"Blue Cats and Chartreuse Kittens" by Patricia Lynne Duffy

For people with synesthesia, letters, words and numbers have their own colors, and you can smell the shape of milk

By Alison Motluk

Nov. 27, 2001 | The letter "S" is red: "Sand," "sea" and "sky" are all red words. "Rain" is shiny black. "Mist" is green. "Lust" is a sad dull yellow.

Bizarre? Certainly. But not nearly as uncommon as you might think. This condition of mixing up sensations -- known as "synesthesia" -- affects about one person in 2,000. Most people just intermingle colors with letters, numbers and days of the week. But others experience colored pain or can tell when the cream has gone sour by sniffing its "shape."

Synesthesia is enjoying something of a renaissance. A hundred years ago, it was all the rage. Artists and composers were thrilled by the creative possibilities, and scientists were trying to untangle its cause. The composer Aleksandr Scriabin believed musical keys had inherent colors; he composed a few pieces calling for a colored organ. The writers Charles Baudelaire, Arthur Rimbaud and Joris Karl Huysmans all dabbled in the cross-sensory, though whether they were genuine synesthetes is unclear. Vladimir Nabokov was definitely one, and apparently so were his mother, wife and son.

After a long hiatus, artists are once again painting it, composers playing it and writers writing about it. In the past decade, at least four popular books have been dedicated to the topic. The most recent, "Blue Cats and Chartreuse Kittens," by Patricia Duffy, is -- importantly -- the first to be written by someone who actually has the condition.

Synesthesia isn't easy to fathom. People who don't have it have a hard time understanding -- let alone explaining -- what it's like. Duffy gives us an insider's view.

Most synesthetes, for instance, don't realize that there's anything unusual about the way they think. The numeral 9 just happens to be, say, silver. Or trumpets just always sound blue. They simply take it for granted -- and assume everyone else realizes it too. Then one day, they let slip, and their world changes forever.

Not unusually, Duffy made it all the way to age 16 before that happened. On that memorable day, she was talking with her father in the kitchen about how she'd had trouble as a kid learning to write the letter R. "I realized that to make an R all I had to do was first write a P and then draw a line down from its loop," she recalls saying to him. "And I was so surprised that I could turn a yellow letter into an orange letter just by adding a line." Father was intrigued.

Almost all synesthetes will say their mixed sensations have been there for as long as they can remember and they have always been the same. The color is an essential element, not decoration, Duffy stresses. "To me, a red O seems as peculiar and wrong as the notion of a triangular O," she writes. "An O is circular! And it is white!"

Hear, hear. An O is indeed white. But that is one of the few colored letters that we synesthetes can agree on. Duffy describes her yellow P and orange R. Nothing could be more ludicrous: In my world, P is pale blue and R is black.

Next page: The special shape of Wednesday