Demonstration of Blind Spot

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Demonstration of Blind Spot

• J.W. Whitlow
• Rutgers University

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Basic Phenomenon

• The next slide has a cross on the left and a
  circle on the right.
• Close or cover your left eye, then look at the
  cross with your right eye.
• Move your head slowly either toward the screen or
  away from the screen, staring at the cross with
  your right eye, until the circle disappears
• When the circle disappears, you have found your
  right eyes blind spot.

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Variations on Basic Phenomenon

• The next slide has a colored background with a
  brightness gradient that is darker behind the
  cross and lighter behind the circle
• Find your right eye blind spot
• Is the brightness at the blind spot darker, like
  the gradient behind the cross, or lighter, like
  the gradient behind the circle?

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Variations on Basic Phenomenon

• The next slide has a cross on the left and a
  circle on the right
• The circle has been marked off by a ring
• Find your right eye blind spot
• Determine whether or not you can see the ring.
  If you cannot see the ring, adjust its size to
  make it larger.

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Variations on Basic Phenomenon

• The next slide has a cross on the left and a
  circle on the right
• The circle has been marked off by a ring filled
  with color
• Find your right eye blind spot
• What color is the area where the circle was
  before it disappeared?

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Variations on Basic Phenomenon

• The next slide has a cross on the left and a
  circle on the right
• The circle has been marked off by a ring filled
  with a textured coloring
• Find your right eye blind spot
• What texture is the area where the circle was
  before it disappeared?

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Variations on Basic Phenomenon

• The next slide has a cross on the left and a
  circle on the right
• The circle has been marked off by a ring filled
  with colored stripes
• Find your right eye blind spot
• What happens to the lines that go through the
  blind spot?

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Variations on Basic Phenomenon

• The next three slides have a cross on the left
  and a circle on the right
• The circle has been marked off by a ring filled
  with a color
• The ring around the circle is smaller in each of
  the slides
• Find your right eye blind spot
• What happens as the ring gets smaller?

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Concluding Remarks

• What do your observations suggest about the
  visual processing mechanisms that produce the
  blind spot?