Humans can develop a sixth sense, study proves

AS ANIMALS GO, HUMANS HAVE RELAtively limited senses. We can't smell as well as dogs, see as many colours as mantis shrimp, or find our way home using the Earth's magnetic poles as sea turtles do. But there's one animal sense we can learn: bat-like echolocation.

- SARAH WELLS

Researchers in Japan demonstrated this feat in a paper published in the journal PLoS One, proving that humans can use echolocation - or the ability to locate objects through reflected sound - to identify the shape and rotation of various objects without light.

As bats swoop around objects, they send out high-pitched sound waves that then bounce back to them at different time intervals. This helps the tiny mammals learn more about the geometry, texture, or movement of an object.

If humans can similarly recognise these three-dimensional acoustic patterns, it could literally expand how we see the world, says study author Miwa Sumiya, PhD, a researcher at the Center for Information and Neural Networks in Osaka, Japan.

'Examining how humans acquire new sensing abilities to recognise environments using sounds, or echolocation, may lead to the understanding of the flexibility of human brains,' says Sumiya. 'We may also be able to gain insights into sensing strategies of other species by comparing with knowledge gained in studies on human echolocation.'

This study is not the first to demonstrate echolocation in humans - previous work has shown that people who are blind can use mouth-clicking sounds to 'see' twodimensional shapes. But Sumiya says that this study is the first to explore a particular kind of echolocation called time-varying echolocation. Beyond simply locating an object, time-varying echolocation would enable human users to better perceive its shape and movement as well.