What color are the numbers 0 through 9 and the letters A through Z?
This question will strike many as odd. After all, numbers and letters are usually black, and if they're colored, it's usually in an arbitrary fashion. But what if I told you that the number 2 is green, 4 is blue, 5 is red, C is yellow, and T is purple? You'd probably think I'm insane, but I'm not: I simply experience a phenomenon known as "synesthesia."
Here's a picture of what I mean. Note that the colors are approximate; some of the colors I "see" cannot be reproduced on the screen. Also note that someone else's colors will likely be completely different from mine.
According to Wikipedia, synesthesia "is a neurologically-based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway." In other words, people who experience synesthesia associate one stimulus with something that seems unrelated – like seeing each letter and number as having a specific color, seeing the numbers in different spatial locations, or "seeing" music.
I have associated colors with letters/numbers – grapheme-color synesthesia – for as long as I can remember. At first, I thought it was normal, but when everyone I mentioned this to just stared at me with a blank look, I realized that I had an unusual quality. It wasn't until recently that I actually found out that this phenomenon was called "synesthesia". After that, I realized that I had more forms of synesthesia than just grapheme-color.
What forms of synesthesia do I have?
My most prevalent form is grapheme-color synesthesia, which involves me associating a color with each letter. The interesting thing about my variant of it is that the color is usually associated with the form of the letter and not the sound. The English letter "B" and the Russian letter "В" (which has a "V" sound) are of the same color because they look identical, while the Russian letter "Б" (which has a "B" sound) has a different color. (Technical note: be sure to set your page's encoding to Unicode (UTF-8) to properly see the Russian characters.)
Another form is something I don't know the scientific name of but refer to as "spatial location synesthesia." This involves the number line for me, as well as the alphabet. It is difficult to explain, but I see the number 0 at the beginning of a real, physical sidewalk I walked down regularly as a young child; 20 is farther along this path, and 100 is even farther along, although the higher the numbers get, the more abstract the path becomes.
The alphabet is similarly seen as being above the whiteboard in my first grade classroom. A problem I have, though, is with months; I seem to have remembered the row of months in my classroom as well, with January on the far left and December on the far right, so I always think of months as being linear. This is quite inconvenient since I need to manually count 6 months down in order to figure out what the "opposite" time is. The interesting thing about the last 3 examples is that these seem to be learned stimuli – unlike the grapheme-color synesthesia where colors have been assigned since birth more or less (or so I say), I have actually seen the aforementioned items in real life.
Association of concepts
Someone once asked me a very good question:
If you see A as being red, what would happen if someone put a black "A" on a red background? Would the letter "disappear"?
The simple answer is "no." But to see why, we need to delve deeper into the concept of "color" in the first place.
"Color" is not a wavelength; rather, it is a concept which is associated with a certain stimulus, namely a certain wavelength of light entering the eye. Note that pure yellow light and a combination of red + green light are both associated with the color "yellow" in the brain. This also allows for the existence of colors that our eyes can never see; some of the colors of letters I see aren't reproducible on a computer screen.
Text is inherently colorless; this is why we are able to read black text on a white page and large red text on a blue billboard and get the same meaning out of it. But the synesthetic association with colors happens AFTER the textual processing takes place. Since the text itself carries no color information, the black letter A and red background it's rendered on are not present when the text is stored in the brain as such, there simply is no "red background" behind the red letter A.
You're probably thinking, "so, this is cool and all... but what is it good for?" Many things, actually. If you have synesthesia, you grow to appreciate the many small ways in which it helps you in your daily life.
I won first place in my junior high school's spelling bee in 7th grade, and I won third place in regional (just google my name). I've also been good at spelling, and particularly good about noticing proper spellings of certain similar-sounding words. I later realized that this was, in part, due to my synesthesia.
Let's take a common grammatical issue people have: "than" versus "then".
than versus then
The distinct color difference between "a" and "e", which is also remembered along with the word and its meaning, ensures that I will almost never mix up similar-sounding words. (Try to unfocus your eyes until you see each word as a blob of color, and notice how they look quite different even because of one letter.)
Practical applications of synesthesia
The concept of synesthesia can be applied to various things. Artificial synesthesia can be used for improving the usability of a user interface, or can even be used to prevent IDN homograph attacks (a method of phishing that replaces the letter "e" in "ebay.com" with its Cyrillic equivalent, for example, thus fooling the unsuspecting visitor into revealing personal information to a fake site). This would work if all similar-looking letters were colored differently; people would thus memorize the "color" of the URL as well as the name, and would be suspicious of improperly colored URLs. The two downsides of this is that it is difficult to standardize the colors, and it would drive us synesthetes crazy since our colors would end up being different.
How do people get it?
Apparently, synesthesia runs in families. Both of my parents report some sort of synesthetic experiences – from a spatial number map to "seeing" different colors of music. In my experience, some forms of it (like each number having a color) came "naturally", while other forms (the number line being associated with a location) have their roots in events that happened in my childhood.
Do you experience any form of synesthesia, or do you know someone who does? Please state your experiences here... I would really like to know how others see things!