Malcolm Gladwell is out with a new New Yorker piece on the troubles with FBI serial killer profiling, and how the whole thing can be led awry by adept "cold readers":
Astrologers and psychics have known these tricks for years. The magician Ian Rowland, in his classic “The Full Facts Book of Cold Reading,” itemizes them one by one, in what could easily serve as a manual for the beginner profiler. First is the Rainbow Ruse—the “statement which credits the client with both a personality trait and its opposite.” (“I would say that on the whole you can be rather a quiet, self effacing type, but when the circumstances are right, you can be quite the life and soul of the party if the mood strikes you.”) The Jacques Statement, named for the character in “As You Like It” who gives the Seven Ages of Man speech, tailors the prediction to the age of the subject. To someone in his late thirties or early forties, for example, the psychic says, “If you are honest about it, you often get to wondering what happened to all those dreams you had when you were younger.” There is the Barnum Statement, the assertion so general that anyone would agree, and the Fuzzy Fact, the seemingly factual statement couched in a way that “leaves plenty of scope to be developed into something more specific.” (“I can see a connection with Europe, possibly Britain, or it could be the warmer, Mediterranean part?”) And that’s only the start: there is the Greener Grass technique, the Diverted Question, the Russian Doll, Sugar Lumps, not to mention Forking and the Good Chance Guess—all of which, when put together in skillful combination, can convince even the most skeptical observer that he or she is in the presence of real insight.