Are you a tetrachromat?

Riding in on the train of *that* dress – is it gold/white or blue/black a lot of colour vision questions have emerged. Despite people becoming quickly bored after the initial couture virality and now that it’s been around the world’s media 50 times in all its shades, there is still plenty to say. Wired pretty much wrapped up the threads, so I won’t go into that and you can Google it if you really want to see their article.

But, there’s a “spectrum” looking chart of different colourful shades, hues doing the rounds now. If you see fewer than 20 different hues, the article accompanying it says, you’re probably a dichromat, two cones in the retina of your eye or one of the three not functioning in the way it should. If you see between 20 and 32 you’re a trichromat, three fully functioning cones. But, if you see 32-39 different colours you have a fourth type of cone in your retina making you a tetrachromat; colours are much more distinguished apparently, but they’re not so keen on yellow. If you can see more than 39 colours, you’re not a pentachromat, you’re a little fibber.

When I looked at the chart, I thought I could see 36 hues, well definitely more than 32…it seemed to depend on what angle I was looking at my laptop screen and whether my eyes were scanning across the width of the spectrum rather than staring as to whether distinct bands appeared. I couldn’t get a consistent count, definitely at least 32, but possibly just 32. So, I scouted around for an alternative test for tetrachromicity, which looks a bit like the standard test for so-called “colour blindness” (dichromaticity). If you can see anything other than the three obvious colours seen by trichromats, then you’re obviously a tetrachromat…except that…hmmm…

It got me thinking. How can these tests be valid? Computer screens only use red-green-pixels, they cannot display all the hues a tetrachromat would be able to see. I checked around and found another blogger who agrees, an online test cannot demonstrate tetrachromicity. As she says: “computer screens do not provide enough colour information to be able to ‘tap into’ the extra dimension that tetrachromats may possess”. Vision expert, Mark Changizi confirmed this point.

So, if you were counting almost 50 shades hues of colour in that chart and imagining that you somehow have a superpower, well, the odds are against you.

Incidentally, Hummingbirds and Blue Tits are a couple examples of tetrachromats in nature.

Author: bob投注平台

Award-winning freelance science writer, author of Deceived Wisdom. Sharp-shooting photographer and wannabe rockstar.