November 11, 2011

Predicting behavior: The case of the missing militant

There is an oft-repeated axiom in our field that the most reliable predictor of future behavior is what a person has done in the past.

But is this axiom valid?

Let's take the example of Ronald Stanley Bridgeforth, featured on America's Most Wanted.

Forty-three years ago, while being detained on suspicion of trying to buy merchandise with a stolen credit card, the 24-year-old Black militant pulled out a revolver and shot at police. He jumped bail and, three years later, became a suspect in the killing of a police sergeant during an armed invasion of a police station in San Francisco.

Would this information lead you to predict that he was likely to engage in more violence in the future?

If so, you would be wrong.

Bridgeforth vanished from the radar screen, and eventually police figured he might have died. But the former community activist was far from dead. After fleeing to Africa, he moved to Ann Arbor, Michigan, married, and raised two sons. Under the assumed name of Cole Jordan, he worked as a janitor, earned a bachelor’s degree from Wayne State University and a master's degree in counseling from Eastern Michigan University, became a licensed professional counselor, and eventually worked his way up to the rank of a full-time faculty member at Washtenaw Community College.

Bridgeforth with attorney Paul Harris (L) and wife Diane (R)
Last week, Bridgeforth finally turned himself in. Authorities were not closing in, but he had a troubled conscience. He plans to plead guilty in the assault case, in which he faces a maximum of five years in prison. Prosecutors announced they will not prosecute him in the infamous murder of Sgt. John Young at San Francisco's Ingleside Station on Aug. 29, 1971. That case unraveled two years ago in part due to allegations (aired in a documentary, Legacy of Torture) that police used torture with electric shock, cattle prods, beatings, sensory deprivation and asphyxiation to obtain confessions from three of the nine suspects.

One might argue that Bridgeforth is an exception to the rule. Only, he's not. Time and again, we hear about a long-time fugitive who lived a quiet life, surrounded by friends and co-workers who had no clue about his or her violent past.

David Gonzales, William Walter Asher III, Katherine Ann Power, Claude Daniel Marks and Donna Jean Willmott, to name just a few.

These cases are testament to the weak validity of the axiom that past behavior is a good predictor of the future. There are several flaws with the theory, among them:
  • The base rate: Most serious crimes have a low base rate of recidivism. That makes us most likely to be correct if we predict that the behavior will NOT reoccur. For example, because of the base rate of rearrest for murder, we would be wrong in the broad majority of cases if we predicted that someone who has killed once will most likely kill again. The same is true for sexual offending. In one recent study, 95 out of 100 people arrested on sex charges had no prior sex crimes; an inordinate focus on the five percent lends an illusion of a higher base rate of reoffending than the evidence warrants.
  • Desistance: A second major problem with static predictions is that people change. In fact, even hard-core criminals almost universally desist from crime as they age. This holds true across all eras and cultures. As scholars Shadd Maruna and Laub and Sampson have shown, crime is mainly a young man's game. As they age, offenders settle down and become less impulsive. Or, they simply burn out.
  • Environmental context: The axiom of past as prelude also ignores the circumstances that contribute to offending. Criminologists have long known about the critical importance of context. For example, peer influence is critical to crime by adolescents and young adults, who have the highest rates of offending. Lifestyle circumstances that can -- and often do -- change over time influence other types of crimes as well, such as robberies and drug offenses. For Bridgeforth and others of the 1960s-1970s era, the context was a militant revolutionary movement that swept up many idealistic young people.
  • Unproven allegations: The Bridgeforth case also highlights the problem of relying on allegations of past misconduct that may not be reliable. Bridgeforth has denied the charge that he was the getaway car driver in the San Francisco police killing, and now prosecutors have chosen not to prosecute him.   

Ultimately, the past-as-prelude axiom may hold better for some behaviors than others. Perhaps it is more reliable when predicting scripted or compulsive acts that a person engages in with high frequency over a lengthy period of time. However, it is less reliable when applied to context-influenced behaviors with low base rates of reoccurrence.

And never should we ignore the influence of aging. Bridgeforth is not the same man at 67 as he was at 24. Think back to your own adolescence or early adulthood; are you the same person now as you were then?

The viewpoint that past is prelude is fundamentally pessimistic, leaving little room to acknowledge that human beings are highly adaptive, and often capable of learning from mistakes and changing our lives.