from Hacker News

Tetrachromatic Vision

by surprisetalk on 6/14/25, 2:53 PM with 38 comments

  • by crazygringo on 6/17/25, 10:25 PM

    > The first known human tetrachromat, an English social worker identified in 1993, sees 10 distinct colors looking at a rainbow, whereas the rest of us see only five.

    What does this even mean? It's setting off my BS detector.

    I can see as many colors in the rainbow as I want, since colors are culturally determined. Cyan is prominently there in the rainbow, even though most people don't include it in the traditional "Roy G Biv" -- red, orange, yellow, green, blue, indigo, violet. Speaking of which, where did 5 even come from in that quote? I mean, the fact that we can argue over how many colors the rainbow has just shows how unscientific such a statement is.

    If there's anything potentially scientific here, you could say that humans see three primary colors associated with the three cones -- red, green, blue -- and therefore three intermediate colors -- yellow, cyan, magenta. A fourth cone between red and green means that it might be possible to see 8 primary and intermediate colors instead of 6. But it also might not do much of anything at all, if it's then mapped to our existing opponent process [1] that is fundamentally based on red vs. green and blue vs. yellow. In other words, it would just be a redundant or ignored sensory input to our conceptual color processing.

    [1] https://en.wikipedia.org/wiki/Opponent_process

  • by lizknope on 6/18/25, 2:07 AM

    I remember this article from a few years ago about a tetrachromat artist.

    https://concettaantico.com/

    https://www.theguardian.com/society/2022/jan/30/im-really-ju...

    https://munsell.com/color-blog/tetrachromat-artist-concetta-...

    Many flowers have patterns only visible in ultraviolet. Many pollinators can see ultraviolet and these patterns on the flower direct them to the pollination areas.

    https://en.wikipedia.org/wiki/UV_coloration_in_flowers

    http://www.naturfotograf.com/UV_ANGE_SYL.html

    The lens in our eye filters out a lot of UV.

    After Monet had cataract surgery his color perception changed so his later paintings have a different color balance.

    https://jamanetwork.com/journals/jamaophthalmology/fullartic...

  • by IAmBroom on 6/20/25, 1:01 PM

    A lot of false assumptions are going on.

    Tetrachromats are not seeing four well-separated colors. They are seeing the exact same blue-area and green-area colorrs, with two different cones responding slightly differently to red-area light.

    So, instead of a color looking RGB(200,100,100) to them, it might look (200.26,100,100).

    The very slight difference is why it's so hard to detect in people, and frankly, doesn't affect much (which is why there's apparently very little evolutionary "pressure" on the color genes).

  • by TomMasz on 6/18/25, 11:06 AM

    Kind of the opposite of colorblindness, where people (mostly male) see fewer colors in the rainbow and are often unaware of it.
  • by sublinear on 6/18/25, 12:44 AM

    I can't find any consistent estimates on prevalence or whether this is strictly X chromosome related (why it's assumed that only females can have this).
  • by oofbey on 6/17/25, 9:16 PM

    At some point the world's gonna figure this out and start making tetrachrome cameras and screens and it's gonna be the next big TV upgrade after 8k.
  • by _vaporwave_ on 6/17/25, 9:25 PM

    Is there a simple (visual) way to test for this?
  • by supermatt on 6/18/25, 6:12 AM

    Impossible to read on an iPhone. Undismissable ad obscuring top part of screen. https://imgur.com/a/W1yweDQ
  • by spondylosaurus on 6/17/25, 10:54 PM

    When I learned about tetrachromacy as a kid I remember being devastated for like a week afterwards that I wasn't one too. It felt like discovering that superpowers are real but that you'll never have any :P