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Optical illusions


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Optical illusions

  1. 1. Optical Illusions Seeing Is Deceiving By Rizwan
  2. 2. What is an Illusion? <ul><ul><ul><li>il·lu·sion (  -l  zh  n ) noun </li></ul></ul></ul><ul><ul><ul><li>1. a. An erroneous perception of reality. </li></ul></ul></ul><ul><ul><ul><li>b. An erroneous concept or belief. </li></ul></ul></ul><ul><ul><ul><li>2. The condition of being deceived by a false perception or belief. </li></ul></ul></ul><ul><ul><ul><li>3. Something, such as a fantastic plan or desire, that causes an erroneous belief or perception. </li></ul></ul></ul><ul><ul><ul><li>4. Illusionism in art. </li></ul></ul></ul><ul><li>Latin root of illusion is illudere which means “to mock” </li></ul><ul><li>Optical illusions mock our trust in our senses </li></ul><ul><li>Suggest that the eye is not a passive camera; rather, </li></ul><ul><li>perception is an active process that takes place in the </li></ul><ul><li>brain and is not directly predictable from simple </li></ul><ul><li>knowledge of physical relationships </li></ul>
  3. 3. What’s the big deal? <ul><li>Human reliance on correspondence between conscious experience and physical reality </li></ul><ul><li>Continual verification of our senses </li></ul><ul><li>Cultural Heritage </li></ul><ul><ul><li>“ Seeing is Believing” </li></ul></ul><ul><ul><li>“ See it with my own two eyes” </li></ul></ul>
  4. 4. History of Illusions <ul><li>Prehistory : </li></ul><ul><li>Afterimage caused by glancing at the sun </li></ul><ul><li>A stick half in and half out of water </li></ul>
  5. 5. History of Illusions <ul><ul><ul><li>500 B.C. - Height of the Greek Period </li></ul></ul></ul><ul><ul><ul><li>“ The eyes and ears are bad witnesses when they are at the service of minds that do not understand their language” </li></ul></ul></ul><ul><ul><ul><li>-Parmenides </li></ul></ul></ul><ul><ul><ul><li>Two Viewpoints on Perception: </li></ul></ul></ul><ul><ul><ul><ul><li>1. Sensory inputs are inaccurate. Mind corrects these inaccuracies to </li></ul></ul></ul></ul><ul><ul><ul><ul><li>provide an accurate representation of the environment. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Illusions : Senses are relied on more than the Mind </li></ul></ul></ul></ul><ul><ul><ul><ul><li>2. Senses are inherently accurate and produce a true picture of the </li></ul></ul></ul></ul><ul><ul><ul><ul><li>environment. Mind is limited. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Illusions : Mind interferes with the Senses </li></ul></ul></ul></ul>
  6. 6. History of Illusions c. 450 B.C. “ The mind sees and the mind hears. The rest is blind and deaf.” -Epicharmus “ Man is nothing but a bundle of sensations” -Protagoras c. 300 B.C. “ We must perceive objects through the senses but with the mind” - Plato 384 - 322 B.C. “ Each sense has one kind of object which it discerns, and never errs in reporting that what is before it is color or sound; Although, it may err as to what it is that is colored or where it is, or what it is that is sounding, or where it is.” -Aristotle
  7. 7. History of Illusions <ul><li>A. Ideal Parthenon </li></ul><ul><li>B. Architrave Illusion </li></ul><ul><li>(Jastrow-Lipps) </li></ul><ul><li>C. Illusionary Distortion </li></ul><ul><li>D. Alterations made to offset illusion </li></ul>
  8. 8. History of Illusions “ For the sight follows gracious contours; and unless we flatter its pleasure by proportionate alterations of the modules--so that by adjustment there is added the amount to which suffers illusion--an uncouth and ungracious aspect will be presented to the spectators.” -Vitruvius
  9. 9. History of Illusions Entasis : Convexing of column to overcome parallel lines appearing concave Irradiation Illusion : Bright objects appear larger
  10. 10. History of Illusions Conclusion: “ More of an Art than a Science” Early Preparadaigmatic Science -Trial and error -Aesthetic, not scientific -No factual understanding -No treatsies -No schools of thought
  11. 11. History of Illusions 1596 - 1650 Descartes: There is both a registration stage and an interpretation stage in the perceptual process. Perceptual error or illusion may intrude at either of these two steps along the road to consciousness. 1700 - 1800 Given at Birth vs. Learned through Experience Reid & Kant: All knowledge of the external world comes directly through the senses and is interpreted by innate mechanisms Berkeley & Hume: All perceptual qualities are learned through experience with the environment
  12. 12. History of Illusions <ul><li>1800 - 1870 Experimental Foundations </li></ul><ul><li>Mueller, E.H. Weber, Helmholtz, Baldwin, Hering use Physics , Physiology , Philosophy to form treatises </li></ul><ul><li>Specialist and Non-specialist working in area of visual geometric illusions carrys on to the present </li></ul><ul><li>1922 - Luckiesh: lighting engineer 1964 - Tolansky: physicist 1972 - Robinson: psychologist </li></ul><ul><li>1900s Revolution and Rebirth </li></ul><ul><ul><li>Behaviorists vs. Gestalt </li></ul></ul><ul><ul><li>Methodology vs. Theoretical </li></ul></ul><ul><ul><li>Percepual response & Brain wave patterns </li></ul></ul>
  13. 13. Current State of Illisions Conclusion: Paradigmatic Science (Psychology) 1900s Normal Sciences => Anomoly => Crisis => Revolution Current status: Normal Science - mopping up - puzzle solving - guidelines for research
  14. 14. Ambiguous Figures Face or Vase?
  15. 15. Ambiguous Figures L'Amour de Pierrot c.1905 Gossip and Satan Geo. A. Wotherspoon RetroActive Nels Isralson
  16. 16. Ambiguous Figures Slave Market With the Disappearing Bust of Voltaire - Salvadore Dali, 1940 Bust of Voltaire - Houdon, 1781
  17. 17. Ambiguous Figures The Great Panoramic - Salvadore Dali, 1936
  18. 18. Ambiguous Figures 2 2 2 3 Multiple Figures
  19. 19. Ambiguous Figures Mask Concavity
  20. 20. Ambiguous Figures Mach’s Figure
  21. 21. Ambiguous Figures Schroder’s Staircase
  22. 22. Ambiguous Figures Oscillating Cubes
  23. 23. Ambiguous Figures Necker Cube
  24. 24. Ambiguous Figures
  25. 25. Ambiguous Figures Cube looks like a cube. “ Equal sides and right angles.” Eye: Perspetive projection Reverse : Topless pyramid change of shape Cube looks distorted, on face smaller than the other. Depth is paradoxical Reverse : No Change
  26. 26. Ambiguous Figures Cube does not look like a cube. Eye: Near face is same size as far face Reverse : Topless pyramid further face always looks larger Necker Cube. No face is front or back by perspective Depth is paradoxical Reverse : No change
  27. 27. Ambiguous Figures <ul><li>Possible views: </li></ul><ul><li>Cube with corner missing </li></ul><ul><li>Box in corner of room </li></ul><ul><li>Small cube infront of large cube </li></ul>3 in 1 Illusion
  28. 28. Ambiguous Figures Cube / Room <ul><li>Possible views: </li></ul><ul><li>3D Cube </li></ul><ul><li>Corner of Room </li></ul>