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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