One was Martha Stout, from the Harvard Medical School, author of The Sociopath Next Door. (You may be wondering what the difference is between a psychopath and a sociopath, and the answer is, there really isn’t one. Psychologists and psychiatrists around the world tend to use the terms interchangeably.) They are everywhere, she said. They are in the crowded restaurant where you have your lunch. They are in your open-plan office.