A new brain imaging study revealed the mechanism behind judgments made about how severely a person who has hurt another human should be punished.
The study, published on Aug. 3 by the journal Nature Neuroscience, determined the area of the brain responsible for deciding whether a violent act was intentional or unintentional, Vanderbilt University reported. They found this part of the brain trumps the emotional urge to punish a person who has committed a gruesome act.
"A fundamental aspect of the human experience is the desire to punish harmful acts, even when the victim is a perfect stranger. Equally important, however, is our ability to put the brakes on this impulse when we realize the harm was done unintentionally," said Rene Marois, the Vanderbilt University professor of psychology who headed the research team. "This study helps us begin to elucidate the neural circuitry that permits this type of regulation."
To make their findings the researchers looked at the brains of 30 volunteers (20 male and 10 female with an average age of 23) using functional MRI (fMRI) while they read off violent scenarios. These stories depicted four levels of harm: "death, maiming, physical assault and property damage." In half of the scenarios the harm was identified as intentional while in the other half it was unintentional. The stories also came in more graphic or tamer versions.
After reading each scenario the participants were asked to list how much punishment they thought the characters deserved. When the responses were analyzed the researchers found the way the scenarios were described significantly impacted the level of punishment the participants felt was deserved; graphic descriptions set the punishment level higher. This finding was true only when the harm was caused intentionally. This finding suggests graphic material could influence the outcome of a case in the courtroom.
"Although the underlying scientific basis of this effect wasn't known until now, the legal system recognized it a long time ago and made provisions to counteract it," said Michael Treadway, a post-doctoral fellow at Harvard Medical School and lead author of the study. "Judges are permitted to exclude relevant evidence from a trial if they decide that its probative value is substantially outweighed by its prejudicial nature."
The fMRI scans revealed areas of the brain involved in the complex process. They discovered the amygdala (which plays a role in processing emotions) responded to the graphic language. The amygdala showed a stronger communication with the dorsolateral prefrontal cortex (which deals with decision making) when read the scenarios that depicted intentional violent actions. When the harm was done unintentionally a different regulatory network became more active and suppressed amygdala responses to the graphic language.
"This is basically a reassuring finding," Marois said. "It indicates that, when the harm is not intended, we don't simply shunt aside the emotional impulse to punish. Instead, it appears that the brain down-regulates the impulse so we don't feel it as strongly. That is preferable because the urge to punish is less likely to resurface at a future date."
