Lecture 13

Question 1

V4 was originally proposed as a sort of ‘___ __’

Answer 1

V4 was originally proposed as a sort of ‘color centre’

Question 2

Achromatopsia

Answer 2

color blindness, can cooccur with prosopagnosia

Question 3

Monochromats

Answer 3

has a very rare hereditary condition which could be considered to produce ‘true’ colour-blindness

Question 4

Monochromats have no functioning ___ (only ___), leading them to only perceive the world in tones of white, grey and black

Answer 4

Monochromats have no functioning cones (only rods), leading them to only perceive the world in tones of white, grey and black

Question 5

Monochromats have __ visual acuity because of lack of ___

Answer 5

Monochromats have poor visual acuity because of lack of cones

Question 6

Monochromats are __ sensitive because of having all ___

Answer 6

Monochromats are very sensitive because of having all rods

Question 7

Dichromats

Answer 7

are missing one of the 3 types of cones

Question 8

3 types of dichromats

Answer 8

protanopia, deuteranopia and tritanopia

Question 9

unilateral dichromats

Answer 9

has trichromatic vision in one eye and dichromatic in the other

Question 10

Protanopia

Answer 10

missing the long-wavelength pigment, see short-wavelengths as blue, a form of red-green colourblindness (red looks more green and less bright ), above neutral point of 492 nm they see yellow

Question 11

Deuteranopia

Answer 11

missing the medium-wavelength pigment, see short-wavelengths as blue, a form of red-green colourblindness (green look more red), above neutral point of 498nm they see yellow

Question 12

Tritanopia

Answer 12

missing the short-wavelength pigment, see short-wavelengths as blue, a form of blue-yellow colour-blindness (difficulty separating blue and green, red and yellow), above neutral point of 570 nm they see red

Question 13

Colour constancy

Answer 13

perception of colours as relatively constant in spite of changing light sources

Question 14

Chromatic adaptation

Answer 14

occurs with prolonged exposure to chromatic colours. When the stimulus colour selectively bleaches a specific cone pigment over an extended period of time, this results in a decrease in sensitivity to the associated color

Question 15

Colour constancy works best when an object is surrounded by ___ ___

Answer 15

Colour constancy works best when an object is surrounded by many colours

Question 16

Showing participants scenes with masked surrounding ___ ‘accuracy’ of colour perception reports

Answer 16

Showing participants scenes with masked surrounding reduces ‘accuracy’ of colour perception reports

Question 17

Hansen et al. showed participants photographs of fruits e.g. strawberries with characteristic colours against a grey background. When shown a spot of light which physically matched the grey background, participants accurately perceived the spot as being grey. However, when the fruits were adjusted to be grey, they were still perceived as being slightly coloured in a characteristic way i.e. participants reported seeing a grey strawberry as being slightly reddish

This was interpreted to mean that …

Answer 17

past knowledge of an object’s colour impacts colour perception

Question 18

Lightness constancy

Answer 18

achromatic colours are perceived as remaining relatively constant across different lighting condition

Question 19

Lightness

Answer 19

perception of the shade of achromatic colour (white, grey, black)

Question 20

Perception of lightness is not related to the __ ___ of light reflected by an object, but rather the __

Answer 20

Perception of lightness is not related to the total amount of light reflected by an object, but rather the percentage

Question 21

The intensity of light reaching the eye from an object depends on:
1) the intensity of illumination (total amount of light hitting the object)
2) The object’s ____ (the proportion of light reflected back by the object)

Answer 21

The intensity of light reaching the eye from an object depends on:
1) the intensity of illumination (total amount of light hitting the object)
2) The object’s reflectance (the proportion of light reflected back by the object)

Question 22

Lightness constancy is determined by ___ not __

Answer 22

Lightness constancy is determined by reflectance not intensity

Question 23

Ratio principle

Answer 23

states that two areas reflecting different amount of light look the same if the ratios of their intensities are the same

Question 24

When perceiving lightness under uneven illumination, the perceptual system must distinguish between…

Answer 24

reflectance edges and illumination edges

Question 25

Reflectance edges

Answer 25

edges where the amount of light reflected changes between two surfaces i.e. changes in material

Question 26

Illumination edges

Answer 26

edges where lighting of two surfaces changes i.e. changes in lighting

Question 27

Bornstein et al. found by the ___ ___ technique and the pattern of __ and ___ to 3 wavelengths, that ___ __ have colour vision

Answer 27

Bornstein et al. found by the looking time technique and the pattern of habituation and dishabituation to 3 wavelengths, that young infants have colour vision