Crime and punishment

A truly interdisciplinary collaboration between biology, law and neuroscience at Vanderbilt University has used functional magnetic resonance imaging, fMRI, to watch how the brain changes when a person thinks about crime and punishment.

When someone is accused of committing a crime, it is the responsibility of impartial third parties, most commonly judge and jury to figure out whether the suspect is guilty of the alleged crime and then to decide, on a guilty verdict, a suitable punishment for the criminal. But, Vanderbilt professor Owen Jones, who is one of the nation's few professors of both law and biology, and colleague psychologist and neuroscientist René Marois wanted to know what happens within the brain when a person is making such a decision. The answer could have implications for understanding our social evolution as well as for how real-life cases work out in the court-room.

Working with neuroscience graduate student Joshua Buckholtz, the researchers scanned the brains of sixteen volunteers using fMRI to discern which regions of the brain are most active when a person was making a judgement about someone else's guilt and the degree to which they should be punished for a harmful act. The researchers found that, surprisingly, two distinct areas of the brain assess guilt and decide penalty.

The researchers displayed a scenario on a computer screen while the volunteers were being scanned. The scenario described a person committing an arguably criminal act that varied in the degree of harm the act caused. The criminal was described as intentionally committing an action ranging from simple theft to rape and murder.

With each scenario displayed, the researchers asked the volunteer to decide on the severity of a suitable punishment on a scale of 0 (no punishment) to nine (extreme punishment). Some of the scenarios also provide extenuating circumstances or background information that might sway one's decision such as whether the protagonist was coerced into the act by someone else, whether they had been threatened, or whether there was any mentally illness present.

"We were looking for brain activity reflecting how people reason about the differences in the scenarios," explains Jones.

The researchers found that activity in an analytic part of the brain, known as the right dorsolateral prefrontal cortex, tracked the decision of whether or not a person deserved to be punished. However, it was an entirely different part of the brain that was activated when the volunteer was making a decision about the degree to which the "criminal" should be punished. Activity was increased in the brain regions involved in processing emotions, such as the amygdala, at this point.

"These results raise the possibility that emotional responses to criminal acts may represent a gauge for assessing deserved punishment," Marois says.

Experts in law have long-debated about the proper roles in law of "cold" analysis and "hot" emotion. "Our results suggest that, in normal punishment decisions, the distinct neural circuitries of both processes may be jointly involved, but separately deployed," adds Jones.

An additional, intriguing aspect of the results of this study is that that the part of the brain apparently involved in determining guilt is the same brain as that revealed in other research into how our brains punish unfair economic behaviour in two-party interactions.

"The convergence of findings between second-party and third-party punishment studies suggests that impartial legal decision-making may not be fundamentally different from the reasoning used in deciding to punish those who have harmed us personally," Marois concludes.

Given that large-scale cooperation among genetically unrelated individuals is the rule in Homo sapiens and rare among other animals, it is perhaps no surprise that society and our legal systems are deeply entrenched in age-old human instincts. Fundamentally, they are aimed primarily at retribution: offenders are jailed or executed to punish them for their transgression, issues of rehabilitation and preventing future harm to society are, some observers suggest, only secondary.

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.