1. Sensation and Perception psyc Takashi Yamauchi © Takashi Yamauchi (Dept. of Psychology, Texas A&M University)
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2. Sensation & Perception
Ch. 1: Introduction to perception
Main topics
Perceptual processes
How to study perception
How to measure perception
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3. Sensation & Perception
How is this course different from other psychology courses?
learn sensation & perception
Some very basic form of mind (sensing & perceiving)
Deal with fundamental principles of psychology
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4. Questions: What is perception? Perception is about perceiving.
What is perceiving?
What do we do when we perceive?
We see, smell, hear, feel, taste, …
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5. What tools do we have for perceiving?
Eyes, ears, nose, tongue, skin,
eyes  see,
ears  hear,
nose  smell,
tongue  taste,
skin  feel (temperature)
skin  feel (touch)
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6. What do eyes, a nose, ears, a tongue, and skin do?
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7. What does the eye do? Eye: Seeing, yes but what is seeing?
detecting light
What is light?
electromagnetic energy
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8. What is electromagnetic energy?
Electro + magnetic + energy = electromagnetic energy
Electromagnetic energy is a stream of photons.
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9. What are photons?
They are massless particles each traveling in a wave-like pattern and moving at the speed of light.
The smallest (quantum) unit of light/electromagnetic energy.
It is the carrier of electromagnetic radiation of all wavelengths
such as gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.
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10. So what is “seeing”?
Detecting some form of the movement of photons (electromagnetic radiation).
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11. What does the ear do? Hears sound What is sound? the vibration of air.
What is the vibration of air?
Where do they come from?
Air moves when something else moves
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12. What does the nose do? Nose: Where does smelling come from?
is for smelling
Where does smelling come from?
Smelling is a “sensation caused by odorant molecules dissolved in air.” (wikipedia.org)
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13. Odorant molecules? What are they?
Odorant (aroma compound)
 chemical compound (e.g., H2O; a chemical substance of two or more different chemical elements.)
Where do they come from?
Organic compounds  foods, flowers,
Inorganic compounds  ammonia,…
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14. Taste How do we get that? Where do we get that? From our tongues.
From foods we eat.
From specific chemicals.
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15. What does the skin do? Detect temperature: What is temperature?
It is about how hot or cold something is.
How does something get hot or cold?
Temperature is the result of the motion of particles which make up a substance.
Temperature increases as the energy of this motion increases. (wikipedia)
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16. What does the skin do? feels touching
 It responds to mechanical stimulation or pressure
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17. So, what is perception?
Perception is a system that tells us about an environment.
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18. Eye, ear, nose, tongue & skin
They are sensors.
They are detecting some kind of changes in an environment.
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19. So, studying perception we need to study
How the eye works,
How the ear works,
How the nose works,
How the tongue works, and
How the skin works
Is that all?
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20. What tools do we have for perceiving?
Eyes, ears, nose, tongue, skin,
Eyes  see, ears  hear, nose  smell,
tongue  taste, skin  feel
Are these all?
NO!
 Brain (not Bryan)
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21. The brain is the locus of perception
the study of perception entails the study of the brain and behavior.
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22. A quick demonstration
Tell me what you see.
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25. ch 10

26. ch 10

27. (A)
(B)
(A)
(B)
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28. Visual Illusions Why does this happen?
Tell me what these illusions teach us.
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29. What is perception? Perception involves: Perception is about
Detecting the information in the environment.
Sending the information to the brain, and interpreting it.
Perception is about
Detecting and interpreting
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30. Let’s have some break.
Listen to music
See a painting
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31. Paul Klee: Golden fish
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32. Paul Klee: Ad Parnassum
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33. Anselm Kiefer: Nuremberg
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Anselm Kiefer: Nuremberg

34. Henri Rousseau: The Dream
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35. What’s going on?
Perception is about detecting, but also more than detecting.
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36. What’s going on when we see the pictures?
When we listen to beautiful music, we often see a picture.
When we see a beautiful picture, we hear music. How come?
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37. How come?
Different types of physical information (air vibration, light energy) are translated into a common language in the brain
 neural information
Environmental Stimuli (e.g., light energy)
Transduction
Neural Processing
Perception
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40. Key points:
Perception is about finding out what is going on in an environment.
Perceptual organs (eyes, ears, nose, skin, a tongue) are basically detectors (sensors)
Perception requires transforming physical information (e.g., light) into neural information.
Perception also involves “interpretation,” which is carried out by the brain.
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41. Studying perception How perceptual detectors work.
How physical information is transformed (e.g., light) into neural information.
How neural information is processed in the brain.
How neural information is interpreted and triggers a specific form of perception.
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42. How come?
Different types of physical information (air vibration, light energy) are transformed into a common neural language in the brain
 neural information
Environmental Stimuli (e.g., light energy)
Transduction
Neural Processing
Perception
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43. Demonstration (attention & perception)
An interaction between
attention and perception
cognition and perception
Tell me what you see.
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44. Tired
Old
Sick
Dark
Slow
Heavy
Hospital
ugly
death
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46. Beautiful
Young
Fresh
Fast
Energy
Juicy
Clean
cheerful
Vigorous

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49. Demonstration (knowledge and perception)
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55. What did you see?
What does this tell?
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56. Perceptual process Perception is the end result of complex processes.
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57. Why study perception?
If the doors of perception were to be cleaned, man would see everything as it truly is…..Infinite.
William Blake
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58. How to approach the study of perception
Levels of analysis
Psychophysical level of analysis
Physiological level of analysis
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59. Measuring Perception Psychophysical level of analysis Description
Phenomenological method
E.g., Let a person describe what they see
Recognition
Detection
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60. Detection Absolute threshold
is the smallest amount of stimulus energy necessary to detect a stimulus.
E.g., eye exam
Difference threshold
is the smallest difference between two stimuli that a person can detect.
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62. Demonstration
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67. Demonstration: Measuring weight
DL (difference threshold) gets larger as the standard stimulus gets larger.
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69. Demonstration
Color, line, length
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70. The impact of standard stimuli
DL (difference threshold) gets larger as the standard stimulus gets larger.
Weber’s law
DL/S=K
DL: difference threshold
S: standard stimulus
K: constant
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71. Weber’s law
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72. Question:
With a standard stimulus 1 kg, John’s difference threshold was 0.25kg. With a standard stimulus 10kg, what would be John’s difference threshold?
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73. Question:
With a standard stimulus 1 kg, John’s difference threshold was 0.25kg. With a standard stimulus 10kg, what would be John’s difference threshold?
DL/S=K
DL: 0.25
S: 1
K: 0.25
DL/S=K
DL: ?
S: 10 K:
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74. Magnitude estimation Assign a value to a standard stimulus
The subject estimates the value of a target stimulus.
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75. Magnitude estimation Standard: == 10 Target: == ? Standard: == 100
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76. Standard: == 100
Target: == ?
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77. Standard: == 100
Target: == ?
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78. Steven’s power law
S is the physical magnitude of a target that you are estimating.
P is your estimation
K is some value (constant)
n is some value
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79. Magnitude estimation
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81. Steven’s power law
S is the physical magnitude of a target that you are estimating.
P is your estimation
K is some value (constant)
n is some value
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82. Experiment (you are estimating the length of lines)
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83. Target = ?
Standard = 100
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84. K: some value (constant) = 21.5 P = S raised to the n-th power
P: your estimation
S: stimulus intensity
n: some value =0.33
K: some value (constant) = 21.5
P = S raised to the n-th power
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85. Experiment (you are estimating the intensity of electric shock)
Standard = 100
Target = ?
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86. K: some value (constant) = 0.1
P: your estimation
S: stimulus intensity
n: some value =1.5
K: some value (constant) = 0.1
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87. Estimating electric shock
Estimating the length of lines
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88. Steven’s power law
S is the physical magnitude of a target that you are estimating.
P is your estimation
K is some value (constant)
n is some value
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89. Threshold
Absolute threshold
Difference threshold
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90. Difference threshold
Weber’s law
Stevens’s law
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