Scientists have successfully trained a small group of people to navigate while moving around using echolocation, that is, the way some species of living things, such as dolphins and bats, communicate with each other. And although the possibility of using this method by blind people has already been proven in the past, scientists could not fully figure out whether seeing people are able to develop the same ability, since the latter fully rely on their visual perception of the environment.
“We thought that if we are talking about a seeing person, then nothing will work out here. Therefore, we thought that there was hardly any benefit,”said Virginia Flanagin, a researcher at the Ludwig Maximilian University of Munich.
However, the results of an experiment involving 11 seeing people and one blind volunteer showed a completely opposite picture. One of the people who did not have vision problems and who most effectively mastered the method of using echolocation was able to determine a 4 percent difference in the resizing of the created virtual room.
“People who performed less efficiently were still able to spot a difference of 6 to 8 percent. At the same time, the least effective indicator among volunteers was 16 percent,”the researchers say.
"Overall, the picture is similar to those of visual acuity - the level of ability to detect differences in the environment - that are determined in some visual assessment tests," commented Flanagin.
At the beginning of the experiment, the scientists first trained the volunteers in the very method of echolocation, placing them in a soundproof and shielded anechoic room. People, while in it, listened to audio recordings of certain clicking (rather, even clicking) sounds, previously recorded under normal conditions in rooms of various sizes. Ultimately, the researchers trained people in this way to distinguish the difference between click sounds recorded in small and large rooms. Once the people had gone through the initial training session, they were sent for a magnetic resonance imaging procedure. The tomograph itself was connected to a virtual 3D computer model of a nearby church building.
While in the tomograph, people either created clicking sounds with their own languages, or the machine did it for them. Thus, the principle of "active" and "passive" echolocation was created. After that, people listened to these sounds echoing through the virtual room. Based on the difference in echo, the volunteers were able to determine the size of the virtual room.
Research has shown that humans perform much better at this task when using active echolocation. That is, the clicking sounds they create turned out to be a more effective tool for positioning ourselves within the virtual environment. Scientists have also noticed that people use this technique more actively when they exhale. In addition, it was noted that the sound of the echo activates the motor cortex of sighted volunteers - the part of the brain responsible for movement. When scientists compared the results of an MRI scan (which made it possible to determine which parts of the brain are activated when a person creates clattering sounds) with active and passive echolocation, in both cases the activity of this area of the brain was noted. In general, the motor cortex turned out to be most active every time in the case of more spacious virtual scenes than with small ones. This, in turn,can talk about a certain connection between the virtual and physical positioning of a person in space.
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“It looks like the motor cortex is somehow involved in sensory processing,” notes Flanagin.
As for the blind volunteer, in this case, the echo activated the unused visual cortex of the brain. The brain, apparently, thereby tried to imagine a picture of an echo bouncing off the walls inside the virtual room.
Nevertheless, one should take into account the fact that the experiment is being carried out on a very small group of people, so it would be premature to draw any definitive conclusions. At a minimum, similar experiments should be carried out on a wider and more diverse group of volunteers. However, given what we already know about the human predisposition to the use of echolocation, it becomes clear that sighted people can use sound waves as a means to position themselves in their environment.
Below you can see the level of the most famous expert in human echolocation, Daniel Kish, who, despite his blindness, demonstrates his cycling abilities using this method.
NIKOLAY KHIZHNYAK
