Separate event detection is already used by the popular smart phone app Bump, which lets users exchange information by shaking, or “bumping,” two phones close together. PhoneTouch differs in that it allows the pairing of a personal device with a shared device, says Gellersen. “PhoneTouch not only establishes a connection but allows the Phone to be used as a stylus on the surface, to select specific widgets.”
Schmidt says that there is a slim chance that the system will be confused when two phones touch it simultaneously. But a user study has shown that it identifies the correct device 99.99 of the time. The researchers will present the work at the User Interface Software and Technology symposium in New York this week.
“It’s a great idea,” says Rob Miller, head of the User Interface Design Group at MIT. “The traditional desktop approach of username and password entry doesn’t make much sense on a multitouch tabletop,” because text entry is less natural.
Mitsubishi Electric has demonstrated a touch surface called DiamondTouch that uses sensors in chairs to match touches to different people. But using a phone may be more convenient. “Mobile phones are already ubiquitous–people carry them anyway.” Miller agrees. “Phones are very personal. We almost always have them with us.”