Chap 9

Question 1

Color

Answer 1

Is not physical but psychological

Question 2

Problem of unvariance

Answer 2

An infinite set of different wavelength intensity combinations can give the same response from a single type of photoreceptor therefore one type photoreceptor can’t make color discrimination based on wavelength

Question 3

Photopic

Answer 3

Light that is bright enough to stimulate the cone receptors and bright enough to saturate the rod receptor

Question 4

Scotopic

Answer 4

Light that is bright enough to stimulate the rod receptor but too dim to stimulate cone receptors (moonlight & dim indoor light)

Question 5

Scotopic

Answer 5

Light that is bright enough to stimulate the rod receptor but too dim to stimulate cone receptors (moonlight & dim indoor light)

Question 6

Rods

Answer 6

Sensitive to scotopic light levels

All rods contain the same photo pigment molecule (rhodopsin)

All rods have the same sensitivity to various wavelengths of light

Rods suffer from the problem of univariance and can’t sense differences in color

Under scotopic conditions only rods are active which is why the world seems drowned of color

Question 7

Cone photoreceptors

Answer 7

S-cones - cones that are sensitive to short wavelengths (blue )

M-cones - sensitive to middle wavelengths (green)

L-cones -sensitive to long wavelengths (red)

Question 8

Trichromacy (young Helmholtz)

Answer 8

The theory that the color of any light is determined by the relationship of three numbers , the outputs of three receptors types know to be three cones

Question 9

Metamers

Answer 9

Different mixtures of wavelengths that look identical ,any pair of stimuli that is perceived as identical in spite of physical differences

Question 10

Addictive color mixing

Answer 10

A mixture of lights

Question 11

Subtractive color mixing

Answer 11

A mixture of pigments