1. Exam next week Covers everything about all sensory modalities except hearing This includes: vision balance/touch/taste/smell/ proprioception/theroception

2. Binocular Disparity points nearer than horopter have crossed disparity points farther than horopter have uncrossed disparity The Horopter

3. Autostereograms Any repeating objects that have a spacing different from the background will have either crossed or uncrossed disparity when the convergence angle of the eyes is set to a point in front of or behind the screen What would you see?

4. “Magic Eye” Stereograms Usually viewed with uncrossed convergence Imagine gazing farther than the surface (let your eyes “relax”) Now try to notice objects or forms in the blurriness As you become aware of shapes, try to focus (accommodate) the plane of the image without converging your eyes

5. Autostereograms

9. What color is this box?

10. Wavelength and Color Recall that light is electromagnetic radiation

11. Wavelength and Color Recall that light is electromagnetic radiation Light waves have a frequency/wavelength

12. Wavelength and Color Recall that light is electromagnetic radiation Light waves have a frequency/wavelength Frequency/wavelength is the physical property that corresponds (loosely) to the perception called color

13. Color Vision Different wavelengths correspond roughly to the “colors” of the spectrum Wavelength and Color

14. Color Vision White light is a mixture of wavelengths –prisms decompose white light into assorted wavelengths Wavelength and Color

15. Color Vision Primary colors Perceiving Color What are the primary colors?

16. Color Vision Primary colors Perceiving Color Red Green Blue

17. Color Vision Primary colors Perceiving Color What makes them primary?

18. Color Vision Primary colors Every color (hue) can be created by blending light of the three primary colors in differing proportions Perceiving Color

19. Color Vision Primary colors Every color (hue) can be created by blending light of the three primary colors in differing proportions Led to prediction that there must be three (and only three) distinct color receptor types Perceiving Color

20. Color Vision Perceiving Color Four absorption peaks in retina: 3 cone types plus rods Absorption/Cone response

21. Color Vision Trichromatic Theory of Color Vision “Blue” “Green” “Red” Blue Wavelength InputCone Signal to Brain

22. Color Vision Trichromatic Theory of Color Vision “Blue” “Green” “Red” Green Wavelength InputCone Signal to Brain

23. Color Vision Trichromatic Theory of Color Vision “Blue” “Green” “Red” Red Wavelength InputCone Signal to Brain

24. Color Vision Trichromatic Theory of Color Vision “Blue” “Green” “Red” Yellow Equal Parts Red and Green = Wavelength InputCone Signal to Brain

25. Color Vision Trichromatic Theory of Color Vision “Blue” “Green” “Red” Yellow Equal Parts Red and Green = Wavelength InputCone Signal to Brain

26. Color Vision Trichromatic Theory of Color Vision “Blue” “Green” “Red” Yellow Equal Parts Red and Green = Wavelength InputCone Signal to Brain

27. Color Vision Trichromatic theory of color vision: –brain interprets the relative amounts of signaling from each of these cone types Theories of Color Vision: Trichromatic Theory

28. Color Vision Trichromatic theory of color vision: –brain interprets the relative amounts of signaling from each of these cone types This means that some colors can be matched by a pair of wavelengths –metamers: colors that have no definite single wavelength (e.g. yellow) Theories of Color Vision: Trichromatic Theory

29. Color Vision Trichromatic theory of color vision: –brain interprets the relative amounts of signaling from each of these cone types This means that some colors can be matched by a pair of wavelengths –metamers: colors that have no definite single wavelength (e.g. yellow) This also means that any color can be matched by mixing (not more than) three different wavelengths Theories of Color Vision: Trichromatic Theory

30. What color can only exist as a metamer (an additive mixture of wavelengths)? In other words, what color cannot be made with a single wavelength?

31. Magenta Think about why!

32. Both yellow and blue pigments reflect a bit of green wavelength Amount of reflection blue greenyellowred

33. Subtractive mixing is commonly used in color printers

34. Problem with Trichromatic Theory: Theories of Color Vision: Trichromatic Theory

35. Problem with Trichromatic Theory: YELLOW Theories of Color Vision: Trichromatic Theory

36. Problem with Trichromatic Theory: –most people categorize colors into four primaries: red, yellow, green, and blue –some colors simply cannot be perceived as gradations of each other redish green !? blueish yellow !? –It is as if these colors are opposites Theories of Color Vision: Trichromatic Theory

37. Opponent-Process Theory –color is determined by outputs of two different continuously variable channels: red - green opponent channel blue - yellow opponent channel Theories of Color Vision: Opponent-Process Theory

38. Opponent-Process Theory –Red opposes Green –(Red + Green) opposes Blue Opponent-Process Theory explains color afterimages Theories of Color Vision: Opponent-Process Theory

39. Everything you’ve learned so far is wrong.

40. Well, not really wrong, just far from complete.