I have synesthesia. Don't worry, it's not harmful (and sadly) not contagious. Synesthesia has been defined and explained over and over again, so I will not (also not the point of this post so). Here is the wiki about synesthesia. Also, if you suspect you may be a fellow synnie, go here for a nifty test!
SO. I have grapheme synesthesia. This means letters and numbers each have a unique and SPECIFIC color for me. I am not a projecting synnie, but rather a "mind's eye" synnie. I don't literally see text in rainbow colors, but when I look at words/numbers/etc my brain attaches that extra color information to the characters I see. (Note: some mind's-eye synnies, when inebriated become projecting, so they actually see printed text in color! I wouldn't know though.)
This chart will give a a rough idea of my colors. The colors are not even close to the exact shades I want them to be, but hey, technology...amiright? I did not randomly make up these color associations, and I cannot change them. I don't even like some of these colors, but again, I have no control over them.

It cracks me up in TV shows when a character has synesthesia (Heroes) because their colors are always beautiful and coordinate nicely. Reality is not so kind. Pull out your crayons/colored pencils/markers and write your name in my colors. Probably not very pretty. I get excited when I meet someone who has a name where all the letters look good together. Spelling is also critical to me. Kathryn=/=Catherine=/=Katherin. I always want to know how someone spells their name so I can see the colors in my mind properly. I feel let down when I get to know someone named Sean, and then find out weeks later he spells it Shawn or Shaun. Gak! It's like I don't even know them.
These color/character associations are incredibly strong. Trying to tell me the number 4 is green is like trying to convince any non-colorblind person that the sky is yellow with neon pink polka dots. Not going to happen anytime soon...
Synesthesia can be both helpful and annoying. In an 8am college math course, it was a nuisance. I would wake up as late as possible and slide into my seat just as class started. Having only been out of my bed maybe twenty minutes, I was still rather sleepy. Tiredness has a similar effect on synesthesia as alcohol. Before I totally woke up my colors would project and I wouldn't be thinking straight, so my class warm ups looked something like this:
Which totally doesn't make sense because magenta plus medium purple equals sort of a light maroon, definitely NOT bright green. Ten minutes into class or so I would be more awake and my colors would be less pronounced.
One summer I worked as a painter. Oddly enough, one of my coworkers was also a music education major with grapheme synesthesia. We had interesting arguments.
Musical notation also has colors for me. The note colors correspond to the letter name colors. (G, any octave or clef is pumpkin orange. Accidentals do not change the color. Enharmonics are a NIGHTMARE.)
While fabric and scrapbook paper that look like this is cute, the colors are ALWAYS WRONG!!!1!
Synesthesia is vastly more common in children, but adults tend to ignore preschoolers who say things like, "Look daddy! The purple crayon is the mommy and the gold and blue ones are her twin babies!" This demonstrates yet another variety of synesthesia (there are anywhere from dozens to hundreds of types, depending on where you get your info.) I have experienced a few other types. (I'll save it for another post.) As a child I experienced a type where colors/letters/numbers/something has fixed and diverse personality/sex/gender/physical attributes. Mine was color --> personality/sex. My strongest memory of this flavor of synesthesia is from the four crayons and coloring page from restaurants.
In my next post about synesthesia I will try to illustrate the one time I experienced pain-->color. I will also try to draw some of the cooler/possibly more useful types (ticker tape, spatial calendar).



