L2 Light and colour

Question 1

trichromat theory

Answer 1

three cones RBG which all combine different saturations and intensities to give all colours

Question 2

saturation

Answer 2

red = pink

Question 3

evidence for the trichromat theory

Answer 3

3 types of dichromacy

Question 4

protanopia

Answer 4

missing the long cone

Question 5

deuterenopia

Answer 5

missing M cone

Question 6

tritanopia

Answer 6

missing the small cone

Question 7

opponent theory

Answer 7

b/y r/g b/w cones

Question 8

opponent theory evidence

Answer 8

colour after effects - dichromats lose colours in pairs - people pick out yellow as a true colour

Question 9

dual processes theory

Answer 9

Retina =trichromat theory. LGN = opponent theory

Question 10

Light constancy

Answer 10

we perceive objects as the same lightness despite changes in lighting conditions (changes in sensation but not perception).

Question 11

luminance

Answer 11

the amount of light reflecting of an object

= I*R

Question 12

illumination

Answer 12

the amount of light emitted by a light source

Question 13

reflectance

Answer 13

the proportion of light being reflected from an objects surface

Question 14

we consciously receive information about

Answer 14

reflectance only

Question 15

adaptation theory

Answer 15

(rejected) as we move from light to dark conditions our visual system becomes more sensitive (photo adaption doesn’t happen that quickly)

Question 16

unconscious interference theory

Answer 16

we use previous knowledge to estimate illuminance (we are crap at estimating illumination)

Question 17

relational theories

Answer 17

we use ratios to determine luminance - as illuminance changes the luminance ratio stays the same. There is experimental evidence for these.

Question 18

retinex theory

Answer 18

we ignore gradual changes in luminance and instead focus on the sharper changes as these indicate signifiant features such as shadows and plane changes or a new object. absolute luminance isn’t very important to us

Question 19

problems for the relational theories

Answer 19

1. scaling (solved by the anchoring heuristic) 2. illuminance edges

Question 20

Anchoring heuristic

Answer 20

we use the thing of highest luminance in the visual field and mark this as white. everything else is scaled around this.

Question 21

fuzzy heuristic

Answer 21

illumination edges are less sharper than reflective edges

Question 22

planarity heuristic

Answer 22

reflectance edges are often coplanar

Question 23

ratio magnitude heuristic

Answer 23

the luminance ratio in the reflective edges is usually smaller

Question 24

colour constancy

Answer 24

can cause us to see two objects as the same colour despite same wavelengths, or vice versa

Question 25

illumination spectrum

Answer 25

(colour) how much light emitted from each frequency -

- natural light has a much more even ill spectr.

Question 26

although we don’t use background luminance for light constancy

Answer 26

we do use background wavelength for colour constancy

Question 27

colour constancy

Answer 27

-we use colour memory (can cause after effects like blue bananas). and background wavelength

Question 28

V1

Answer 28

Absolute colour - changes to background lumination cause changes in firing pattern

Question 29

v4

Answer 29

perceived colour - background changes doesn’t change the firing pattern

Question 30

v8

Answer 30

colour after effects

Question 31

which areas respond better to colour than black and white

Answer 31

v1238

Question 32

cerebral achromatopsia

Answer 32

intact visual system - patients cannot perceive colours but can discriminate wavelengths (as shades of grey). - have access to wavelength information but cannot see colour