Prediction of Crime and Recidivism

Despite its long history and obvious advantage of economy and reproducibility, a statistical approach is used in only a minority of predictive decision-making points in the criminal justice system. Primary reliance is placed on the use of intuitive human judgment in many situations calling for a prediction of future crime.

Many studies have attempted to validate the ability of psychiatrists and psychologists to predict violent behavior. Here we consider three of the best ones. Harry Kozol, Richard Boucher, and Ralph Garofalo conducted a ten-year study involving almost six hundred male offenders, most of whom had been convicted of violent sex crimes. At the Massachusetts Center for the Diagnosis and Treatment of Dangerous Persons, each offender was examined independently by at least two psychiatrists, two psychologists, and a social worker. These clinical examinations, along with a full psychological test battery and "a meticulous reconstruction of the life history elicited from multiple sources—the patient himself, his family, friends, neighbors, teachers, employers, and court, correctional and mental hospital record" (p. 383), formed the database for their predictions.

Of the 592 patients admitted to their facility for diagnostic observation, 435 were released. Kozol and his associates recommended the release of 386 as nondangerous and opposed the release of 49 as dangerous, with the court deciding otherwise. During the five-year follow-up period, 8 percent of those predicted not to be dangerous became recidivists by committing a serious assaultive act, and 35 percent of those predicted to be dangerous committed such an act.

In 1966, the Supreme Court held that Johnnie Baxstrom had been denied equal protection of the law by being detained beyond his maximum sentence in an institution for the criminally insane without the benefit of a new hearing to determine his current dangerousness (Baxstrom v. Herold, 383 U.S. 107 (1966)). The ruling resulted in the transfer of nearly one thousand persons reputed to be some of the most "dangerous" mental patients in the state of New York from hospitals for the criminally insane to civil mental hospitals. It also provided an excellent opportunity for naturalist research on the validity of the psychiatric predictions of dangerousness upon which the extended detentions were based.

In their classic 1974 study of careers of the criminally insane, Henry Steadman and Joseph Cocozza found that the level of violence experienced in the civil mental hospitals was much less than had been feared, that the civil hospitals adapted well to the massive transfer of patients, and that the Baxstrom patients received the same treatment as the civil patients. Only 20 percent of the Baxstrom patients were assaultive to persons in the civil hospital or the community at any time during the four years after their transfer. Furthermore, only 3 percent were sufficiently dangerous to be returned to a hospital for the criminally insane during a four-year period after the decision. The researchers followed 121 Baxstrom patients who had been released into the community, that is, discharged from both the criminal and civil mental hospitals. During an average of two and a half years of freedom, only 9 of the 121 patients (7.5 percent) were convicted of a crime, and only one of those convictions was for a violent act.

Lidz, Mulvey, and Gardner (1993) took as their subjects not prisoners but rather male and female patients being examined in the acute psychiatric emergency room of a large civil hospital. Psychiatrists and nurses were asked to assess potential patient violence to others over the next six-month period. Violence was measured by official records, by patient self-report, and by the report of a collateral informant in the community (e.g., a family member). Patients who elicited professional concern regarding future violence were found to be significantly more likely to be violent after discharge (53 percent) than were patients who had not elicited such concern (36 percent). The accuracy of clinical prediction did not vary as a function of the patient's age or race. The accuracy of clinicians' predictions of male violence substantially exceeded chance levels, both for patients with and without a prior history of violent behavior. In contrast, the accuracy of clinicians' predictions of female violence did not differ from chance. While the actual rate of violent incidents among released female patients (49 percent) was higher than the rate among released male patients (42 percent), the clinicians had predicted that only 22 percent of the women would be violent, compared with predicting that 45 percent of the men would commit a violent act. The inaccuracy of clinicians at predicting violence among women appeared to be a function of the clinicians' serious underestimation of the base rate of violence among mentally disordered women (perhaps due to an inappropriate extrapolation from the great gender differences in rates of violence among persons without mental disorder).