Psychopaths get time off for bad brains

Biological evidence may prompt sentencing break for violent offenders

A callous, manipulative psychopath convicted of a brutal crime can count on a long prison stint. But a judge may issue a slightly shorter sentence if presented with a biological explanation for the criminal’s psychopathic personality.

Supplying judges with scientific evidence about suspected brain deficits in psychopathy led to a reduction in prison sentences from about 14 years to 13 years, researchers report in the Aug. 17 Science. The results come from a nationwide, online survey of state judges given a hypothetical scenario about a psychopath convicted of what lawyers call aggravated battery.

Judges taking the survey tended to view psychopathic criminals as dangerous, whether or not scientific evidence was introduced, say psychologist Lisa Aspinwall, lawyer Teneille Brown and philosopher James Tabery, all of the University of Utah in Salt Lake City. A hypothetical psychopath in the new study got sent to the slammer for longer than the average nine-year sentence given to non-psychopaths found guilty of aggravated battery in real courts.

Aspinwall and her colleagues informed judges that clinicians use psychopathy — which is not an official psychiatric diagnosis — to refer to individuals who are impulsive, emotionally shallow, outwardly charming, lacking in empathy or remorse, chronic liars and callous manipulators (SN: 12/9/06, p. 379). Judges were told that psychopathy is incurable.

But any tendency toward reduced sentences for psychopathic convicts in a survey would be weaker in actual courtrooms where judges hear evidence contested by prosecutors and defense attorneys, says psychologist Jennifer Skeem of the University of California, Irvine.

“It is premature to apply neuroscience on psychopathy to decisions about criminal responsibility and sentencing,” Skeem says.

It’s hard to know whether defense attorneys could win reduced prison sentences for actual psychopathic offenders by introducing brain evidence, Tabery acknowledges. Even in the new 19-state survey, evidence about biological contributions to psychopathy led to substantially reduced sentences in two states (Utah and Maryland), slightly reduced or unchanged sentences in six states and slightly increased sentences in three states (Colorado, New York and Tennessee). The remaining eight states included too few participants to determine statewide trends.

“No one knows if real-world sentencing of psychopathic defendants works as it does in this study, or even whether most judges consider psychopathy when imposing sentences,” says lawyer and psychologist Stephen Morse of the University of Pennsylvania Law School in Philadelphia.

Aspinwall’s group can’t say whether psychological or social explanations for a psychopath’s crime would affect sentencing decisions as much as biological evidence did, Morse adds.

In the online study, 181 judges read a scenario in which a man beat a store clerk with a gun during a robbery, causing brain damage to the victim. All judges saw evidence that the criminal was a psychopath. In addition, 90 judges received scientific findings from either the prosecution or the defense about psychopathy’s biological roots. Prosecutors argued that biological evidence supported a longer sentence; defenders sought a reduced sentence.

About 87 percent of judges listed at least one factor, such as the crime’s seriousness, as relevant to lengthening the sentence. When judges received biological explanations of psychopathy from the defense, the proportion taking at least one sentence-reducing factor into account rose from around 30 percent to 66 percent.

For unclear reasons, the judges didn’t rate psychopaths as having less free will or being less responsible after hearing evidence about brain influences on the condition.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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