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by lucideer 85 days ago
> admittedly, hella rare. Apparently there are less than a few dozen confirmed world-wide

What's actually hella rare is tests for tetrachromacy. Given the total number of people who have ever taken such a test, I think it's reasonable to assume there are significantly more than a few dozen actual tetrachromats out there.
1 comments
mark-r 83 days ago
It's theoretically related to color blindness, so you'd expect it to be as common. But the problem is even if your eye has the extra primary, your brain may not have developed the ability to "see" it. They had to test quite a few people with the proper genetic background before they finally found one.
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lucideer 82 days ago
That's fair but even colour blindness is mostly undiagnosed in practice - even with the comparatively high prevalence & awareness, actual figures for colour blindness are still grounded in speculative extrapolation.

I think it fundamentally comes down to whether your sense anomaly represents a significant disability. Colour blindness is a disability, but not one that's significant for the vast majority of people who suffer from it - I've worked with multiple colour blind graphic designers & they were good at their job. There's very little impetus to even seek diagnosis - if they weren't working in a colour-focused industry I suspect they may not have ever realised they had a disability at all.

Tetrachromacy then is an even harder case because it's not a disability at all. The impetus to seek "diagnosis" is zero. Also, even though as you mention there's technically multiple ways of detecting the various factors that need to coexist in tetrachromacy (i.e. (1) sensory testing, (2) physical presence of extra primaries, (3) neurological processing pathways), the latter two are either not directly detectable or never directly tested for - even in speculative cases of people having a 4th primary, the number of primaries present is generally hypothesised via some other avenue like testing for anomalous trichromacy. Ultimately we're heavily relying on direct sensory testing which is almost nonexistent in the general population. There's no way to accurately speculate on how prevalent it might be.

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