Research News

Neuroscientists can measure criminal intent – at least in the moment

Owen Jones, Vanderbilt professor of law and of biological sciences.
Owen Jones (Vanderbilt University)

Intent to commit a crime is a crucial factor in determining prison sentences, yet some theorists worry that different grades of criminal intent are fictions and should not be given weight in courtrooms.

A new neuro-imaging study suggests it is possible to measure the subtle variations in intent that matter to law – at least while a crime is being committed. Brain activity reveals whether a subject has knowledge that he is committing a crime or is merely being reckless, according to research published the week of March 13 in the Proceedings of the National Academy of Sciences.

The study is one of dozens pursued under the auspices of the MacArthur Foundation’s Research Network on Law and Neuroscience, which is headquartered at Vanderbilt Law School and directed by co-author Owen Jones, a professor of law and biological sciences.

“Our experiments are a coordinated exploration of both the promise and the limitations of using neuroscience to further the goals of criminal justice,” said Jones. “This particular experiment was our designated moon shot. We didn’t know if would be possible, even in principle, to detect brain activity implicated in different mental states that matter to law.”

“We are not replacing juries with brain scanners, but we can now say that some debated differences in degree of criminal intent have a real neural basis,” said Yale’s Gideon Yaffe, professor of law and professor of philosophy and psychology.

The study

In the study, researchers from Yale University and Virginia Tech asked 40 subjects to decide whether to take a suitcase through a security checkpoint. During some trials, the subjects knew there was contraband in the suitcase. In others, they were aware only that there were differing risks they might be carrying contraband. The subjects knew they would be rewarded for sneaking contraband through, but punished if caught carrying it.

By examining neuro-images of the brains of these subjects as they made their choices, researchers were able to predict which subjects knew they were carrying contraband and which were aware only of a risk.

In the law, these distinctions are important both for establishing guilt and for sentencing. In general, knowing actors are guilty of more serious offenses and punished more harshly than reckless actors.

“Building on this first proof of concept may improve our understandings, for instance, of the relationship between legally relevant mental states and conditions of addiction or mental illness,” Jones said.

The research was part of an inter-disciplinary and trans-institutional effort, pulling together 10 neuroscientists and legal scholars from Yale University, Virginia Tech, University of Pennsylvania, University of Virginia, Vanderbilt and others.