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Lecture Slides from Sir.VISCOM Spring 2012

Transcript of Visual perception-illusions-paradoxes

  • 1. Visual Perception Illusions & Paradoxes dPriyadarshi Patnaik Associate ProfessorDepartment of Humanities & Social S iD fH ii S i l Sciences IIT Kharagpur

2. What about visuals?Many things which are visually communicated orperceived are biologically determinedBut many other things are learntVisuals communicate powerVisuals communicate emotionsVisuals communicate culture 3. The PanopticonJeremy Bentham (1785)Discipline and PunishParanoiaControlFearClose circuitEPR 4. Visuals and the Communication of Emotions 5. What is perception?Sensation+ Interpretation 6. In philosophy psychology and the cognitive philosophy, psychology,sciences, perception is the process of attainingawareness or understanding of sensoryinformation. The word "perception" comesfrom the Latin words perceptio percipio and meansperceptio, percipio,"receiving, collecting, action of takingpossession,possession apprehension with the mind orsenses." 7. When external stimuli is transmitted to our brainthrough our senses sensationDevoid of any definition, any interpretation,meaningThe simplest building blockBut then it is taken up by the mind and analyzedMemory is stirred up remembering usedup,Sensation identified, matched, given a name,defined,defined interpreted and remembered for futureuse 8. Part of what we perceive comes through thesenses from the objects before us; another partalways comes out of our own headWilliam JWilli James 9. Subjective perception Image credit: Mark R. Homes @ National Geographic Society 10. To resolve ambiguities and make sense of theworld, the brain also creates shapes fromincomplete data.dataThe i lTh triangle you saw was d l d b I lideveloped by Italianpsychologist Gaetano Kanizsa. 11. IllusionImage credit: Mark R. Homes @ National Geographic Society 12. Illusion created because of size constancy size constancyeffect to be discussed a little later. 13. OrientationImage credit: Mark R. Homes @ National Geographic Society 14. According to noted neuroscientist V.VRamachandran of University of California, SanDiego,Diego the brain can make guesses based oninformation available and some simpleassumptionsPattern of shadowsLightLi h usually from top ll f 15. Which are the concaves now? 16. Orientation 17. From the eye to the mindRetina12braineye 1: R l t ti 1 Relay station - LGN 2: Primary and more advanced area of visual cortex 18. Rods: Monochrome and in low lightCones: colour vision 19. AttentionThe perceptual process of selecting certaininputs for inclusion in our conscious experienceor awareness at any given time 20. Flash animationImage taken Flash Animation Software demo movie 21. FilteringWhy does focus shift?We filter, partly bl ki certain iW fill blockingi inputs Limited Mental Capacity 22. Perception is taking in, filtering and interpretation tomake sense of the world. Memory and learning play animportant part, but so do certain innate organizationalabilities of the mind, highlighted by Gestaltpsychologists.The limits of my perception are the limits of my worldThe word is the world (since it takes us a step furtherand helps us cognize what we have perceived) 23. What we shall do nextForm perceptionColour perceptionDepthD h perception iThese will give us some idea of how and why wevisually perceive the many things that we do. ypy g 24. Form Perception andGestaltGl 25. Gestalt (German) used to indicate the form-form-forming capabilities of the mind (Whole formapproach) and the belief that this holisticperception is innate to the mind 26. Figure-g ou dFigure-groundgu e M.C. Escher: Moebious with Birds 27. The visual system uses an innate binary division the figure we look at and the ground which iseverything else and forms the backgroundThis relation is reversibleButB we cannot perceive the same thing as fii hhi figureand ground at the same time it requires amental switching l i hi 28. GestaltMax WertheimerKurt KoffkaWolfgang K hlW lf KohlerWe are surrounded by sounds and forms that donot have a sole meaning. At any moment, our gy ,perception is what gives it form and meaning. 29. What do we have here? Twelve lines 4 vertical 4 horizontal 4 oblong 30. The vase and the two facesA demonstration of multi-stability: popping back and forthbetween two or more unstable perceptions 31. Organization in form perception The whole is more than the sum of itsh hfiparts 32. A PoemA Black CoatIt was a dark evening d ki Simple Life 33. Subjective Contour/ReificationImage credit: Mark R. Homes @ National Geographic Society 34. Proximity 35. Similarity 36. The law of good figure 37. Continuity 38. Closure 39. Emergence 40. Shape constancy or invariance 41. Analysis 42. Analyze these Dali imagesSalvador Dali: Mae West 43. Salvador Dali: Narcissus 44. Salvador Dali: The Phantom Cart 45. Salvador Dali: Galatea of Spheres 46. Depth Perception 47. Depth PerceptionD th Pti MonocularBinocular 48. Binocular 49. Photograph: Priyadarhsi Patnaik 50. Linear perspectiveVanishing i tV i hi pointHorizon Road 51. Dali: Vertigo 52. Interposition 53. Relative SizeThe farther an object is from the eye, the smallereyeit looksThe episode of the buffalos 54. Gustave Caillebotte: Paris 55. Size Constancy 56. Illusion roomSource: Blog site: MirageStudio7 57. Perceptual assumption Source: Encyclopedia Britannica Deluxe Edition 2007 58. Colour Perception 59. Source: Encyclopedia Britannica 2007 Deluxe Edition 60. Colour wheelWebsite of The Joy of Perception 61. Simultaneous ContrastWebsite of The Joy of Perception 62. Source: Color in Mind: Adobe Magazine, November 1996 63. SizeSource: Color in Mind: Adobe Magazine, November 1996 64. Brightness, colour and depth Website of The Joy of Perception 65. The light coloured dot seems to pop out while the dark coloured dot seems to sit further backSource: Color in Mind: Adobe Magazine, November 1996 66. Analysis 67. Seurat: the Bathers 68. De Chirico: The Nostalgia of Infinite 69. Munch: The Scream 70. Francis Bacon: Crucifixion 3 71. Van Gogh: Cypress in Starry Night 72. Van Gogh: Wheatfield under threatening skies 73. Tibetan Buddhist Tanka painting 74. Colour symbolismCultural differencesAge differenceClass differenceCl diffGender differenceTrend or current fashion 75. IllusionThere is an innate ambiguity in retinal input. For a g ypgiven retinal image, there are infinite number of threedimensional images available for interpretation. Usuallywe get the interpretation right. When we dont, we have t th i t rpr t ti ri ht Whd than illusion.Some illusions arise because there are more than onepossible interpretations.An illusion is a distortion of the senses, revealing howthe brain normally organizes and interprets sensorystimulation. 76. Types ofAmbiguous illusions are pictures or objects thatg p jelicit a perceptual switch between the alternativeinterpretations.Distorting illusions are characterized by distortionsof size, length, or curvature.Paradox illusions are generated by objects that areparadoxical or impossible. d i l i iblFictional illusions (Hallucinations) are defined asthe perception of objects that are g p pbjgenuinely not thereyto all but a single observer, such as those induced byschizophrenia or a hallucinogen. 77. Image source: Encyclopedia Britannica 2007 deluxe edition 78. Image source: Encyclopedia Britannica 2007 deluxe edition 79. Image source: 80. Shape contrast: contextImage source: 81. Simultaneous contrast/spreadingImage source: 82. Image source: 83. Escher: Birds & fish 84. Escher on Escher"In the horizontal center strip there are birds and fishInequivalent to each other. We associate flying with sky,and so for each of the black birds the sky in which it isflying is formed by the four white fish which encircle it.Similarly swimming makes us think of water, andwatertherefore the four black birds that surround a fish becomethe water in which it swims." swims 85. Escher: Bond of union 86. Escher: Day & night 87. Escher: Mobius strip II 88. Magritte: Call of the Peaks 89. Magritte: the blank cheque 90. GiuseppeArcimboldo(1527-1593)(1527 1593)Italian Artist 91. Pieter Bruegel the Elder (1525-1559), Netherlands 92. Jos de Mey(1928 - 2007)Belgian Artist 93. Rob Gonsalves (1959-)Canadian Painter 94. Octavio Ocampo(1943-)Mexican Artist 95. Shigeo Fukuda(1932-2009) 96. References and images Doors of Perception The Joy of Perception Perception Online Perception. E l p di Britannica 2007 Deluxe Edition. P ti Encyclopedia B it iD l Editi Art and Visual Perception. Rudolf Arnheim, University of California Press, 1984. Mark Hardins A hi ( M k H di Artchive ( hi Colour. Bettey Edwards, Tarcher/Penguin, 2004. Perception, Gestalt, Panopticon, etc ( p p(Wikipedia) p)