4. Colour vision & perception Flashcards
What is meant by human trichromacy?
Three cone types
Maximally sensitive at short (S), middle (M) and long (L) wavelengths
What is trichromacy evolution related to?
Foraging for ripe fruit/berries
What colour do things appear with the following?
1. More blood
2. More oxygen
3. Less blood
4. Less oxygen
- Bluer
- Redder
- Yellower
- Greener
What are Monochromats
Have only one cone
(or no cones, only rods)
What are the three types of dichromats?
- Protanopia (lack L cone)
- Deuteranopia (lack M cone)
- Tritanopia (lack S cone)
What are the two types of Anomalous trichromats?
- Deuteranomoly (M cone shifted towards L)
- Protanomoly (L cone shifted to M)
Gene therapy turns d____ into t____
Dichromate into trichromat
Red opsin gene, virus and DNA were injected into some cones of dichromatic male squirrel monkeys. What effect did this have?
Can see colours previously not seen
Brain able to use signal even though circuitry not in use early on in life
Psychophysical tests and genetic analysis found what in relation to human tetrachromacy?
Only one woman was behaviourally tetrachromatic
Still need cortical processing of extra signal
Output from three cones is combined and contrasted to give…
Three cone-opponent channels
- L/(L+M): “cherry-teal”
- S/(L+M): “violet-lime”
- L+M: achromatic (or luminance axis)
What are the three types of colour-opponent cells in the LGN?
- Parvocellular
- Koniocellular
- Magnocellular
Some objects have a ____ ____ that we learn from experience and therefore expect
Typical colour
Bananas are typically yellow, so to make a banana look grey it is necessary to …
Add a little extra blue to counteract the memory colour.
The error is not present for a simple circle of colour
What are two theories of why we prefer some colours more than others?
- Biological Components theory
- Ecological Valence Theory
What is the main idea of the Ecological Valence Theory?
Colour preference is due to colour-object associations
