lecture 10 Flashcards
Why do things look colored?
Sun emits white light (white light has blue yellow green red)
Some wavelengths more than others, get absorbed (vs reflection) by the pigment of the shirt (every color but red get absorbed by shirt bc shirt is red)
Reflects mostly wavelength light
Reflected wavelengths go into your eye (red is the reflected wavelength bc the shirt is red)
what are the 2 types of color
Spectral colors and broadband
what are spectral colors
single color
Example: a rainbow
what are Broadband colors
multiple colors
Example: “white” is equal energy of all wavelengths
The suns wavelengths are mostly blue, the atmosphere scatters blue light so we experience it in the sky
what are the 3 Cone Types (trichromacy) based on color vision
- Long wavelength selective, L (555 nm , looks yellow-green)
- Medium wavelength selective, M (525 nm, looks greenish)
- Short wavelength selective, S (450 nm, looks violet)
What happens if we weaken the M and S cones and then look at something that reflects white light?
Response profile will show L as a high response and S and M as low response
what are Metamers in color vision
2 stimuli with different wavelength compositions that yield the same response profiles (of the 3 cones)
(you have no choice but to perceive them as identical)
why are Metamers are more frequent in color blindness
Color blind (dichromats) people lack one cone type (usually M or L) bc they are linked to sex linked chromosome
… which leads to them having trouble discriminating between (some colors)
what is area v4 and the damage to area v4
Area v4 (in left and right hemisphere) - shows curves like shown in response profile, not just 3 types of central sensitivity
Damage to area v4 → “achromatopsia” (color blind - see world in black and white)
what is area MT and what is damage to area MT
Area MT (movement perception) → translational motion - motion that only has one direction to it
Damage to MT → “motion blindness”
