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Why do violet and purple look the same?

  1. Sep 14, 2010 #1
    First of all, thanks to the folks who answered my question about near-IR light. I've got a question about the other end of the visible spectrum now: why does violet (light with a shorter wavelength than blue) look like purple (a mix of red and blue)? Does our long-wavelength cone have some sort of secondary maximum or something like that?
  2. jcsd
  3. Sep 14, 2010 #2


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    It has nothing to do with the sensory neurons (rods and cones) and everything to do with processing. It (purple) is basically a "label" to represent the mixture of red and blue so we can differentiate it from other mixtures.

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    Last edited by a moderator: Apr 25, 2017
  4. Sep 15, 2010 #3


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    I was wondering also whether one can perceive a blue which is even bluer than pure blue by first looking into red light, thus getting the red receptors tired, and then into blue light.
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