Capitalizing on the web's weird dress fetish the other day, an inaccurate Linkedin article about tetrachromacy (having 4 types of retinal cone cells instead of the usual 3) wormed its way off the internet and into 3 million people's heads. The article offered a bar of 39 web-safe colors (pictured above) and told readers that the number of colors they saw indicated the makeup of their cone cells. This article was so misleading, I refrain from even linking to it, but I will point you to this video that gives a fun 5-minute crash-course in cone science. I've also posted some reputable sources at the bottom of this post.
How (aside from spelling and grammatical errors) was said Linkedin article inaccurate? Let me count the ways:
- The title statement, "25% of the people [sic] have a 4th cone"is false. Only the half of us with two X chromosomes (primarily women) are eligible to have four types of cone cells (RGB+1), and of these a possible 12% are tetrachromats, meaning that only 6% of "the people" (half of 12%) can have a 4th cone. Of these 6%, very few are functioning tetrachromats: that "+1" cone is akin to the low-functioning mutant cone in X-linked colorblindness (see #3 below).
- An online rainbow will NOT tell you if you have a 4th cone. Because color monitors are trichromatic (RGB) like the cones in our eyes, they do not produce colors that trichromats cannot see.
- The statement, "You are dichromats, like dogs," is not true for all people who have trouble differentiating color. In common X-linked color blindness, a third cone is present instead of the red or green cone, it's just low-functioning. Many color-impaired people have other retinal disorders, such as cone dystrophy or macular degeneration, which can limit perception of color. They are not dichromts.
- Saying that colorblind people, "are likely to wear black, beige and blue," is baloney. Colorblind people often ask color-seeing friends to help them pick out and label clothes and advise them as to what matches with what. Or they just go through life wearing whatever.
- Also false: "25% of the population is dichromat" and, "50% of the population is trichromat." Almost everyone (at least 94%) is trichromatic.
- Saying that tetrachromats are "irritated by yellow" and therefore own no yellow clothes is a sham Just as with the "black, beige and blue" statement from #4, the author is picking colors that tend to be popular or unpopular and misleading readers into thinking that they are retinal mutants.
- Finally, who in the world puts a winky-face with its tongue hanging out in the title of their article and expects it to be taken seriously? 'Nuff said.
Further reading:
- Good popular science article on the subject: Greenwood, Veronique. "The Humans with the Super Human Vision." Discover. August, 2012.
- A little more academic: Katta, Samata. "Ask a Neuroscientist: Human Tetrachromacy." Neuroblog. Stanford University. December, 2013.
- Again, this short video from Blue Man Group gives a quick introduction to how rods and cones work.
- And this podcast piece about tetrachromacy is as excellent as it is entertaining:
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