1. Be able to diagram and explain the relationship between radiance, illuminance, luminance, and reflectance.

2. Remember anableps, the 4-eyed fish? It has two visual systems in a single eye, for seeing both above and below the waterline. Are we like the anableps? What is the duplex retina? What is the evidence for having a duplex retina? How should we think about having a duplex retina?

3. In discussions about brightness, I said that the rule is "the coal is always black." Using two objects, like a piece of coal and my white-if-it-was-clean coffee cup, explain what this statement means with respect to illuminance, luminance, and reflectance. Is this an illusion or is it real?

4. What are Mach bands? Are Mach bands real or are they illusions?

5. Explain the concept of "lateral inhibition." Draw and explain a retinal circuit that shows how lateral inhibition could produce Mach bands.

6. Draw a portion of a Hermann grid. Explain the illusion seen. Explain the illusion according to a lateral inhibition explanation. Where is the illusion? Is what we see real or an illusion?

7. Explain the simultaneous contrast illusion. Where is the illusion located? Is it an illusion or is it real?

8. Explain the relationship between the spectrum, wavelength, and color. What is the meaning of the difference between the layout of the color circle and the spectrum? Why is purple considered such an important color?

9. How many colors can we discriminate? How was that estimated?

10. Explain how the Munsell system works. Explain how the CIE color system works.

11. Explain how to make my coffe cup look purple, using additive and subtractive color mixing.

12. Explain the development of trichromatic theory. What did Helmholtz do? What did he find?

13. How does trichromatic theory explain seeing colors like purple, black, and gold?

14. Explain the development of opponent process theory. What did Hering consider to be the critical evidence supporting his hypothetical color receptors?

15. Be able to draw and interpret the spectral sensitivity curves for the three types of cone receptors in humans. What are the "primary" colors according to the cones? Does this contradict our tendency to talk about red, yellow, green, and blue as being primary colors?

16. Using hypothetical opponent color receptors, explain how opponent process theory explains seeing colors like black and gold.