Somewhat unrelated story, but I used to be in astronomy and two friends of mine were once on an observing run together. Observing can sometimes be a bit dull and as you're getting night shifted it's hard to do anything productive while you're waiting for the exposures to finish. So you're looking for ways to pass the time.
Anyway, somehow my two friends started looking at color blindness tests. One of them had grown up in Latin America and hadn't seen a color blindness test before, so the other was explaining how there's a number in the center that you can't see if you're color blind. And he said... "what number?" That was how he learned at age 26 that he was color blind.
Anyway, somehow my two friends started looking at color blindness tests. One of them had grown up in Latin America and hadn't seen a color blindness test before, so the other was explaining how there's a number in the center that you can't see if you're color blind. And he said... "what number?" That was how he learned at age 26 that he was color blind.