4.8 - trichromatic theory, 4.9 mono to tetra, 4.10 opponent process theory, 4.11 lateral inhibition

trichromatic theory

colour vision is determined by three different cone types that are sensitive to short, medium, and long wavelength light.

the activity of trichromatic theory

The combined activity of all three cones that generate a unique signature associated with each perceived colour even colours without a corresponding wavelength.

magenta

cant be seen on the wavelength, odd way our brain happens to respond when hit red with blue light.

colour deficiency

colour blindness, two cones functioning
only on x chromosome

monochromatism

one cone type

dichromatism

two cone type

tetrachromatism

three cone type

opponent-process theory

percieve colour in terms of opposite ends of the spectrum (red to green, yellow to blue, white to black)

what to do ganglion cells provide

three colour channels
certain colours are natural opposites

negative afterimages

opponent process theory supported by evidence from negative afterimages

horizontal cells

inhibitory interneurons (GABA releasing) that connect between photoreceptors

beyond the retina: optic chiasm

crossover point for optic nerve at midpoint of the brain

beyond the retina: lateral geniculate nucleus

region within thalamus that directs visual information throughout the brain, also receives 90% of visual signals from optic nerve

primary visual cortex: feature detection cells

neurone that respond selectively based on specific aspects of a stimulus as well as to specific regions of the visual field

primary visual cortex:

all possible angles are accounted for at any location in our vision