The reason why I think bigsleep finds colours more difficult that symbols is that we are used to dealing with symbols, particularly familiar ones like numbers and letters. Show someone a card with a six digit number on it and there is a good chance they will recall it even if seen for a fraction of a second. Do the same with colours and I believe that there will be less of a chance.
Now, say you're trying to familiarise yourself with something symbolic like the Chinese alphabet or the periodic table. Imagine a program that created a sudoku puzzle out of a random selection of the symbols you are trying to learn and presented this with a definintion of each symbol.
The sudoku puzzle would be soluable without knowing anything of the symbols, but using them would improve your familiarity with the symbols and increasing your familiarity with the symbols would improve the speed and ease with which you could solve the sudoku puzzle.
Imagine this: "Puzzle 39: Sudoku difficulty: Hard, Traditional Chinese Level: Basic."-- st3f, Sep 08 2006 but don't all numbers have their own colours? not to mention flavours... mmmmm, nine. http://en.wikipedia.org/wiki/Synesthesia [po, Sep 08 2006] //The sudoku puzzle would be soluable// Is it important that it dissolves in water then?-- DrBob, Sep 08 2006 Damn.-- st3f, Sep 08 2006 I used to play that "Shanghai" tile solitaire game - that taught me to distinguish different Chinese symbols and it was a lot more fun than sudoku. (Just saying, I like the idea but maybe a non-sudoku version would be nice :)-- phundug, Sep 08 2006 The only thing I have ever learned from Sudoko is that I am too stupid to count to 9.-- shapu, Sep 08 2006 Visual artists might find this easier. Not all of us are symbolic thinkers.-- Galbinus_Caeli, Sep 09 2006 I think that we are all symbolic thinkers. It is this that gives us our ability to read. Those with dyslexia show some difficulty with symbols but would all beat me reading a normal book if I had to read one where each letter were represented by a colour square.
Anyhow, the idea is not to make the puzzle easier (I don't think it will) but rather to use the act of solving the puzzle to gain familiarity with a set of symbols. [mouths 'Polonium' to himself as he writes Po into a box.]-- st3f, Sep 11 2006 random, halfbakery