Schneier on Security

The Sham of Criminal Profiling

Malcolm Gladwell makes a convincing case that criminal profiling is nothing more than a “cold reading” magic trick.

A few years ago, Alison went back to the case of the teacher who was murdered on the roof of her building in the Bronx. He wanted to know why, if the F.B.I.’s approach to criminal profiling was based on such simplistic psychology, it continues to have such a sterling reputation. The answer, he suspected, lay in the way the profiles were written, and, sure enough, when he broke down the rooftop-killer analysis, sentence by sentence, he found that it was so full of unverifiable and contradictory and ambiguous language that it could support virtually any interpretation.

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.

[…]

They had been at it for almost six hours. The best minds in the F.B.I. had given the Wichita detectives a blueprint for their investigation. Look for an American male with a possible connection to the military. His I.Q. will be above 105. He will like to masturbate, and will be aloof and selfish in bed. He will drive a decent car. He will be a “now” person. He won’t be comfortable with women. But he may have women friends. He will be a lone wolf. But he will be able to function in social settings. He won’t be unmemorable. But he will be unknowable. He will be either never married, divorced, or married, and if he was or is married his wife will be younger or older. He may or may not live in a rental, and might be lower class, upper lower class, lower middle class or middle class. And he will be crazy like a fox, as opposed to being mental. If you’re keeping score, that’s a Jacques Statement, two Barnum Statements, four Rainbow Ruses, a Good Chance Guess, two predictions that aren’t really predictions because they could never be verified—and nothing even close to the salient fact that BTK was a pillar of his community, the president of his church and the married father of two.

Posted on November 14, 2007 at 6:47 AM • View Comments