I spent a couple of days this week at CHI, the big annual meeting of the Association for Computing Machinery’s Special Interest Group on Computer-Human Interaction (ACM SIGCHI). It was the first time since 1994 that the conference—the main international gathering for scholars and practitioners in user interface design—has come to Boston. But it wasn’t the first time that a single company, namely Microsoft, has dominated the proceedings. Matching statistics from other recent CHI meetings, authors from Microsoft Research supplied nearly one out of eight papers presented at the conference, and researchers Ken Hinckley and Meredith Ringel Morris from MSR’s Adaptive Systems and Interaction Group in Redmond were co-chairs of the technical program.
I’m a sucker for this stuff, so I thought almost all of Microsoft’s 25 CHI papers were interesting. But two of the talks in particular, presented back-to-back on the closing day of the conference, contained enticing new ideas about how we might use computing devices in the future. One of them was Hinckley’s own paper on Codex, a prototype dual-screen computer system. The other was a paper by Patrick Baudisch on “back-of-device” interfaces, an intriguing alternative to today’s touch-screen-based devices.
Baudisch, a German native, is a former Xerox PARC researcher who joined Microsoft in 2002 and recently accepted a joint position at the Hasso Plattner Institute at the University of Potsdam in Germany. One of the questions he’s been studying over the past few years is whether it’s feasible to move the main touch interface for small mobile devices (think phones, mini-tablet computers, iPods, Zunes, and the like) from the front—where your fingers occlude your view of the screen—to the back.
After all, the smaller devices get, the less screen real estate they’ll offer, and the larger the fraction of the screen that’s covered up by your finger when you try to manipulate it. “The scientific term for this is the fat finger problem,” Baudisch deadpanned during his talk.
If the touch-sensitive surface on a mobile device were on the back instead, gestures like pointing, tapping, and selecting wouldn’t get in the way of the screen. At least, that’s the idea. But that creates a new challenge—seeing where your finger is going. So Baudisch’s team has been experimenting with a variety of approaches, including using transparent screens (which, unfortunately, don’t leave room for the electronic guts of most devices) and attaching a boom with a camera to a device’s backside (which is predictably clunky).
Baudisch’s newest prototype, and the one he described yesterday, is called nanoTouch. It’s a squarish little gadget resembling an iPod nano, with a 2.4-inch screen that dominates the front and a capacative trackpad similar to the mousepad on a laptop computer attached to the back.
The nanoTouch is designed to be held by the edges in one hand while you operate the trackpad with the index finger of your other hand. The cleverest touch, so to speak, is that the device uses “pseudotransparency” to provide visual feedback—basically, the “cursor” is a life-size picture of a finger that tracks with the position of your actual finger, as if you were looking through the device with X-ray glasses.
It’s a nifty effect that neatly captures the concept of back-of-device interaction; the tip of the simulated finger even turns white when you press harder against the screen, as if the blood were rushing away from that spot. Baudisch’s nanoTouch demo provoked a little flurry of publicity back in December, with coverage by Engadget and New Scientist, among others (I’ve embedded a nanoTouch video from New Scientist below). But as Baudisch explained yesterday, the finger is just for show—it’s there to quickly train the user on what’s happening. “You never see the finger in an application,” he said. “For any real application, we reduce the touch to a single point—which is how we get the finger out of the equation and enable high precision.”
By masking the screen of the nanoTouch prototype and leaving less and less of the trackpad active, Baudisch’s group has been studying just how tiny manufacturers might be able to make future devices without sacrificing usability. They’ve found that as long as a target (meaning, say, an onscreen button) is more than about 3 millimeters across, it’s possible to accurately manipulate a device with a screen measuring as little as 8 millimeters diagonally—less than the size of the fingernail on your pinky.
Baudisch suggests that such devices might be made into pendants, wristbands, or belt buckles—all of which would surely be more fashionable than wearing your smartphone on a geeky belt holster. “Back-of-device interaction is the key to making extremely small pointing devices,” Baudisch concluded.
But while certain types of devices such as music players may keep shrinking (as this classic Saturday Night Live skit about the “iPod Invisa” predicted), we’ll probably still want to
