Vision Continued (colour vision) Flashcards

0
Q

How many colour words do we have

A

Approx 11

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1
Q

How many colours can we see?

A

Up to 20 thousand colours and shades

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2
Q

How can we tell different colours/shades apart?

A

We use light and wavelength

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3
Q

We can perceive in the range of …….in light waves

A

380-740nm

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4
Q

Higher light wavelengths we see tend to see colours as

A

Reds etc

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5
Q

Smaller light waves are seen as colours:

A

Blues and purples

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6
Q

If the wavelength is higher than the highest then we see

A

Infrared wavelengths

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7
Q

Infrared spectrum wavelengths are

A

We can’t detect them visually, outside our visual perception.

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8
Q

Photoreceptors in the retina are sensitive to different

A

Wavelengths

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9
Q

Preferential absorption is

A

Absorbs only a Particular range of wavelengths

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10
Q

The brighter the light the

A

More we are able to detect it

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11
Q

Colour is a product of our perception rather than our

A

Reality

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12
Q

What colours we see is largely based on

A

The way our individual visual system is set up/designed

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13
Q

Three steps to colour perception: 1st step is:

A

Detection: light must first be detected by the retina

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14
Q

2nd step to colour detection is:

A

Discrimination: have to be able to tell wavelengths apart

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15
Q

3rd step to colour perception:

A

Appearance: different colours go with different objects. Colours remain relatively constant as viewing conditions change I.e in different lighting etc

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16
Q

Two broad light section conditions are:

A

Photopic

Scotopic

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17
Q

Photopic is

A

Light is bright enough to saturate cones and rods. Ie sunlight

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18
Q

How many different types of cones are there?

A

3

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19
Q

Scotopic is

A

Light that is bright enough to stimulate rods and not cones. Ie moonlight

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20
Q

Phototopic and Scotopic are apart of which step of colour perception?

A
  1. Detection
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21
Q

How many kinds of photoreceptors?

A

4

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22
Q

What are the 4 kinds of photoreceptors?

A

1 kind are rods

3 are cones

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23
Q

Different kinds of cones are sensitive to different wavelengths of light due to the

A

Different photopigment they carry

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24
Q

S-cones are sensitive to what kind of wavelengths?

A

Short (420nm)

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25
Q

M-cones sensitive to……….wavelengths

A

Medium (535nm)

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26
Q

L-cones are sensitive to

A

Long wavelengths (565nm)

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27
Q

What is the problem of univariance?

A

We can’t just rely on the output of one type of photoreceptor to tell us what wavelength we are encountering in terms of light. For any single photoreceptor there is an infinite pairing of wavelengths that produce the sane response rate for that particular type of photoreceptor

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28
Q

To solve the univariance problem we rely

A

On the combined out put of the three types of cones

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29
Q

The combined pattern activation/output of the three cones is called

A

Trichromatic theory

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30
Q

450nm and 625nm produces the

A

Same level in M-cones need to add S-cones and L-cones to really distinguish the colour

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31
Q

Brain looks at the patterns across all cones to

A

Try and figure out what light frequency it’s actually detecting

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32
Q

The relationship/relative ratio of activation from each type of cone tells us

A

About different wavelengths

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33
Q

The rod gives us info on the

A

General illumination conditions.

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34
Q

Most objects produce a

A

Combination of different wavelengths

35
Q

We see one colour when we look at items because we are restricted by our

A

Trichromatic visual system

36
Q

How do we only see on colour from a particular object?

A

Using trichomatic visual system

37
Q

Yellow light with a medium frequency produces the same amount of activation in the

A

M and L cones

38
Q

Combo of red and green lights produce same activation in L & M cones as what colour…

A

Yellow

39
Q

When you mix green and yellow light together you actually see

A

Yellow light

40
Q

Visual system can’t tell apart between a

A

Single yellow light and a mixture of red and green lights

41
Q

Metamer is

A

Any pair of stimuli that are perceived as being identical by our perceptual system even though they are physically different

42
Q

We only need three primary colours to get all the different colours because

A

We have only three types of cones

43
Q

Are the primary colours of paint different to those of light?

A

Yes

44
Q

Primary colours of light are:

A

Green red and blue

45
Q

Additive colour mixing is

A

The mixing of light colours

46
Q

Subtractive colour mixture is

A

The mixing of pigments/paint

47
Q

Mixing green and red light =

A

Yellow

48
Q

Mixing red and blue light =

A

Pink (magenta)

49
Q

Mixing blue and green light =

A

Light blue (cyan)

50
Q

Three primary colours mixed and you get

A

White light

51
Q

Subtractive light mixing primary colours are :

A

Yellow magenta and cyan

52
Q

Secondary subtractive colours are:

A

Red green blue black in middle

53
Q

Trichomatic visual scale is used as a basis for

A

Printing, computers, TV etc because we only need 3 primary colours to give us the effect of lots of different colours

54
Q

The other way our visual system works that can’t be explained by the trichromatic colour theory…

A

Afterimages

55
Q

Afterimages are

A

After looking at an image you see it looking away at a white space

56
Q

Afterimages are different from the actual image how?

A

Colours on the afterimage are inverted (darker bits lighter yellow bits blueish) etc

57
Q

Visual opponent process theory

A

Certain colours that can combine together and we can see combinations of those colours.

58
Q

Combinations of colours we CAN see are:

A

Greeny-yellow
Bluish-green
Yellowy-red

59
Q

Combos of colours we should never be able to see:

A

Greeny-red
Yellowy-blue
Whiteish-black

60
Q

Cone-opponent cells are cells that

A

Work similarly to ganglion cells they have centre surround receptor fields. Stimuli activate it’s centre and it produces inhibition.

61
Q

Cone-opponent cells increase our

A

Perception to colour contrast.

62
Q

Cone-opponent cells process colour by

A

Encoding it in terms of its proportion of red or green and blue or yellow

63
Q

How do opponent processes explain afterimages?

A

When staring at a green image for a long time green receptors become temporarily desensitised. Patches of red light can be seen when looking at a white wall. Opponent colours red and green!

64
Q

Trichromatic theory is what type of Visual processing?

A

Photoreceptor level

65
Q

Opponent process theory is what level of visual processing?

A

Ganglion cell, LGN and V1 level

66
Q

Does everyone see colour in exactly the same way?

A

Yes. Similar ways. Use meta metric matching in experiments

67
Q

How much % of pop are colour blind?

A

8% male .5% female

68
Q

Dueteranope

A

A person who has no M cones. Reduced red/green discrimination. Green looks red.

69
Q

Protanopia

A

Person who lacks L cones. Reduced red/green discrimination. Reds look green

70
Q

Tritanopia

A

Person who lacks S Cones (rare). Blue is black. Sees world in green, red, yellows.

71
Q

Sensory systems have different

A

Receptors, signalling pathways and processing areas in the brain.

72
Q

Many of our sensory pathways pass through the

A

Thalamus (except smell)

73
Q

Benefits of our senses combining…

A

Gives us survival advantage

74
Q

Why does our senses combining give us a survival advantage?

A

We generate coherent internal representation of the world

Increased accuracy and reliability of experience

75
Q

Taste combines

A

Taste, smell, trigeminal nerves (tells about touch experiences in our mouth)

76
Q

Walking combines these:

A

Propriception, vision

77
Q

Engaging in conversation combines these:

A

Audition, vision mcgurk effect

78
Q

Identifying objects combines these

A

Audition, vision, touch, smell, taste

79
Q

Synaesthesia is

A

Colours may elicit the sensation of sound. Associations made between apparently unrelated phenomena!

80
Q

Synaesthesia types

A

Colours elicit sounds
Shapes elicit tastes
Sounds elicit smell
Ordinal personification (numbers have characters)

81
Q

We all may have some form of synaesthesia for example in the case of

A

Music and emotion

82
Q

How is synathesia caused?

A

Cross modal connections between normally separate brain areas produces brain cross-activation. Genetic link. Psychological reality not physical.

83
Q

Can be a connection between synaesthesia and

A

Metaphor

84
Q

Why connection between synaesthesia and metaphor?

A

Due to some modalities having the same qualities/pattern. They feel qualitivity similar in ways Ie Kiki and bobar

85
Q

How do we screen for synaesthesia?

A

How many no 2s? Can pick out 2s VERY quickly with colour