Well, that is true for everyone. We all see the background of this website as “blue”, but is it the same blue? I mean, if for some reason you interpret all the colors inverted, so what you see in complete absence of light is interpreted by your brain with what I’d call white, but we both call darkness black because that’s what we’ve always seen?
If we want to avoid the philosophical question, then the answer is in how color vision is processed. We actually see just three colors: red, green and blue. That’s why they’re primary colors: we have cone cells in our retinas that react to different wavelengths that mostly correspond to R, G and B. Colorblind people have defects in one (or more) particular kind of cone. Knowing which cone type allows you to know how then a particular wavelength (aka “color”) is interpreted by the eye according to how the other cones are activated.
That’s also why we know that dogs are completely color blind (no cones, only rod cells) and also why we lose color vision in the dark. Cones need a high intensity to be activated. Low light conditions make everything fade to grey because rods are much more sensitive, allowing you to see the shapes, but don’t distinguish the color.
I already asked this question to my friend, because I was curious too.
He is colorblind on red/green.
So, to have a clearer idea of what he sees, I showed him this image:
He said that the area from dark red to dark green, it’s the same color, but not grey. And not one of the other colours (purple, blue, white, black). Light green and light red are two different colors for him, and he names them correctly.
He sees, practically, a sort of “dark yellow”, even if the color is dark red (brown) or dark green.
Yeah, it´s less black and white than I remembered actually. But obviously there should be more yellow in the skin tones, judging by the graph that has lots of yellow tones in it.
I have noticed the same thing applies to sounds. If you hear a song on the radio, very softly and you recognize it and turn it up… bam! different pitch!
Quite embarrassing when you started singing along while it was still turned down…
She could never get colors right, always called them by the wrong name and things like that. So I showed her an Ishihara plate with a star and asked what she saw in it. And she answered “balls”. That’s why I got worried
So I used that tool to draw other shapes she knew in all possible color schemes. After she understood that she had to watch the colors, she could name all the shapes correctly. Now, at the age of 2.5y, she finally recognizes all colors.
