New app for Google Glass can gauge how others are feeling

Fast enough to catch micro expressions — the tiny facial tells that help mentalists, psychics and other stage performers profess to be able to read minds — the app isn't just good at being able to tell the difference between a smile and a frown. 

It can read a host of expressions and translate what it reads into overall emotional sentiment — whether someone feels positive, negative or neutral about something or someone — and can spot both primary and advanced, nuanced emotions. So everything from joy, surprise and anger through to frustration and confusion.