A blind woman has revealed how she uses echolocation, a sensory system used by bats and dolphins, as a means to see the world around her.
Fiona Gameson, who had her eyes removed when she was three following a rare form of eye cancer, says she calls the ability her "bat sense".
In a podcast by Nature magazine, Gameson said she never knew anyone else was able to echolocate and that she "just grew up doing it".
Bats view the world around them by issuing high-pitched clicks that are echoed back to them, providing a picture of their surroundings.
Like them, Gameson echolocates by making clicking sounds. She pulls her tongue from the roof of her mouth to make a sharp tick sound then listens for the echoes that bounce off the objects around her.
She said: "I tend to do it quite quietly. I call it my bat sense. It's just one of these other senses I use to give me a lively picture of where I am."
Gameson is not alone in her ability. Echolocation in humans has been studied since the 1950s. More recently Lore Thaler, a neuroscientist at Durham University, tried to teach people who can see to echolocate.
"One of the tricky things is getting people to make the right sonar emission. Many people start with a low-pitched click, which is not as useful [as other clicks]," she said.
"In cases where input through the eyes is lost, it's a very common finding for parts that are visual in the brain respond to other sensory inputs such as touch, hearing or smell."
Talking about the idea of her other senses becoming heightened as a result of her blindness, Gameson said this was not the case: "[My] other senses are not more acute – but one processes the information coming in more accurately than someone who has got sight."
She said she does not use echolocation all the time and that it is not useful in noisy or crowded places but it is helpful when going to unfamiliar places.
Gameson said: "Certainly just around a house it gives me the sense of a size of a room. If I go to a place I've never been to before, I very rapidly learn from a mixture of memories and echolocation. Because of the echolocation, I can use that and the air movement to discover where the door is to get out, for example.
"If someone said to me: 'Do you hear the walls?' I would say: 'No but I can feel them.'"
Explaining what Gameson might experience, Thaler added: "If we draw from the brain activity then we might expect that echolocation might resemble spatial visual experience that might resemble vision."