'red and blue' averages into green? Yeah, that's not really how our eyes perceive light. We see the colors that we see because certain wavelengths of light sti

'red and blue' averages into green? Yeah, that's not really how our eyes perceive light. We see the colors that we see because certain wavelengths of light stimulate certain cones in our iris, which makes our brains hallucinate in color, basically. We see green when the short-wavelength-sensitive, medium-wavelength-sensitive, and long-wavelength-sensitive cones are all stimulated. A single wavelength of light around 520nm will stimulate all of these cones and satisfy the requirement for green to be seen. In fact this is usually the wavelength of light we'll find in a green laser. But there can be multiple different wavelengths of light in combination to make the eye perceive green as well. And that's what's happening when we see purple. When we see purple (magenta), we're never, ever, seeing just one wavelength. Because as we've said, there is no such thing as a magenta wavelength. It's not in the rainbow. So take red-wavelength light, and blue-wavelength light, with the key absence of green-wavelength light, and we'll see purple/magenta. But green-cone stimulating light must be absent or we will not see magenta. It's pretty interesting how what we see is not necessarily what's out there. Another interesting one is gray. There is no "gray" on the rainbow. Any time we're seeing gray, we're actually seeing a bunch of colors at once. Which is weird because gray appears colorless. But depending on the colors present that make us hallucinate that grey, there could be as few as 3 colors or even millions. We just don't see them because they're stimulating our cones in such a way as to neutralize each other. So under natural lighting, an aluminum macbook will be grey and colorless. But walk inside a room that only has red lighting (so no white lights) and that gray colorless macbook is now a colorful red. Anyways, what we perceive has never been a literal transcription of what's actually present. The brain takes in stimuli from the outside world, but it alone ultimately decides what we see. It shows us different things under different conditions. Different lighting conditions, under the influence of drugs, colors next to other colors, light arranged in certain textures, whether we're malnourished, whether we're daydreaming with our eyes wide open, whether we've just finished staring at an intensely bright light or a colored wall and are now looking at something else, all of it influences the colors that we actually end up seeing. The brain always has the final say in what we perceive, not the outside world. We're basically hallucinating 24/7, all the while thinking what we see is what actually is.