HUMANS WHO ECHOLOCATE

DANIEL KISH, A 52-YEAR-OLD American, navigates by echolocation. Blind since losing his eyes to cancer at 13 months, he taught himself to use tongue clicks to find his way around as a toddler and now cycles on busy roads, hikes in forests and climbs mountains.

In 2000 he founded World Access for the Blind, a non-profit aimed at spreading the word about human echolocation and teaching blind kids how to use it. Greg Downey, a Macquarie University anthropology professor who studies people with extraordinary skills, is a board member of the body’s Australian sister organisation.

“Echolocation in humans is a behavioural and cultural input that can change the brain,” Greg says. The biggest change in a blind person is that the part of the brain that normally deals with sight can turn to processing sound; the visual cortex begins to help the auditory cortex. Remember that in echolocating animals the auditory cortex does all the echo processing.

“The human brain is usually dominated by sight,” Greg says. “About 80 per cent of electrical activity in the brain is allocated to sight when you’re moving around. If you take that away, you free up an enormous amount of real estate to be reallocated to other tasks.”

Another major change is the treatment of echoes. Sighted humans don’t hear them well, if at all, due to the ‘precedence effect’. This focuses on a primary sound and discounts the echo as having no use. In blind people this effect weakens, and echoes become stronger.

With training, a blind person can come to detect echoes very clearly. But, Greg says, you have to work hard at it.

However, he’s convinced most people can do it. “My observations are that it’s pretty universal,” he says. “It’s an incredibly exciting idea because instead of seeing blind people as disabled, we can see them as people who have a really unusual skill. A lot of folks who develop this skill say it changes them fundamentally, giving them greater independence and freedom.”

Greg says many human echolocators don’t tongue click, preferring instead to tap their canes, snap their fingers or listen for the echo of their footsteps.

Anthropologist Greg Downey studies the effects on the brain of acquiring new skills. He believes learning to echolocate can be transformative for a blind person.

Daniel Kish, who lost his sight as a toddler, is dedicated to helping blind people ‘see’ better without their eyes. He refers to human echolocation as “flash sonar”.