Lecture Week 5 Flashcards Preview

PSYC2022 - Perception & Cogition > Lecture Week 5 > Flashcards

Flashcards in Lecture Week 5 Deck (17)
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1
Q

From Spots to Stripes

A

• The retinal ganglion cells are interested in detecting spots of light • The brain is interested in perceiving stripes

2
Q

Principles of Colour Vision

A

• Colour is not a physical property • There is no such things as colour • Colour is a psychophysical property of vision • The way we perceive reflected light is interpreted as colour by the brain

3
Q

Three steps to colour detection

A
  1. Detection
  2. Discrimination
  3. Appearance.
4
Q

Colour Detection: Step 1 - Detection

A

Wavelengths of light must be able to be detected by receptors

5
Q

Colour Detection: Step 2 - Discrimination

A

We need to be able to tell the difference between one wavelength and another

6
Q

Colour Detection: Step 3 - Appearance

A
  • We decide how to categorise perceived colours of lights and surfaces
  • We want these categories to be stable over time
7
Q

Scotopic light

A
  • Relates to Rods
  • Dim light, moonlight, no colours
  • Does not stimulate Cone Receptors
  • When Rods are saturated they don’t respond
8
Q

Photopic Light

A
  • Bright enough to stimulate Cones and Saturate Rods
  • Stimulates photoreceptors to maximum responses
9
Q

Preferential Absorbtion

A
  • Cones exitatory activity changes depending on the wavelength of light
  • Three cone types prefer their maximally sensitive light of short, medium or long
10
Q

Principle of Univariance

A
  • A single Photorecptor can give the same response to an infinite set of wavelength variations
  • Thus one photoreceptor alone cannot discriminate colours based on wavelength
  • We need 2-3 cones to discriminate colours from light wavelengths
  • We can detect light with one cone but not discrmininate colour with only one cone
11
Q

Trichromatic Theory

A
  • Also known as Young-Helmholz theory
  • We have three types of cones
  • We need to know the variance in Nanometers between S-cones, M-cones and L-cones to pinpoint the exact Nanometers of a particular wavelength and perceive a colour
12
Q

Metamers

A

Sometimes different mixtures of wavelengths may look identical but but have different levels of Nms; they may thus be perceived as identical

13
Q

Additive Colour Mixing

A
  • What happens when we mix different wavelengths of light
  • The wavelengths add together and this will change the perception
  • The lights do not actually combine physically, but the mind will add them together to change the perception
14
Q

Non Spectral Colours

A
  • There is no such thing as purple light wavelengths
  • We perceive Spectral colours when the edges of two wavelengths blend together.
15
Q

Opponent Cell Physiology

A
  • Lateral Geniculate Nucleus has cells that have centre surround organisation
  • They are maximally stimulated by spots of light
16
Q

Cone-opponent Cells

A
  • A neuron that receives energy from two or more sets of cones
  • Its output is based on the difference between these cones
  • Also have centre-surround organisation
17
Q

Opponent Colour Theory

A
  • Colour Perception depends on the output of three mechanisms -
  • Each mechanism is based on two colours
    • Red-Green
    • Blue-Yellow
    • Black-White