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Visual perception-illusions-paradoxes

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Visual perception concepts
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Visual perception-illusions-paradoxes

  1. 1. Visual Perception Illusions & Paradoxes d Priyadarshi Patnaik Associate Professor Department of Humanities & Social S i D fH ii S i l Sciences IIT Kharagpur
  2. 2. What about visuals? Many things which are visually communicated or perceived are biologically determined But many other things are learnt Visuals communicate power Visuals communicate emotions Visuals communicate culture
  3. 3. The Panopticon Jeremy Bentham (1785) Discipline and Punish Paranoia Control Fear Close circuit EPR
  4. 4. Visuals and the Communication of Emotions
  5. 5. What is perception? Sensation + Interpretation
  6. 6. In philosophy psychology and the cognitive philosophy, psychology, sciences, perception is the process of attaining awareness or understanding of sensory information. The word "perception" comes from the Latin words perceptio percipio and means perceptio, percipio, "receiving, collecting, action of taking possession, possession apprehension with the mind or senses."
  7. 7. When external stimuli is transmitted to our brain through our senses – sensation Devoid of any definition, any interpretation, meaning The simplest building block But then it is taken up by the mind and analyzed Memory is stirred up remembering used up, Sensation identified, matched, given a name, defined, defined interpreted and remembered for future use
  8. 8. Part of what we perceive comes through the senses from the objects before us; another part always comes out of our own head William J Willi James
  9. 9. Subjective perception Image credit: Mark R. Homes @ National Geographic Society
  10. 10. To resolve ambiguities and make sense of the world, the brain also creates shapes from incomplete data. data The i l Th triangle you saw was d l d b I li developed by Italian psychologist Gaetano Kanizsa.
  11. 11. Illusion Image credit: Mark R. Homes @ National Geographic Society
  12. 12. Illusion created because of “size constancy size constancy” effect to be discussed a little later.
  13. 13. Orientation Image credit: Mark R. Homes @ National Geographic Society
  14. 14. According to noted neuroscientist V. V Ramachandran of University of California, San Diego, Diego the brain can make guesses based on information available and some simple assumptions Pattern of shadows Light Li h usually from top ll f
  15. 15. Which are the concaves now?
  16. 16. Orientation
  17. 17. From the eye to the mind Retina 1 2 brain eye 1: R l t ti 1 Relay station - LGN 2: Primary and more advanced area of visual cortex
  18. 18. Rods: Monochrome and in low light Cones: colour vision
  19. 19. Attention The perceptual process of selecting certain inputs for inclusion in our conscious experience or awareness at any given time
  20. 20. Flash animation Image taken Flash Animation Software demo movie
  21. 21. Filtering Why does focus shift? We filter, partly bl ki certain i W fil l blocking i inputs Limited Mental Capacity
  22. 22. Perception is taking in, filtering and interpretation to make sense of the world. Memory and learning play an important part, but so do certain innate organizational abilities of the mind, highlighted by Gestalt psychologists. The limits of my perception are the limits of my world The word is the world (since it takes us a step further and helps us cognize what we have perceived)
  23. 23. What we shall do next Form perception Colour perception Depth D h perception i These will give us some idea of how and why we visually perceive the many things that we do. yp y g
  24. 24. Form Perception and Gestalt G l
  25. 25. Gestalt (German) used to indicate the form- form- forming capabilities of the mind (Whole form approach) and the belief that this holistic perception is innate to the mind
  26. 26. Figure-g ou d Figure-ground gu e M.C. Escher: Moebious with Birds
  27. 27. The visual system uses an innate binary division – the figure we look at and the ground which is everything else and forms the background This relation is reversible But B we cannot perceive the same thing as fi i h hi figure and ground at the same time – it requires a mental switching l i hi
  28. 28. Gestalt Max Wertheimer Kurt Koffka Wolfgang K hl W lf Kohler We are surrounded by sounds and forms that do not have a sole meaning. At any moment, our g y , perception is what gives it form and meaning.
  29. 29. What do we have here? Twelve lines 4 vertical 4 horizontal 4 oblong
  30. 30. The vase and the two faces A demonstration of multi-stability: popping back and forth between two or more unstable perceptions
  31. 31. Organization in form perception The whole is more than the sum of its h h fi parts
  32. 32. A Poem A Black Coat It was a dark evening d k i Simple Life
  33. 33. Subjective Contour/Reification Image credit: Mark R. Homes @ National Geographic Society
  34. 34. Proximity
  35. 35. Similarity
  36. 36. The law of good figure
  37. 37. Continuity
  38. 38. Closure
  39. 39. Emergence
  40. 40. Shape constancy or invariance
  41. 41. Analysis
  42. 42. Analyze these Dali images Salvador Dali: Mae West
  43. 43. Salvador Dali: Narcissus
  44. 44. Salvador Dali: The Phantom Cart
  45. 45. Salvador Dali: Galatea of Spheres
  46. 46. Depth Perception
  47. 47. Depth Perception D th P ti Monocular Binocular
  48. 48. Binocular
  49. 49. Photograph: Priyadarhsi Patnaik
  50. 50. Linear perspective Vanishing i t V i hi point Horizon Road
  51. 51. Dali: Vertigo
  52. 52. Interposition
  53. 53. Relative Size The farther an object is from the eye, the smaller eye it looks The episode of the buffalos
  54. 54. Gustave Caillebotte: Paris
  55. 55. Size Constancy
  56. 56. Illusion room Source: Blog site: MirageStudio7
  57. 57. Perceptual assumption Source: Encyclopedia Britannica Deluxe Edition 2007
  58. 58. Colour Perception
  59. 59. Source: Encyclopedia Britannica 2007 Deluxe Edition
  60. 60. Colour wheel Website of “The Joy of Perception”
  61. 61. Simultaneous Contrast Website of “The Joy of Perception”
  62. 62. Source: “Color in Mind: Adobe Magazine, November 1996
  63. 63. Size Source: “Color in Mind: Adobe Magazine, November 1996
  64. 64. Brightness, colour and depth Website of “The Joy of Perception”
  65. 65. The light coloured dot seems to pop out while the dark coloured dot seems to sit further back Source: “Color in Mind: Adobe Magazine, November 1996
  66. 66. Analysis
  67. 67. Seurat: the Bathers
  68. 68. De Chirico: The Nostalgia of Infinite
  69. 69. Munch: The Scream
  70. 70. Francis Bacon: Crucifixion 3
  71. 71. Van Gogh: Cypress in Starry Night
  72. 72. Van Gogh: Wheatfield under threatening skies
  73. 73. Tibetan Buddhist Tanka painting
  74. 74. Colour symbolism Cultural differences Age difference Class difference Cl diff Gender difference Trend or current fashion
  75. 75. Illusion There is an innate ambiguity in retinal input. For a g y p given retinal image, there are infinite number of three dimensional images available for interpretation. Usually we get the interpretation right. When we don’t, we have t th i t rpr t ti ri ht Wh d ’t h an illusion. Some illusions arise because there are more than one possible interpretations. An illusion is a distortion of the senses, revealing how the brain normally organizes and interprets sensory stimulation.
  76. 76. Types of Ambiguous illusions are pictures or objects that g p j elicit a perceptual 'switch' between the alternative interpretations. Distorting illusions are characterized by distortions of size, length, or curvature. Paradox illusions are generated by objects that are paradoxical or impossible. d i l i ibl Fictional illusions (Hallucinations) are defined as the perception of objects that are g p p bj genuinely not there y to all but a single observer, such as those induced by schizophrenia or a hallucinogen.
  77. 77. Image source: Encyclopedia Britannica 2007 deluxe edition
  78. 78. Image source: Encyclopedia Britannica 2007 deluxe edition
  79. 79. Image source: www.scientificpsychic.com
  80. 80. Shape contrast: context Image source: www.colorcube.com
  81. 81. Simultaneous contrast/spreading Image source: www.colorcube.com
  82. 82. Image source: www.scientificpsychic.com
  83. 83. Escher: Birds & fish
  84. 84. Escher on Escher "In the horizontal center strip there are birds and fish In equivalent to each other. We associate flying with sky, and so for each of the black birds the sky in which it is flying is formed by the four white fish which encircle it. Similarly swimming makes us think of water, and water therefore the four black birds that surround a fish become the water in which it swims." swims
  85. 85. Escher: Bond of union
  86. 86. Escher: Day & night
  87. 87. Escher: Mobius strip II
  88. 88. Magritte: Call of the Peaks
  89. 89. Magritte: the blank cheque
  90. 90. Giuseppe Arcimboldo (1527-1593) (1527 1593) Italian Artist
  91. 91. Pieter Bruegel the Elder (1525-1559), Netherlands
  92. 92. Jos de Mey (1928 - 2007) Belgian Artist
  93. 93. Rob Gonsalves (1959-) Canadian Painter
  94. 94. Octavio Ocampo (1943-) Mexican Artist
  95. 95. Shigeo Fukuda (1932-2009)
  96. 96. References and images Doors of Perception http://www.doorsofperception.com/doors The Joy of Perception http://www.yorku.ca/eye Perception Online http://www.pion.co.uk/perception “Perception.” E l p di Britannica 2007 Deluxe Edition. “P ti ” Encyclopedia B it i D l Editi Art and Visual Perception. Rudolf Arnheim, University of California Press, 1984. Mark Hardin’s A hi (www.artchive.com) M k H di ’ Artchive (www.artchive.com) hi Colour. Bettey Edwards, Tarcher/Penguin, 2004. Perception, Gestalt, Panopticon, etc ( p p (Wikipedia) p )

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