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Reading Assignment

Reading Assignment. Read chapter by Pinker for Wed. of next week. Shape from Shading. Investigating Perception. Perception is mysterious So how do we go about understanding how it works?. Investigating Perception. What is Science?. Investigating Perception. What is Science?

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Reading Assignment

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  1. Reading Assignment • Read chapter by Pinker for Wed. of next week.

  2. Shape from Shading

  3. Investigating Perception • Perception is mysterious • So how do we go about understanding how it works?

  4. Investigating Perception • What is Science?

  5. Investigating Perception • What is Science? • Science is a method for understanding how nature works

  6. Science • What isn’t Science? • Headlines on www.reuters.com Science Page: • Juan Strengthens Into Hurricane, Misses Bermuda

  7. Science • What isn’t Science? • Headlines on www.reuters.com Science Page: • Juan Strengthens Into Hurricane, Misses Bermuda • Japan's Mt Fuji Shows Subsidence, No Eruption Danger

  8. Science • What isn’t Science? • Headlines on www.reuters.com Science Page: • Juan Strengthens Into Hurricane, Misses Bermuda • Japan's Mt Fuji Shows Subsidence, No Eruption Danger • Official Report: French Heat-Wave Death Toll 15,000

  9. Science • What isn’t Science? • Headlines on www.reuters.com Science Page: • Juan Strengthens Into Hurricane, Misses Bermuda • Japan's Mt Fuji Shows Subsidence, No Eruption Danger • Official Report: French Heat-Wave Death Toll 15,000 • Man Questioned in Australia Over Mutilated Whale Carcass

  10. Science • Science is like a set of procedures: Identify a question

  11. Science • Science is like a set of procedures: Make a Hypothesis Identify a question

  12. Science • Science is like a set of procedures: Make a Hypothesis Identify a question Make a Prediction

  13. Science • Science is like a set of procedures: Make a Hypothesis Identify a question Make a Prediction Test It

  14. Science • Science is like a set of procedures: Make a Hypothesis Identify a question Make a Prediction Prediction Fails Prediction holds Test It

  15. Example: The horizontal-vertical illusion

  16. Example: The horizontal-vertical illusion • Question: • Hypothesis: • Prediction: • Test:

  17. Example: The horizontal-vertical illusion • Question: Why does the vertical line seem longer? • Hypothesis: • Prediction: • Test:

  18. Example: The horizontal-vertical illusion • Question: Why does the vertical line seem longer? • Hypothesis: Wundt -> vertical and horizontal eye movements scan the image differently • Prediction: • Test:

  19. Example: The horizontal-vertical illusion • Question: Why does the vertical line seem longer? • Hypothesis: Wundt -> vertical and horizontal eye movements scan the image differently • Prediction: Stabilized image should eliminate the illusion • Test:

  20. Example: The horizontal-vertical illusion • Question: Why does the vertical line seem longer? • Hypothesis: Wundt -> vertical and horizontal eye movements scan the image differently • Prediction: Stabilized image should eliminate the illusion • Test: Illusion is still present in afterimage!

  21. Muller - Lyer Illusion

  22. Muller-Lyer Illusion What theory does Gregory take up?

  23. Muller-Lyer Illusion What theory does Gregory take up? Thiery / Woodworth : Muller-Lyer figure “suggests perspective” implicit is that the brain shrinks things that are perceived as near and expands things that are perceived as far away

  24. Size Constancy Brain shrinks things that are near and expands things that are far The Ponzo Illusion:

  25. Size Constancy The lines of perspective in the Ponzo Illusion make the top line appear farther away Why isn’t it this simple for the Muller-Lyer Illusion ?

  26. Size Constancy The lines of perspective in the Ponzo Illusion make the top line appear farther away Why isn’t it this simple for the Muller-Lyer Illusion ? Because the Muller-Lyer figure looks flat !

  27. Paradox of Pictures What does Gregory find so paradoxical about pictures?

  28. Paradox of Pictures What does Gregory find so paradoxical about pictures? What does he do to remove the paradox so that the Muller-Lyer figure no longer looks flat?

  29. Paradox of Pictures

  30. Removing the Background With background removed, Muller-Lyer figure actually looks 3D What prediction can you make about how the perceived size and the perceived distance of the center line are related? How did Gregory test that?

  31. Removing the Background Perceived size and perceived distance are tightly related

  32. Size Constancy in Motion What does Gregory wonder about size constancy and motion? How does he test that?

  33. Size Constancy in Motion Gregory finds that motion does invoke size constancy in certain cases:

  34. Size Constancy in Motion Gregory finds that motion does invoke size constancy in certain cases: only when observer is accelerating

  35. Science Works at Different Scales • What’s the “Big Picture” theory, amid the more specific hypothesis? (hint: look in the first paragraph)

  36. Science Works at Different Scales • What’s the “Big Picture” theory, amid the more specific hypothesis? (hint: look in the first paragraph) • That illusions occur because of perceptual mechanisms evolved to handle vision under normal circumstances

  37. Science Works at Different Scales • What is Gregory’s theory about how the brain accomplishes this?

  38. Science Works at Different Scales • What is Gregory’s theory about how the brain accomplishes this? “it is as though the brain entertains alternative hypotheses of what object the eye’s image may be representing”

  39. Next Time • More on seeing in 3D • Read chapter by Pinker for Wed. next week

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