Some blind people use echolocation to take in their surroundings as a replacement for visual assessment, researchers say. Echolocation is a process where sound waves instead of sight are used to figure out the location and size of objects in the surrounding area. Most people are familiar with echo location from learning about bats. Bats use the returning sound waves that have bounced off of nearby objects to figure out where things are.
Some blind people apparently have also put echolocation to work for them. In a study published in Psychological Science, scientists from Canada’s Brain and Mind Institute at Western University have shown that some people who are blind use a type of echolocation.
“Some blind people use echolocation to assess their environment and find their way around,” Dr. Gavin Buckingham, who authored the study, explained. “They will either snap their fingers or click their tongue to bounce sound waves off objects, a skill often associated with bats, which use echolocation when flying.”
In the recent echolocation study, three groups of participants were tested for their ability to fall for a size-weight illusion known as the Charpentier illusion, according to Medical News Today. This illusion is the term that describes an error in judgment that happens when people who see with vision try to make judgments correlating size and weight. For example, a small box containing one pound of fluffy feathers and a large box containing one pound of metal weigh the same, but the Charpentier illusion makes it so that people wrongly judge the weights of the objects.
“The size-weight illusion causes people to perceive the smaller box as heavier, despite them both having the same mass,” according to Medical News Today.
Participants were divided up according to whether they had no visual impairment, were blind and used echolocation, or were blind and did not use echolocation. All participants were told to determine the weights of cubes that were different in size, but identical in weight by lifting a cube that was in front of them by a string attached to each box.
The blind participants who did not use echolocation did not fall for the illusion. This group correctly reported that all the objects were the same weight.
The blind people who used echolocation ended up perceiving the cubes in the same erroneous way that the people who saw the boxes with vision perceived them. Both of these groups fell for the Charpentier illusion. The blind individuals who used echolocation were susceptible to what the boxes “looked” like, though they were seeing the boxes with information gathered from sound waves, not with their eyes.
“Ironically, the proof for the vision-like qualities of echolocation came from blind echolocators wrongly judging how heavy objects of different sizes felt,” Melvyn Goodale, director of the institute where the study was held, explained. “This new study shows that echolocation is not just a functional tool to help visually impaired individuals navigate their environment, but actually has the potential to be a complete sensory replacement for vision.”
The research compounded on an earlier study which showed that people who are blind and use echolocation actually use areas of the brain associated with vision.
[Photo via BBC on YouTube]