Some people have four differently pigmented cone receptors in their eyes instead of three. The fourth is on the UV side of the normal blue. This is sex linked and is more common in women. Brent On 12/14/2019 6:57 AM, Bill Gosper wrote:
http://www.tweedledum.com/rwg/squares.htm problem 2, can you see the color boundary between "18" and "14"? Maximal zoom. Slide "10" and "4" off the left edge to show only the middle right portions of "14" and "18". Slide up and down. Suspicion: Girls can see it better. Color vision is on the X chromosome. —rwg ("8" and "10" are identical shades of light blue. Proof: TextEdit>Format>Font>Show Colors> <eyedropper>.) I used to grumble at color-enhanced astronomy photos. Until I realized I am colorblind compared to most space aliens. _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun