How does science know that a dog is color blind?

[pravnik]

@Pyper

Interesting. I was able to see all three of those images after a few seconds of examination, even though I am not colorblind.

Are you sure?

[EdwardLost]

I’m colorblind and I failed all of those tests.

I’ve concluded that my problem is a decreased sensitivity to red. I don’t experience green=brown. My biggest pain is distinguishing purple from blue.

[BigT]

^That’s a deficiency in a different cone type–I believe the blue-yellow one.

Also, one thing I’ve always found interesting is that, in theory, only two cones are needed, along with the rods for determining shades. Heck, JPEG compression takes advantage of this fact–along with the fact that our rods are more sensitive than our cones.

[Spectralist]

@pravnik

Incidentally, can any of the non-colorblind people here see the word on this page’s Reverse color blindness test? (scroll down to middle)

Not really. My guess had one of the letters right but not the other letter and I was by no means confidant even on the one I had right.

@pravnik

ETA: or these?

Didn’t get either of those. Interestingly the bottom one is very apparent after seeing the answer key but the top one isn’t

@Pyper

Interesting. I was able to see all three of those images after a few seconds of examination, even though I am not colorblind.

Keep in mind that different monitors all display colour and luminosity somewhat differently so tests like these probably aren’t reliable on a screen that hasn’t been intentionally calibrated for them. The “Red Spectrum Gradient” one, for example, is very apparent on one of my monitors but not on either of the others that are currently hooked up.

[SciFiSam]

@pravnik

Incidentally, can any of the non-colorblind people here see the word on this page’s Reverse color blindness test? (scroll down to middle)

ETA: or these?

I could see the word in the first one OK, but that was mainly because it said it was about luminosity, so I looked for a pattern in the white bits. Nothing jumped out at me, but I could see it when I tried.

In the second one, I could see the top one immediately, but funnily enough the colours were different to the linked answer - I saw the symbol as pink, not grey. I couldn’t see anything in the second one at all.

Often I find myself pointing out colours as being different from one another and everyone else saying they’re the same, when to me it’s not even that subtle a difference.

Thanks for the interesting link, and John DiFool’s one was fascinating too - seeing the world through other people’s eyes.

[Eyebrows_0f_Doom]

@pravnik

Incidentally, can any of the non-colorblind people here see the word on this page’s Reverse color blindness test? (scroll down to middle)

ETA: or these?

All three of those seemed pretty obvious to me and I am definitely not color-blind. I mean, they look like they are trying to be hidden within the image, it’s not like black on white, but I could tell what they were with just a glance.

They were “No,” the number 6 and a circle, right? Or was that supposed to be obvious and I missed something else?

[elfkin477]

@EdwardLost

I’m colorblind and I failed all of those tests.

I’ve concluded that my problem is a decreased sensitivity to red. I don’t experience green=brown. My biggest pain is distinguishing purple from blue.

Hmm. I have trouble with some shades of blue and purple too, but as far as I know I’m not at all color blind - I’m female and there’s no family history, so it’s unlikely anyway. Anyway, we used to use post-its that were slightly lighter than this, and 98% of people insisted that they were blue. A few of us see that as purple. I have trouble with other things that are either lavender or slate blue as well.