Dunno if this is a late-in-life thing or I was always like this, but I definitely need more blue to see blue than most (this test put me at 82%, I think that means I'm in the lowest quintile for seeing blue?) Bright blue still looks mighty blue, but when light is dim, I basically see black where most would still see blue.

Practical ramifications: * Some of my 'black' shirts are blue when it's sunny * Popular desktop themes (solarized dark) have text that is completely unreadable

I think your monitor or room lighting might just be different from others'

Same here at 82%, although I don’t think I’m seeing blues as black.