After checking the first two seasons of Homicide out of the library, I have murder on the mind. Fortunately for me, an article from the Dana archives looks at crime through the eyes of a neuroscientist.
In 1999, Adrian Raine, now at the University of Pennsylvania, wrote “Murderous Minds: Can We See the Mark of Cain?” Using positron emission tomography (PET), Dr. Raine conducted the first brain-imaging study of killers.
Dr. Raine and his colleagues compared the brain function of 41 people who pled not guilty to murder by reason of insanity to 41 non-murderer controls and saw measurable differences in certain areas of the brain. He wrote:
“We believe this study is the ﬁrst evidence from brain imaging that the brains of a large sample of murderers are functionally different from those of normal people. Prefrontal deﬁcits have also been found in schizophrenia and depression, but those studies have never revealed our speciﬁc pattern of ﬁndings involving the prefrontal cortex, corpus callosum, angular gyrus, amygdala, hippocampus, and thalamus. This suggests a unique PET ‘signature’ of the brains of some murderers.”
Raine’s findings led him to tackle the ethical issues at hand:
“Brain-imaging research on violence troubles us by challenging the way we think about crime. It questions our treatment of murderers in the way that, looking back 200 years, we question the shackling of the mentally ill. The history of civilization suggests that, at least over the long term, society has tended to become more humane. Two hundred years from now will we have reconceptualized recidivistic, serious criminal behavior as a clinical disorder with roots in early social, biological, and genetic forces beyond the individual’s control? Will we look back aghast at the execution of seriously violent offenders? Will we view execution of prisoners as we now view the burning of witches?”
What has research shown in the twelve years since? And what ethical questions are researchers asking now?
In a LiveScience article for earlier this year, Dr. Raine discusses a long-term study that followed 1,795 children from ages 3 to 23, 137 of whom committed crimes. These 137 people showed a lack of fear response when they underwent a fear-conditioning test (in which a tone becomes associated with a mild shock) at three years old. This does not mean that all three year olds with this result will become criminals, but it does suggest a correlation between an early response and a later behavior.
A Chronicle of Higher Education article from June indicates that identical twins are more likely to share aggressive and antisocial traits than fraternal twins, indicating, said Dr. Raine, that “at least 50 percent of this can be attributed to genetics."
Dr. Raine has also linked a brain-development defect to criminal behavior. People with cavum septum pellucidum—which occurs when a wall of tissue in the brain fails to form, and is often linked to structural abnormalities, including of the amygdala—had been arrested and convicted of crimes more than those without the defect.
If we could predict who will become a criminal from a brain scan or behavior test, should we intervene? Dr. Raine is conducting a study to see if omega-3 fatty acid supplements and cognitive behavioral therapy can dampen aggressive behavior in children. But many questions remain: If biology is to blame for behavior, how should we punish criminal acts? Where do personal responsibility and morality fit into the equation? And if science gets to the point of being able to predict who will become a criminal, what comes next?