1. Sensation and Perception

2. “Sensation” “Perception”
The noticeable activity in a sense organ, usually caused by a stimulus.
(“I hear a sound”)
“Perception”
The organization and meaning of sensations.
(“I hear the professor’s voice”)

3. Perception is not always accurate….
1) Lots out there you don’t perceive

4. OK, but that’s just static pictures that are artificially flickering
OK, but that’s just static pictures that are artificially flickering. Not exactly realistic.

6. The change does not need an interruption:

7. Perception is not always accurate….
1) Lots out there you don’t perceive
2) Some things not out there are perceived anyway
-phantom limbs
-hallucinations

8. 2) Some things not out there are perceived anyway

9. Sensation ≠ Perception ≠ Reality
1) Lots out there you don’t perceive
2) Some things not out there are perceived
3) One set of sensations can give rise to > 1 perception

10. Sensation ≠ Perception ≠ Reality
1) Lots out there you don’t perceive
2) Some things not out there are perceived
3) One set of sensations can give rise to > 1 perception

11. Sensation ≠ Perception ≠ Reality
1) Lots out there you don’t perceive
2) Some things not out there are perceived
3) One set of sensations can give rise to > 1 perception
4) Perception is often different from what you’d predict based on the sensations

13. Because perception is a constructive process
Why does this happen?
Because perception is a constructive process

17. Perception is a constructive process
…based on rules…

18. Gestalt Psychology
X X X
Proximity
X O X O
Similarity
Good Continuation

19. -but first, a few factoids about light
The Visual System
-but first, a few factoids about light
Light is a wave.
No, wait….light is a particle….

20. -but first, a few factoids about light
The Visual System
-but first, a few factoids about light
-light behaves as both a wave and a particle
-light usually travels in a straight line
…unless…
a) It passes close to a large gravitational field
b) It passes through a medium of a different density relative to that it is currently in

21. Physiology of the eyeball
Presbyopia
Proximal stimulus
Aqueous Humour
Vitreous Humour
Distal stimulus

22. Pigment epithelium

24. Distinctions: Cones Rods ~ 6 million/eye ~120 million / eye
-mostly in fovea
-mostly in periphery
-wavelength-sensitive
-insensitive to wavelength
-insensitive to light intensity
-very sensitive to light intensity
-high acuity
-low acuity
-mostly a one-to-one relationship to ganglions (6:1)
-many-to-one relationship to ganglions (120:1)
OK, that’s enough physiology. What about perception?

25. Colour Perception Physical Psychological “Intensity” “Brightness”
“Wavelength” “Colour” or “Hue”

26. Newton’s colour studies
Colour Perception
Newton’s colour studies

27. Colour-perception phenomena requiring an explanation:

28. Colour-perception phenomena requiring an explanation:
1) Complementary colours
A version of Newton’s Colour wheel
Generally speaking, Red-green and blue-yellow are the two basic complements

29. Subtractive mixing

30. Subtractive mixing

31. Subtractive mixing

32. Subtractive mixing

33. Colour-perception phenomena requiring an explanation:
1) Complementary colours
2) Negative Afterimages
3) Colourblindness x

34. Theories of Colour Vision
Colour-perception phenomena requiring an explanation:
1) Complementary colours
2) Negative Afterimages
3) Colourblindness
(Young/Helmholtz, circa 1800)

35. Theories of Colour Vision
Colour-perception phenomena requiring an explanation:
1) Complementary colours
2) Negative Afterimages
3) Colourblindness
(Hering/Hurvich, circa 1860)

36. Early evidence: three cone types!
Subsequent work: opponent-process cells in visual pathway (starting with ganglions in the retina)

37. Anomalous Colour Illusions

39. McCullough Effect

49. Depth perception Pictorial Cues II. Pictorial Cues -overlap
I. Oculomotor Cues
-accomodation
-convergence
Pictorial Cues
II. Pictorial Cues
-overlap
-relative size
-relative height
-linear perspective
-atmospheric perspective
-texture gradient

50. Size illusions based on perceived distance

51. Size illusions based on perceived distance

52. Size illusions based on perceived distance
Ponzo Illusion

53. Size illusions based on perceived distance
Muller-Lyer Illusion

54. The Moon Illusion

56. The Moon Illusion

58. Hearing

59. Hearing