The answer is physiological. According to the zone theory of colour vision, colour does not reside in the linear spectrum but is created by the visual system in the form of two opponent signals, red vs green and yellow vs blue. With their four possible combinations these create a circular range of hues: red, red and yellow, yellow, yellow and green, green, green and blue, blue, blue and red. When all wavelengths are present the red vs green and yellow vs blue opponent signals both cancel out, and we see the light as white: http://www.huevaluechroma.com/036.php
No, not a lurker, in fact I'm not really sure where I am yet! I have a Google Alert set for "Color Wheel" that brought me here. I think there's quite a lot of fiction in the quote below about Newton, but it's getting too late here for a detailed response just now. I have a few of my own thoughts about Newton's circle here:
http://www.huevaluechroma.com/071.php#Newton_s_hue_system
Are you familiar with that little half height floor in Being John Malkovich? You are pretty much there, but for the internet. In all seriousness, interesting article. Quoting you, quoting Newton: I don't think we can point to anything unlike this, correct?: up/down are sensations of gravity, temperature is a sensation of molecular motion, etc. Random thought: I can't think of any sensations that result from multiple physical phenomenon. Color and intensity, frequency and amplitude, perhaps... but nor from 'green and hot' or 'down and loud'. I wonder if any intelligence combines two unique phenomenon into a useful sensation.No, not a lurker, in fact I'm not really sure where I am yet!
Newton also said something very strange: he said that "the rays to speak properly are not coloured". By this he meant that a colour is really a sensation of the mind resulting from light, just like a sound is a sensation of the mind resulting from physical vibrations of the air.
Well, that's very exciting! Perhaps length would be at the objective extreme, but even there we at least sometimes need to make a distinction between physical and perceived length, for example in the T illusion. I see the gap between spectral distribution and colour as being at the other extreme, in that there are two gaps of subjectivity involved. With just three cone cell types we can't know the spectral distribution of a light, only some limited qualities of it (dominant wavelength and purity as defined by an opponent visual system), so many different spectral distributions look identical to us. And then these limited qualities that we do detect are tagged for us with entirely subjective experiences whose relationships have no basis in the linear spectrum. In between you have perceptions that correlate more directly (if non-linearly) with the physical stimulus, such as sound and vibration rate, or warmth and molecular motion.
This is great David, thanks for sharing. In fact, I think it deserves its own post. Also, wasoxygen mentioned in a comment on this thread that some women can perceive more colors than men. Is this a result of some women having either more cone cells? Again, thanks for sharing and don't be a stranger.The reason why primary colours come in sets of three is that human eyes have three types of light-detecting cells, called cone cells, used in seeing colour. L cones respond to all wavelengths, but respond most to those we see as yellow. M cones also respond to all wavelengths, but respond most to those we see as green. S cones respond most to wavelengths we see as blue and violet.
-This is something I likely learned about years ago but had forgotten. It's fascinating to think that our visual perception of our entire human experience is predicated by our cone cells. Do you know, are there animals with more cone cells that respond to different wavelengths than we do?
Yes, as indicated below, insects see ultraviolet. At the other extreme marine mammals have only one cone type, I think. A small minority of women are have four cone types, the usual L, M and S, plus a polymorphic variation of either the L or the M, but this doesn't necessarily mean that the retina is wired up to take advantage of the extra cone type. A recent investigation of 24 such women found that 23 had normal colour vision but one saw differences between pairs of stimuli that could be matched by all other observers.
I briefly learned about nectar guides in optics.are there animals with more cone cells that respond to different wavelengths than we do?
Images of a Mimulus flower in visible light (left) and ultraviolet light (right) showing a dark nectar guide that is visible to bees but not to humans
-How much of our experience while on psychotropic drugs is us enhancing our cone cells or some other such biology? theadvancedapes, is this part of what you are studying? Someday, perhaps we will be able to easily turn on and off such enhancements.
I'd wager a hefty sum that psychotropic substances don't enhance or modify the sensory receptors themselves, but that they change the way these signals are processed within the brain.