MIT's Nexi robot has been teaching us about social interaction for years, and has even done a stint with the US Navy. Its latest role, however, involved studying those moments when society falls apart. Northeastern University researchers made Nexi the key ingredient of an experiment where subjects were asked to play a Prisoner's Dilemma-style game immediately after a conversation, whether it was with a human or a machine. Nexi showed that humans are better judges of trustworthiness after they see the telltale body language of dishonesty -- crossed arms, leaning back and other cues -- even when those expressions come from a collection of metal and plastic. The study suggests not just that humans are tuned to watch for subtle hints of sketchy behavior, but that future humanoid robots could foster trust by using the right gestures. We'll look forward to the friendlier machine assistants that result... and keep in mind the room for deception when the robots invariably plot to take over the world.