I am personally working on a similarly “impossible” idea, which I may publish on a blog or something, involving creating an ideographic script that would transcend linguistic boundaries, basically one that any human would be able to learn, in their own language, and be able to communicate in it with people of other languages–any language. The biggest go-ahead in my quest is the fact that there are very few genuinely unanswered questions around and just because generations prior to ours have failed to answer these questions doesn’t mean there’s no answer to them. One just has to learn to think outside the box. My advice to you is that this is where you need to concentrate your efforts. You’ll be surprised at how creative the human mind can be, given the permission to wander freely in the world of unbridled imagination.

Perhaps the fact that your brain struggled to create something new out of nothing explains why there’s a general readiness to render such questions impossibile to solve.

You are right though that as long as this new color is imagined, it’s probably impossible to prove. In the case of Daniel Tammet, all the test could really prove in the end was that he has an incredibly good memory, but not necessarily that he sees the world as he does. Instead, we simply have to take his word for that.

But if you are able to take it one step further by combining tetrachromacy with synesthesia (rewiring of the brain by linking our novel color to our rod receptors), the same type of tests used to detect colorblindness could be used to prove this. It’s an interesting idea, though one I wouldn’t really welcome. Especially since inducing synesthesia would probably require you to inflict some form of damage to your brain.

How are you planning on ever “proving or explaining” anything that you would call a success in this experiment though ? I mean, I could say that I’ve designed a new colour, but it’s not part of the spectrum, and I can’t really explain it but it still exists. There’s no way for me to prove any of that. Another interesting phenomenon is people that have synesthesia. These people are in fact able to see the colour five, or thirteen, or what have you. Not sure if the colours they see are always part of the spectrum though.

Daniel Tammet for example in an interview while explaining how he memorized a few thousand numbers of pi, said that pi to him is like a large, infinite painting. Or a landscape through which he can wander. Anyway, I’m interested in part II :)