Friday, December 28, 2012

The best predictor of future behavior is …

Original Article


… past behavior.

Past as prelude. So neat, so clean. So full of certitude. Like a fortune cookie Confucianism. Or something you might hear on CSI: Special Victims Unit, or from pop psychologist "Dr. Phil" McGraw. Actually, McGraw does cite it, in one of his many self-help books.

I'm sure you have heard the mantra. It's creeping into risk assessment reports and court testimony by forensic psychologists. Sometimes, it's augmented with incendiary metaphors: The subject is "a ticking time bomb"; he is "carrying a hand grenade and it's just a matter of when he pulls the pin."

One current case of mine involves a guy with a cluster of several violent offenses a few years ago, when he was in his 20s. He was using drugs back then, and hanging around with a bad crowd. Plus, he is chronically psychotic. Not a good combination.

But if you predict future violence based on a set of risk factors like his, you will be wrong more often than not. Only about four out of ten of those individuals judged to be at moderate to high risk of future violence go on to reoffend violently, according to research. The low base rates of violent recidivism will be working against you.

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