Colour vision Flashcards
1
Q
Define trichromatic
A
Having normal colour vision, which is sensitive to all three primary colours.
2
Q
Having normal colour vision, which is sensitive to all three primary colours.
This is known as…?
A
Trichromatic
3
Q
True or False?
Of all mammals, all species have the necessary hardware to see “colours” in a way comparable to us (trichromatic).
A
False
Of all mammals, only a few species have the necessary hardware to see “colours” in a way comparable to us (trichromatic).
4
Q
Which mammals have a trichromatic vision? List 2
A
1) Catarrhine monkeys (Old World monkeys and man)
2) Platyrrhine monkeys (New World monkeys -only the females)
5
Q
Which animals have 4 types of colour vision?
A
Some tropical fish and birds
6
Q
Which animal has 5 types of colour vision?
A
Pigeons
7
Q
Define tetrachromacy
A
Having normal colour vision, which is sensitive to four colours
8
Q
Define pentachromats
A
Having normal colour vision, which is sensitive to five colours
9
Q
Having normal colour vision, which is sensitive to five colours
This is known as…?
A
Pentachromats
10
Q
Having normal colour vision, which is sensitive to four colours
This is known as…?
A
Tetrachromacy
11
Q
What is colour good for? List 3 uses
A
1) Scene Segmentation
2) Camouflage
3) Perceptual Organisation
12
Q
What is Scene Segmentation?
A
Variations in colour often signal object boundaries
13
Q
What is Camouflage?
A
Animals use this fact to disguise themselves by colour markings
14
Q
What is Perceptual Organisation?
A
Our visual system uses colour to group elements in a scene
15
Q
Variations in colour often signal object boundaries
This is known as…?
A
Scene Segmentation
16
Q
Animals use this fact to disguise themselves by colour markings
This is known as…?
A
Camouflage
17
Q
Our visual system uses colour to group elements in a scene
This is known as…?
A
Perceptual Organisation
18
Q
Colour vision is linked with a strong evolutionary force depending on the species.
How do living things in the evolutionary past use colour vision? List 2 things
A
1) Food Identification
2) Camouflage
19
Q
Colour vision is linked with a strong evolutionary force depending on the species.
Living things use colour vision for food identification. What do these living things look for using their colour vision?
List 4 things
A
- Ripe fruit
- Correct leaves
- Harmless or harmful berries
- Poisonous or venomous animals
20
Q
What is colour?
A
Visible light that forms a narrow band of
frequencies in the electromagnetic spectrum
21
Q
Visible light that forms a narrow band of
frequencies in the electromagnetic spectrum
This is known as…?
A
Colour
22
Q
Visible light that forms a narrow band of
frequencies in the electromagnetic spectrum
What is present within this narrow band?
A
Within this band, there are different frequencies (or wavelengths) that have different hues, ranging from red (for long wavelength light) to violet (for short wavelength light).
23
Q
A red hue on the visible light band is for (short/long wavelength)
A
Long wavelength
24
Q
A violet hue on the visible light band is for (short/long wavelength)
A
Short wavelength
25
How many nanometers are there in a millimetre on an electromagnetic spectrum?
1 000 000 nanometers
26
A whole spectrum of visible colours covers just ...nm
400 nm
27
The electromagnetic spectrum ranges from ..... meters to ..... meters
0.00000000000001 meters to 10 000 meters
28
The visible light on the electromagnetic spectrum ranges from ..... meters to ..... meters
0.00000390 and 0.00000750 meters
Simply = 4 thousandths of a millimetre
29
On the electromagnetic spectrum, what is the nanometer point for violet light?
400 nm
30
On the electromagnetic spectrum, what is the nanometer point for blue light?
450 nm
31
On the electromagnetic spectrum, what is the nanometer point for cyan light?
500 nm
32
On the electromagnetic spectrum, what is the nanometer point for green light?
550 nm
33
On the electromagnetic spectrum, what is the nanometer point for yellow light?
600 nm
34
On the electromagnetic spectrum, what is the nanometer point for orange light?
650 nm
35
On the electromagnetic spectrum, what is the nanometer point for red light?
700 nm
36
On the electromagnetic spectrum, what is the nanometer point for infrared light?
750 nm
37
How do objects appear in colour?
Different objects absorb and reflect different wavelengths of light
This gives them colour
38
What does colour depend on, other than absorbing and reflecting wavelengths of light?
Depends on the light source
39
The wavelength of the light reflected only determines the ....?
Hue which is seen
40
Apart from wavelength judgement (Observed hue), what else is perceived colour determined by? List 2 determinants
1) Intensity of reflected light
2) The saturation of the colour
41
What is perceived colour determined by? List 3 determinants
1) Wavelength judgement (Observed hue)
2) Intensity of reflected light
3) The saturation of the colour
42
What does the intensity of reflected light mean?
How bright the light is
43
What does the saturation of the colour mean?
How much white light is mixed in with the pure hue
44
What are the 3 properties of light?
- Wavelength
- Intensity
- Spectral Purity
45
What are the psychological attributes of the 3 properties of light?
- Hue (colour)
- Brightness (perceived intensity
- Saturation (how much colour or how much white)
46
Match the property of light with the psychological attribute
Property of light:
Wavelength
Psychological attribute:
a. Hue (colour)
b. Brightness (perceived intensity
c. Saturation (how much colour or how much white)
a. Hue (colour)
47
Match the property of light with the psychological attribute
Property of light:
Spectral Purity
Psychological attribute:
a. Hue (colour)
b. Brightness (perceived intensity
c. Saturation (how much colour or how much white)
c. Saturation (how much colour or how much white)
48
Match the property of light with the psychological attribute
Property of light:
Intensity
Psychological attribute:
a. Hue (colour)
b. Brightness (perceived intensity
c. Saturation (how much colour or how much white)
b. Brightness (perceived intensity
49
The difference between the colour blue and red is...?
Hue (colour)
50
The difference between light blue and dark blue is...?
Intensity (brightness)
51
The difference between red and pink is...?
Saturation (how much of colour or how much of white)
52
What happens when white light is shone through red glass?
Only red light is perceived
53
What happens when white light is shone through green glass?
Only green light is perceived
54
What happens when white light is shone through blue glass?
Only blue light is perceived
55
What happens when white light is shone through white glass?
White light is perceived because white reflects all primary colours/wavelengths
56
What happens when white light is shone through black glass?
No light is perceived because black absorbs all primary colours/wavelengths
57
What are the 2 theories of colour perception?
1) Trichromatic Theory
2) Opponent Process Theory
58
Who thought of the Trichromatic Theory of colour perception?
Young and Helmholtz
59
What did the Young-Helmholtz Trichromatic Theory of colour perception suggest?
There are three receptor types and their combined responses account for all colours
60
According to the Young-Helmholtz Trichromatic Theory of colour perception, blue-sensitive cones are mainly responsive to what wavelengths?
Short wavenegths
61
According to the Young-Helmholtz Trichromatic Theory of colour perception, green-sensitive cones are mainly responsive to what wavelengths?
Medium wavelengths
62
According to the Young-Helmholtz Trichromatic Theory of colour perception, red-sensitive cones are mainly responsive to what wavelengths?
Long wavelengths
63
Blue-sensitive cones are known as...?
S-cones
64
Green-sensitive cones are known as...?
M-cones
65
Red-sensitive cones are known as...?
L-cones
66
According to the Young-Helmholtz Trichromatic Theory of colour perception, how many colour-sensitive cones are there? And what are they?
1) 3
2) Blue, Green, Red
67
According to the Young-Helmholtz Trichromatic Theory of colour perception, which colour-sensitive cones respond to short wavelengths?
Blue-sensitive cones
68
According to the Young-Helmholtz Trichromatic Theory of colour perception, which colour-sensitive cones respond to medium wavelengths?
Green-sensitive cones
69
According to the Young-Helmholtz Trichromatic Theory of colour perception, which colour-sensitive cones respond to long wavelengths?
Red-sensitive cones
70
Cones that respond to short wavelengths respond at what nanometer specifically?
419 nm
71
Cones that respond to medium wavelengths respond at what nanometer specifically?
531 nm
72
Cones that respond to long wavelengths respond at what nanometer specifically?
558 nm
73
True or False?
Rods respond to colour
False
Only cones respond to colour. Rods respond to light intensity
74
What is the point of a red alert in a submarine?
Once you're deep in the ocean, the outside environment in the ocean gets dark
If the submarine is lit up with bright, white light, your rods would adapt to the strong light intensity. When you attempt to look outside using a periscope, it might take a while for your eyes (rods) to adjust to the dark to see outside clearly
Whereas, if the submarine is lit with red light, your eyes (rods) have already adapted to the dark because rods do not respond to red light
75
True or False?
Rods respond to red light
False
Rods do not respond to red light
76
Why do some animals have an additional reflective layer over the eye?
e.g. cat's eyes "glow in the dark" when light shines on it
To allow the light another chance to hit the receptors to enhance visual sensitivity at low light levels
77
What is the additional reflective layer on the eye which allows a second opportunity for photon-photoreceptor stimulation, thereby enhancing visual sensitivity at low light levels?
Tapetum lucidum
78
What is Tapetum lucidum?
An additional reflective layer on the eye which allows a second opportunity for photon-photoreceptor stimulation, thereby enhancing visual sensitivity at low light levels
79
What determines which wavelengths each colour-sensitive cone responds to best?
Pigments in the cones
80
Objects themselves don't have colour; they simply reflect some wavelengths and absorb some wavelengths
True or False?
True
81
True or False?
Light is coloured, objects are coloured and the visual signal is coloured
False
Light is not coloured, objects are not coloured and neither is the visual signal
82
From the cones, light is encoded as ...?
Electrical signal
83
True or False?
Electrical signals and light are not coloured but the brain actually puts a "label" on that sensation
True
84
What is the explanatory gap?
The difficulty in explaining how physical properties give rise to the way things feel when they are experienced
Simply = The difficulty in explaining a subjective experience to another person
85
There is a concentration of cones in an area called...?
Fovea
86
Where is the fovea located?
In a small pit in the retina
87
How big is the retina in mm?
32 mm
88
How big is the fovea in mm?
1.5 mm
89
When the eye concentrates on an object, where does the image of the object fall on?
The fovea (centre of the eye)
90
Which area of the eye has the highest density of receptors?
Fovea
91
Fovea has the highest density of receptors. What does this suggest?
Fovea has the best acuity (1% - 50%)
92
True or False?
Both rods and cones are in the centre of the fovea
False
There are no rods in the centre of the fovea
93
Which is more sensitive?
a. Rods
b. Cones
a. Rods
94
Rods are very sensitive. What does this mean?
They don’t need much intensity to be activated
95
True or False?
Cones need the minimum lighting conditions to be activated
False
Cones need good lighting conditions to be activated
96
What are rods sensitive to?
Intensity (black and white) only
97
What are cones sensitive to?
Different wavelengths (3 types)
98
Where are rods found?
Rods are found all over the retina except the centre of the fovea
99
Where are cones found?
Cones are concentrated in the fovea
100
There are ...... times more rods than cones across the whole retina
20
101
What did the Young-Helmholtz Trichromatic Theory of colour perception hypothesise?
There are three different sorts of receptors and they respond best to different wavelengths of light
102
According to the Young-Helmholtz Trichromatic Theory of colour perception, what do the 3 receptors respond best to?
The cones respond best to long wavelength (which looks yellow/red), medium (green) or short (blue) wavelength light
103
The colour you see is determined by ...?
The relative levels of activity in the three sorts of receptors
104
True or False?
Green objects reflect more long wavelength light than other wavelengths
False
Red objects reflect more long wavelength light than other wavelengths
105
What are the 3 types of evidence supporting the Trichromatic Theory?
1) There are 3 primary colours combined to produce all possible colours
2) There are 3 forms of dichromatism (colour blindness)
3) A mixture of green and red light produces
the same perception of yellow colour as monochromatic yellow light (metamerism)
106
When you stare at a blue circle for a long period of time, what happens to your colour vision when the blue circle suddenly disappears?
Only red and green cones can respond, which produces a yellow circle
107
When you stare at a blue circle for a long period of time and the blue circle suddenly disappears, you'll see a yellow circle.
Why does this happen?
The blue-sensitive cones/channel fatigued/adapted
So only red and green cones can respond, which produces a yellow circle
108
Who proposed the Opponent Process Theory?
Hering; Hurvich-Jameson
109
What did Hering notice when people are presented with a large number of colour
samples and were asked to pick out those that are pure (not a mix)?
People picked a red, a green and a blue colour sample (as predicted by trichromatic theory; primary colours)
But people also picked yellow
110
According to the Opponent Process Theory of colour perception, what are the 3 processes/receptors opponent in nature?
1) Red-Green
2) Yellow-Blue
3) Black-White
111
According to the Opponent Process Theory of colour perception, Red-Green Receptors will signal either Red or Green or both
True or False?
False
Red-Green Receptor will signal either Red or Green but not both
112
According to the Opponent Process Theory of colour perception, what colours do Red-Green Receptors signal?
Either Red or Green but not both
113
According to the Opponent Process Theory of colour perception, what colours do Yellow-Blue Receptors signal?
Either Blue or Red and Green but not both
114
According to the Opponent Process Theory of colour perception, what colours do Black-White Receptors signal?
All colours (red, green and blue) or None of the colours but not both
115
What are the 4 types of evidence supporting the Opponent Process Theory?
1) Non-existence of certain colours, e.g., bluish-yellow
2) Colour confusion in colour blindness (red and green)
3) Complementary afterimages
4) Colour context effects
116
What is the colour context effect?
When 2 colours are side by side and they interact with one another, which changes our perception accordingly
117
What is lightness constancy?
When the illumination of a visual scene changes, the quantity of light reflected from objects is altered
Despite this, the perceived lightness of the objects generally remains constant
Simply = perceive objects as having a consistent level of brightness or lightness, regardless of variations in the illumination falling on them.
e.g. We perceive a piece of paper in a dimly lit room as white the way way as we perceive the same piece of paper outside on a sunny bright day. Even though the paper outside has higher illumination falling on it, we still perceive both papers as white
118
Trichromacy theory vs Opponent process theory
Which is correct?
Both are correct
119
Which colour perception theory identifies the perception of colour at the level of the cones?
Trichromacy
120
Which colour perception theory identifies the perception of colour at the level of LGN (The Lateral Geniculate Nucleus) and cortical cells?
Opponent process theory
121
The Opponent process theory identifies the perception of colour at the level of ...?
The LGN (The Lateral Geniculate Nucleus) and cortical cells
122
The Trichromacy theory identifies the perception of colour at the level of ...?
The Cones
123
Who first described colour blindness and when?
John Dalton in 1794
124
When was John Dalton diagnosed with colour blindness?
200 years after he investigated it
125
What are the 2 main types of colour blindness?
1) Anopias
2) Anomalies
126
What is Anopias in colour blindness?
Insensitive to L, M or S wavelengths of light. (missing a type of cone)
127
What are Anomalies in colour blindness?
Misalignment of L or M in trichromats. (distribution or deficiency)
128
Misalignment of L or M in trichromats. (distribution or deficiency)
This is known as...?
Anomalies
129
Insensitive to L, M or S wavelengths of light. (missing a type of cone)
This is known as...?
Anopias
130
What is the term used to describe people who see the world in only black and white?
Cortical colour blindness
131
What is Cortical colour blindness?
People who see the world in only black and white
132
What are the 3 types of anopia colour blindness?
1) Protanopia
2) Deuteranopia
3) Tritanopia
133
What happens in protanopia in anopia colour blindness?
L-cone pigment missing
134
What happens in deuteranopia in anopia colour blindness?
M-cone pigment missing
135
What happens in Tritanopia in anopia colour blindness?
S-cone pigment missing
136
Which type of anopia is this?
L-cone pigment missing
Protanopia
137
Which type of anopia is this?
M-cone pigment missing
Deuteranopia
138
Which type of anopia is this?
S-cone pigment missing
Tritanopia
139
How many % of males and females suffer from Protanopia?
1.3% Males, 0.02% Females
140
How many % of males and females suffer from Deuteranopia?
1.2% Males, 0.01% Females
141
How many % of males and females suffer from Tritanopia?
0.001% Males, 0.003% Females
142
What are the 2 types of anomilies (Anomalous Trichromatism)
1) Protoanomaly
2) Deuteranomaly
143
What is Protoanomaly Anomalous Trichromatism?
L-cone pigment deficiency
(need more ‘red’ in ‘red-green’ mixture to match ‘yellow’)
144
What is Deuteranomaly Anomalous Trichromatism?
M-cone pigment deficiency
(need more ‘green’ in ‘red-green’ mixture to match ‘yellow’)
145
Which type of Anomalous Trichromatism is this?
M-cone pigment deficiency
(need more ‘green’ in ‘red-green’ mixture to match ‘yellow’)
Deuteranomaly
146
Which type of Anomalous Trichromatism is this?
L-cone pigment deficiency
(need more ‘red’ in ‘red-green’ mixture to match ‘yellow’)
Protoanomaly
147
Which type of colour blindness involves the deficiency of a certain cone?
Anomilies (Anomalous Trichromatism)
148
Which type of colour blindness involves missing certain cones?
Anopia (Dichromatism)
149
What is Dichromatism?
Missing cones
150
How many % of males and females suffer from Protoanomaly Anomilies (Anomalous Trichromatism)?
1.3% Males, 0.02% Females
151
How many % of males and females suffer from Deuteranomaly Anomilies (Anomalous Trichromatism)?
5.0 % Males, 0.35% Females
152
True or False?
Both colour blindness types support both colour vision theories
True
153
Both colour blindness types support both colour vision theories
How? List 2 ways
1) The whole fact of anopia points to there being 3 cone types
2) Opponent process theory is supported by the fact that people who have trouble with RED also have trouble with GREEN and etc.
154
Human Tetrachromats (those who have 4 pigment cone types) can detect variations in hue that we normally can not
What variations of hue can they detect?
Shades of green
