In Mixed Feelings, Sunny Bains tells a number of fascinating stories about sensory prosthetics:
For six weird weeks in the fall of 2004, Udo Wächter had an unerring sense of direction. Every morning after he got out of the shower, Wächter, a sysadmin at the University of Osnabrück in Germany, put on a wide beige belt lined with 13 vibrating pads — the same weight-and-gear modules that make a cell phone judder. On the outside of the belt were a power supply and a sensor that detected Earth’s magnetic field. Whichever buzzer was pointing north would go off. Constantly.“It was slightly strange at first,” Wächter says, “though on the bike, it was great.” He started to become more aware of the peregrinations he had to make while trying to reach a destination. “I finally understood just how much roads actually wind,” he says. He learned to deal with the stares he got in the library, his belt humming like a distant chain saw. Deep into the experiment, Wächter says, “I suddenly realized that my perception had shifted. I had some kind of internal map of the city in my head. I could always find my way home. Eventually, I felt I couldn’t get lost, even in a completely new place.”
The effects of the “feelSpace belt” — as its inventor, Osnabrück cognitive scientist Peter König, dubbed the device — became even more profound over time. König says while he wore it he was “intuitively aware of the direction of my home or my office. I’d be waiting in line in the cafeteria and spontaneously think: I live over there.” On a visit to Hamburg, about 100 miles away, he noticed that he was conscious of the direction of his hometown. Wächter felt the vibration in his dreams, moving around his waist, just like when he was awake.
There are all kinds of senses humans don’t naturally have:
Direction isn’t something humans can detect innately. Some birds can, of course, and for them it’s no less important than taste or smell are for us. In fact, lots of animals have cool, “extra” senses. Sunfish see polarized light. Loggerhead turtles feel Earth’s magnetic field. Bonnethead sharks detect subtle changes (less than a nanovolt) in small electrical fields. And other critters have heightened versions of familiar senses — bats hear frequencies outside our auditory range, and some insects see ultraviolet light.
In the 1960s, Paul Bach-y-Rita installed a 20-by-20 array of metal rods in the back of an old dentist chair, and people could “see” pictures poked into their backs:
Having long ago abandoned the vaguely Marathon Man like dentist chair, the team now uses a mouthpiece studded with 144 tiny electrodes. It’s attached by ribbon cable to a pulse generator that induces electric current against the tongue. (As a sensing organ, the tongue has a lot going for it: nerves and touch receptors packed close together and bathed in a conducting liquid, saliva.)So what kind of information could they pipe in? Mitch Tyler, one of Bach-y-Rita’s closest research colleagues, literally stumbled upon the answer in 2000, when he got an inner ear infection. If you’ve had one of these (or a hangover), you know the feeling: Tyler’s world was spinning. His semicircular canals — where the inner ear senses orientation in space — weren’t working. “It was hell,” he says. “I could stay upright only by fixating on distant objects.” Struggling into work one day, he realized that the tongue display might be able to help.
The team attached an accelerometer to the pulse generator, which they programmed to produce a tiny square. Stay upright and you feel the square in the center of your tongue; move to the right or left and the square moves in that direction, too. In this setup, the accelerometer is the sensor and the combination of mouthpiece and tongue is the transducer, the doorway into the brain.
The researchers started testing the device on people with damaged inner ears. Not only did it restore their balance (presumably by giving them a data feed that was cleaner than the one coming from their semi circular canals) but the effects lasted even after they’d removed the mouthpiece — sometimes for hours or days.
The author tried out a rig connecting camera goggles to the tongue zapper:
I cranked up the voltage of the electric shocks to my tongue. It didn’t feel bad, actually — like licking the leads on a really weak 9-volt battery. Arnoldussen handed me a long white foam cylinder and spun my chair toward a large black rectangle painted on the wall. “Move the foam against the black to see how it feels,” she said.I could see it. Feel it. Whatever — I could tell where the foam was. With Arnold ussen behind me carrying the laptop, I walked around the Wicab offices. I managed to avoid most walls and desks, scanning my head from side to side slowly to give myself a wider field of view, like radar. Thinking back on it, I don’t remember the feeling of the electrodes on my tongue at all during my walkabout. What I remember are pictures: high-contrast images of cubicle walls and office doors, as though I’d seen them with my eyes. Tyler’s group hasn’t done the brain imaging studies to figure out why this is so — they don’t know whether my visual cortex was processing the information from my tongue or whether some other region was doing the work.
I later tried another version of the technology meant for divers. It displayed a set of directional glyphs on my tongue intended to tell them which way to swim. A flashing triangle on the right would mean “turn right,” vertical bars moving right says “float right but keep going straight,” and so on. At the University of Wisconsin lab, Tyler set me up with the prototype, a joystick, and a computer screen depicting a rudimentary maze. After a minute of bumping against the virtual walls, I asked Tyler to hide the maze window, closed my eyes, and successfully navigated two courses in 15 minutes. It was like I had something in my head magically telling me which way to go.
This leads into a device for helping pilots:
First we set a baseline. Schnell sat me down in front of OPL’s elaborate flight simulator and had me fly a couple of missions over some virtual mountains, trying to follow a “path” in the sky. I was awful — I kept oversteering. Eventually, I hit a mountain.Then he brought out his SOES, a mesh of hard-shell plastic, elastic, and Velcro that fit over my arms and torso, strung with vibrating elements called tactile stimulators, or tactors. “The legs aren’t working,” Schnell said, “but they never helped much anyway.”
Flight became intuitive. When the plane tilted to the right, my right wrist started to vibrate — then the elbow, and then the shoulder as the bank sharpened. It was like my arm was getting deeper and deeper into something. To level off, I just moved the joystick until the buzzing stopped. I closed my eyes so I could ignore the screen.
Finally, Schnell set the simulator to put the plane into a dive. Even with my eyes open, he said, the screen wouldn’t help me because the visual cues were poor. But with the vest, I never lost track of the plane’s orientation. I almost stopped noticing the buzzing on my arms and chest; I simply knew where I was, how I was moving. I pulled the plane out.