The Science Thread
- Thread starter Tigger
- Start date
Crazy 10 year mission to land a probe on a comet hits the third arc...
Math did this...
That's some trick shot.
Math did this...
That's some trick shot.
Highlander
Active member
Man I didnt know this site was filled with such Brainiac's. Good for you all!
Heroic Shrimp
New member
Tigger said:
Unfortunately, the author of the article doesn't have much understanding of colour vision deficiencies. Coloured lenses are nothing new when it comes to trying to aid colour vision deficient individuals distinguish between colours a little better. They can help a colour vision deficient individual, say, distinguish different coloured wires better or to perform better on a colour vision test. It's simple technology that's been used for decades and has fairly limited practicality. Distinguishing between shades of colours isn't remotely the same as seeing them "normally" in the full visual spectrum. Such lenses don't cure colour vision deficiencies and they certainly don't allow colour vision deficient individuals see the full visual spectrum of colours. But if the marketer can get ?190 a pop for them, more power to him. I can guarantee that virtually any colour vision deficient individual who buys these glasses will use them briefly to test out on a few things and then will quickly realize that they have no practical value in real life.
Interesting, thanks Shrimp, you have first hand knowledge of this? The article does state that the glasses hamper other areas of colour perception after the headline. To me it seems like this 'accident' contributed to a refinement of subtle red green perception, not that it cured anything. It peaked my interest as one of my good buddies and his brother are colour blind and are looking at this to help them.
Heroic Shrimp
New member
Tigger said:
I'm an optometrist, so among my studies I've taken a course in colour perception. By now, I've seen thousands of patients with colour vision defects and diagnosed hundreds of those (the rest had been previously diagnosed).
I'll try to explain it all in simple terms, though I'm not sure how simple I can make it. Normal human colour perception of the visual spectrum involves three colour vision pigments in the retina. In simple terms, they can be considered the pigments for the detection of short, medium and long wavelength light. Short wavelengths are blue, medium wavelengths are green, long wavelengths are red. People with colour vision defects are either entirely lacking or partially lacking one of the three pigments. How does this affect their perception of colour? I wish I had a chalkboard to draw on to illustrate, but given that I don't, I don't know, maybe I can sort of draw here. Consider normal colour perception to be represented by a triangle. All the colours of the visual spectrum can be represented by a point anywhere within that triangle. The points of the triangle represent the three colour vision pigments, which I'll call B, G, and R. Here's a X-Y axis to try to represent what I'm saying, with B on the traditional negative side, G on the Y axis, and R on the traditional positive side:
G
|
| 1
|
|
|
| 23 4
|
|
B--------------------------------------------------------------------R
How we perceive colours depends on where the colour falls within the triangle, basically representing how much that wavelength of light stimulates each of the colour vision pigments, so by it's position along the -X axis, the +X axis, and the Y-axis. Colours 1, 2, 3 and 4 will all look different to somebody with normal colour perception, although 2 and 3 will appear similar. Now, somebody who is entirely deficient in the G pigment will see no difference between colours 1 and 2, as they fall equally far along the X-axis, and it doesn't matter in the least where they fall on the Y-axis. Those colours will appear obviously different to somebody with normal colour vision but very much the same to somebody who's G-deficient. Colour vision tests are designed to exploit this situation, where certain numbers are essentially invisible to colour vision deficients because of where their component colours fall in the spectrum.
When anybody (normal colour vision or not) looks through a tinted lens, it alters their perception of colours, and so too will these glasses. In the case of somebody who's colour vision deficient, when looking at a colour vision test, it will alter the perceived wavelength of the carefully designed and chosen colours too allow the distinction of what was designed to be invisible to the colour vision deficient. Say, it might make 2 look a little more like 3, so the invisible distinction between 1 and 2 might be skewed more to be like the distinction between 1 and 3, which is more detectable to the G-deficient. This isn't restoring colour vision; it doesn't grant the ability to make colour distinctions along the Y-axis, and it never can or will. If one is looking through blue-purple lenses, it will make everything look a lot more blue-purple. Yes, for the colour vision deficient, it can allow some more distinction between some shades that might otherwise appear identical. On the other hand, not only does it not provide any more richness of colour perception, it actually takes away from it. Try seeing how long you'd want to wear blue-purple lenses before you couldn't stand how skewed it makes all colours to looking blue-purple. That statement applies equally to colour vision deficient people.
To me, the "accident" part of the story is either an angle to try to pitch the supposed novelty (and it actually is nothing novel in the least) of the item, or perhaps it was something that was accidentally enough "discovered" by whoever is making this product in the same way that Columbus "discovered" America long, long after others had already done so. If your friend and his brother would desperately like to be able to conceivably "pass" a traditional colour vision test and it's worth the money to them to do have whatever experience that might be, then I suppose they can do it. But they should know that it really only helps them "pass" the test by actually changing the test, as it's effectively changing the carefully chosen colours (as they meet the eye) enough to see some colour distinctions better. At that point, they're not really passing the colour vision test, but rather a drastically altered version of the colour vision test, so it's pretty meaningless outside of a fleeting revelation of sorts, I suppose. Beyond that, it's just an expensive pair of glasses that makes everything look really blue-purple.
Heroic Shrimp
New member
Bullfrog said:
Generally, that would mean you have a partial colour vision deficiency, so you would have a full complement of two of the colour vision pigments and a partial complement of the third. Sometimes when people fail the Ishihara test as you do and pass the D15 as you also do, there are other, further colour vision tests that might be done to screen through candidate pilots.
Bullfrog
Active member
Interesting. The pilot comment was based on what the doc said. Not that I'm actually considering it. I'm assuming my general vision would be too bad as I'm myopic and have astigmatism (slightly different in each eye, but the optometrist made both lenses the same.)
I have real troubles with distinguishing darker colours like dark blue/black or dark brown/black. They all seem like black to me. Also, certain green/brown mixes are difficult and green/greys. This isn't great because part of my job is picking colours and finishes for buildings.
If I had the cash, I'd seriously consider laser eye surgery. Apparently I have a thick cornea. I guess that means they can screw up and still have tissue left to fix it? lol
Though in truth, the thought of anything coming remotely close to my eyes freaks me the hell out, so I probably couldn't go through with it. I just about died while watching "the needle scene" in Fire in the Sky.
I have real troubles with distinguishing darker colours like dark blue/black or dark brown/black. They all seem like black to me. Also, certain green/brown mixes are difficult and green/greys. This isn't great because part of my job is picking colours and finishes for buildings.
If I had the cash, I'd seriously consider laser eye surgery. Apparently I have a thick cornea. I guess that means they can screw up and still have tissue left to fix it? lol
Though in truth, the thought of anything coming remotely close to my eyes freaks me the hell out, so I probably couldn't go through with it. I just about died while watching "the needle scene" in Fire in the Sky.
Heroic Shrimp
New member
Tigger said:
The only reason I mentioned more than once passing a colour vision test is that it's one of the very few practical real-life benefits of using such a lens, and even then it's not at all very practical or applicable to anything in real-life. Your friends would not be able to see any colours they don't normally see, they would merely be able to differentiate between colours that otherwise look the same a little better. Meaning if there are two visibly different coloured objects that they can't differentiate, putting on such a lens could make them say, "oh, yeah, those two objects aren't the same colour after all". They still wouldn't be able to see the colours that you and I see, not even close.
I've spent more time (by choice) writing and answering about this than I normally would because bad science writing and science misinformation just gets under my skin. And there are number of flat-out falsehoods in that article that are grossly misleading to the layperson.
"cured colour blindness?" False.
"glasses that allow people to see full spectrum" So very false.
"allowing those with the most common form of the condition to see them properly" Oh my God, so false, false, false.
I'll make a couple of analogies to hearing. If we consider the normal hearing experience to be like listening to FM radio, a colour vision deficiency is like listening to AM radio. Words can be heard and understood, music can be listened to. But it's not the full audio experience. Using a tint lens is like adding a graphic equalizer to AM radio. You can enhance some of the sound and suppress some of it. But you can't turn the AM radio audio range into FM with it.
The other imperfect hearing analogy I would make would be to imagine a colour vision deficiency being like the inability to distinguish between some voices, meaning some entirely different people would sound so alike that you can't tell their voices apart, even though most people can easily tell them apart. Adding an intensely tinted lens would be like putting on earphones that, say, changed the pitch of perceived similar voices (imagine Alvin and the Chipmunks kind of voices) to make them sound more dissimilar and distinguishable. On the upside, hey, you can hear the difference between the voices better now, for whatever that's worth; on the downside, everybody sounds like Alvin now (just like everything would look purple), and it's pretty irritating.
Heroic Shrimp
New member
Bullfrog said:
I'd only heard of her through a Keith Law tweet to an article a while back, but after reading that, yes you're very right.
bustaheims
Active member
Bullfrog said:
Ugh. Food Babe. The worst.