lec5 - Resesarch Topics in Neuroscience Peter H Schiller...

Resesarch Topics in Neuroscience
Peter H. Schiller, year 2006
Color vision and adaptation

Central questions about color vision and adaptation:
1. What are the basic facts and laws of color vision?
2. What are the major theories of color vision?
3. How is color processed in the retina and the LGN?
4. How is color processed in the cortex?
5. What is the nature of color blindness?
6. How is adaptation achieved in the visual system?
7. What are afterimages?

Color vision

Basic facts and rules of color vision
1. There are three qualities of color: hue, brightness, saturation
2. There is a clear distinction between the physical and psychological
attributes of color: wavelength vs. color, luminance vs. brightness.
3. Peak sensitivity of human photoreceptors:
S = 420, M = 530, L = 560, Rods = 500
4. Grassman's laws:
1. Every color has a complimentary which when mixed propery yields gray.
2. Mixture of non-complimentary colors yields intermediates.
5. Abney's law:
The luminance of a mixture of differently colored lights is equal to the
sum of the luminances of the components.
6. Metamers: stimuli producing different distributions of light energy that
yield the same color sensations.

Newton's prism experiment
red
red
orange
yellow
green
blue
indigo
violet

red
orange
yellow
green
blue
indigo
violet
AC circuits
Broadcast
band
Radar
Infrared rays
Ultraviolet rays
X rays
Gamma rays
Wavelength in meters
Wavelength in Nanometers
The visible spectrum
10
8
10
6
10
4
10
2
10
-2
10
-4
10
-6
10
-8
10
-10
10
-12
10
-14
700
600
500
400
1
Figure by MIT OCW.

The color circle
white
white
Green
Red
Blue
Yellow
saturation
hue
black

Figure by MIT OCW.
Saturation
Y
B
R
G
Hue

Major theories of color vision

Earlier Leonardo da Vinci: "Of different colors equally perfect, that will appear most
excellent which is seen near its direct contrary...blue near yellow, green near red:
because each color is seen, when opposed to its contrary, than to any other similar to it.