'Synesthesia'

I have this but I never knew it until a few months ago when I saw something on TV about it. Here's an article in Salon ("The letter E is purple"). I never thought much about it and never had a problem with it, as apparently this writer has.

There are different forms of synesthesia. I have "spatial-sequence" synesthesia, whereas the writer of the article has "grapheme-color" synesthesia. (Sounds like more fun than what I have.) See Wikipedia here. Lots of people have it.