Color blindness

I am color blind.

Well, not really.  My color vision is fine, thank you.  However, my color vision is abnormal.  That doesn’t mean that it is bad.  It just means that it is different from what is typical.

I should note that I am posting this because I intend referring to it in a future post about human cognition and perception.

Growing up

As a child, I had no idea that there was anything unusual about my color vision.  The world looked the way that people described it, as best I could tell.  I developed an interest in electronics, and I never had any difficulty with the color coding of resistors and other components (giving the resistance as a series of color bands).  As far as I could tell, my vision was normal.

Discovering the problem

In my last two years of high school (in Australia), we were encouraged to participate in a cadet program.  This was something similar to the ROTC program in the USA.  So I signed up to be an air force cadet.

As part of that program, we were give a vision test, which included a color vision test.  That’s where I learned that my vision was not normal.

I was given a test somewhat like THIS ONE.  I was shown cards with coloured dots, and asked to identify the numbers.  (I’m using the Australian spelling for “coloured” since that was where I was tested).

The examiner told me that I am blue-green color blind.

I’m not really quite sure what that means.  Looking at various web pages, I suspect that my condition is “deuteranomaly”.  That is said to be the most common color vision abnormality.  And the online color vision tests seem at least partly compatible with that conclusion.

(The spell checker doesn’t like “deuteranomaly”.  It wants to change it to “Deuteronomy”.)

Apparently my vision abnormality disqualified me from pilot training in the air force. And perhaps it qualified me for being able to detect camouflage from the air.

Online color vision tests

There are various online tests for color vision.  You can easily find them with google or other search engine.  But they are not very good.

I can go through the online tests.  And it is clear from those tests that I have an abnormality.  But it isn’t clear which abnormality.

Here’s the problem.  If I try the tests on my laptop computer, I get somewhat different results from what I get on my desktop computer.  The test is sensitive to the details of how a color computer monitor screen works.  And the monitor screen is tuned to people with normal vision, so the contrasts that it present don’t quite work the right way for people with abnormal color vision.  If I really want an accurate diagnosis, I would need to do that some other way.  However, it isn’t important enough for me to bother.

Ordinary life

How does my abnormality affect ordinary life?  Very little, as far as I can tell.  For almost everything that I do, I never notice a problem.

There are, however, two exception.  And I’ll describe those.

My blue car

For a while, I was driving a blue car.  It was a Toyota Corolla hatchback.

Well, I called it a blue car.  My wife always corrected me, and said that it was green.  So I’ll consider that an example from ordinary life, where something became apparent about my color vision.  Again, it was not crippling or problematic in any way, except that my wife disagreed with me over the color of the car.

According to the manufacturer’s specification, the car was actually “metallic blue green”.  So it was on the border between blue and green.  I could see the greenness there,  but I saw it as blue with a greenish tinge.  And I guess my wife saw it as green, with a bluish tinge.

A disagreement on whether blue-green is closer to blue or closer to green never seemed like an important issue.

The linux command line

The only other place where I might be seeing an issue, is the linux command line.  In a newly installed linux system, the bash shell is usually given aliases to show the output of some commands in color.  So, for example the “ls” command (for listing file names) colors the name depending on the type of file.  I find that colored output hard to read.  Some of the colors do not have enough contrast.  So I always disable those aliases.

I’m not sure whether this is related to my abnormality.  I presume that the choice of colors works well for people with normal vision.  But I don’t know that for sure, since I don’t have normal vision.  I only know that the coloring does not work well for me.

Summary

So there you have it.  My color vision is a tad off.  There isn’t anything to be done about this.  And there really isn’t anything that needs to be done about it.

John Searle titles his perception book “Seeing things as they are”.  Assuming that Searle has normal color vision, then the way the he sees things is a little different from the way that I see things.  Which one of us is seeing things as they are?