July 8, 2021 -- Humans have a sixth sense that most of us aren't using, but could learn to.
Some people who are blind have already figured out how to tap into this, in much the same way dolphins navigate underwater and bats find their way in pitch darkness. And it is only a matter of time before others figure out how to do this too, scientists say.
Our five senses -- sight, sound, smell, taste, and touch -- help us understand and perceive the world around us. But according to two recent studies, people can tap into a so-called sixth sense and learn how to navigate through darkness when our eyesight can't break through.
Dolphins and some other animals use a biologic sonar, called echolocation, to get around even when dim, murky waters prevent them from seeing. Bats seem to sense sound as it bounces off obstacles as they fly unhindered through dark spaces.
"People passively use echolocation all the time," according to Lore Thaler, PhD, an associate professor of psychology at Durham University in the United Kingdom.
When a person walks into a room and intuitively understands whether the space is small or large and whether or not it contains furniture, they are probably basing their intuition on echoes and reverberations, Thaler explains.
People who are blind sometimes tap a cane or lightly stomp a foot to help them get a sense of the space around them. Humans can also echolocate by snapping fingers or making clicking sounds with their mouths, scientists say, because the sound waves it creates bounce off nearby objects.
People with little or no training can learn to use those echoes to determine the shape, size, or texture of an object.
This is not some farfetched superpower. Active sensing is something many people have already mastered, says Daniel Kish, founder and president of World Access for the Blind. The California-based nonprofit helps train people who are unable to see to use echolocation, among other tactics, to navigate the world around them.
Picking Up a Superpower
In a new study, Thaler and her colleagues tested whether people can learn to echolocate.
Participants attended 20 training sessions -- two a week for 10 weeks -- and then tried to use echolocation to identify the size of an object and its orientation in the laboratory. In addition, they completed a computer-based navigation task, in which they listened to sounds and navigated around objects.
"We had a huge age range -- 21 to 79 years -- and included both sighted and blind people, and they all learned," Thaler says.
For people who were unable to see, developing their active sensing ability increased their ability to get around independently and improved their feelings of well-being.
In a second study, Miwa Sumiya, PhD, who has since joined Thaler's lab, and her colleagues had 15 participants not trained in echolocation send out sound waves, from computer tablets, which were similar to the noises bats use when they fly through darkness. They were then asked whether a cylinder in the room they could not see was moving or stationary.
Even with no training, most of the participants knew the answer. It's probably not difficult for people to grasp the technique and use it as they interact with their environment, Sumiya and her colleagues say.
Still, some participants were much better at this than others, they say.
This is something Kish says his nonprofit has seen in the real world, outside the lab, as well. "Blind people catch on to this much more quickly," he notes.
The human brain is predisposed to use vision, and people who can see rely heavily on their sight to navigate the world around them. But people who are blind must rely on their other senses, Kish points out.
"I believe that early humans were highly auditory and probably did use echolocation," he says. "Most of human existence occurred without artificial light, so we spent a lot of time in the dark. We spent time in caves, and we had to know what was around us to avoid threats and predators. And you can hear around corners much easier than you can see around them, and you can hear through foliage much easier than you can see through it."
In fact, there is evidence that as early as the 1700s, blind people used echolocation to maneuver through society, says Andrew Kolarik, PhD, from Anglia Ruskin University in the United Kingdom.
And studies have already shown that, in the absence of sight, the brain will amp up other senses to compensate.
"The brain kind of rewires itself in the event of blindness," Kolarik explains.
This remake amplifies the auditory system to improve a person's ability to hear and use other senses in new and powerful ways.