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11:18am on Monday, 1st May, 2006:



When I was a child, perhaps aged 7 or 8, I was talking to my mother about colours and she said that actually there was no way to tell whether people saw colours the same way. What I see as green, someone else might see as what I'd call red (if I could see inside their head). Yes, we'd both point to a leaf and say it was green, but that's just a label. How we painted it in our brains could be completely different.

In my teens, I began experimenting with overwriting my senses — in particular, my vision. After I managed to perfect my patching process, whereby I replace what I see on-the-fly with a looks-real-to-me imaginary substitute, I remembered what my mother had said about colour and had a play with the idea. I began by making everything yellow show up as an equivalent green (yellow because it seems to stand out more, and green because that's my favourite colour). It took a while, because wholesale patching of unrelated parts of an image with new parts related to those I was patching was not something I'd tried before, but after a while I mastered the technique. Once it had clicked, I was able to do it pretty well at will, replacing one colour with another. It's easier to do with primary colours, because the blends are more natural: if you replace red with orange, how much more green does something yellow look? Needless to say, my original choices of yellow and green were therefore not good ones... Oh, I should say that "primary" here means light, by the way, not pigment.

I don't think the matches in my substitutions are exact in RGB terms, in that if I made the grass red instead of green, it would have the same red/green/blue colour values except with the red and green swapped; it's more impressionistic than that. The grass looks red with the same "feel" as its usual green, but it could well be rather less intense. Hmm, maybe I should crank up CorelDraw, it would be easy enough to test.

[10 minutes later]

No, they're not. I have to calm down intense greens to make them look like equivalent reds. In the following image, on my monitor anyway, the green on the left is RGB 0,255,0 and the red in the middle is 255,0,0. When I substitude the red for a green that "feels" the same as the red does, I get (near enough) the one on the right, which is 34,241,0. There are probably some changes at the low end, too, but I didn't check those out. I suspect the main reason for the difference is the physiognomy of the eye in focusing light of different wavelengths, but since I'm playing with sensory inputs I have to account for that.

Oops, I just realised I should have done that experiment with green and blue rather than red and green, so colour-blind people could see what I meant. Sorry.

Anyway, having overwritten one colour for another, naturally the next thing to try was switching them round: make green things seem yellow and yellow things seem green.

This is a lot harder.

The problem I had was that things I'd switched from green to yellow would suddenly flip back to green. It would be like a wash effect: I'd have the whole scene with green and yellow reversed, then suddenly something "yellow" in the corner of my eye would flip back to green and then it would rush across like a contagion, changing everything in pretend-yellow back to green (but keeping everything in pretend-green still green). It was very exhausting and took a tremendous amount of concentration to fix, but eventually I could sustain the image. I didn't like it, though; I've never had a headache, but this seemed the kind of thing that might give me one... I only ever do this very occasionally now, just to see if I still can.

Of course, all this colour-swapping stuff was only tangentially related to what my mother had told me. The really interesting thing is not that you and I may see colours interchangeably, but that how the colours manifest in our brains may be different. What I see as green may simply not be in your palette; what you see as green may not be in mine.

This leads to something I've been struggling with, on and off, for years.

Most humans have 3 pigments in their retinas, so get to see 3 colours. Except, some women are tetrachromats and have 4 pigments. Some birds, such as pigeons, have 5 pigments. There are at least 2 primary colours out there that I can't see but that are capable of being interpreted.

If you're red/green colour blind, you only get to see the world in shades of two colours. This is because your hardware (your eyes) are only supplying your brain with 2 colours. Could you imagine a third colour? The brain is clearly able to handle 3 colours, because most people see 3 colours perfectly well. If you only see 2, can you imagine the third?

I'm not colour blind. However, I'm only a trichromat; I know there are colours out there that I can't see. The challenge: can I imagine them? Can I bring to my mind a colour that isn't made up of a combination of red/green/blue, but something else entirely that I could never possibly see in the real world simply because my eyes can't provide me with the data? I know it's possible for the brain to handle, because tetrachromats exist. So can I do it?

Well, no, I can't — but I'm getting closer. I had a breakthrough last night: I managed to conceive of a "feeling" for a colour that doesn't match any "feeling" I get from real colours. I'm using the word "feeling" here to express the way I tokenise structured concepts as thoughts. Basically, it means that I can now think about a fourth primary colour on equal terms with the other three primary colours. It's pretty good, but the hard part is going to be overriding my vision so I can see it. I'm nearer to doing this than I was, but I'm not there yet. The next step is to construct the colour in my imagination, which will be tricky. I'm pretty sure I won't get any choice over what it looks like because it's tied to the "feeling" I constructed; however, once I've done it, I may be able to create other "feelings" for new colours, and then the floodgates could open.

Something that I'm interested in finding out, assuming I do eventually manage to manifest this extra colour (at least in my mind's eye) is how it mixes with the existing colours. If I add a dash of it to pure red, what will the result look like? It'll be an off-red, but by necessity it won't be off in a way I can imagine at present. Will I have to think of each combination "manually", or will it happen automatically as it does when I'm switching normal colours?

Of course, if I do manage to envisage a new colour and I use my patch-the-senses ability to see it "with my own eyes", so to speak, I still won't have 4-colour vision of the real world. The best I'll be able to do is substitute some part of the real world spectrum with this new colour, as I won't be able to tell what parts would look different (nor in what ways). I could create an artistic image, say of a crown featuring 4 colours, and patch it over my vision stream so it appears to me that you're wearing it, but the combination of colours wouldn't look how they'd look to someone with actual 4-colour vision.

If I manage it, though, it'll be rather nice. It'll be utterly useless, naturally, but that's never stopped me in the past...

Referenced by Becoming a Polychromat.

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Copyright © 2006 Richard Bartle (richard@mud.co.uk).