Besides projecting directions and e-mails in front of your face, Google Glass can also measure biological signs like heart and breathing rates, according to new research. The work suggests a new way for wearable devices to track a person’s stress level and provide instant fitness feedback. Researchers from MIT’s Media Lab and the Georgia Institute of Technology’s School of Interactive Computing say that they can accurately ferret out this data by monitoring a Glass wearer’s head movements with the gyroscope, accelerometer, and camera built into Google Glass. A paper on the research will be presented at the MobiHealth conference in Athens, Greece, in November.