Seeing Spots

Dr. Shinobu Ishihara created some of the most beautiful designs of the 20th century. Large spots composed of seemingly random patterns of smaller dots in various diameters and colors. I looked at them occasionally as a kid, wishing that I could have them to keep, as wall paper or curtains or clothing. But the only time that I was permitted to look at Dr. Ishihara's artwork was when I visited the eye doctor.

To me Ishihara's colorblindness tests have the chaotically gorgeous aesthetics of chameleon skin: a jumble of tiny scales whose pigmentation tends to change over time. But someone with better working cones receptors might see numbers or shapes embedded in these designs.

Do you see numerals embedded in these dots? I don't, at least not on the examples I've given here. I do a suggestion of numerals in some of these patterns, but in none of these could I tell you (or an eye doctor) what they are.

For folks with fully functioning cones, this example can clue you in as to what I do see. On the far right is how a person with X-linded reg-green colorblindness might see an Ishihara image with mixed pigment dots—that's not what I see. I'm the example in the middle—"partially colorblind"—and, truth be told, the leftmost image and the center image look identical to me.

When was your last Ishihara test? You can take one version of the test here. 38 plates, starting with number identification and then moving onto counting squiggly lines. It tracks all your answers and then grades each one as "correct", "partially correct" or "wrong", comprising an overall rating of red-green color blindness. I felt like my color blindness was strong, but it rated me as "moderate". If you take the test, I'd love to know your results and experiences. Leave them in the comments below.