Wearing a computer instead of carrying one could eliminate all those downsides. The Google Glass prototype projects information—photos, e-mails, navigation cues—onto a screen positioned in front of one eye. The system will most likely have its own cellular radio, so it could work independently of a smartphone. Motion sensors, a video camera, and a GPS radio will allow developers to code apps that monitor a person's behavior in real time. An HUD implementation of the Google Goggles image-recognition software, for example, could keep track of what a person eats, reads, and buys. New apps could establish an instant feedback loop— perhaps a reward for skipping the morning doughnut in favor of a banana.