An echo which is used to locate oneself in space: this is what the bat uses. Blind humans also use it. This sixth sense is extremely precise.
You don’t have to be bombarded with radioactive waste, like the superhero Daredevil, to develop a sixth sense. Echolocation, which bats use in flight, is accessible to everyone. An experiment, published in Psychological Science, shows that this sense almost replaces vision in blind people.
Like a sonar
A team from Heriot-Watt University in Edinburgh (UK) and the Brain and Mind Institute (Canada) tested 10 people. Four were sighted, three blind. Three blind people mastered echolocation. This sense works much like sonar. It consists of making “clicks” with the tongue or fingers. The echo which returns makes it possible, according to its intensity, to determine the size, the shape and the texture of the object in front, but also its distance. It’s a real sixth sense, as shown in this video produced by the World Access to the Blind association, spotted by The world.
Echolocation is not a recent discovery. But for now, “we don’t yet understand how close human echolocation is to how a clairvoyant uses vision,” admits Gavin Buckingham, co-author of the study.
Deceived by the size
To better understand how echolocation works, the researchers gave all three groups the same test. With a handle connected to a pulley and their other senses, each participant had to assess the weight of three cubes of different size but the same mass. The non-echolocator blind concluded that all the cubes were the same weight.
Seers and echolocateurs, on the other hand, got it wrong. “It is interesting to note that echolocators, which assess the size of the object solely by echolocation, also undergo the Charpentier illusion,” notes Gavin Buckingham. This phenomenon is a sensitive illusion: when faced with two objects of different size but of similar weight, a sighted person will think that the smaller one is lighter.
Extreme precision
The fact that echolocators succumbed to Charpentier’s illusion speaks volumes, according to Melvyn Goodale, co-author of the study. “The irony is that echolocation has been proven to have similar properties to vision thanks to blind echolocators who were wrong about the weight of objects according to their size,” said the director of the Brain and Mind Institute. This is not surprising since in 2011, the same researcher demonstrated that echolocation activates an area of the brain involved in vision. And this sense can prove to be incredibly precise when mastered, as shown in this excerpt from “The Boy Who Sees Without Eyes” (The boy who sees without eyes).
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