Real Rhapsody In Blue

As a child, Julian Asher had a theory about the symphony concerts he attended with his parents. "I thought they turned down the lights so you could see the colors better," he says, describing the "Fantasia"-like scenes that danced before his eyes. Asher wasn't hallucinating. He's a synesthete--a rare person for whom one type of sensory input (such as hearing music) evokes an additional one (such as seeing colors). In Asher's ever-shifting vision, violins appear as a rich burgundy, pianos a deep royal purple and cellos "the mellow gold of liquid honey."

It wasn't until Asher began studying neuroscience at Harvard six years ago that he learned there was a name for this phenomenon--synesthesia, from the Greek roots syn (together) and aesthesis (perception). Almost any two senses can be combined. Sights can have sounds, sounds can have tastes and, more commonly, black-and-white numbers and letters can appear colored. For Patricia Lynne Duffy, author of "Blue Cats and Chartreuse Kittens," five plus two equals green: her color for seven. Sound crazy? For most of the last century, scientists dismissed synesthesia as the product of overactive imaginations. But in recent years they've done an abrupt about-face, not only using modern technology to show that it's real but also studying it for clues to the brain's creativity. "Synesthesia is not a mere curiosity," says retired neurologist Richard Cytowic, who helped spur the current interest. "It's a window into an enormous expanse of the mind."

Scientists have devised ingenious tests to prove that synesthetes didn't simply invent their unusual associations. In a 2001 study, Dr. V. S. Ramachandran and Edward Hubbard of the University of California, San Diego, showed volunteers a display of black-and-white digital 2s hidden among 5s (illustration). Most people took several seconds to find all the 2s. To synesthetes, they popped out immediately in contrasting colors. "This proves that it's a real perceptual phenomenon," says Ramachandran. Brain scans are confirming the findings. At a Society for Neuroscience meeting in New Orleans two weeks ago, Colin Blakemore and Megan Steven of Oxford University showed that a key color-processing region of the brain really is being activated in one synesthete who says he sees colors when he hears certain words. "What makes this interesting is that he's been blind for 10 years," says Steven.

Why do people develop synesthesia? The truth is that no one knows. But scientists at Rockefeller and Cambridge universities are hunting for genes that may help unravel the mystery. Synesthetes may have unusually dense connections between sensory regions of the brain (the most common forms of synesthesia involve adjacent brain areas)--or perhaps their brains activate connections that are usually inhibited. Similar connections must exist in most of us. How else can we explain the temporary synesthesia that people experience on hallucinogenic drugs like LSD? "People don't suddenly grow new neural connections in half an hour," says Peter Grossenbacher, head of the Consciousness Laboratory at Naropa University in Boulder, Colo.

The implications are dramatic. It is possible that most of us not only have these connections but use them regularly, although at such a low level that we don't realize it consciously. After all, we describe subzero weather as "bitter" cold, while a taste like cheddar cheese may be "sharp" and a color like hot pink "loud." "Maybe metaphor, abstract thought and synesthesia all have a similar neural basis," says Ramachandran. Clearly, synesthesia is related to creativity. A new survey by Grossenbacher found that out of 84 synesthetes, 26 were professional artists, writers or musicians, and 44, serious amateurs. "Synesthesia for them is part and parcel of what ends up being a more expressive life," he says.

For artist Carol Steen, who paints the music she sees, it's also answered more prosaic questions, like: which type of recording produces richer sound--CD or vinyl? "Vinyl," she says. "The colors are more beautiful, as if someone gave them an extra shine." End of debate--the eyes have it.