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Flashcards in week 8 Deck (45)
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1
Q

is there colour perception ?

A

There is no real colour there is only perception

2
Q

What is the definition of for colour perception?

A

colour perception is the product of network activity

3
Q

What are the properties of light?

A

light is a psychophysical property
light is a reflection
only 400 - 700 nm is visible on the spectrum

4
Q

how is visible light processed ?

A

visible light causes activity on the receptors

5
Q

What are the basic principles of colour perception?

A

Detection
Discrimination
Appearance

6
Q

Definition of Detection Colour perception?

A

Wavelength of light must be dated in the first place

7
Q

Definition of Discrimination of colour perception?

A

Must be able to tell the difference between one wavelength and another

8
Q

Definition of Appearance of colour perception?

A

Assign perceived colours to light surface
have the preceded colours be stable overtime
regardless of lighting conditions

9
Q

What are the two types of colour detection?

A

Photopic
Scotopic

10
Q

What is Photopic colour detection?

A

Light intensities that are bright enough to stimulate the cone receptors and saturate the rod receptors
eg. sunlight

11
Q

What is Scotopic Colour detection?

A

Light intensities that are bright enough to stimulate the rod receptors but too dim to stimulate the cone receptors
eg. moonlight

12
Q

What are three types of photopic vision?

A
S-cones = short ƒ
M-cones = medium ƒ
L-cones = Large ƒ
13
Q

What is the peak sensitivity and colour corresponding of the L-cone?

A

565 nm
yellow

14
Q

What is the problem of univariance?

A

an infinite set of different wavelength - intensity combinations can elicit exactly the same response demo a single type of photoreceptor
one type of photoreceptor cannot make colour discrimination based on wavelength

15
Q

What are the properties of scotopic vision?

A
  • Rods sensitive to scotopic light levels
  • all rods contain photopigments
  • All rods have the same sensitivity
  • rods suffer from invariance and cannot sense difference in colour
  • only rods are active under scotopic conditions
16
Q

What is the minimum about of colour intensity required for the cones to be active?

A

colour vision needs more than one tenth of a wavelength

17
Q

What is the basis of colour vision?

A

The three cones that distinguish between lights of different wavelength

18
Q

What is the theory of trichromatic?

A

colour of any light is defined in out visual system by the relationships of three numbers, the outputs of three receptors types now to be the three cones

19
Q

What is the trichromatic theory known as?

A

Young-Helmholtz

20
Q

What does metamers mean?

A
  • Different mixtures of wavelength that look identical.
  • two stimuli perceived as identical spite physical differences
21
Q

What are the two different colour cone responses?

A

LGN
Cone-opponent cell

22
Q

What does the LGN says do ?

A

Visual pathway stops at LGN beofre visual cortex

LGN has receptive fields with center- surround organization.

23
Q

what are the three Detection of discrimination?

A
  • Output is important even if the phsically wavelength are different
  • Retina and LGN contain cells repackage into cone-opponent differnt signials
  • Brain disciminates between 2 million colours
24
Q

What doe Cone-opponent cells ?

A

A neuirn whose output is based on a difference between sets of cones.

25
Q

What is colour appearance?

A

A 3D space that descirbes all colour

26
Q

What is the Equivalent of the RGB colour space?

A

similar to the long, medium short wavelength

27
Q

What is the HSB stand for?\

A

Hue

Situation

brightness

28
Q

what is hue ?

A

the chromatic aspect (colour)

29
Q

What is saturation?

A

The chromatic strength of hue (intensity)

30
Q

What is the brightness??

A

The distance from the black in colour space

31
Q

What is the opponent colour theory?

A

Thery that perception of colour is based on the output of three mechanise (opponency between two colour)

red-green

blue-yellow

black-white

32
Q

The relationship between the LGN and cone in regards to colour opponent?

A

LGN are exited by L-cone onset in centre which is inhibited by the M-cone onsets in surround

Eg. Red verse green

S-cone onset in centre, inhibited by (L+M)-cone onset in their surround

eg. Blue verse yellow

33
Q

What is an after-image?

A

A visual seen after a stimulus has been removed

34
Q

what is a negative afterimage?

A

An afterimage whose polarity is the opposite if the original stimuli (seeing opposite colour

35
Q

What is the process of opponent colours?

A

Step 1: detection (s,m, L cones)

step 2: discrimination

Step 3: Appearance

36
Q

Does everyone see colour the same way?

A

Yes: some variations due to age

No: About 8% of male population, 0.5% of female.

37
Q

What are the three types of colour blindness due to lacking cones?

A

Protanope: Absence of L-cone

Deuteranope: Absence of M-cones

Tritanope: Absence of S-cones

38
Q

What are the three types of colour blindness due to colour difference?

A

Colour-anomalous: two cones so similar can’t tell the difference.

Cone monochromat: having only one cone type

Rod monochromat: having no cones only

39
Q

What is colour contrast?

A

Colour perception effect in which the colour of one region indices the opponent colour in the neighbouring region

40
Q

what is colour assimilation?

A

Colour perception effect in which two colours bleed into each other, each taking up qualities of the other.

41
Q

What is colour constancy?

A

The tendency of a surface to appear the same colour under a fairly wide range of illuminations.

-visual system must take note of the lighting source

42
Q

Which two colours are furtherest apart in wavelength

A

Blue and red

43
Q

According to the opponent colour theory, the perception of colour is based on the output of ____ cones, each of them an opponency between ____ colors.

A

three; two

44
Q

If a video game labels friendly characters as green and enemy characters as red, who might have a hard time seeing the difference
between friendly and enemy characters?

A

Both deuteranopes and protonopes

45
Q

In tie case of a negative afterimage, a yellow stimulus would produce a ____ afterimage.

A

Blue