I think some people have an unusual ability get extra information from other people, but I believe it's mostly biochemical extra-sensitivities that allow them to pick up subtle cues from the people around them and translate that information.
Some studies have already proven that it's an ability we've selectively bred into dogs. In study after study dogs were able to pick up subtle cues about what a human was trying to get them to do, whereas even wolves, coyotes, and foxes were not able to pick up the same cues.
And cats? forget it! They were too busy trying to get the humans to pick up subtle cues about what THEY wanted the humans to do.