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Comment by sandworm101 | Hacker News Reader

Funny colorblind story. Back when I joined the military i had to do every eye test imaginable. I was already deep into a multi-month recruiting process when they sent me for an "update" at a base. The medic handed me one of those color dot flip books, the ones with numbers hidden amongst the dots. I read out all the early numbers easily but then hit a page of colored dots with no discernible pattern. Seeing my career ending before it could even begin, as the medic reached for the book I locked onto it with a death grip.

"Can't see any numbers? Your done."

"No! Give me a minute. I know I'm not colorblind."

"No. You are done. Only people who are colorblind see numbers in the last pages."

I had bent several creases in their book.

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There's a genuine military use for colour-blind people.

They're better at detecting camouflage than trichromats.

But not in the trade for which I had applied. Any trade involving extensive maps/charts, and everything associated with aircraft, are usually closed to those suffering common forms of colorblindness.

Tell me about it. During basic training (1983) the sgt was introducing us to camouflage.

Something like "Out there are twenty soldiers hiding and you can't see them!"

Me: Raises hand, "Permission to speak? Yeah, there's one there, and there, and over there..."

Sgt: "Your colorblind, right? Drop and start pushing the ground down until I'm tired."

And after pushing the ground I hope he made you the designated camouflaged-enemy spotter? This is a really cool superpower to have.

I honestly had no idea that this was a thing, but I guess it makes sense; colour blind people do see colour, but they see it in a different way, which could be leveraged to spot things people with normal vision don't.

I guess that also means that every squad should have one colour blind person, and camouflage should be designed to foil colour blind people too. Of course there are different kinds of colourblindness, which makes things more complicated.

Yes, designated for that and night patrols (I used to have spectacular low-light vision).

> Drop and start pushing the ground down until I'm tired.

I've never understood, and feel I have no intuition for, responses like this. What's the value added by this? Any excuse for exercise? Internalising that the sergeant is always right even when they're wrong? Or is "permission to speak" just a Hollywood affectation not really present in the military?

You have a very good moral compass for perceived injustice. But theres nothing wrong with someone in the militairy doing push ups. There IS something wrong with questioning authority because you can see campuflaged soldiers, which was probaly the training other recruits were supposed to be doing but some smartass with good colorblind eyes ruined it for them.

Technically, soldiers absolutely are (legally) required to question authority in some cases (e.g. if they think an order is immoral, like participating in a genocide or murdering civilians or torture). In practice it provides more utility to stomp out any desire to challenge or question authority though because if a soldier spends time critically thinking about an order they're given, that's time they're not spending being highly alert or implementing that order.

> But theres nothing wrong with someone in the militairy doing push ups.

Sure, it's the "until I get tired" (emphasis mine) part that's the main surprise to me. The extremity, more than the specific exercise.

That's just humor.

Basic training filters out anyone who would object - same reason there are so few smart people in the police.

Basic training filters out the stupid: those who cannot understand that there is a proper time and place to be a talkative smartass. Basic training is about learning, not showing off. Anyone who cannot check thier pride, check thier attitude, for a few weeks will not make a good soldier.

I guess it also filters out people who would object to gleefully torturing people in the most inhumane way possible [1]

[1] - https://en.wikipedia.org/wiki/Abu_Ghraib_torture_and_prisone...

Yes. Basic isnt like the movies: a quick few weeks afterwhich one is a soldier. Basic is only the very start of training. More advanced stuff comes later at more trade-specific training. Basic is deinitely not the place to test potential soldiers for such problems.

Smart people don’t even make it to police basic training. If the application test shows you are intelligent, you will be rejected from joining the police. At least in the USA.

You are correct. Any excuse for exercise and dominance (sgt is always right) in basic training.

The "permission to speak" is to train discipline and to prevent chaos. After basic, it pretty much goes away except in outstanding circumstances (eg, addressing a very high ranking individual).

I lost a link to the study, but I read somewhere that color blindness is a feature that lets you see colors better during twilight, and lion share of it is registered in folks in more northern population (white and mostly men) where average twilight is the longest.

Haha - I have an opposite experience. When i finally went to MEPS i found out i was colored blind. I had gone my whole life without doing any of those colored charts. Sometimes a dark red would look black, sometimes a blue and purple looked very similiar but i never really thought anything of it.

Turns out it disqualified me for around 70% of all jobs in the Air Force. Turned out to be a blessing in disguise because of the jobs left, they were the likes of Computer Systems programming, contracting, intellegence, etc. It made sure i wasn't going to be working in some warehouse doing electrical, or gaurding some gate as security forces.

I have done that book during an eye test - or at least a similar one. I could read the numbers on maybe the first five pages, then nothing... Optician flipped to the last 4-5 pages and asked me to try again, I could read those numbers! :-(

I would describe myself as a sort of green/brown colour blind - at least I know which colours cause me issues.

The vast majority of people that are colour blind primarily have trouble with green/red. I would say green/brown falls under that category.

> "No. You are done. Only people who are colorblind see numbers in the last pages."

Do they have special ink and printers for color blind/ tetrachromats?

No need for that.

Basically, you add noise to the picture that can only be picked up by non-colour-blind people.

Can a non-colorblind see the numbers in dim light, when color vision is "turned off"?

There are multiple versions of colour-blindness.

Most colour-blind people can still see colours. Only a small fraction is reduced to greyscale.

Those pictures would likely be calibrated to the different versions of colour-blindness.

Your idea might work for some pictures.

If the dotted image has a mixture of different hues and brightnesses, your brain only sees noise, while a color blind person doesn't see the different hues. The number is shaped only in brightnesses arrangement.

However, I've been told my color blind friends that they don't work so well depending on your type.

For years, I had a poster which looked like your average Ishihara test in my office - an assortment of random dots. If you had normal colour vision, that is.

If you were the right kind of deficient, though, it read 'Color vision? We don't need color vision where we are going!'

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