Schiffman, Chapter 6

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Schiffman, Chapter 6
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Lateral inhibition

• How neurons are connected in retina enhances
  contrast, edge detection
• Each neuron inhibits firing of neuron next to it

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Tutorial on lateral inhibition

• Receptive Fields as Edge Detectors
• Be sure to click on the full screen slide show
  icon in the lower right part of the screen after
  you get to this page

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Lateral inhibition Mach bands
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Hermann Gridphantom spots

• At intersections of lines or boxes, net effect of
  lateral inhibition is to cause spot of lighter or
  darker appearance than surround
• Note that spot disappears when you look directly
  at it, at least for large illusion displays.
  Why? Size of receptive field is smaller in
  foveasmall enough for lateral inhibition to
  occur even within intersection

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Brightness contrast
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Ganzfeld

• With no patterned light, or with stabilized
  retinal image, ends up looking like diffuse fog
• Visual system needs changing input to keep
  responding