Am I correct in thinking that our brains are “hard wired” to interpret different wavellengths of light as color?
That is, even if some super science gave us to ability to directly see into the infrared and ultraviolet spectrum, we would not perceive any “new” colors, correct? Perhaps deeper and deeper red or purple, but nothing brand new.
And as a sort of corollary, if someone who was completely blind from birth were given the ability to see, they would perceive the same colors we do?
Our eyes are sensitive to the visible spectrum , from about 350 to 700 nm, peaking at 550 nm in the Green. We can perceive the whole range of colors there, although the sensitivity fades off from green in either direction, with blue and deep red being less apparently bright, even for equal energy. That’s why a green laser pointer looks brighter than a red laser pointer of equal output.
You can perceive a bit beyond if the source is really bright. I’ve seen bright red laser light beyond 700 nm. But it doesn’t get “redder”. You just see about the maximum red you can. It’s not a question of being “used to” or “trained to” see other colors – you see what your sensors let you see. (There are two sets of sensors in the eye – “cones” and “rods”. The rods are for low-level, black-and-white viewing. There’s a slight difference in sensitivity, but for practical purposes, they’re the same range. )
The traditional theory of vision is the “tristimulus” theory, by which we can see three degrees of freedom in colors, and you only need three phosphors on a computer/color Tv screen or three colors of ink to pretty well duplicate the colors we can see. The theory works pretty well. It’s unlike the ear, where we rerally do perceive different wavelengths. You can “see” the same apparent color using two different mxes of three base phosphors (provided the base phosphors aren’t identical). So the eye is fooled. You can’t fool the ear – try to make the same note using two different combinations of notes and the ear can perceive the difference.) This is just as well – it’s easier to build a monitor using only three different basis colors than if you had to have each pixel capable of producing the entire visible spectrum.
But then it turns out that color vision is even more complex than that. Edwin Land, inventor of polaroid filters and instant photography, discovered the “Land Effect”, in which the eye could be made to perceive apparent color without using the traditional three basis colors. weird stuff.
In addition to what Cal said, if our extended-range wavelength perception was done by simply shifting the wavelength range that our cones (I think it’s the cones) are sensitive to, then most likely you’d still perceive what you think is color, but infrared would now just look red to you, or UV would just look blue.
If you got that extended range by adding additional cone types, then you get into the area of brain processing. Our brain is hard-wired to process three dimensions of color, so adding a fourth or a fifth would require some serious architecture changes in your brain.
I guess this is as good a time as any to ask my question about a supposed fourth color receptor type in certain females. I can’t find any info online about it, but if it truly
– senses a different range than the others
– is processed differently by the brain,
then that means potentially that females process color in different ways from men! (Or, that we have untapped potential to potentially wire in non-light photonic artifical receptors to.)
Well, that is very interesting. Thanks, so far, to all. Your input is really appreciated!
Not so much our brains, but our eyes are hard-wired. There are 3 genes for our rods, one for each type. The medium- and long-wavelength cones (sometimes called “green” and “red”) are, in fact, both on the X chromosome and right next to each other. In addition, if you look at their spectral response curve, they have surprisingly similar curves. I believe, as do others, that they were once a single gene that first mutated by duplicating itself on the chromosome, and later minor mutations caused their individual response curves to drift apart. The ability for some women to see additional color information is due to having one of the genes on one of their X chromosomes to be distinctly different than its counterpart on the other chromosome.
Each of the cones’ output signals does not go directly to the brain. Instead, they each interact with nearby cones’ signals. The interaction of short-wavelenth cones and either the medium- or long-wavelenth cones produces a signal that indicates a blue-versus-yellow signal. The interaction of two neighboring cones with the same response curve produces a signal indicating the change in color across the eye. The interaction of all three cone types produces a signal expressing the brightness of the light. For women with a fourth cone type, they can see subtle differences in red/yellow/green tones that for most folk would appear the same, called “monomers” – colors with different wavelength distributions that look the same.
Finally, for seeing light outside of the 400nm - 700nm range, I believe that one of the issues is that the cornea filters out a good deal of the light ouside of that range. In fact, by doing so it reduces the amount of damage that would be done to our retinas if it transmitted all light. Even if it did, though, your cones would only respond weakly to the light outside that range.
Here is a link that shows the spectral responses of the rods and cones in your eyes. Note that the curves are all normalized. Your short-wavelength cones have a much weaker response than your other cones, and your rods have a much stronger response, but are mostly inactive in normal lighting conditions.
Bloody hell, there are women walking around with a 4th colour receptor? Remind me to coordinate my clothes better.
I did wonder how I was able to just about see wavelengths on the edge of colour vision, so thank-you for the explanation Punoqllads. I know 780nm lasers are just about visible as a deep red, and 410nm blue lasers are the most beautiful violet.
Talking of violet, some flowers contain colours in the UV spectrum as some pollinating insects can see in UV, and in the special few minutes before sunset, when the light is low but contains a much higher proportion of UV than at midday, these flowers seem to fluoresce. Tagetes (marigolds) can become the most vibrant oranges, but my favourite is the overgrown edible thistle that is the globe artichoke flower. At the end of the day they seem to light up like beacons, with the most unearthly violet glow. And they taste great steamed with a little butter.
What I’d like to know is why we see the colour spectrum that we do (i.e. red, orange, yellow, green, blue, violet) as these distinct colours with some blending inbetween, as in the classic rainbow or spectrum from a prism, and not as a smoother tone blend across the spectrum, or recognise yellowy-green as a standout colour in the spectrum. I know the Japanese have no linguistic distinction between green and blue, but surely that’s just an oversight?
We think of ROYGBP as distinct colors because that’s what we’ve been trained, but in actuality, we do see a continuum. It’s just a matter of history that we think of those six (or seven, if you include indigo) as “the colors of the rainbow”. With the passage of time, more and more colors get distinct identities, such that during the middle ages, for instance, folks would tell you that carrots are a shade of red. Cecil on this topic
The labels we apply to colors are completely independent of the lightwaves we can actually see.
When we are VERY young, the adults around us point out different colors, and tell us that such and such is Green, while another such and such is Red, etc.
We do not have enough words for the infinite range of colors that we can see on the light spectrum, and different languages have different sets of words for those colors.
As with most other phenomenon we experience, if we see a color (a specific lightwave pattern) that we have not seen before, we are likely to classify it as something similar to a value that we already know, then use the same (or a similar) label to identify the new value. This is why we have crayons that are labelled Yellow Green or Orange Red in the US.
If the color can be associated with another specific experience, it might be given a different name, like maroon (which comes from the French word for the brownish-red color of a chestnut) or violet.
While there is a normal range of lightwaves/colors that a typical human can see, I do believe is it possible that some humans see colors outside of that normal range. However, since we don’t have specific words for every lightwave we can see, we are more likely to simply use a word that we already know to describe even a new color.
>subtle differences in red/yellow/green tones that for most folk would appear the same, called “monomers” – colors with different wavelength distributions that look the same.
I think you mean “metamers” (sp?). Monomers are single-unit molecules that, strung together, are polymers. Dimers, trimers, et cetera are 2, 3, et c.
D’oh! Yeah.
