It turns out echolocation is not just limited to bats and whales. People who are blind can also use echolocation, most commonly by clicking their tongues and assessing the echoes that the clicks make when bouncing off other objects. The process allows them to make out the shape, size, position, and material properties of objects.
Now, new research shows that echolocation can play a similar role as sight in people who are blind. In particular, people who are blind and have been practicing echolocation for a while seem to use regions of the brain normally associated with visual perception when they echolocate, according to Melvyn Goodale, a neuroscientist and director of the Brain and Mind Institute at the University of Western Ontario in Canada.
Using a brain imaging technique called functional magnetic resonance imaging, the researchers found that blind echolocators showed a higher level of activity in the visual cortex compared to sighted people and blind non-echolocators when listening to recordings of clicks made by other echolocators.
"People who are expert echolocators can detect the presence of something beyond their bodies, just as we do with sight," said Goodale. "They have a kind of auditory, or echo-based, image of things out there."
The closer an object is to the ground, the harder it is to detect
To learn more about the experience of echolocating, Motherboard spoke with Daniel Kish, one of the participants in Goodale's study. Kish, who has been called a "real life batman," was blinded as an infant and started using echolocation before he turned two. Today, he runs a nonprofit called World Access for the Blind, which teaches blind people echolocation among other skills for freely navigating the world.
MOTHERBOARD: How did you start echolocating?
Daniel Kish: I lost my right eye to retinoblastoma [a cancer of the eye] at seven months of age and then my left at 13 months of age. I was probably clicking by all reports somewhere between 15 and 18 months of age.
I don't remember the process. What started it was probably my parents' attitude. They just had an attitude of getting on with it. They did not raise me in fear or anxiety or despair, they raised me with a sense of normalcy, and the assumption that I would grow up to become an equal citizen and enjoy the same freedoms and responsibilities as every other citizen. In their mind I was to be among typical kids doing typical things.
Watch Daniel Kish ride a bike using echolocation.
What can you sense with echolocation?
Well, the world is a bit like a network of 3-dimensional fuzzy geometry, so it doesn't have the same resolution or definition or vision obviously, but you do get a sense of contour, edges, boundaries, degree of reflectivity of surfaces, density, texture (to a degree), position of things, and relationships among things.
How far away can you sense objects?
Depending on the reflectivity of a surface, the effect goes out for hundreds of meters. A large reflective surface the size of, say, an airport, could be detected from maybe half a kilometer [1/3 of a mile]. An object the size of a quarter could be detected from maybe half a meter [1.5 feet].
What do you mean by reflective?
Something that's reflective in an acoustic context will catch more sound and throw more sound back. So a highly textured, hard surface is likely to be more reflective than a soft or totally smooth surface. A larger object is likely to be more reflective than a small object. A tall, thin object is likely to be less reflective than a short, fat object—although, that said, the closer an object is to the ground, the harder it is to detect.
Maybe 50 percent of blind people, maybe more, develop some form of echolocation
What's the resolution of what you can see?
It's a little hard to say because you can only go so far into getting into someone's head. You can find a good example in a recent video of Brian Bushway [Bushway works with Kish at World Access for the Blind] from the Discovery Channel.
In the video, Brian is clicking at some abstract art sculpture somewhere. The goal is to describe what he is clicking, what he is experiencing, without touching it. He's describing to a forensic artist who has not seen this thing before, and it's her job to try to sketch the thing based on his description.
It's actually very remarkable, I think it really highlights an example of this spatial geometry resolution. The Human Eclipse is another video you can watch, of another one of our students.
Brian Bushway, one of Kish's colleagues, uses echolocation to describe an abstract art sculpture to a forensic artist.
What about moving objects?
They're not really a problem. It's just like a moving target. It doesn't really change the detectability. You're clicking every so often for spatial updating. Let's say that you're moving through an airport, and you're passing objects. Every step you take, your surroundings are now different relative to you. You're updating your perception of your surroundings as you move to maintain a sense of continuity with those surroundings.
Do you vary your clicks to adjust the signal?
The sharper the clicks, the better the signal. And the more variable the clicks, the better the signal. The biggest variable is amplitude. So you would use a softer signal in quieter environments or for closer objects, and you'd use a much louder, stronger signal in louder environments, more open environments, or where targets are farther away. So it's a very active process, kind of like focusing the eye.
What about the rate of clicking?
The rate varies depending on the activity and circumstances. If you're in a relatively familiar place and you know where things are and the surfaces are very easy to detect, or the environment is relatively quiet, then relatively few clicks are necessary. If you're in a place that you don't know at all, that may be fast moving and may be quite congested, spatial updating is at a premium, and then you'd be clicking more frequently.
Are you consciously aware of how you're clicking as you do it?
It's actually quite unconscious. It's remarkable how few people can actually articulate what they're doing and how they're doing. It's true for sighted people too. Say you ask a sighted person, "So tell me about seeing. How do you see?" Most people really would be at a loss to explain that.
Do you know how many people who are blind use echolocation?
We've worked with over 1,000 students, and I would say that less than 10 percent of blind people—and I'm probably being generous—learn to develop echolocation to a degree that they are using it as a principal means of navigation on their own.
Maybe 50 percent of blind people, maybe more, develop some form of echolocation that they use in a more rudimentary sense and might not be aware of it. Then there's a percentage of blind people who have minimal use of it, and really don't have a sense of space around them. That percentage is significant, probably 30 to 50 percent. Then you have those who learn to use echolocation through our program or some other instructor.
Schools for the blind still actively discourage it sometimes because they think clicking is stigmatizing
There was a survey, done by a researcher named Lore Thaler, of how many people echolocate and how they use their echolocation. She then ran a bunch of correlations and found that people who echolocate more have a higher index of employment and things like that. What that basically boils down to is that blind people who echolocate are more confident. They move better and feel more comfortable in their environment, so they're more likely to be out there.
Can you tell me about your work with World Access for the Blind?
Our goal is to help more blind people develop freedom of movement in their life and freedom to navigate their life.
For us, it's not necessarily about "to click or not to click," It's more about freedom, and people claiming their freedom. A big mistake that I think blind people tend to make—sighted people as well—is that freedom is something that is given, rather than something to be earned and claimed for oneself. We're adamant about every individual's sovereign right to liberty. Those rights are routinely dismissed and marginalized when it comes to blind people.
I think freedom of movement, however that comes about, is most certainly something that every blind person, no matter how old and no matter where they are, should have access to. And the majority do not. Many people are not aware that echolocation is a tool they can use. It's often actively discouraged, and schools for the blind still actively discourage it sometimes because they think clicking is stigmatizing, though I think that's happening less and less.
Have you experienced stigma from clicking?
No, my experience has been pretty much unconditionally positive. I think frankly people who are concerned about stigma are barking up the wrong tree. What the general public tends to notice is not the clicking, in my opinion, but the poise a good echolocator tends to have. They tend to look like they know what they're doing. They have their head up and look around them. They project an air of confidence. They move in a relatively natural way. That's what people tend to notice.
I hear that people also use other types of signals in addition to tongue clicking, like jingling coins in a pocket or snapping fingers.
I think of signal production in terms of a continuum of activeness. The most active signals would be ones you have complete control over.
I find shopping malls relatively challenging
Tongue clicking pretty much gives you total control. Finger snapping gives you pretty good control, but it does require one hand. It also doesn't focus as well as a tongue click, because by defining the shape of the oral cavity, you're able to direct and focus the clicks a bit better than a finger snap. Cane taps are farther down the spectrum, because your cane tip is a particular material so it's only going to resonate in a particular way, and that resolution will change depending on the surface you're on, which you may not have a lot of control over. Similar thing with footsteps.
Can you describe what it's like to navigate a busy street?
That's really not particularly hard. You can hear things that make noise, and if you're clicking, you can cause things that don't make noise to make noise. So everything makes noise. There are usually building lines, or if not building lines, something else to get your line of reference from. For crossing the road, you basically just go with parallel traffic. You learn to read the traffic.
What kind of environment might be more difficult to navigate then?
I think that varies from person to person depending on their experiences. I find shopping malls relatively challenging. There's a lot less cuing, surfaces aren't straight, there's lots of clutter, lots of people milling about not really knowing where they're going, a lot of extraneous noise. There are a lot of open spaces, with junctions, and food courts. But I don't frequent malls very much, maybe blind folks who spend a lot of time in malls might find it easier.
If some future technology could give you the capacity to see, would you use it?
That is quite a hypothetical question because I think, in my case, it's unlikely. But yes, why not? I don't think either blindness or vision is a bad thing. It is what it is. I'm kind of an explorer by nature, and seeing would be quite a new and interesting thing to explore.