Transcript opponent-process hypothesis

The Basics of Light
Figure 10.23 The Color Solid (Part 2)
Color Perception Requires receptor cells that differ in
their sensitivity to different wavelengths
The trichromatic hypothesis of color perception:
• Three different types of cones
• Each responds to a different part of the spectrum
• Each has a separate pathway to the brain
The opponent-process hypothesis of color perception:
• Four unique hues and three opposed pairs of colors—blue versus yellow, green
versus red, and black versus white.
• Three systems that produce opposite responses to different wavelengths
Each human cone has one type of pigment—with a different peak of
sensitivity:
• Short (S)–peak sensitivity at 420 nm
• Medium (M)–530 nm
• Long (L)–560 nm
Spectral Sensitivities of Human Photopigments
A Model of the Connections of Wavelength Discrimination Systems in
the Primate Retina
Red Green Contrast
Visual Subsystem Pathways
Ganglion Neurons
LGN
(L/M) “Midget”
Parvocellular in
layers 3,4,5,6
Visual Cortex
Subsystem
Color
V1 layer 4C beta >V2 Thin -> V4
S(L+M) “Bistratified”
Koniocellular
Between each of the
M and P layers
Motion
Diffuse "Parasol"
Magnocellular in
layers 1, 2
V1 layer 4C -> 4B ->
V2 Thick -> V5
Dynamic Form
Diffuse "Parasol"
Magnocellular in
layers 1, 2
V1 layer 4B -> V2
Thick -> V3
A Model of the Connections of Wavelength Discrimination Systems in
the Primate Retina
Responses of the Four Main Types of Spectrally Opponent Cells in Monkey LGN
Responses of the Four Main Types of Spectrally Opponent Cells in
Monkey LGN (Part 1)
Responses of the Four Main Types of Spectrally Opponent Cells in
Monkey LGN (Part 2)
Responses of the Four Main Types of Spectrally Opponent Cells in
Monkey LGN (Part 3)
Responses of the Four Main Types of Spectrally Opponent Cells in
Monkey LGN (Part 4)
A Model of the Connections of Wavelength Discrimination Systems in
the Primate Retina