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When I was young, I liked when people would "write" on my back with their fingertip and I'd try to guess the word they spelled out. Now, MIT researchers are developing a vibrating vest for the military that does the same thing. Sixteen small vibrating motors connected to a wireless PC display Braille-like patterns on the wearer's back. The research is supported by the US Army who want a method to communicate with soldiers non-vocally and hands-free. So far, the researchers tested how well volunteers recognized 15 symbols, eight of which came from US military hand signals. From New Scientist:
Five volunteers were asked to follow the tactile symbols while being directed around an obstacle course. They were also sent signals meaning "raise arm horizontally", "raise arm vertically" and "hop". Out of the five, only one volunteer made a single mistake during the tests. The vest was also shown to work while worn under a backpack.Link
"This is best suited to command-based situations like the military or fire-fighters," says (MIT engineer Lynette) Jones. "It could also be used to direct blind people around a city, but because their path is less defined, that would be more difficult."