Colour perception

This ones gonna be a lil technical

Why do some objects appear to have a different colour to others?

Some objects are better at reflecting specific wavelengths of light over others

What is the term given to the range of wavelengths at which an object can reflect light effectively?

Reflectivity Spectra

What colour do short wavelengths of light represent the best?

Blue

What colour do long wavelengths of light represent the best?

Red

What colour do medium wavelengths of light represent the best?

Green

What is the name of the photo-pigment found in photo-receptor cells?

Rhodopsin

What wavelength does rod pigment receive light best at?

500 nm

Name the three types of cones that aid colour vision?

S, M and L Cones

True or False: Each type of cone is more effective at receiving a different portion of the visible light spectrum

True

Why is it impossible for rod cells to aid in colour vision?

There is only one type of rod cell, nothing to compare against

Outline the principle of uni-variance

Increase in photons makes colour unperceptive to a single rod cell, regardless of wavelength

What is another term for the number of photons from a light source?

Light intensity

What is the name given to the theory that all 3 types of cone cells are required for colour colour signalling?

Tri-chomatic theory

What are the 4 primary colours?

red, green, blue, yellow

What is a limitation of the tri-chromatic theory?

It does not outline how these cones mix their wavelengths to signal the correct colour

Outline the opponent process theory?

Perception of colour is processed by two opponent neural channels of cones

Using opponent process theory, outline the two channels required to perceive Red-Green colours

L cone channel and M cone channel

How can tri-chromatic and opponent process theory be used together to understand colour perception?

Tri-chromatic: response of cones —> Opponent process: Response of neurons

Outline Saturation

intensity of the dominant wavelength of that colour, relative to the rest of the spectrum

What is Monochromatism?

No Functioning Cones

What colours can monochromats see?

Black, White and Grey

What is Protonopia?

No L cones

What colours can people with protonopia not see?

Red

What is Deuternopia?

No M cones

What colours can people with deuternopia not see?

Green

What is Tritonopia?

No S cones

What colours can people with Tritonopia not see?

Blue

What is the term given to people with colour deficiencies that leave them with only two functioning cones?

Dichromats