When Sound Is Red: Making Sense of Mixed Sensations
By Shankar Vedantam
Washington Post Staff Writer
Monday, October 14, 2002; Page A12
Joanne Innis was around 5 years old when she asked her mother, "How come if you and Aunt Pat are sisters, you're red and she's brown?"
When Glenda Larcombe hears a truck backing up, making a beep-beep-beep sound, she "sees" the beeps as a series of red dots.
And when psychologist Thomas Palmeri gives one of his test subjects a difficult test -- to spot a tiny "2" on a computer screen scattered with tiny "5s" -- the man finds it instantly: To him, the "2" shows up bathed in a different color.
These are all examples of synesthesia, an unusual phenomenon whereby people experience different senses blending into one another. Some synesthetes experience individual words in particular colors. Others experience smells when exposed to shapes or hear sounds inside tastes.
While most experts do not consider it a disorder -- synesthetes are usually glad to have the ability, and it sharply improves their memory -- research into synesthesia is teaching scientists important lessons about the normal brain, perhaps even about aspects of creativity.
"Synesthesia is seven times more common among artists, novelists and poets," said Vilayanur Ramachandran, a neurologist at the University of California at San Diego, who is researching the phenomenon. "What do artists have in common? They have the ability to link seemingly unconnected domains."
Ramachandran thinks that the power of metaphor and the blending of realities that artists strive for are phenomena that synesthetes experience all the time. While that is currently only a hypothesis, it is certainly true that synesthetes seem to experience the world with more intensity -- what scholars call "affect." However, many of them don't realize they have a unique ability, believing that everyone else experiences the same sensations, too.
While superficially resembling a drug-induced hallucination, synesthesia feels profoundly normal to synesthetes. After Innis, an assistant professor of Russian at Goucher College in Baltimore, realized that she saw the world differently than most people, she understood why she was never interested in experimenting with drugs like LSD: "There was too much going on in my head already," she quipped.
Various explanations have been offered for synesthesia, and while there are tantalizing clues and plausible theories, no one has yet identified a gene or found a neurotransmitter responsible for it.
One theory is that synesthesia may be caused by "cross-wiring" between areas of the brain that process different sensations. Palmeri says his research at Vanderbilt University has ruled out cross-wiring at least in some areas of the cortex through experiments that show subjects different pictures through each eye. Ramachandran says synesthesia likely arises from connections in the fusiform gyrus of the temporal lobe. He expects that scientists will eventually find a gene or genes that cause "leakage" of information between disparate parts of the brain, given that synesthesia seems to run in families.
Another theory is that everybody may be born with synesthesia, that infants may experience the world as a jumble of interwoven sensations and their different senses may slowly grow distinct, like lenses being brought into focus. Carol Mills, a psychologist at Goucher College, says synesthesia might also be a normal part of all adult brains -- with synesthetes at one end of a spectrum.
"It may go on in all of us even if we don't have synesthesia," said Mills, who published a paper last week based on Innis in the journal Perception. "For example, if I give you a very high-pitched note and a series of colors and ask you to match one, you are going to pick a light color. If I give you a low bass note, you are probably going to pick a dark color. [The difference is] when a synesthete hears a low note, they see dark. When they hear a high note, they see a light color."
The mingling of senses is often difficult for synesthetes to describe. Larcombe, for instance, an electronics technician at the Navy base at Dam Neck in Virginia Beach, said the red dots she sees when she hears beeping are not part of her actual vision. "It's not like I would see a red dot right in front of me -- it's in my mind's eye," she said in an interview. She also reported "feeling" her interviewer's voice, "like a wave, like water, with yellow and orange."
Richard Cytowic, a Washington neurologist and the author of a book about synesthesia called "The Man Who Tasted Shapes," described the case of a dinner host who told him the chicken didn't have "enough points" on it.
While a minority of synesthesias are unpleasant, he said -- like vile-tasting words, musically induced nausea or billboard colors out of whack with the synesthete's internal color scheme -- many synesthetes report intense pleasures at trivial tasks.
"Remembering someone's phone number is delightful; balancing a checkbook is delicious," Cytowic said in an interview. "It's also a rule of thumb that exceptional talents come at a cost. [Synesthetes] often have trouble with arithmetic, right-left orientation and finding directions."
No firm figures exist for how common synesthesia is; the best estimates range from 1 in 200 to 1 in 2,000. The most common forms of synesthesia link numbers or letters with colors. Even within this group, there are variations of type and intensity. Innis, for instance, associates words with the color of the first letter. Her question to her mother about her aunt Pat was because she saw the "M" in "mom" as red and the "P" in her aunt's name as brown.
Innis said she could also "turn on" the individual colors of every letter in a word, an especially useful trait when she was learning Russian in high school. Mills's research with Innis has explored the unusual fact that Innis not only has synesthesia for English words using the Roman script, but for Russian words in Cyrillic. Mills has determined that Innis's Cyrillic letters drew their colors from their English counterparts.
Innis said she used to have trouble remembering Russian words that start with "o," because the letter in her mind was an unremarkable transparent whitish gray. So she opened up such words into their constituent colors. For instance, she distinguished "ostavit," which means "to leave," from "ostanovitsja," which means "to remain," by homing in on the letter "n," which occurs only in the latter word.
"The 'n' gives me a bright orange to stand out," she said, confiding that she avoids mentioning her special ability to her students, who have to learn the Russian words the hard way.
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