visual perception 2 NBEO.txt

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cjensen20
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305124
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visual perception 2 NBEO.txt
Updated:
2015-07-13 08:35:45
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visual perception NBEO optometry
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visual perception 2 NBEO optometry
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  1. How are sensitivity and threshold related?
    Inversely
  2. What subjective testing methods test threshold?
    • Method of ascending limits
    • Method of constant stimuli
    • Stairstep method
    • Adjustment method
  3. What method is exploited in automated visual testing?
    Stairstep method
  4. What semi-subjective methods test threshold?
    • Forced choice
    • Signal detection
  5. What is the size of resolution acuity?
    30 sec arc
  6. What is the size of detection acuity?
    1 sec arc
  7. What is the size of vernier acuity?
    3 sec arc
  8. What is radiometry?
    Measurement of energy per time
  9. What does a watt represent?
    • Energy per second produced by a light source
    • 1 joule/second
  10. What is radiant intensity?
    • Energy per second in a given direction
    • Watts per steradian
  11. What is radiance?
    Intensity per projected area of source
  12. What is irradiance?
    • Amount of radiant power per unit area of surface
    • Amount of radiant power that hits an object
  13. What units are included in radiometry?
    • Radiant power
    • Radiant intensity
    • Radiance
    • Irradiance
  14. What units are included in photometry?
    • Luminous power
    • Luminous intensity
    • Luminance
    • Illuminance
  15. What is luminous power?
    • Total power produced by a light source in all directions
    • Lumen
  16. What is luminous intensity?
    • Luminance power in a given direction
    • Lumens per steradian = candela
  17. What is luminance?
    • Amount of light leaving a surface in a specific direction
    • Candela per square meter = nit
  18. How many nits are there in 1 foot-lambert?
    3.43 nits
  19. What is illuminance?
    • Power falling on a surface in all directions
    • Lumens per square meter = lux
  20. How many lux are there in 1 foot-candle?
    10.8 lux
  21. What are narrow band filters?
    Allow only a small range of wavelengths to pass through
  22. What are interference filters?
    Transmit only one wavelength
  23. What are broad band filters?
    Transmit large range of wavelengths
  24. What are long-pass filters?
    Transmit only long wavelengths
  25. How do sunglasses filter UVR?
    By use of long-pass filters
  26. What are neutral density filters?
    The transmit wavelengths equally at different intensities
  27. What happens if a neutral density filter is placed over the right eye?
    The planar pendulum appears elliptical and moves in a counterclockwise direction
  28. What happens if a neutral density filter is placed over the left eye?
    The planar pendulum appears elliptical and moves in a clockwise direction
  29. What percentage of rods need to be bleached in order to saturate?
    10%
  30. What are metamers?
    Two visual stimuli which are physically different, but appear identical
  31. What nanometer is most sensitive in S cones?
    • 440nm
    • Cyanolabe
  32. What nanometer is most sensitive in M cones?
    • 535nm
    • Chlorolabe
  33. What nanometer is most sensitive in L cones?
    • 564nm
    • Erythrolabe
  34. What nanometer is most sensitive for rods?
    • 498 nm
    • Rhodopsin
  35. What is the Bezold-Bruke phenomenon?
    Wavelengths show a slight change in hue as the intensity of light is increased
  36. What is the copunctal point?
    Where colors are indistinguishable on a CIE color system
  37. How do you calculate contrast?
    • Example problem
    • Projected luminance 50 units
    • Onto a background of 100 units
    • Contrast = (50-100) / (50+100) = 50/150 = 33 percent
  38. What are monocular clues in depth perception?
    • Pictoral depth
    • Motion parallax
  39. What are binocular clues in depth perception?
    • Uncrossed retinal disparity
    • Crossed retinal disparity
  40. What is uncrossed retinal disparity?
    If the image falls on the nasal side of the retina, the object is perceived to be farther away
  41. What is crossed retinal disparity?
    If the image falls on the temporal side of the retinal, the object is perceived to be closer
  42. What is the Troxler phenomenon?
    The fading of retinal images that are stabilized
  43. What is the broca-sulzer effect?
    Light appears brightest when they last for about 50-100msec
  44. What is the bruke-bartley effect?
    Flicker light of the same luminance appears brighter than steady light
  45. What is masking?
    When one stimulus (mask) decreases the visibility of another stimulus
  46. What is forward/backward masking?
    Mask proceeds/follows the target
  47. What is paracontrast masking?
    Mask appears first and target appears second
  48. What is metacontrast?
    Target appears first and then the mask second
  49. What does the parvo pathway detect?
    Detail color, and object size
  50. What does the magno pathway detect?
    Motion

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