colour theories

Question 1

trichromatic theory history names in order (4)

Answer 1

Palmer (1777), Young (1802), Maxwell (1856), Helmholtz (1911)

Question 2

Palmer’s (1777) theory

Answer 2

light composed of 3 differently coloured rays (r,y,b) that move particles on the retina

Question 3

Young’s (1802) theory

Answer 3

3 types receptors in human eye sensitive to r, g, v; based on colour matching with 3 primaries

Question 4

Maxwell’s (1856) theory

Answer 4

more colour-matching data supported Young’s theory; 4 more primaries needed

Question 5

colour matching

Answer 5

-supported Young’s theory
-perception of any colour can be matched by additive combo of 3 primary colours (1 primary can’t be perceptual match to mixture of other 2 primaries e.g. metameric matches)

Question 6

metameric matches

Answer 6

two lights that look the same but have different wavelength compositions

Question 7

best primaries for colour matching and why?

Answer 7

red, green, blue cuz far apart in colour space; can be mixed to match broadest range of standard colours

Question 8

in colour matching, each colour can be uniquely described in terms of

Answer 8

a proportion of the 3 primaries

Question 9

Young-Helmholtz trichromatic theory

Answer 9

perceived colour of any light is determined by the output of 3 receptor types

Question 10

physiological evidence of trichromatic theory by Rushton (1960)

Answer 10

found cones that absorb long wavelengths and medium wavelengths

Question 11

microspectrophotometry

Answer 11

technique for measuring wavelengths absorbed by individual cones

Question 12

microspectrophotometry physiological evidence for trichromatic theory

Answer 12

found cones absorbing short wavelengths

Question 13

Photo pigment curves are physiological evidence for

Answer 13

3 primaries needed for colour matching

Question 14

Why do we need more than 1 type of photoreceptor?

Answer 14

Principle of univariance

Question 15

Principle of univariance

Answer 15

The response of each photoreceptor only varies in one dimension

Question 16

What is example of univariance?

Answer 16

Response of photoreceptors only varies in amplitude

Question 17

T/F: response of photoreceptors can be the same but the wavelengths are different

Answer 17

True, that’s why we need multiple photoreceptors

Question 18

T/F: output of single photoreceptor is ambiguous which means we need only 1 dimension

Answer 18

False; is ambiguous which means we need 2 dimensions (intensity and wavelength info needed)

Question 19

what two dimensions are needed to perceive colour?

Answer 19

intensity and wavelength

Question 20

when 2 wavelengths produce the same response in 1 cone type, the 2 wavelengths ___

Answer 20

produce different patterns of responses across 3 cone types

Question 21

metameric colour match example

Answer 21

perception of red + green = yellow

Question 22

is colour discrimination possible in all parts of the spectrum with only 2 types of cones?

Answer 22

no

Question 23

Opponent process theory history: who’s the main guy?

Answer 23

Hering (19th c., Germany)

Question 24

Hering’s theory

Answer 24

there are 4 colour words rather than three used to describe sensations (red, green, blue, yellow) that are excited or inhibited

Question 25

which colours inhibit which colours in opponent process theory?

Answer 25

[B- W+], [G- R+], [B- Y+]

Question 26

psychological evidence for opponent process theory

Answer 26

complementary hues, complementary afterimages, unique hues

Question 27

complementary hues vs complementary afterimages

Answer 27

complementary hues cancel out and look grey; complementary afterimages appear after fixating on opposite colours for a while

Question 28

unique hues

Answer 28

hues that can be described with only a single colour term (red, green, yellow, blue)

Question 29

cardinal hue

Answer 29

when red-green and blue-yellow axes are in perceptual colour space

Question 30

hue cancellation also known as

Answer 30

colour nulling

Question 31

hue cancellation technique is strong psychophysical evidence for what theory?

Answer 31

opponent theory

Question 32

hue cancellation theory

Answer 32

adjusting proportions of colour to cancel out colour (e.g. cancelling out bluish and yellowish)

Question 33

T/F: values above the dotted line in the hue cancellation graphs mean that you are cancelling the colour shown with opponent colour

Answer 33

true; yellow line above line means you are adding blue to cancel yellowness

Question 34

spectral opponency

Answer 34

neuron is excited by wavelengths from one part of the spectrum and inhibited by wavelengths from a different part of the spectrum; also known as colour opponency

Question 35

physiological evidence for colour opponency

Answer 35

retinal ganglion cells: blue-yellow (bistratified cells; one blue, one yellow); red-green/spatial opponency (foveal midget cells; centre vs surround (4 variations)); midget & parasol for brightness axis

Question 36

dual-process theory of colour vision (order)

Answer 36

light-> receptors (trichromatic) (detection)-> opponent cells (opponent theory) (discrimination)-> brain

Question 37

how is trichromatic theory involved in dual-process theory of colour vision?

Answer 37

the receptors participate in colour matching; cones and additive wavelength

Question 38

how is opponent theory involved in dual-process theory of colour vision?

Answer 38

retinal ganglion cells; afterimages, complementary hues, colour nulling

Question 39

retinal ganglion cells for red-green channel & related cones (square brackets)?

Answer 39

foveal midget ganglion cells; [L-M] or [M-L]

Question 40

retinal ganglion cells for yellow-blue channel & related cones (square brackets)?

Answer 40

bistratified ganglion cells (all yellow, all blue); [(L+M)-S] or (S-(L+M))

Question 41

retinal ganglion cells for achromatic channel (brightness axis) & related cones (square brackets)?

Answer 41

midget & parasol ganglion cells; [L+M]

Question 42

trichromacy

Answer 42

normal colour vision; 3 cone photopigments; 3 primaries needed for colour matching

Question 43

anomalous trichromacy

Answer 43

colour deficiency with 3 cone photopigments but 1 is abnormal; abnormal proportions with 3 primaries for colour matching; colour discrimination difficulties

Question 44

types of anomalous trichromacy (most common to least)

Answer 44

deuteranomaly, protanomaly, tritanomaly

Question 45

dichromacy

Answer 45

colour deficiency with 1 missing cone photopigment; normal # of cones; 2 primaries for colour matching; neutral point in spectrum where grey perceived

Question 46

types of dichromacy (most common to least)

Answer 46

protanopia, deuteranopia, tritanopia

Question 47

monochromacy

Answer 47

rare, total colour blindness, missing 2 or 3 types of cones

Question 48

types of monochromacy

Answer 48

cone monochromacy, rod monochromacy

Question 49

difference between anomalous trichromacy, dichromacy, and monochromacy?

Answer 49

number of cones missing and/or abnormal cone photopigment; tri has 1 abnormal, di has 1 missing, mono has 2/3 missing

Question 50

anomalous trichromacy vs dichromacy morpheme endings for different types within each

Answer 50

anomalous trichromacy: -anomaly dichromacy: -anopia

Question 51

all the __-anomaly/-anopia and __-anopia/-anomaly, and cone monochromacy involve X-linked recessive inheritance

Answer 51

deuter; prot

Question 52

__-anomaly/- anopia linked with autosomal dominant inhertiance, chromosome 7

Answer 52

trit

Question 53

deuter____ associated with _ cone photopigment

Answer 53

M

Question 54

prot___ associated with _ cone photopigment

Answer 54

L

Question 55

trit____ associated with _ cone photopigment

Answer 55

S

Question 56

deuteranomaly

Answer 56

type of anomalous trichromacy -abnormal M cone photopigment; more green primary for matching -genetic mutation in opsin genes (X-linked recessive inheritance)

Question 57

protoanomaly

Answer 57

type of anomalous trichromacy -abnormal L cone photopigment; more red primary for matching -genetic mutation in opsin genes (X-linked recessive inheritance)

Question 58

tritanomaly

Answer 58

abnormal S cone photopigment; more blue primary for matching; autosomal dominant inheritance, chromosome 7

Question 59

deuteranopia

Answer 59

-type of dichromacy -M cone photopigment missing -neutral point ~ 498nm -X-linked recessive inheritance

Question 60

protanopia

Answer 60

-type of dichromacy -L cone photopigment missing -neutral point ~ 492 nm -X-linked recessive inheritance

Question 61

tritanopia

Answer 61

-type of dichromacy -S cone photopigment missing -neutral point ~ 570nm -autosomal dominant inheritance, chromosome 7

Question 62

cone monochromacy

Answer 62

-only 1 type of cone (usually S) -shades of grey -X-linked recessive inheritance

Question 63

rod monochromacy

Answer 63

-no cones -shades of grey -poor acuity, difficulty with photopic vision -autosomal recessive inheritance, chromosome 2 or 8

Question 64

how do inherited retinal colour deficiencies support dual-process theory?

Answer 64

-missing/abnormal photopigments in each type of colour support trichromacy at photopigment level -neutral points/colours perceived support opponency

Question 65

neutral points in dichromacy determined by ____ channels

Answer 65

opponent