Wednesday, March 14, 2007

Ishihara cat test

What number do you see in the following picture?

When we went for a walk over the weekend, we were followed by a large dog and a little Dusty camo cat.

This picture reminded me of those round pebbly tests for colorblindness, so I looked up the name just now (Ishihara). I was surprised to also learn that up to eight percent of men may be colorblind. That goes a long way towards proving the theory that men don't talk. Sure they talk, some more than others, but... well, numbers don't lie.

If you'd asked me yesterday, I'd have said that in all my life, I'd only known two colorblind men. One was my grandfather, and when my step-uncle told me about it (during some fairly recent geneological questioning) I was astounded. I was 18 when he died and had never suspected. Never had a clue. Neither he nor my father had ever told me. (And this wasn't some distant grandfather in another state who I only saw once or twice a year. This was Pop, who ate supper with us almost every night of the week.)

The other colorblind man I'd known was the boyfriend of a roommate, and actually it was my (female) roommate who'd told me. Probably when I'd known her for a few months.

Can you imagine knowing a woman for any length of time at all and not knowing that she was colorblind? Only one half of one percent of women are born colorblind, so it's not surprising to never have met one. But to think that up to one in twelve men are colorblind...! Now I can't stop wondering how many colorblind men I may have known. And how they could possibly keep such a thing to themselves.

The article referenced above does go on to say:
From a practical stand point though, many protanomalous and deuteranomalous people breeze through life with very little difficulty doing tasks that require normal color vision. Some may not even be aware that their color perception is in any way different from normal. The only problem they have is passing color vision tests.
I used to have a periwinkle dress that I loved and wore often. You could also call it lavender-blue. I realized that different people called it different colors. I mistakenly called it cornflower blue myself at first, because in truth it was between a cornflower blue and a periwinkle. A dark periwinkle, you might say. But nobody else said that. They only ever said it was purple, or sometimes, blue. People thought I was nuts because I'd always go around asking, "What color would you say this dress was?" But I never did figure out if people called it just "purple" or "blue" due to different color perceptions, or lack of a colorful vocabulary, or what. Maybe they just wanted to get rid of me in a hurry.

Wow, I'm really rambling now. If you've stuck around to read all of this, I really like you a lot, even if you're colorblind and haven't told me.


Anonymous said...

I'm colorblind. Don't want you to think that I'm hiding anything.

I am what they call red/green colorblind. I know that red and green are different colors but I have trouble telling which is which.

A cardinal sitting on a limb of a juniper - totally invisible to me. However if it is pointed out to me, sometimes the cardinal will mysteriously change color and appear. I suppose the brain compensates somehow.


prairie point

Clare said...

About the dress, you see to men there are only six colours, at the most. Peach is a fruit, salmon is a fish. Periwinkle?

Being colourblind bars one from being a member of the RCMP, but I knew one colourblind member. He actually cheated on his "ishihara" test. Just as he was about to be given the test the doctor was called out of the examination room. He looked at the back of the cards and quickly memorized what the numbers were supposed to be.

lisa said...

I dated a man who was colorblind, and he DID talk about it. What he didn't tell me about were his dentures! He was only 46, but had bad teeth all his life and got dentures right before we started dating. I never knew until I came across denture cleaning stuff in the bathroom when I moved in. He also colored his hair, another tidbit I figured out on my own. So I guess the disclosure of secrets is directly relevent to how many you are keeping! BTW...the secret that ended our relationship was the fact he'd been married 4 times, not 3...and he still "got together" with an ex from time to time! Guess it's easy to lose count...

Your other sister-in-law said...

Your sister-in-law, Linda, is color blind. Our shopping trips include arguing about the colors of clothes.

Nuthatch said...

I find red/green colorblindness in men is quite common, and I discovered it training bird banders who need to distinguish some very subtle reddish colors in plumage or bird eyes. I don't think they'd be considered color blind in any classic tests, but when it came to these sorts of indistinct separations, a lot of guys were really awful at it.

pablo said...

Colorblindness is a key plot point in the film Little Miss Sunshine.


Ki said...

I just read in Discover magazine that researchers doing studies on colorblindness think that color blind early humans may have had an advantage in hunting concealed prey. Studies done with capuchin monkeys foraging for surface insects show that colorblind ones made nearly 20 capture attempts while the normal vision ones made only about 16 attempts.

Apparently the reduction in color signals made texture and brightness more evident so it made it easier to see past the color camouflage.

KFarmer said...

I've only known one color blind person and it was a female. Her younger sister used to tell her before school what matched- and it didn't. Good thing she was a good sport- still is :)

Rurality said...

Thanks for the comments! I learned a lot.

Bill, I think that is the most common one. It's the one my roommate's boyfriend had. He said he always bought a lot of blue clothing because he could see it so well. Interesting about the cardinal... Now I wonder if that's what's happening sometimes when I'm trying to point out a tanager to someone.

Clare, it's interesting how women tend to differentiate between shades so much. And it's not just fashion -- I have no clue about fashion or clothes but I do tend to say peach instead of orange, for example.

Lisa, that's funny! I am usually totally oblivious to dentures, wigs, etc. Most of the time I never notice, when everybody else thinks they're completely obvious.

OK, now, is Linda really colorblind, or does she just not differentiate so much between colors? (I asked hubby about this and he didn't have a clue.)

Nuthatch, that's interesting. Especially when men are supposedly more visually oriented than women.

Pablo, I've heard that, but haven't rented the movie yet. (I want to.)

Ki, I wondered about that before. But it seems like it would have the opposite effect.

KF, I suspect that like me, you have known lots of men who just haven't revealed themselves!

Floridacracker said...

Most color blindness is pretty mild... not the black and white version people picture.
Back in the day of Smith Corona pop in, pop out ribbon cartridges, I typed a term paper half in black and half in a dark green.
My girlfriend pointed it out and I could not see the difference unless I took the paper to the bright window and angled it just soooo.

So count me in the 1 in 12 club.

Xris said...

The kitten looks like a 4 to me.

I'm a color-sensitive male. I often dream in color. I notice subtle differences in colors. Made my partner nuts when we selected paint for the house.

El said...

Hi Rurality

What Ki said.

I've also read recently that there is some kind of advantage, militarily, in having a colorblind member in each platoon or unit or whatever in that s/he can suss out the camouflaged enemy. (Hmm, I say.)

I'm sure this gene was passed on for a reason, yes?

Rurality said...

FC, interesting! And yet you're such a fan of Christmas. :) Maybe this is just something that does not come up in everyday conversation. (Still not buying that excuse for my grandfather though!)

Xris, you are entirely correct! That IS the right answer.

El, that's an interesting concept. I really wonder if there is some biological advantage, or if like bad eyesight, it has just multiplied because it's not that important of a defect nowdays?

I wonder if colorblind people have ever noticed that there are certain color-related things that they do better than other people? (I have not found that my defective myopic eyesight has helped with anything at all!)

Cathy said...

I see that Pablo already mentioned the fact of color-blindness in "Little Miss Sunshine". Oh yes! Do rent it and don't let the first 15 minutes discourage you.

Ontario Wanderer said...

I just mentioned to another person in another context that I see colours differently in each eye. He responded that he too had the same experience. From what I have read, and observed, colour is a very subjective experience. In art classes some people are much more sensitive to colour changes than others and context, light, surrounding colours and textures can all affect colour vision. I wonder what "colour" the world "really" is. I've read that at the microscopic level colours start to disappear.

Maktaaq said...

What was wrong with the first fifteen minutes of Little Miss Sunshine?

Rurality said...

OW, hmm differently in each eye? That's a new one for me -- I just checked to be sure, and yep, it's the same for me in each eye.

I've been wanting to see Little Miss Sunshine but will probably have to wait a bit longer. Hubby doesn't have much free time and I'd rather we watch it together. At this rate it'll be on broadcast tv before we see it!

Anonymous said...

Men are more likely to have some degree of colorblindness than women because the gene(s) for color vision are associated with the x chromosome. Since we women have two "x's" we have a backup in case one is defective, whereas men (possessing the xy configuration) have only one shot at functional colorvision.

As was already mentioned, colorblind men may have had an advantage as hunters. Certainly color vision was essential to women as gatherers. The inability of a berry picker to differentiate between a poison red berry and a benign blue berry could have fatal consequences for the whole tribe.