March 17, 2010 -- Four bikers headed off down a street in Southern California, safely navigating through traffic and past parked cars, and turned onto a narrow bike path leading up a steep hillside. None of them veered off the dirt path, and all safely avoided boulders along the way, always conscious of their surroundings and any possible obstacles.
It happens all the time, right? Well, not quite like this. Three of the four were blind.
"They had no problem whatsoever," said Lawrence Rosenblum, the only biker in the pack who could see. But the blind bikers could "see" about as well as Rosenblum, just not with their eyes. Like three bats in a dark cave, they knew where they were, and where they were going, because of echolocation, the sounds echoing from the trees and the dirt and the rocks around them as they sped along the path.
That may not seem all that surprising, since we've known for decades that people deprived of their eyes, or any of the five primary senses, compensate by enhancing their remaining senses. But here's what's new: Anybody can learn how to do it, because we all possess extraordinary powers when it comes to our perception of the world around us.
Rosenblum, a psychology professor at the University of California, Riverside, has spent 25 years studying how the human brain can rewire itself -- sometimes temporarily -- so we can better perceive the world around us and offset any deficiencies among our senses. In his new book, "See What I'm Saying," he describes how anyone wearing a blindfold can learn in about 10 minutes how to walk toward a wall and stop before hitting it.
Like the bikers on the path, it's through echolocation, learning how sound changes as the distance between an observer and an obstacle changes.
"We use it all the time, not just when we are blindfolded," Rosenblum said in a telephone interview. "When we walk into a room we get an idea of its space not only by looking around, but also from the way it reflects sound."
Walking by Smell
As part of his research, Rosenblum has had his grad students blindfolded, wearing sound-deadening headphones -- and crawling around on the lawn to see if they could track a smell just like a dog, using only their noses. They could.
It's all part of a growing field of research called neuroplasticity, or how the brain changes, sometimes reallocating its own resources, in response to experience or changes in the environment. The best known example is the natural ability of blind persons to enhance their auditory system, literally redirecting the neurons in the brain to "listen" instead of "look." But we all do it, to varying degrees, according to Rosenblum.
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His interest in the field dates back to his early childhood. Both of his parents worked with sensory-impaired persons, as he put it.
"My dad ran an agency for the blind, and my mom worked with deaf kids," he said. When he visited their offices as a child, he added, he was intrigued with "the skills these folks acquired to compensate for their losses."
So some years later, he naturally found himself on that bike path with three blind companions. Two of the bikers, Daniel Kish and Brian Bushway, were experts at echolocation. The third, Megan O'Rourke, was a beginner, at least as far as biking was concerned, and she was a bit nervous.
"They did a few things to make sure they didn't run into each other," Rosenblum said. They twisted plastic ties onto their spokes to make a clicking sound so they could always know where the other bikers were. They also made a clicking sound with their tongues, about once every two seconds, he added, which they could hear reflected back from the curbs, shrubs, parked cars, and other obstacles.
Riding down the street was the scariest part, but "once they were on the bike trail they just went nuts," Rosenblum said. "They had a great time. They never went off the trail. They can hear texture. They can hear the difference between the dirt trail and the grass along the side of the trail."
Don't Try this at Home. Or Maybe Do
Of course, he's not suggesting that biking blindfolded down a narrow path is easy. Both Kish, who was diagnosed with retinoblastoma in both eyes at four months and has never been able to see, and Bushway have honed their skills to near perfection over the years. It takes practice to get that good.
But here's something anyone can try. Make a sound -- even hissing will work -- as you approach a moveable wall blindfolded. The sound changes slightly, depending on the distance to the wall, and after about 10 minutes you should be able to do it consistently without running into the wall. At least that's how it works in Rosenblum's lab.
Echolocation is just one of several ways that we can use our various senses much more effectively. Your nose, for example, is a bit of a marvel.
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Rosenblum soaked a long rope in oil, giving it a faint smell, and laid it out in a twisted pattern on the lawn at the Riverside campus. His students were blindfolded and equipped with headphones and heavy gloves. Using only their noses, they were told to find the rope and follow it.
"The difference in odor intensity between the two nostrils allows us to track a scent like a dog," he said. If the odor is strong in the right nostril than the left, turn right.
The students, he said, had no trouble finding the rope and following its meandering course.
Some changes in sensor perception take a little longer to accomplish, but not as long as might be expected. In just 90 minutes, he said, a blindfolded person should see improvements in hearing, and possibly even smell.
The brain makes that adjustment in the same way that blind persons enhance their hearing, by redirecting traffic from the visual cortex to the auditory system, but in the case of a blindfolded person, the change is temporary. After about 24 hours, the system returns to its default settings.