Why There Are No Bluish-Yellow Crayons: The Forbidden Color Experiment

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hey everybody today I'm going to be seeing if there's any of you that can see forbidden colors in order to understand what a forbidden color is we have to learn a little bit about how we actually perceive color for example this a on my action lab shirt looks yellow right but what that means actually is that there's both red and green light coming off of this and the pigment in there it absorbs the blue light so just red and green light are coming off and when we see red and green light together it makes yellow light and if you don't believe me that red and green light make yellow well let me actually show you that red and green light actually do make yellow for example I have here a red light a green light and a blue light bulb so let me show you what it looks like when we have all of them on when I have all of these on you can see that this white poster board in the back looks white but then when I unscrew the blue light bulb now everything is yellow so you can see that green light plus red light makes yellow light now yellow might seem a little bit weird because if you know a little bit about color vision you know that the color from our vision comes from some cells in our eyes called cones and there's cone cells in our eyes that are sensitive to short wavelengths medium wavelengths and long wavelengths and so that corresponds to the colors blue green and red but you'll notice that you don't see any yellowish colors in here so where does the yellow come from usually these three types of cone cells get the most attention when color vision is taught but we can't forget about where the signal from these cone cells actually go to next is what actually determines the color that we perceive so this first step is called the trichromatic stage this is where the cones receive the wavelength of light but then after that is a secondary stage and this is where it gets really interesting at this point there are four different colors that can be perceived and these different colors come from two different types of cells one is a type of cell that I've labeled here with a B and the other is a type of cell that I've labeled here is with a G and you'll see why in a second so with this B cell over here when it receives light from these cones and a kind of addition subtraction process with the light so what it does is it takes the signal from all these cones and it adds red and green together and it subtracts blue and if it ends up with a positive number then we're going to perceive yellow if it ends up with a more negative number we're gonna perceive blue well and when it's some combination of a more in the middle then we're gonna get kind of a white light and these G cells over here do a similar thing so when they receive red plus blue light sorry that's a B right there then it goes in the positive direction but if it receives green light then it goes in the negative direction so basically blue light inhibits the signal on these B cells and green light inhibits the signal on these G cells so what does all this have to do with forbidden colors well look at the final output down here you'll notice that one cell can only give two signals some shade of blue or some shade of yellow and this cell can only give some shade of red and some shade of green if you combine all of these colors together you can get every color that we can visually perceive but you'll notice one interesting thing you can see that there's no way that you can kind of have a yellowish bluish color because as you add more blue it doesn't turn to a bluish yellow but it turns more white and as you keep adding blue then it turns blue and actually this color isn't exactly red but it's actually a magenta color so as you have red plus blue you get magenta and as you add more green to it it goes towards a white color and then it turns to a darker and darker green but there's never a point where you see a reddish green and there's never a point where you see a bluish yellow and again if you don't believe me that's true let me show you a physical experiment that shows you this you'll never see a bluish yellow so back to my setup here I have a blue red and green light and we know that red and green make yellow so basically I have a yellow light and a blue light and I can adjust how much yellow or blue it's getting just by covering the blue light or by covering the red and green light so for example let's say I start off with yellow light and what I'm going to do is I'm going to add more and more blue lights this yellow light and you'll see that you never have a point where you see a yellowish blue at all so let's start off with completely yellow now I'm going to add blue so I'm adding more and more blue to it more and more blue and you can see that now that yellow is just becoming a lighter yellow it's going more towards white and the more blue I add to it the lighter that yellow becomes until eventually that yellow is now white and now as I continue to add more and more blue light to it I just add more and more and more blue that white becomes a darker and darker and darker blue until eventually it's completely blue so you can see that by adding blue light to the yellow light there was never a point where I saw yellowish blue but only it got lighter and lighter yellow until it was white and then it got darker and darker blue and now if I add yellow light to this blue and more and more and more yellow light eventually it becomes white and then as I add more and more and more yellow light to it it just goes from white to a dark yellow to show you that's not true for everything just yellow and blue let me show you what it looks like when you just mix red and blue together so let me start off with blue again and I'm going to mix more and more red light with that blue so I'm going to start to add red so you can see that the blue now just starts to look more red it just becomes redder and redder and redder now it's full magenta and then as I add more and more and more red light more and more and more it goes all the way to red so you can see during that whole process you could see it slowly turning from blue to red so the whole time you could describe any point in the middle as bluish red or reddish blue so now go backwards add more and more blue light to it you can see it getting bluer and bluer and bluer and bluer and bluer and bluer and bluer and bluer and bluer and tell it's blue so for all the other color combinations besides blue and yellow and magenta and green you can combine them in any way and you can describe them as a bluish red or a greenish yellow but you can never describe something as a bluish yellow now this is where it may get confusing for artists or people that are used to mixing paint together because you know that when you mix yellow paint with blue paint you get green paint so you may be thinking of course I can see yellowish blue yellowish blue is just green but that's not true yellowish blue is not green green is a different color all together that you get when you mix yellow and blue so there is no such hue as yellowish blue there's no such hue as yellowish blue and that is the reason why it's called a forbidden color yellowish blue is a forbidden color but does that actually mean we can't see it well maybe not the way that our eyes are set up are such that you cannot see through the same eye a yellowish blue color but what if in one eye we're getting a yellow signal and then the other eye we're getting a blue signal and then in our brain we mix them together well for most people it still doesn't work but for some people they might be able to see a yellowish blue so let's see if you can see it so on one side of the screen here I have yellow and on the other side I have and what I want you to do is I want you to cross your eyes together so that the cross appears right in the center and you'll notice a weird thing start to happen you'll notice that those colors don't really mix together and form really anything for most people most people will see that your eyes kind of start flashing either color it's either yellow or blue yellow or blue yellow or blue it's your brain trying to decide what's going on here it's gaining this input signal of yellowish bluish then normally it can't get it's forbidden to get and so it doesn't know what to do with it and so for most people when they look at it they don't really see a yellowish blue they see one or the other in some part of the picture in the 1980s they did a study similar to this where they saw if people could actually perceive yellowish blue by getting different inputs in their eyes and what they found is for some participants they did actually perceive a new color that they had never seen before and they didn't know how to describe it the best way they could describe it is yellowish blue and says then that study has tried to be replicated and in some cases they found the same result and in some cases they found different results there's a lot of things that you have to control in a study like this brightness is a very important factor and also where you're focusing on the image is an important factor so there's been conflicting evidence and scientists still aren't quite sure if some people can perceive yellowish blueish so let me know in the comments section if you're actually able to perceive a new type of color that you've never seen before yellowish blue or bluish yellow hey everybody thanks for watching another episode of the action lab I hope you enjoyed it hope you learned something if you did and you're not subscribed yet remember to hit the subscribe button and hit the bell to be notified for my latest videos out and if you haven't checked out the action lab comm head over there right now you can get yourself an action lab t-shirt it glows in the dark which is really awesome and also you can get yourself an action lab subscription box this is a box where I send out quarterly experiments to your house and you can replicate similar experiments that you've seen me do on my channel thanks for watching everyone and I'll see you next [Music]

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Channel: The Action Lab

Views: 1,704,136

Rating: 4.7078996 out of 5

Keywords: color, forbidden color, impossible colors, the action lab, action lab, greenish red, reddish green, yellowish blue, bluish yellow, science, educational video, color theory, primary colors, science for kids, vacuum chamber, venus fly trap, iron man, hydraulic press, foil ball, stretch armstrong, blackest black, science experiment, how to, black 2.0, aluminum foil ball, zombie ant, 32000 lumen, vac man, brightest flashlight, home science, fire ants, science tricks

Id: cQCsDfEqr9o

Channel Id: undefined

Length: 10min 8sec (608 seconds)

Published: Tue Sep 04 2018

Reddit Comments

Yeah, what he's explaining is more that the color wheel has limitations. We experience the full RGB spectrum as "white"

So none of that video came as a surprise to me. He also made many mistakes. When he added blue to yellow, he then didn't "add more blue", but "took more yellow away".