1. 4. Perception

2. Lesson 1
Empiricism
Common-sense realism
Perceptual illusions

3. Perception
“awareness of things through our 5 senses”

4. Choose a sense to lose!
In groups they discuss which sense they would choose to lose if they had to lose one. They need to justify their choice (remembering this is all about knowledge – which sense do we get least knowledge of the world from (and why?)

5. Choose a sense to lose! Which sense did you choose? Why?
Which sense is most identified with knowledge? Why?
Most will probably choose to lose smell. In what way is smell important or unimportant? Taste is very smell dependent! Perhaps could do a taste test with noses pegged!

6. Empiricism
All knowledge is ultimately based on perceptual experience

7. The subjects you study?
Can you list the role perception plays in your different IB subjects? Are there any areas of knowledge where perception plays NO role?
In groups students discuss the question. Perhaps introduce the idea that senses are extended in Science with apparatus.

8. Common-sense realism
Perception is passive and gives us an accurate picture of reality
Do you think our senses give us an accurate picture of how the world really is?
There follow examples of how our senses can trick us.

9. Green spots appear!

10. The Following slide removes the background
The Following slide removes the background. Flip between slides to show the squares are actually the same colour.

13.
Show the clip – very clever!

14. Perception is a complex process
Sensation and interpretation
Perception depends very much on how we interpret what our senses show us.

15. Interpretation: Context
The context tells us that the man is not actually holding the sun!

16. Interpretation: Expectations
We expect it to make sense so do not notice the extra “the”

17. Interpretation: Expectations
The following four slides will be shown very quickly. Try to remember what the four cards are.
The six of spades is shown as red. Because we don’t expect that most will see it as the six of hearts or diamonds.

22. Can you name them?

23. Can you name them?

24. Illusions from other senses?
Can you think of any illusions from our other senses?
Any aural illusions? (Throwing voice, echoes). Taste? (water always tastes sweet after you’ve been sick etc.) others?

25. Perceptual illusions
Pass the two blocks around. Which one is colder? Put ice cubes on the blocks and watch
I’ll show you how to do this. One block “feels” cold even though they are at the same temperature. When you put the ice on one will melt unexpectedly fast. Hopefully there is a Physicist in the room who can explain why! Our hands are awful thermometers.

26. Perceptual illusions
How did your sense of touch score?!

27. Lesson 2 Selectivity of perception Seeing and believing
Distinguishing appearance from reality

28. Selectivity of perception
Discuss in groups how the following picture would be interpreted through the eyes of a religious figure, a physicist, a painter or a farmer?

29. Monk sees God creation etc
Monk sees God creation etc. Physicist sees blue light scattered by the atmosphere to form the blue sky. Because this light is removed the sun looks redder. Artist sees the graduation of colour in the sky etc. Farmer can tell the weather (red sky at night etc.)

30. Selectivity of perception
Discuss in groups how the following picture would be interpreted through the eyes of a biologist, logger, environmentalist, a native American?

31. Biologist thinks of variety of species in the jungle and reason why etc. Naturalist see endangered rain forest. Logger sees trees/money. American indian sees an interrelated habitat etc.

32. Selectivity of perception - emotion
There’s someone for everyone.
Beauty is in the eye of the beholder? DISCUSS

33. Seeing the world clearly?
In what emotional state do we see the world clearest? Why?
In groups they discuss if emotions can cloud our jedgement etc. Why? Shouldn’t we have evolved to see clearest when frightened?!

34. Selectivity of perception - education
What do you see? What would a doctor see?
Doctor sees sickle cell anameia

35. Selectivity of perception - education
What do you see? What would a musician see?
Musician sees very unusual key signature and different key in the two piano parts (very unusual)

36. Selectivity of perception - education
What do you see? What would a dentist see?
This is an absecsed tooth

37. Selectivity of perception - education
What do you taste? What would a wine expert taste?

38. Seeing/believing
In the 19th century scientists believed there is a planet between Mercury and the sun. Some believed it so much they said they had seen it in their telescopes. No such planet exists.
Example of seeing what you believe to be there

39. Seeing/believing
Perception of this event very different between British Army view and Republican’s view.

40. Seeing/believing
UFOs?!

41. Seeing/believing
Jesus?

42. Seeing/believing
YouTube - Godless Comedy from That Mitchell and Webb Look
Very funny clip. I love this.

43. Eye witnesses
YouTube - Impossible eye witness funny sketch - A Bit of Stephen Fry & Hugh Laurie – BBC
YouTube - The Eyewitness Test: How do you stack up?
The you tube has an exercise they can do to see how good eye witnesses they are.

44. Distinguishing appearance from reality
How can we trust our senses?

45. Confirmation by another sense
It looks like poo, it smells like poo. I’ll taste it just to make sure.
Confirmation by another sense
If confirmed by another sense we can be surer.

46. Coherence
We know pigs don’t normally fly.

47. Independent testimony
More than one person saw it.

48. Lesson 3 Extension of the senses Ultimate reality
What is really out there?
Theories of reality
What should we believe?

49. Extension of the senses
Science has extended our sense

50. Electromagnetic spectrum
λ ≈ nm
Visible light is a very small part of the electromagnetic spectrum. Some snakes can “see” infrared which we can’t. Much of what we know about the Universe we know from radio, x rays etc which we cannot detect without Scientific instruments. How would the world “look” if we could see these types of light?
λ ≈ m
λ ≈ m
λ ≈ m
λ ≈ m
λ ≈ m
λ ≈ m

51. Radio telescope – sees much that does not give out visible light.

52. Ultrasound
How is a bat’s perception of what the world looks like different to ours?

53. What is really out there?
The big question.

54. What is really out there?
Does the “sweetness” exist in the coke or only in your mouth?

55. What is really out there?
Where is the green in the grass? In the grass or in your eye (or brain?)
If we had evolved differently, sensitive to electromagnetic radiation of different frequencies we would not see grass as green at all…….in conclusion the world really has no colour at all!
A difficult one this. The experience of “green” takes place in our brain.

56. What really is out there?
If a tree falls in a forest, and nobody is there is hear it, does it make a sound?
Similarlt, “sound” is experienced in our heads.

57. Two types of sound? Physical – vibrations in the air
Experienced – the sound we hear/experience in our brains
The resolution to the problem?

58. No experienced sound before life on earth?
No human’s to hear it, so the early earth was silent?

59. A rose with no colour?
If no one sees it, it’s not red?

60. Does anything exist independent of our experience?
Discuss?

61. I think we need to show them the Matrix too!

62. Theories of reality

63. Common-sense realism
The way we perceive the world mirrors the way the world is
Can you outline the main arguments against common sense realism?
Important for them to answer the question.

64. Scientific realism
The world exists as an independent reality, but very different from how we perceive it.
The table is actually mainly made of nothing! ( % of an atom is “nothing”). What we experience as “hard” is just the electrostatic repulsion between the electrons in our hand and the electrons in the table. It appears solid due to the interaction between photons of light and the electrons in the outer orbits of the atoms on the outside of the table.

65. The world does not exist independent of our experience of it
Phenomenalism
This comes from empiricism. We cannot say there are tables in a room, only that if we go into a room we will have various table experiences!
The world does not exist independent of our experience of it

66. The world does not exist independent of our experience of it
Phenomenalism
If you believed in phenomenalism, what difference would it make to your practical life?
The world does not exist independent of our experience of it

67. Are you bothered?
Does it bother you that we can’t know anything about what the Universe is like independent of our existence of it?

68. Quotation walk
Around the lower school corridors are posted various quotations about perception. Choose one as a starting point for your next TOK essay. Explain what the quotation means, link it to at least two IB subjects you are studying, and link it to at least two experiences from your own life. Due ………………
Copy the quatations about perception from the front of the chapter. Put them up around school. Set date for essay.