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Reason behind so called Optical illusion or Simultaneous contrast

  1. Dec 20, 2011 #1
    Hello everyone,

    I am really looking out for some literature which has reported the physics behind the occurrence of the phenomena in which two blocks of same color seems different when kept in different background. I have attached an image which depicts the query in a very evident manner.

    I would be really happy if you can kindly send me the reasons for this.

    With best regards

    Attached Files:

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  2. jcsd
  3. Dec 20, 2011 #2

    Doc Al

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    I would think that this is more a question of biology and visual perception than physics.
  4. Dec 20, 2011 #3

    Andy Resnick

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    According to "Basic Vision: an introduction to visual perception" by Snowden et. al., the underlying reason is that the last layer of cells in your eye, the retinal ganglion cells, perform some intermediate optical processing prior to the next stage of vision- the lateral geniculate nucleus.

    The retinal ganglion cells signal the presence of edges or rapid changes within their visual field, and are classified as either 'on-center' or 'off center', depending on what happens to the firing rate when light hits the center of the visual field. Each retinal ganglion cell has concentric and antagonistic receptive fields to accomplish this function- the phenomenon is called 'lateral inhibition', and is responsible for the illusion you showed in addition to a few others: the Hermann grid and the Craik-O'Brien-Cornsweet illusion.
  5. Dec 22, 2011 #4
    I very well agree to your reasons given for the phenomena, but suppose when i image this through camera it should have given me the same RGB value at center boxes. But does this really occur. I am really looking out for the physics behind this if it has been quoted anywhere.
  6. Dec 22, 2011 #5
    There isn't any physics behind it. It's about how our brains process things.
  7. Dec 23, 2011 #6
    Can somebody else please comment on this phenomena..??
  8. Dec 23, 2011 #7

    Andy Resnick

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    Suppose you try it and tell us.
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