Exam next week

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

6. Autostereograms

7. Autostereograms

8. COLOR VISION

9. Color is an illusion • 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 Wavelength and Color • Different wavelengths correspond roughly to the “colors” of the spectrum

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

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

16. Color Vision Perceiving Color • Primary colors RedGreenBlue

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

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

19. Color Vision Perceiving Color • 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

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 Signal to Brain Wavelength Input Cone “Blue” Blue “Green” “Red”

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

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

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

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

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

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

28. Color Vision Theories of Color Vision: Trichromatic Theory • 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)

29. Color Vision Theories of Color Vision: Trichromatic Theory • 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

30. Color Mixing • 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. Color Mixing • 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? Magenta Think about why!

32. Color Mixing • Both yellow and blue pigments reflect a bit of green Amount of reflection green yellow red blue wavelength

33. Color Mixing • Subtractive mixing is commonly used in color printers

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

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

36. Theories of Color Vision: Trichromatic Theory • 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

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

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

39. Color is an illusion • Everything you’ve learned so far is wrong.

40. Color is an illusion • Everything you’ve learned so far is wrong. • Well, not really wrong, just far from complete.