A prototype device that causes the tongue to tingle shows promise as something that could help blind people navigate without the use of canes or seeing-eye dogs.
The device, tentatively called the Tongue Display Unit (TDU), consists of a coin-size grid (about the size of a Canadian quarter) that is placed on the tip of the tongue. It is held in place by the user pressing the tongue to the roof of the mouth. The grid, in turn, is attached to a wire connected to a transducer, a small camera and a battery pack.
The camera “sees” what is in front of the user and the information is converted, via the transducer, into pulses that feel something like champagne bubbles, says Maurice Ptito, a professor of visual science at the University of Montreal.
The device is only at the proof-of-principle stage, but brain scans in blind people show that while they are using the device to navigate, the visual centres of their brains are activated. Right now, the device detects tones of grey: White causes no tongue tingling, black strong tingling.
In tests, subjects walked through a white corridor with several black-coloured obstacles, including boxes on the floor and items mounted on walls. The TDU gives the wearer an idea of what’s coming up at a distance of up to nine feet, Ptito says.
“Nine feet, that’s not bad. They stand in front of the wall, and there is a big bar there. If you ask them what they sense, they will tell you there is something there on the wall that is vertical. They perceive the environment.”
This doesn’t mean they see anything, but some aspects connected to vision are apparently being used, Ptito says. As well, subjects report a different sort of sense of their surrounding environment. “They can feel depth by distance. They are probably experiencing something analogous to stereo vision. They can tell you something is in front or in the back. They tell you something is out there and they can walk to it. That’s not bad when you’ve never seen before.”