1. Vision

2. Our eyes receive light energy and __________ it into neural messages that our brain processes into what we consciously see.
transduces

3. Light Energy
When we look at things, we actually see the light reflected off of them.
Visible light is a thin slice of the whole spectrum of electromagnetic energy.

4. Light and sound use similar descriptive language because both have properties of waves:
● wavelength ● amplitude
(hue or color) (intensity)

5. The Structure of the Eye

6. The Structure of the Eye
Cornea = outer covering of the eye.

7. The Structure of the Eye
Pupil = the adjustable opening in the center of the eye through which light enters.

8. The Structure of the Eye
Iris = a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening.
The iris dilates/constricts in response to changing light intensity

9. The Structure of the Eye
Lens = the transparent structure behind the pupil that changes shape to help focus images on the retina.

10. The Structure of the Eye
Retina = the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

11. The Structure of the Eye
Blind Spot = the point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there.

12. The Structure of the Eye
Fovea = the central focal point in the retina, around which the eye’s cones cluster.

13. The Structure of the Eye
Let’s take a closer look at the Retina!!
Optic Nerve = the nerve that carries neural impulses from the eye to the brain.

14. The Retina’s Receptor Cells
Rods
Detect black, white, and gray; necessary for peripheral and twilight vision.
Cones
Concentrated near the center of the retina and function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.

15. The Retina’s Receptor Cells
Rods
Cones

16. The Retina’s Receptor Cells

17. The Retina’s Reaction to Light

18. Eyes are important organs in your sight process, but you see as much with your _____ as you do your eyes!
brain

20. Visual Information Processing
Feature Detector Cells
Specialized neurons in the brain that respond to specific features, such as shape, angle, or movement.
Get their name from the ability to respond to specific features
Pass information to teams of cells (supercell clusters) that respond to specific features.

22. fMRI scans show different activation areas.
Research indicates we have a “vast visual encyclopedia” of specialized cells that respond to one type of stimulus.

23. Visual Information Processing
Parallel Processing: the brain divides stimuli into subdivisions
Motion
Form
Depth
Color
The brain processes these in separate cortex areas, then our perceptions are formed by them being integrated together.

24. Movement Video

25. Parallel Processing: the brain divides stimuli into subdivisions

26. Parallel Processing: the brain divides stimuli into subdivisions

27. Parallel Processing: the brain divides stimuli into subdivisions

28. Parallel Processing: the brain divides stimuli into subdivisions

29. Parallel Processing: the brain divides stimuli into subdivisions

30. A simplified summary of visual information processing
Retinal Processing:
Receptor rods and cones: transduction
Feature Detection:
Brain’s detector cells respond to specific features – edges, lines, angles
Scene
Parallel Processing:
Brain cell teams process combined information about motion, form, depth, color
Recognition:
Brain interprets the constructed image based on information from stored images

31. Assignment:
Complete the Eye handout
It is due Monday and there will be a quiz over its parts then.
P. 82 in Blue Psy-1 book
P in Green AP Psy book

32. Vision Perception

33. A true “optical” illusion

34. Subjective Contours
Source: Gaetano Kanizsa

35. R. C. James Photograph

37. Necker Cube

38. Necker Cube

39. Necker Cube

40. Necker Cube

41. Subjective Necker Cube

42. Hermann Grid

43. The Scintillation Grid: Bernd Lingelbach

46. Color Vision

47. Color Vision Young-Helmholtz Trichromatic theory
Theory that the retina has three different color receptors: red, green, and blue.

52. Color-Deficient People
Most are not truly “colorblind”
Lack functioning in red or green sensitive cones (sometimes both)
Their vision is monochromatic or dichromatic instead of trichromatic.

53. This is how fall foliage looks to a colorblind person.
This is how fall foliage looks to everyone else.

54. Red/Green Color blindness

56. Color-Deficient People
Here is a video of a guy seeing color for the first time in his life with the assistance of EnChroma glasses.

57. Color Vision Why can people who are blind to red and green see yellow?
Opponent-Process theory
Theory that vision has four primary colors arranged in pairs: red and green, blue and yellow, (black & white)
If one in the pair is stimulated, the other cannot be working.

58. Stare at the white dot for 30 seconds

60. Which theory is correct?
Probably both are correct.
Two-stage color processing
RGB cones respond to different stimuli
These signals then processed by the nervous system’s opponent-process cells.