Colour Vision

Question 1

how many cone types

Answer 1

3 - 3 cone opsins
red, green, blue

Question 2

trichromatic theory

Answer 2

a specific colour is a summation of responses from the three primary photoreceptors types
- responding differenting to the same wavelenght

Question 3

long wave length sensitive

Answer 3

red cons (peak 570)

Question 4

medium wave length sensitive

Answer 4

green cones (545)

Question 5

short wave length sensitive

Answer 5

blue cones (445)

Question 6

peak sensitivity of rods

Answer 6

500

Question 7

chromaticity

Answer 7

the colour perceived

Question 8

what does chromaticiity depend on

Answer 8

wavelenght / hue
background composiition
luminance

Question 9

colour discrimination

Answer 9

cortical function related to perception / visual processing

Question 10

dark-adapted peak luminosity

Answer 10

blue-green (500nm)

Question 11

photopic conditions peak luminostity

Answer 11

yellow green 555nm

Question 12

purkinje shift

Answer 12

shorter wavelenghts become birhgt as luminance is reduced, i.e. with dark adapatation

Question 13

hue discrimination

Answer 13

depends on having difference photoreceptors types
2+ or more
the more varitety the more sensitive

Question 14

colour constancy

Answer 14

colour of an object remains the same despitre the wavelenght of refelcted light under varied conditions

Question 16

neural processing of colour begins at

Answer 16

the level of the ganglion cells

Question 17

colour-opponent cells

Answer 17

red-green - detect red/green contrast
blue yellow - ontain summed yellow signal from red and greens cones and contrast it with output from blue cones

Question 18

fine spectral tuning takes places where

Answer 18

V4

Question 19

how to test colour vision

Answer 19

ishihara plates
farnsweoth munsell 100 hue
D-15 (milder types)
lanthony new colour test - children

Question 20

optic nerve disease produces

Answer 20

early red/green defects

Question 21

acquired macular disease prodeuces

Answer 21

blue/yelllow defects

Question 22

anaomalous trichromatisim

Answer 22

e.g. deuteranolomy

relative deficiency inta cone population

Question 23

genes for medium (green) and long (red) are coded

Answer 23

on x chromosome
thf inherited x-linked recessive

Question 24

genes for shot (blue) are coded

Answer 24

on gene 7
thf AD inheritance

Question 25

rod monochromatisms

Answer 25

true achromatic vision, low VA, photosensitive, nystagmus, macular dystrophy

Question 26

Dichormatism

Answer 26

all colours are matched with only two primaries
protan - red
deutan - green
tritan - blue

Question 27

kirchsman’s law

Answer 27

greatest contrast in colour is seen when the luminosity difference is small

Question 28

Bezold-Brucke phenoman

Answer 28

changes in hue perception as luminance changes
increaseed lumince yellow white
decreased achromatic