Alert! Red-green color blindness affects you, even if you don’t have the affliction. Indeed, it could cost you your life!

First of all, it is the most common form of color blindness. It affects males of northern European ancestry (1 in 12) much more than females (1 in 200), and it has a lower incidence in almost all other populations studied, according to the National Institutes of Health.

One in 12 might sound like a small percentage of the population to worry about. Furthermore, why does it affect you if you are not afflicted with red-green color blindness yourself?

Consider this:


If there is a red stop sign in your neighborhood and it is up against a green background like a big green bush, every 12th car with a male driver of northern European ancestry who approaches that intersection might not see the red stop sign fast enough to keep from T-boning your vehicle. Now if that is a busy intersection, that might amount to five to 10 such vehicles per hour who have the potential to run that stop sign.

The same goes for red traffic lights against a night sky. It doesn’t seem to have to be a pure green background for the red to get lost in the visual field. And some pale green traffic lights often look white like other street lights at night, not giving the red-green color-blind driver sufficient notice that he is coming upon a traffic signal and needs to be ready to react in case the signal turns red.

Embeddedness is the culprit

Red-green blindness does not mean that you totally can’t see the colors red and green. If two things, one bright red and one bright green are sitting on a white table cloth, a red-green color-deficient person would be able to identify the one as red and the other as green.

The problem enters when something red is embedded in a green background. In this case, a person with red-green blindness might have trouble picking it out, until it is pointed out to them. The example has already been given of a red stop sign against the background of a big green bush.

Sorting shades of green might be an issue, too.

As a red-green-blindness-afflicted male of northern European ancestry myself, I know I have pulled brown pants out of my closet when I thought they were a dull shade of green. Sometimes socks have gotten mixed up, too. A poorly lighted environment like a closet makes these mix-ups even more likely to occur.


Embeddedness once again poses problems when you are riding down the interstate highway in early autumn and your wife says, “Oh, look at that beautiful red tree on the mountainside.” You say, “What red tree?” because you can’t see it against the rest of the green mountainside that has yet to begin changing colors.

Then she says, “Can’t you see it? It’s right below that cell phone tower about halfway up the mountain.” With those directions, and after dodging five 18-wheelers, you finally notice a tree that looks different from the others. Then it actually starts to appear a bit red to you. That is, you experience what you call red, but my suspicion is that it is never as brilliant as the red your wife sees.


Another time I have noticed my affliction is in playing golf and marking my golf ball on the green with a reddish-copper penny. As an aside to non-golfers, when your ball is in the way of another player’s putt, you put a penny down on the green in place of your ball to allow your playing companion an unobstructed putt at the hole.

The only trouble is, when your playing companion has putted, you have to go back and find your penny. I have looked and looked and not been able to see that reddish-copper penny against the expanse of a golf green.

One solution is to use a dime. But some players might find this offensive because of the reflection off of the shiny dime. This is not to mention that if you lose your dime, you are out nine more cents, an important consideration for me — and Jack Benny — as most of my golfing friends will attest to.

Police cars

Back to safety on the highways. … If my memory serves me correctly, police cars used to have red “bubble-gum machines” on top, a single red light flashing in the middle of the patrol car roof. Think Barney Fife!

In contrast, modern squad cars have a beam of flashing multi-colored lights that can’t be missed by any kind of color blindness. I wonder if public safety took red-green blindness into account when they made that change?


It seems that anything that involves safety (e.g., stop signs, traffic lights) or need for easy identification (e.g., clothing at night, athletic gear, bicycles) should take into consideration the prevalence of red-green blindness in the population. Perhaps the time for blue stop signs has come.

While it is likely too late to change from the green and red traffic light convention we are used to, at least make those reds and greens offensively big and bright and absurdly red and green, so that it would be hard for anyone to miss them, red-green blind or otherwise.

And make it universal that the red lights all flicker, which draws one’s attention to their presence.

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Dr. Tom Dorsel is a “resident emeritus” of Florence now living on Hilton Head Island and serving as a “foreign correspondent” to the Morning News. He can be found on Facebook and at his website,

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