This is the 2007 version. Click here for the 2017 chapter 14 table of contents.

Computer-Generated Profiles

As argued in Chapter 1, intuitions are usually based on correlational information. However, as also described in Chapter 1, computers do better than humans at making predictions, because computers can search a large database and detect odd or unlikely correlations that a human might not notice. Simple, dumb correlational processes consistently outperform experts when it comes to predicting the future. Today a computer usually plays the role of James Brussel, making fantastically precise predictions based on a large base of correlational information.

Why are computers good at making predictions?

What spectacularly detailed prediction was made by John Douglas of the FBI?

For example, there was the case of a 12 year old girl found murdered near her Adairsville, Ga., home in December 1979. The murderer had sexually assaulted her and crushed her head with a large rock. The local authorities called the FBI for help in locating a suspect. John Douglas, a psychologist with the FBI Behavioral Science Unit, told them to look for a man with the following characteristics:

—He would be a divorced white male.

—He would be in his mid-20s.

—He would drive a black or blue car.

—He would have a "macho" laborer's job.

—He would have had some prior contact with the victim.

—He would be a high school drop-out.

—He would have served in the Army or Marines, probably with a medical or dishonorable discharge after less than six months.

—He would have a prior record of sex crimes.

—He would pass a lie detector test, showing no deception.

Douglas recalls, "They told me, 'You just described a guy we released as a suspect in the case,'" Douglas gave them some tips on how to interview the man, Darrel Gene Devier, who later confessed to the FBI and received a death sentence. How accurate was the computer- generated profile?

—Devier was a divorced white male.

—He was 24 years old at the time of the killing.

—He drove a dark blue Pinto.

—He worked as a tree-limb cutter.

—He had worked near the driveway of the victim before the killing, making sexual remarks to her.

—He was an eighth-grade drop-out.

—He received a general discharge from the Army after less than a year in the service.

—He had been accused of attempting to rape a 13-year-old girl in a previous incident.

—He showed no deception on a lie detector examination. (Post, 1982)

How does the computer do it?

How does the computer do it? The computer relentlessly pursues correlations: statistical patterns or trends in the data from past crimes. Over years of feeding crime information into a database, a huge amount of information is stored, and a computer can search for correlations in an instant. In this case, past crime descriptions provided the information that (for example) a person who commits a brutal murder is likely to be driving a dark-colored car. That is an insight that would not necessarily occur to a human.

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