Tetrachromats and That Graphic.

/Tetrachromats and That Graphic.

Hey, you know a few months back, when The Dress Thing was going on, there was all that hoo-hah about people who were “tetrachromats”, i.e. had four cones in the eye rather than three, and could therefore see octarine or whatever? And there was that rainbow graphic with the thirty-whatever colours that people passed around on Tumblr that was supposed to tell you whether you were a Magic Eye based on how many of the bars you could count?

Yeah, remember that?

Well it was all fucking bullshit. Here. Here’s some science about it. Tl;dr, tetrachromatic humans are a real thing, and their existence is linked to the existence of colourblindness. But the population of functional tetrachromats, i.e. people who can actually see a fourth primary colour, has only even been estimated at two. Ever. And yes, people have been looking. For decades.

Also, even if you were a tetrachromat, you couldn’t tell by looking at a computer monitor, because a computer monitor only displays light mixed from red, green, and blue.1 Nobody thought to include a fourth octarine colour mixer because 98% of all humans ever only see in red, green, and blue. And the 2% discrepancy is mostly people who are dichromatic, i.e. only see in mixes of two colours, plus a handful of people with aphakia, or damage to the lens of the eye, which allows them to “see” UV.2

So, no. You’re not a magic special extra-colour perceiving snowflake.

On the other hand, you might be–or might know someone who is–colourblind, and the linked article talks about that, too. Colourblindness isn’t very well understood by most people, I don’t think, despite it being relatively common (my husband has it, for example). I blame all the bullshit pseudo-intellectual “but how do we really know what other people see” rubbish, as if that question actually mattered. Scientifically, everyone perceives colour slightly differently because everyone’s eyes are slightly different in the same way everyone’s everything is slight different because evolution. But that doesn’t mean we can’t simulate what colour blindness looks like based on what we know about how eyes and the light spectrum work. The subjectiveness of the experience is completely irrelevant because you’re comparing apples to apples, i.e. your own subjective colour perception versus your own subjective colour perception. No philosophical bullshit necessary.3

Science!! It’s fucking magic!!!

  1. Each “pixel” on your monitor is made of three tiny lights: one red, one green, one blue. When your monitor wants to show you an image, it sends a signal instructing each of those lights in each pixel to adopt a certain brightness, measured from 0 to 255 or, if you prefer, 00 to FF. Kind of like a really big/tiny cross-stitch pattern. On shitty old CRTs you can actually see the tiny individual lights if you get super, super close. Modern monitors, not so much. The technology is more-or-less the same. The execution is just much, much smaller. ^
  2. “See” is in quote marks because these people still only have three cones, none of which perceive UV as a primary colour in the way, say, bees do. The difference is that, in most people, UV light never hits the retina because it’s filtered out by the lens. With aphakia, the lens is damage and UV light is not removed. People who can see it report UV as bright white-blue or white-violet, a.k.a. the colour we all see when all of our cones are activated. People with aphakia just see it in different places than non aphakic people. ^
  3. Is this the hill I want to die on? Oh yes. Yes, yes it is. Come have a dinner conversation about it with my father sometime. Then you’ll see. ^
2016-05-14T10:30:37+00:004th May, 2015|Tags: science|