Unit 4. Sensation and Perception College Board -  “Acorn Book”  Course Description 6-8% (7-9% in past) Unit IV. Sensation ...
 
 
Overview <ul><li>A. Thresholds </li></ul><ul><li>B. Sensory Mechanisms </li></ul><ul><li>C. Attention </li></ul><ul><li>D....
Unit IV. Sensation and Perception
A. Thresholds <ul><li>Threshold </li></ul><ul><li>Absolute threshold </li></ul><ul><li>Just-noticeable-difference (jnd) </...
Signal Detection Theory Chart Unit IV. Sensation and Perception Response  Yes Response No Signal  Present Signal Absent
Signal Detection Theory   Correctly identifies stimulus present Unit IV. Sensation and Perception Response  Yes Response N...
Signal Detection Theory   Fails to identify stimulus present Unit IV. Sensation and Perception Response  Yes Response No S...
Signal Detection Theory   Incorrectly identifies stimulus as present when absent Unit IV. Sensation and Perception Respons...
Signal Detection Theory   Correctly identifies stimulus as absent Unit IV. Sensation and Perception Response Yes Response ...
B. Sensory Mechanisms <ul><li>Vision </li></ul><ul><li>The Stimulus – Light  </li></ul><ul><ul><li>Amplitude, wavelength, ...
Figure 6.7  The eye Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
Figure 6.8  The retina ’s reaction to light Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
Table 6.1 Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
Color -  Color -  Color <ul><li>Chromatic vs. achromatic (Colors vs. black & white) </li></ul><ul><li>Hue, brightness, sat...
Additive <ul><li>New colors are made by the combination of different colored lights </li></ul><ul><li>The three colors use...
Source: http://en.wikipedia.org/wiki/Color_mixing <ul><li>A simulated example of additive color mixing </li></ul>Unit IV. ...
Subtractive <ul><li>New colors can be made when paints, inks, markers, and other coloring media are combined </li></ul><ul...
Source: http://en.wikipedia.org/wiki/Color_mixing <ul><li>A simulated example of subtractive color mixing </li></ul>Unit I...
http://home.att.net/~RTRUSCIO/COLORSYS.htm <ul><li>The above site provides an informative explanation and description of c...
Color Vision <ul><li>Trichromatic theory –  </li></ul><ul><li>Young-Helmholtz (three color receptors – different wavelengt...
Color Vision: From Weiten.  Themes and Variations . 4 th  ed. Brooks/Cole. 1998 Unit IV. Sensation and Perception
Colors of the Rainbow <ul><li>R  O   Y   G   B   I  V </li></ul><ul><li>Color is determined by wave length </li></ul><ul><...
Hearing <ul><li>The Stimulus – Sound waves </li></ul><ul><ul><li>Amplitude (Loudness), Wavelength or frequency (Pitch), Wa...
The Ear  From Coren, Ward, & Enns.  Sensation and Perception  6 th  ed. John Wiley & Sons, Inc. 2004 <ul><li>Outer Ear </l...
The Inner Ear   From Coren, Ward, & Enns  Sensation and Perception  6 th  ed. John Wiley & Sons, Inc. 2004 Unit IV. Sensat...
Figure 6.16  Hear here: How we transform sound waves into nerve impulses that our brain interprets Myers: Psychology, Nint...
Taste and Smell <ul><li>Taste (Gustatory Sense) </li></ul><ul><ul><li>Stimulus – Chemicals </li></ul></ul><ul><ul><li>Four...
Skin Senses <ul><li>Pressure </li></ul><ul><li>Hot </li></ul><ul><li>Cold </li></ul><ul><li>Pain  </li></ul><ul><ul><li>Ga...
See Reading: WHAT IS PAIN? <ul><li>Messages about tissue damage are picked up by nociceptors and transmitted to the spinal...
Unit IV. Sensation and Perception
<ul><li>This descending pathway sends messages to the spinal cord where it suppresses the transmission of tissue-damage si...
Unit IV. Sensation and Perception
HOW PAIN KILLERS WORK. <ul><li>At the site of injury, the body produces prostaglandins which increase pain sensitivity. </...
Unit IV. Sensation and Perception
Internal Senses <ul><li>Kinesthesis </li></ul><ul><ul><li>Internal body position </li></ul></ul><ul><ul><li>Muscle positio...
C. Sensory Adaptation <ul><li>Sensory adaptation is a change in sensitivity to a stimulus that results from exposure to th...
Sensory Adaptation <ul><li>Light and Dark Adaptation </li></ul><ul><ul><li>Entering / Exiting a movie theatre </li></ul></...
Dark Adaptation <ul><li>Move into a darkened theater and two changes occur to increase sensitivity to light: </li></ul><ul...
Light Adaptation <ul><li>Leaving the theater, you encounter bright light </li></ul><ul><ul><li>Your pupils constrict immed...
Preserving Dark Adaptation <ul><li>It takes 20-30 minutes to become fully dark adapted </li></ul><ul><li>This is destroyed...
Sound Adaptation <ul><li>Adaptation to loud noise </li></ul><ul><li>Very loud sound </li></ul><ul><ul><li>small muscle in ...
Odor / Smell <ul><li>The sense of smell is probably the quickest sense - as a whole - to adapt </li></ul><ul><li>We can de...
Taste <ul><li>Certain tastes may cause rather surprising (and unexpected) anomalies in other taste stimuli </li></ul><ul><...
Touch – Heat – Cold <ul><li>Skin temperature receptors respond more to rate of change in temperature than to steady temper...
Pain Adaptation <ul><li>Acute pain – tells us to get away from the painful stimulus </li></ul><ul><li>Chronic pain – tells...
 
C. Attention <ul><li>Selective Attention </li></ul><ul><li>Bottleneck Theories of Selective Attention </li></ul><ul><ul><l...
Selective Attention and the Cocktail Party Phenomenon  <ul><li>Cocktail Party Phenomenon  </li></ul><ul><ul><li>the abilit...
Selective Attention and the Stroop Test <ul><li>Stroop Test </li></ul><ul><ul><li>Why is this task so difficult to do </li...
Bottleneck or Filter Models of Selective Attention <ul><li>Early selection </li></ul><ul><li>David Broadbent (1958) propos...
D. Perceptual Processes <ul><li>Feature analysis </li></ul><ul><li>Bottom-up processing </li></ul><ul><li>Top-down process...
Is it a circus act? <ul><li>Or a couple dancing? </li></ul><ul><li>Ambiguous or Reversible figure </li></ul><ul><li>Featur...
Bottom-up Processing <ul><li>A progression from </li></ul><ul><ul><li>Individual elements to the whole </li></ul></ul><ul>...
Bottom-Up Processing <ul><li>Perception must be largely data-driven because it must accurately reflect events in the outsi...
Top-Down Processing <ul><li>A progression from </li></ul><ul><ul><li>The whole to the elements </li></ul></ul><ul><li>Also...
Top-Down Processing <ul><li>In many situations your knowledge or expectations (or schemas) will influence your perception ...
<ul><li>Abstract concepts tend to be referred to as higher level </li></ul><ul><li>Concrete details are referred to as low...
<ul><li>Visual Contrast </li></ul><ul><li>Brightness contrast (gray on white appears darker than gray on black) </li></ul>...
Brightness Contrast Unit IV. Sensation and Perception
Principles of Perceptual Organization: <ul><li>Figure-Ground </li></ul><ul><li>Grouping (Gestalt Principles) </li></ul><ul...
Closure Unit IV. Sensation and Perception
<ul><li>Perception of Depth and Distance </li></ul><ul><li>Perception of Motion </li></ul><ul><li>Perceptual Constancy (Si...
Depth Perception <ul><li>“ I could have sworn that mesa was a whole lot farther away” </li></ul>
Unit IV. Sensation and Perception
Necker cube (1) Unit IV. Sensation and Perception
Necker cube (2) Unit IV. Sensation and Perception
Necker cube (3) Unit IV. Sensation and Perception
Necker cube (4) Unit IV. Sensation and Perception
Necker cube (5) Unit IV. Sensation and Perception
Handouts <ul><li>DISTRIBUTION OF RODS AND CONES – Bernstein (Colored pencils) </li></ul><ul><li>Light-Dark Sensory Adaptat...
<ul><li>Monocular Depth Perception Student Assignment </li></ul><ul><li>Chart - Depth Perception Cues (Study Guide / May b...
<ul><li>Moon Illusion (Reading from Bad Astronomy by Philip Plait) </li></ul><ul><li>The Big Picture - Gestalt applied  </...
The Janus Mask
Example of the Ames Room Unit IV. Sensation and Perception
The Magic of the Wundt-Jastrow Illusion
From: Gregory, R. I., Eye and Brain (2 nd  ed.) New York: World University Library, 1973. (pp. 78-80.)
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Sensation outline

  1. 1. Unit 4. Sensation and Perception College Board - “Acorn Book” Course Description 6-8% (7-9% in past) Unit IV. Sensation and Perception
  2. 4. Overview <ul><li>A. Thresholds </li></ul><ul><li>B. Sensory Mechanisms </li></ul><ul><li>C. Attention </li></ul><ul><li>D. Perceptual Processes </li></ul>Unit IV. Sensation and Perception
  3. 5. Unit IV. Sensation and Perception
  4. 6. A. Thresholds <ul><li>Threshold </li></ul><ul><li>Absolute threshold </li></ul><ul><li>Just-noticeable-difference (jnd) </li></ul><ul><li>Weber ’s Law </li></ul><ul><li>Fechner ’s Law (Psychophysical scaling) </li></ul><ul><li>Subliminal perception </li></ul>Unit IV. Sensation and Perception
  5. 7. Signal Detection Theory Chart Unit IV. Sensation and Perception Response Yes Response No Signal Present Signal Absent
  6. 8. Signal Detection Theory Correctly identifies stimulus present Unit IV. Sensation and Perception Response Yes Response No Signal Present HIT Signal Absent
  7. 9. Signal Detection Theory Fails to identify stimulus present Unit IV. Sensation and Perception Response Yes Response No Signal Present Hit MISS Signal Absent
  8. 10. Signal Detection Theory Incorrectly identifies stimulus as present when absent Unit IV. Sensation and Perception Response Yes Response No Signal Present Hit Miss Signal Absent FALSE ALARM
  9. 11. Signal Detection Theory Correctly identifies stimulus as absent Unit IV. Sensation and Perception Response Yes Response No Signal Present Hit Miss Signal Absent False Alarm Correct Negative
  10. 12. B. Sensory Mechanisms <ul><li>Vision </li></ul><ul><li>The Stimulus – Light </li></ul><ul><ul><li>Amplitude, wavelength, purity, saturation </li></ul></ul><ul><li>Structure of the Eye </li></ul><ul><ul><li>Lens, retina, rods & cones, fovea </li></ul></ul><ul><ul><li>Bipolar cells and ganglion cells </li></ul></ul><ul><ul><li>Optic nerve and blind spot </li></ul></ul>Unit IV. Sensation and Perception
  11. 13. Figure 6.7 The eye Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
  12. 14. Figure 6.8 The retina ’s reaction to light Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
  13. 15. Table 6.1 Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
  14. 16. Color - Color - Color <ul><li>Chromatic vs. achromatic (Colors vs. black & white) </li></ul><ul><li>Hue, brightness, saturation (Color, light-dark, purity of color) </li></ul><ul><li>Subtractive mixture vs. additive mixture (filters vs. paints) </li></ul><ul><li>Good Web Site on Color Mixing </li></ul><ul><ul><li>http:// home.att.net /~RTRUSCIO/COLORSYS.htm </li></ul></ul>Unit IV. Sensation and Perception
  15. 17. Additive <ul><li>New colors are made by the combination of different colored lights </li></ul><ul><li>The three colors used are Red, Green, and Blue </li></ul><ul><li>This is used for television screens, video, and computer monitors </li></ul>Unit IV. Sensation and Perception
  16. 18. Source: http://en.wikipedia.org/wiki/Color_mixing <ul><li>A simulated example of additive color mixing </li></ul>Unit IV. Sensation and Perception
  17. 19. Subtractive <ul><li>New colors can be made when paints, inks, markers, and other coloring media are combined </li></ul><ul><li>The three colors used are Magenta, Yellow, and Cyan </li></ul><ul><li>This is used in color printers </li></ul>Unit IV. Sensation and Perception
  18. 20. Source: http://en.wikipedia.org/wiki/Color_mixing <ul><li>A simulated example of subtractive color mixing </li></ul>Unit IV. Sensation and Perception
  19. 21. http://home.att.net/~RTRUSCIO/COLORSYS.htm <ul><li>The above site provides an informative explanation and description of color mixing </li></ul><ul><ul><li>Color Vision </li></ul></ul><ul><ul><li>Mixing Light </li></ul></ul><ul><ul><li>Mixing Dyes – Paints – Ink </li></ul></ul><ul><ul><li>The Basic Three - The physics and biology of color mixing </li></ul></ul><ul><ul><li>Painting </li></ul></ul><ul><ul><li>Photography </li></ul></ul><ul><ul><li>Printing </li></ul></ul><ul><ul><li>Other Considerations </li></ul></ul>Unit IV. Sensation and Perception
  20. 22. Color Vision <ul><li>Trichromatic theory – </li></ul><ul><li>Young-Helmholtz (three color receptors – different wavelengths) </li></ul><ul><ul><li>Color blindness (dichromats, etc.) </li></ul></ul><ul><ul><li>Processing at receptor level </li></ul></ul><ul><li>Opponent-process theory – </li></ul><ul><li>Hering, Jameson, Hurvich (three pairs of color-sensitive neurons) </li></ul><ul><ul><li>Negative afterimage </li></ul></ul><ul><ul><li>Processing at receptive field level (thalamus) </li></ul></ul>Unit IV. Sensation and Perception
  21. 23. Color Vision: From Weiten. Themes and Variations . 4 th ed. Brooks/Cole. 1998 Unit IV. Sensation and Perception
  22. 24. Colors of the Rainbow <ul><li>R O Y G B I V </li></ul><ul><li>Color is determined by wave length </li></ul><ul><li>Red is the longest wavelength of visible light. Violet is the shortest </li></ul><ul><li>Water (mist) refracts light into different wavelengths </li></ul>Unit IV. Sensation and Perception
  23. 25. Hearing <ul><li>The Stimulus – Sound waves </li></ul><ul><ul><li>Amplitude (Loudness), Wavelength or frequency (Pitch), Wave purity or mixture (Timbre)) </li></ul></ul><ul><li>Structure of the Ear </li></ul><ul><ul><li>Outer ear – Auditory canal </li></ul></ul><ul><ul><li>Middle ear – Eardrum, Hammer, Anvil, Stirrup </li></ul></ul><ul><ul><li>Inner ear – Cochlea, Basilar Membrane </li></ul></ul>Unit IV. Sensation and Perception
  24. 26. The Ear From Coren, Ward, & Enns. Sensation and Perception 6 th ed. John Wiley & Sons, Inc. 2004 <ul><li>Outer Ear </li></ul><ul><li>Auditory Canal </li></ul><ul><li>Eardrum </li></ul><ul><li>Middle Ear </li></ul><ul><li>Hammer, anvil, stirrup </li></ul><ul><li>Inner Ear </li></ul><ul><li>Cochlea </li></ul>Unit IV. Sensation and Perception
  25. 27. The Inner Ear From Coren, Ward, & Enns Sensation and Perception 6 th ed. John Wiley & Sons, Inc. 2004 Unit IV. Sensation and Perception
  26. 28. Figure 6.16 Hear here: How we transform sound waves into nerve impulses that our brain interprets Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
  27. 29. Taste and Smell <ul><li>Taste (Gustatory Sense) </li></ul><ul><ul><li>Stimulus – Chemicals </li></ul></ul><ul><ul><li>Four taste receptors </li></ul></ul><ul><li>Smell (Olfactory Sense) </li></ul><ul><ul><li>Stimulus – Chemicals </li></ul></ul><ul><ul><li>Olfactory bulbs, olfactory cilia </li></ul></ul><ul><ul><li>Pheromones </li></ul></ul><ul><ul><li>Taste and Smell </li></ul></ul><ul><li>Demonstrations </li></ul><ul><li>Raw Apple, Raw Potato, Raw Onion </li></ul><ul><li>Jelly Bellies </li></ul>Unit IV. Sensation and Perception
  28. 30. Skin Senses <ul><li>Pressure </li></ul><ul><li>Hot </li></ul><ul><li>Cold </li></ul><ul><li>Pain </li></ul><ul><ul><li>Gate control theory in pain perception </li></ul></ul>Unit IV. Sensation and Perception
  29. 31. See Reading: WHAT IS PAIN? <ul><li>Messages about tissue damage are picked up by nociceptors and transmitted to the spinal cord via small myelinated fibers and very small un-myelinated fibers. </li></ul><ul><li>From the spinal cord, the impulses are carried to the brainstem, thalamus and cerebral cortex, and ultimately perceived as pain. </li></ul><ul><li>These messages are suppressed by a system of neurons that originate in the gray matter of the midbrain. </li></ul>Unit IV. Sensation and Perception
  30. 32. Unit IV. Sensation and Perception
  31. 33. <ul><li>This descending pathway sends messages to the spinal cord where it suppresses the transmission of tissue-damage signals to the higher brain centers. </li></ul><ul><li>Some of these descending pathways utilize naturally-occurring chemicals called opioids. </li></ul>Unit IV. Sensation and Perception
  32. 34. Unit IV. Sensation and Perception
  33. 35. HOW PAIN KILLERS WORK. <ul><li>At the site of injury, the body produces prostaglandins which increase pain sensitivity. </li></ul><ul><li>Some analgesics, such as aspirin, prevent the production of prostaglandins. </li></ul><ul><li>Acetaminophen is believed to block pain impulses in the brain itself. </li></ul><ul><li>Local anesthetics intercept pain signals traveling up the nerve. </li></ul><ul><li>Opiate drugs prevent the transfer of pain signals from the spinal cord to the brain. </li></ul>Unit IV. Sensation and Perception
  34. 36. Unit IV. Sensation and Perception
  35. 37. Internal Senses <ul><li>Kinesthesis </li></ul><ul><ul><li>Internal body position </li></ul></ul><ul><ul><li>Muscle position </li></ul></ul><ul><li>Vestibular sense </li></ul><ul><ul><li>Balance </li></ul></ul><ul><ul><li>Semi-circular canals in ear </li></ul></ul>Unit IV. Sensation and Perception
  36. 38. C. Sensory Adaptation <ul><li>Sensory adaptation is a change in sensitivity to a stimulus that results from exposure to the stimulus. </li></ul><ul><li>Examples include adapting to darkness, adapting to bright conditions, adapting to hot or cold conditions, adapting to the presence of odors, and many more. </li></ul>Unit IV. Sensation and Perception
  37. 39. Sensory Adaptation <ul><li>Light and Dark Adaptation </li></ul><ul><ul><li>Entering / Exiting a movie theatre </li></ul></ul><ul><ul><li>One eye covered demonstration </li></ul></ul><ul><li>The eye has two types of photoreceptors </li></ul><ul><ul><li>Cones (for color) </li></ul></ul><ul><ul><li>Rods (for night vision) </li></ul></ul>Unit IV. Sensation and Perception
  38. 40. Dark Adaptation <ul><li>Move into a darkened theater and two changes occur to increase sensitivity to light: </li></ul><ul><ul><li>The pupils enlarge. This admits more light onto the retina of the eye. </li></ul></ul><ul><ul><li>Light-sensitive chemicals in the photoreceptors increase their concentration. This makes each photoreceptor more sensitive to light . </li></ul></ul>Unit IV. Sensation and Perception
  39. 41. Light Adaptation <ul><li>Leaving the theater, you encounter bright light </li></ul><ul><ul><li>Your pupils constrict immediately, reducing the light reaching the retina </li></ul></ul><ul><ul><li>The light-sensitive chemicals in the photoreceptors quickly bleach out, reducing the photoreceptors ’ sensitivity to light </li></ul></ul>Unit IV. Sensation and Perception
  40. 42. Preserving Dark Adaptation <ul><li>It takes 20-30 minutes to become fully dark adapted </li></ul><ul><li>This is destroyed by exposure to light in a few seconds </li></ul><ul><li>Rods are blind to red light </li></ul><ul><ul><li>Cover light source with red lens </li></ul></ul><ul><ul><ul><li>Read map with cones </li></ul></ul></ul><ul><ul><ul><li>Rods remain dark adapted </li></ul></ul></ul>Unit IV. Sensation and Perception
  41. 43. Sound Adaptation <ul><li>Adaptation to loud noise </li></ul><ul><li>Very loud sound </li></ul><ul><ul><li>small muscle in the inner ear contracts </li></ul></ul><ul><ul><li>dampens sound vibrations being conducted by the ossicles (bones) to the chochlea </li></ul></ul><ul><li>Adaptation does not work well for sudden loud sounds, such as gun shots </li></ul>Unit IV. Sensation and Perception
  42. 44. Odor / Smell <ul><li>The sense of smell is probably the quickest sense - as a whole - to adapt </li></ul><ul><li>We can detect amazingly low concentrations of some chemicals in the air (e.g., perfumes) but although the perfume is still in the air about us, we quickly cease to detect it </li></ul>Unit IV. Sensation and Perception
  43. 45. Taste <ul><li>Certain tastes may cause rather surprising (and unexpected) anomalies in other taste stimuli </li></ul><ul><ul><li>Eating artichoke makes sour substances taste sweet briefly </li></ul></ul><ul><ul><li>Jujuba temporarily abolishes sweet sensitivity </li></ul></ul><ul><li>Spicy foods will also stimulate pain receptors </li></ul>Unit IV. Sensation and Perception
  44. 46. Touch – Heat – Cold <ul><li>Skin temperature receptors respond more to rate of change in temperature than to steady temperature </li></ul><ul><li>This explains why hot bath feels hot at first, then cooler </li></ul><ul><li>This explains why pool/ocean feels freezing at first, then comfortable cool </li></ul><ul><li>Demonstration </li></ul><ul><ul><li>One Hand in Cold Water, the other in Warm Water </li></ul></ul>Unit IV. Sensation and Perception
  45. 47. Pain Adaptation <ul><li>Acute pain – tells us to get away from the painful stimulus </li></ul><ul><li>Chronic pain – tells us not to move something while it heals </li></ul>Unit IV. Sensation and Perception
  46. 49. C. Attention <ul><li>Selective Attention </li></ul><ul><li>Bottleneck Theories of Selective Attention </li></ul><ul><ul><li>We have a limited capacity to attend to stimuli </li></ul></ul><ul><ul><li>There is no limit to how much stimulation can be present </li></ul></ul><ul><li>Selective Attention allows us to select what to attend to </li></ul><ul><ul><li>Sometimes we seem to do it </li></ul></ul><ul><ul><li>Other times it seems to happen to us </li></ul></ul>Unit IV. Sensation and Perception
  47. 50. Selective Attention and the Cocktail Party Phenomenon <ul><li>Cocktail Party Phenomenon </li></ul><ul><ul><li>the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations </li></ul></ul><ul><ul><li>then if someone over the other side of the party room calls out our name suddenly, we also notice that sound and respond to it immediately </li></ul></ul>Unit IV. Sensation and Perception
  48. 51. Selective Attention and the Stroop Test <ul><li>Stroop Test </li></ul><ul><ul><li>Why is this task so difficult to do </li></ul></ul><ul><ul><li>reading is an automatic process </li></ul></ul><ul><ul><li>color naming is a controlled process </li></ul></ul><ul><ul><li>automatic process of reading interferes with our ability to selectively attend to ink color </li></ul></ul>Unit IV. Sensation and Perception
  49. 52. Bottleneck or Filter Models of Selective Attention <ul><li>Early selection </li></ul><ul><li>David Broadbent (1958) proposed that physical characteristics of messages are used to select one message for further processing and all others are lost </li></ul><ul><li>Attenuation </li></ul><ul><li>Treisman (1964) proposed that physical characteristics are used to select one message for full processing and other messages are given partial processing </li></ul><ul><li>Late Selection </li></ul><ul><li>Deutsch & Deutsch (1963) proposed that all messages get through, but that only one response can be mad </li></ul>Unit IV. Sensation and Perception
  50. 53. D. Perceptual Processes <ul><li>Feature analysis </li></ul><ul><li>Bottom-up processing </li></ul><ul><li>Top-down processing </li></ul>Unit IV. Sensation and Perception
  51. 54. Is it a circus act? <ul><li>Or a couple dancing? </li></ul><ul><li>Ambiguous or Reversible figure </li></ul><ul><li>Feature analysis </li></ul><ul><ul><li>Detecting specific elements </li></ul></ul><ul><ul><li>Assembling them in a more complex form </li></ul></ul>Unit IV. Sensation and Perception
  52. 55. Bottom-up Processing <ul><li>A progression from </li></ul><ul><ul><li>Individual elements to the whole </li></ul></ul><ul><li>Also called data-driven processing </li></ul>Unit IV. Sensation and Perception Detect Specific Features Combine features Recognize Stimulus
  53. 56. Bottom-Up Processing <ul><li>Perception must be largely data-driven because it must accurately reflect events in the outside world </li></ul><ul><li>The information is determined mainly be information from the senses (not from your expectations) </li></ul>Unit IV. Sensation and Perception
  54. 57. Top-Down Processing <ul><li>A progression from </li></ul><ul><ul><li>The whole to the elements </li></ul></ul><ul><li>Also known as schema-driven processing </li></ul>Unit IV. Sensation and Perception Form perceptual hypothesis about the nature of the stimulus as a whole Select and examine features to Check hypothesis Recognize Stimulus
  55. 58. Top-Down Processing <ul><li>In many situations your knowledge or expectations (or schemas) will influence your perception </li></ul><ul><li>In this case a schema is a pattern formed earlier in your experiences. </li></ul>Unit IV. Sensation and Perception
  56. 59. <ul><li>Abstract concepts tend to be referred to as higher level </li></ul><ul><li>Concrete details are referred to as lower level </li></ul><ul><li>Top-down occurs when a higher level concept influences your interpretation of lower level data </li></ul><ul><li>Set or expectancy demonstrate top-down processing </li></ul><ul><li>Ambiguous figures often demonstrate top-down processing </li></ul>Unit IV. Sensation and Perception
  57. 60. <ul><li>Visual Contrast </li></ul><ul><li>Brightness contrast (gray on white appears darker than gray on black) </li></ul><ul><li>Mach Bands (Series of bands of increasing darkness - each strip affected by the neighboring strips) </li></ul><ul><li>Lateral inhibition </li></ul>Unit IV. Sensation and Perception
  58. 61. Brightness Contrast Unit IV. Sensation and Perception
  59. 62. Principles of Perceptual Organization: <ul><li>Figure-Ground </li></ul><ul><li>Grouping (Gestalt Principles) </li></ul><ul><ul><li>Proximity (Nearness) </li></ul></ul><ul><ul><li>Similarity </li></ul></ul><ul><ul><li>Continuity </li></ul></ul><ul><ul><li>Closure </li></ul></ul>Unit IV. Sensation and Perception
  60. 63. Closure Unit IV. Sensation and Perception
  61. 64. <ul><li>Perception of Depth and Distance </li></ul><ul><li>Perception of Motion </li></ul><ul><li>Perceptual Constancy (Size, Shape, Brightness) </li></ul><ul><li>Perceptual Illusions </li></ul><ul><li>Perceptual Set </li></ul><ul><li>Perceptual Adaptation </li></ul>Unit IV. Sensation and Perception
  62. 65. Depth Perception <ul><li>“ I could have sworn that mesa was a whole lot farther away” </li></ul>
  63. 66. Unit IV. Sensation and Perception
  64. 67. Necker cube (1) Unit IV. Sensation and Perception
  65. 68. Necker cube (2) Unit IV. Sensation and Perception
  66. 69. Necker cube (3) Unit IV. Sensation and Perception
  67. 70. Necker cube (4) Unit IV. Sensation and Perception
  68. 71. Necker cube (5) Unit IV. Sensation and Perception
  69. 72. Handouts <ul><li>DISTRIBUTION OF RODS AND CONES – Bernstein (Colored pencils) </li></ul><ul><li>Light-Dark Sensory Adaptation Demonstration (Eye patch) </li></ul><ul><li>Simple Compelling Demonstrations of Retinal Disparity ( “Hole in hand” etc.) </li></ul><ul><li>DEMONSTRATING THAT SMELL IS AS IMPORTANT – Beins (Jelly Bellies) </li></ul>Unit IV. Sensation and Perception
  70. 73. <ul><li>Monocular Depth Perception Student Assignment </li></ul><ul><li>Chart - Depth Perception Cues (Study Guide / May be used in a variety of assignments) </li></ul><ul><li>Color Vision – Roygbiv (Demonstration) </li></ul><ul><li>Pulfrich effect (Reading from Wikipedia) </li></ul>Unit IV. Sensation and Perception
  71. 74. <ul><li>Moon Illusion (Reading from Bad Astronomy by Philip Plait) </li></ul><ul><li>The Big Picture - Gestalt applied </li></ul><ul><li>The Neuroscience of Yorick's Ghost and Other Afterimages </li></ul><ul><li>Mindsights Tables (Drawing by Shepard) </li></ul><ul><li>Various Visual Illusions </li></ul>Unit IV. Sensation and Perception
  72. 75. The Janus Mask
  73. 76. Example of the Ames Room Unit IV. Sensation and Perception
  74. 77. The Magic of the Wundt-Jastrow Illusion
  75. 78. From: Gregory, R. I., Eye and Brain (2 nd ed.) New York: World University Library, 1973. (pp. 78-80.)

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