-process theory

Answer 32

each theory describes physiological mechanisms in the visual system trichromatic - explains cones in retina opponent-process - explains neural response from cones to the brain

Question 33

Ishihara plates

Answer 33

color vision test to diagnose people w/ color deficiency try to identify number inside dotted circle image

Question 34

unilateral dichromats

Answer 34

very rare condition where people have normal color vision in one eye but deficient in the other

Question 35

monochromat (definition + effect on daily life)

Answer 35

has one wavelength to see color; see shades of gray only rods, no functioning cones poor visual acuity (unable to see details) and sensitive to bright light color blindness

Question 36

dichromat

Answer 36

has 2 wavelengths to see color perceived some color but not all males tend to have it more because of lack of extra X chromosome color deficiency

Question 37

3 types of dichromats

Answer 37

protanopia (primary - red/long) deuteranopia (secondary - green/medium) tritanopia (third - blue/short)

Question 38

protanopia

Answer 38

lacking red cones sees short wavelengths (blue) fades to gray (neutral point) at 492 nm --difficulty seeing green long wavelengths = yellow above neutral point -- difficulty seeing red

Question 39

deuteranopia

Answer 39

lacking green cones sees short wavelengths (blue) fades to gray (neutral point) at 498 nm -- difficulty seeing green (lacks medium wavelength pigment) long wavelengths = yellow above neutral point (cannot see red as much)

Question 40

tritanopia

Answer 40

lacking blue cones very rare dichromat difficulty seeing blue fades to gray at 570 nm long wavelengths = red above neutral point (cannot see yellow)

Question 41

color constancy

Answer 41

we perceive colors of objects as not changing even under different lighting

Question 42

lightness constancy

Answer 42

we perceived achromatic colors as remaining relatively constant we may see different shades of gray due to amount of light reflected but color itself doesn't change