Radar-like ‘inner vision’ helps blind learn to navigate beyond preconceived limits
Daniel Kish has no eyes, but can ride his bike down the street and walk through an unfamiliar airport on his own. He travels the world teaching other blind people the bat-like navigational technique that gives him so much freedom and allows him to perceive trees, bushes, cars or the furniture in a hotel room.
He makes short, sharp clicking sounds with his tongue and mouth, and is able to translate the slight echoes that are returned into a spatial representation of a curb, a fence or a sofa – a technique called echolocation that he taught to himself.
As a baby, he lost both eyes to cancer. At two, he
started clicking his way around. Friends and family called it his “radar.” He
excelled at school, earned two master’s degrees and, a decade ago, started a non-profit group, World Access for the Blind. It
is based in
Now, the 45-year-old is collaborating with
neuroscientists at the
He says it’s difficult to describe to someone with vision how he can tell a bush from a boulder, a fence from a wall. “There is an image, but it is not a visual image,” he says. “There is no colour scheme, you can’t even call it black and white. It is a spatial representation.”
He can tell the location of objects, their dimensions, like height and width, but also their depth and some surface characteristics. At Western, Lore Thaler and her colleagues discovered that when Mr. Kish processes the sounds that help him navigate he uses the “visual” part of his brain, the region that in sighted individuals processes information from the eyes. The same was true for one of his former students who also was involved in the study.
It is the first brain imaging study on human echolocation and was published Wednesday in the Public Library of Science journal PLoS One. Mel Goodale, the senior researcher on the project, says that while the scientific investigation is at an early stage, it is already clear that the technique “enables blind people to do things that are otherwise thought to be impossible without vision.”
In June, Mr. Kish will return to
The technique, which admittedly can lead to bumps and bruises, takes two to three days to learn. So far, he and his colleagues have taught it to between 500 and 1,000 blind individuals. “Mastery requires individuals to challenge themselves by not depending on others, and to apply echolocation regularly throughout each day,” he says.
Four years ago, he taught Shawn Marsolais
how to echolocate – while she was riding her bike. The
“Before I met Daniel I wasn’t even aware that echolocation existed and how useful it could be,” she says.
Inspired by his “no limits” philosophy, she has set
up her own non-profit group, Blind Beginnings. It helps
Unlike Mr. Kish, she can use her extremely limited peripheral vision to verify what she picks up with echolocation. “If I think I hear a pillar I can check with the corner of my eye,” she says. Her brain also fills in missing details. “If I know it is a mailbox, I do kind of see it in red.”
While Ms. Marsolais did learn to ride her bike on quiet streets, she never felt comfortable. Still, learning echolocation has enriched her life and made her bold enough to tackle an airport on her own.
Even Mr. Kish, the master, says the technique isn’t perfect. On a recent flight, he says, “I must have smacked my head half a dozen times” on the overhead bin – a small price to pay for independence.
The Globe and Mail
Published Wednesday, May. 25, 2011 9:16PM EDT