How are colourblind people able to recognize the colours when they put on the special glasses, they have never seen those colours, right?
In: Biology
**Background**
To humans, all colors are merely a combination of red (R), green (G) and blue (B). We have cells in our eyes (called cones) that compare intensities of RGB. Why RGB? The colors R,G, and B are spaced distinctly far apart on the color spectrum. And the more distinct and farther apart the cones are on the color spectrum, the wider range of colors we can see, and the more precisely we can tell them apart.
**Explanation**
These glasses only work for a **specific kind of colorblindness** where the green cones mutate to become more sensitive to the neighborhood of red, orange and yellow light and less sensitive to green. So now when red light comes in, the brain still gets an signal from the green cone, which is wrong. Also, when green light comes in, the green cones, which the brain usually expects to turn on, don’t. This overlap of sensitivity between mutated green cones and red makes it hard to tell colors between red and green apart.
These glasses help by blocking wavelengths of light between red and green, thus exaggerating the difference such that the mutated green cones can function a bit more like normal green cones. With this comparison ability somewhat restored, the “color-blind” can better discriminate in that otherwise problematic area of red through green.
You have color receptors in your eyes known as ‘cones’. These cones are tuned to one of three different wavelengths of light (generally, red, green and blue). They react most strongly to the exact wavelength of their tuning, but they also react less strongly to color near that wavelength.
Lastly, you have ‘rods’ which detect overall brightness.
So let’s say I shine a pure yellow light in your eyes. Your rods will give you a clue about how bright the light is. To determine the color, your red cones will detect the yellow light as somewhat distant (dim), your green cones will detect the yellow light as relatively close (bright) and your blue cones will detect the yellow light as somewhat distant (dim). The combination of all this information allows you to guess ‘yellow’ as the color of the light.
However, while this system works fairly well for pure wavelengths of light, it doesn’t have enough information to accurately describe an entire spectrum of light. In essence, you’re just making ‘best guesses’ at what mixture of color you’re staring at.
In (most) colorblindness, the issue is that two of your cones are tuned to wavelengths that are abnormally close to one another.
To understand why this causes a problem, imagine we’re playing a game where you try to find me. I tell you how far away I am from New York, Chicago and Los Angeles. With that information, you should easily be able to triangulate my location in three dimensions.
But what if I instead tell you how far away I am from New York, Chicago and Milwaukee? The fact that Chicago and Milwaukee are practically on top of one another means that I’m really giving you information that looks a lot more like two points of data (New York and Chicago/Milwaukee) than three points of data. It becomes much harder for you to locate me because even small errors can confuse the results.
The same is true when your cones are tuned to the ‘wrong’ wavelengths.
What color correction lens do is they block wavelengths located in between the too-close cones to reduce this confusion. As a result, your eyes receive an additional bit of information: a known dead zone. So instead of color wavelengths in that range being easily confused, you don’t see them at all and instead rely on the color ranges you can easily discriminate.
From someone who has protanomalous colorblindness, your assumption is correct. We’ve never seen the colors before and can’t reasonably talk about what they are. When I put my enchroma glasses on I’m seeing literally a different world than I normally do. It’s the reason that you see a lot of emotional videos where people start crying. It’s overwhelming to see the “real” world that we miss out on every day, how vivid and beautiful it is.
Having protanomaly means I’ve never seen the color purple with my own rods and cones in the natural world. My eyes cannot physically process that wavelength. The glasses bend the light coming in to give my brain an imitated sense of seeing purple and the proper shades of loads of other colors as well. It really is a thing of beauty.
Others have already explained this very well.
I want to point out that they are not able to recognize the colors. They can now distinguish between colors that they were unable to before. They do have to learn what they are, however.
My friend got these glasses, and there was a beautiful sunset as we were driving home from an amusement park. She kept commenting on the colors, and calling them by the wrong names. She also is a retro gamer, and there was a game where she said, “It’s so much easier to play this now that I can see the bullets.”
In addition to what’s been said, most of those ‘reveal’ videos are fake.
The glasses kit itself will tell you about the importance of conditioning your eyes by wearing the glasses casually for a few hours a day, for a few weeks.
I’ve known half a dozen people that tried them; they only worked for two of them, and neither of those people had a “Put it on and start crying” moment.
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Pretty sure a lot of those videos where the person sees color for the first time and starts crying were pure marketing. My gf bought those glasses for her brother. There was no “aha” moment. In fact, the instructions say basically to keep trying them for a while and they should start working over time. They were over $300 and they got returned.
If you just put the colours on paper and asked them to put on the glasses in a white room and list what those colours are, such person couldn’t really tell the colours for sure.
It’s more of a: I know the grass is green, I’m looking at the grass, this must be what green really looks like.
Seeing colors is a bit complicated… an object isn’t red or green or blue. It’s made of material that reflects and absorbs different wavelengths (between about 380-650nm).
Now our eyes see those wavelengths by basically catching them in 3 different buckets Red, Green, and Blue. Now the only thing is the buckets aren’t side by side, it isn’t that all the light at 499nm falls into the blue bucket and all the light at 500nm falls into the green bucket. They over lap a bit so droplets inbetween fall a little into both (that’s how we can feel a teal that is somewhere between green and blue). The problem is for color blind people their buckets are a little screwed up and they overlap way too much to the point where it’s hard to differentiate between the two. What the glasses do is they actually block the wavelengths where the overlap is the strongest so you get only the light that is coming at the edges of the two buckets. It’s not perfect but it helps tell things apart.
I’m moderate to strong protanomaly colorblind. Reds appear much darker to me. Purple always looks dark blue and light green often appears yellow. If I have a very large sample I can sometimes distinguish the colors but there is no chance if it is small (like a speck of blood looks black, or the little LED lights that flash yellow/green/red to indicate functions on electronics).
I tend to fail colorblind tests miserably. I tried the glasses and with the glasses I was able to achieve a perfect score. However, it wasn’t like in the youtube videos at all. Maybe if they allowed me to look around a bit more I would have had a more interesting effect. As it was, I passed the test, took a look around the boutique and just thought “Yeah, they’re sunglasses, nothing is in true color but it somehow helped me pass the test”. I was underwhelmed and didn’t consider purchasing them.
Maybe I’ll give it another try some day. But, to answer OP’s question. I know what I can’t see. I know purple is red and blue and I can see it in certain situations if the lighting is right and the sample is large enough. Its the contrast with other colors that is missing mainly.
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