Introductory Psychology: Sensation & Perception (Vision)


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lecture 16 from a college level introduction to psychology course taught Fall 2011 by Brian J. Piper, Ph.D. ( at Willamette University, includes anatomy of eye/brain, dorsal pathway, ventral pathway, figure/ground, many illusions, synesthesia

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Introductory Psychology: Sensation & Perception (Vision)

  1. 1. Sensation & Perception I: Vision Brian J. Piper, Ph.D.
  2. 2. Goals• Sensation• Perception• Myth: Perception = Sensation• Reality: Perception ≠ Sensation
  3. 3. Terminology• Sensation: the process by which sensory receptors receives stimulus energy from our environment• Perception: the process of organizing & interpreting sensory information
  4. 4. Psychophysics• the study of the relationship between the 1795-1878 physical characteristics of stimuli & our psychological experiences• jnd: minimum difference a person can detect between two stimuli• Weber’s Law: 2 stimuli must differ by a proportion (light: 8%, weight: 2%, tone: 0.3%)
  5. 5. Below jnd (Subliminal)• A double-blind study had volunteers listen to tapes for 4 weeks (memory or self-esteem).• Self-reported memory and self-esteem was measured before and after listening. Label Reality Memory Memory Memory Self-esteem Self-esteem Self-esteem Self-esteem Memory Greenwald et al. (1991). Psychological Science, 2, 119-122.
  6. 6. Predicted Results• This study has four groups (Label/Material) – Self-Esteem/Self-Esteem; Memory/Memory; Self- Esteem/Memory; Memory/Self-Esteem• What impact, if any, will the labels have?• In terms of Memory, please rank them from highest (best) to lowest.• In terms of Self-Esteem, please rank them from highest to lowest. Greenwald et al. (1991). Psychological Science, 2, 119-122.
  7. 7. InterpretationSelf-esteem and memory post-test wereexpressed as relative to pre-test.What discussion section would you write? Greenwald et al. (1991). Psychological Science, 2, 119-122.
  8. 8. InterpretationSelf-esteem and memory post-test wereexpressed as relative to pre-test.What discussion section would you write? Greenwald et al. (1991). Psychological Science, 2, 119-122.
  9. 9. Interpretation• People that want to improve, improve.• No benefits of subliminal messages consistent with their advertised intent. Greenwald et al. (1991). Psychological Science, 2, 119-122.
  10. 10. Energy to Action Potentials
  11. 11. Wave Properties• Amplitude: height, small = dull; large = bright• Wavelength: distance from peak to peak, determines color: – blue < green < red
  12. 12. Wavelength Violet Indigo Blue Green Yellow Orange Red 400 nm 700 nmShort wavelengths Long wavelengths Different wavelengths of light result in different colors.
  13. 13. The Eye
  14. 14. Parts of the eye1. Cornea: Transparent tissue where light enters the eye.2. Iris: Muscle that expands and contracts to change the size of the opening (pupil) for light.3. Lens: Focuses the light rays on the retina.4. Retina: Contains sensory receptors that process visual information and sends it to the brain.
  15. 15. Retina Retina: The light- sensitive inner surface of the eye,containing receptor rods and cones inaddition to layers of other neurons (bipolar, ganglion cells) that processvisual information.
  16. 16. Optic Nerve, Blind Spot & FoveaOptic nerve: Carries neural impulses from the eye to the brain.Blind Spot: Point where the optic nerve leaves the eye becausethere are no receptor cells located there.Fovea: Central point in the retina around which the eye’s conescluster.
  17. 17. Test your Blind SpotUse your textbook. Close your left eye, and fixate your right eye on the black dot. Move the page towards your eye and away from your eye. Atsome point the car on the right will disappear due to a blind spot.
  18. 18. PhotoreceptorsE.R. Lewis, Y.Y. Zeevi, F.S Werblin, 1969
  19. 19. Young-Helmholtz Trichromatic “Theory”• Physician/Physicist Thomas Young & Hermann von Helmholtz predicted that the eye would have three kinds of color receptors. 1773-1829 1821-1894“Whoever in the pursuit of science, seeks after immediate practical utility may rest assured thathe seeks in vain.”
  20. 20. Color BlindnessGenetic disorder in which people are blind to green or red colors. This supports the Trichromatic specialization of cones. Ishihara Test
  21. 21. Visual Information Processing Optic nerves connect to the thalamus in themiddle of the brain, and the thalamus connects to the visual cortex.
  22. 22. Feature Detection Nerve cells in the visual cortex respond to specific features, such as edges, angles, and movement.Ross Kinnaird/ Allsport/ Getty Images
  23. 23. Visual Information Processing Processing of several aspects of the stimulus simultaneously is called parallel processing. Thebrain divides a visual scene into subdivisions such as color, depth, form, movement, etc.
  24. 24. Dorsal & Ventral Streams
  25. 25. Figure/Ground Edgar Rubin
  26. 26. Sandro Del-Prete: “Message d’Amour desDauphins” 1987
  27. 27. Grouping & RealityAlthough grouping principles usually help us construct reality, they may occasionally lead us astray. Magazine. .© 1983 PCS Games Limited Partnership Both photos by Walter Wick. Reprinted from GAMES
  28. 28. Which one is continuation? Johann Christian Poggendorff
  29. 29. Parallel Lines? Ewald Hering
  30. 30. Parallel Lines? Johann Karl Friedrich Zöllner
  31. 31. Depth Perception Depth perception enables us to judge distances. Gibson and Walk (1960) suggested that human infants (crawling age) have depth perception. Even newborn animals show depth perception.Innervisions Visual Cliff
  32. 32. Size-Distance Relationship Both girls in the room are of similar height. However, we perceive them to be of different heights as they stand in the two corners of the room.Both photos from S. Schwartzenberg/ The Exploratorium
  33. 33. Ames RoomThe Ames room is designed to demonstrate the size- distance illusion.
  34. 34. Which one is bigger? Ponzo Illusion
  35. 35. Which one is bigger? Ponzo Illusion
  36. 36. Which one is bigger? Ponzo Illusion
  37. 37. Which one is bigger?Hermann Ebbinghaus1850-1909 Ebbinghaus Illusion
  38. 38. Volunteer?
  39. 39. Volunteer?• Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosnt mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.
  40. 40. Compare Darkness Edward H. Adelson Checker Shadow Illusion
  41. 41. Compare Darkness Edward H. Adelson Checker Shadow Illusion
  42. 42. Compare Darkness Edward H. Adelson Checker Shadow Illusion
  43. 43. How many colors do you see?
  44. 44. Number-Color Synesthesia V.S. Ramachandran 1951-
  45. 45. Number-Color Synesthesia
  46. 46. Static Image I: Akiyoshi Kitaoka
  47. 47. Static Image II: Akiyoshi Kitaoka
  48. 48. Mars Surface: Viking I-1976
  49. 49. Devil?
  50. 50. Not Politically Correct
  51. 51. Eye-tracking
  52. 52. “Fusiform Facial Area”
  53. 53. Prosopagnosia• Inability to recognize faces• Sensation without Perception Video Worth -> Sensation & Perception
  54. 54. Selective Attention• o•
  55. 55. Floating Cube
  56. 56. Street ArtWest Vancouver (15 sec):
  57. 57. Summary• Perception > Sensation• Retina -> Optic Nerve -> Thalamus -> Visual Cortex -> Beyond• Illusions: – Figure ground – Faces – “Motion” – Impossible