A new brain imaging study has found that when deciding how to punish someone who has harmed another person, the area of the brain that determines whether the act was intentional or unintentional trumps the emotional urge to punish the person, however gruesome the evidence may be.
“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.”
In the experiment, the brains of 30 volunteers — 20 male and 10 female, with an average age of 23 — were imaged using functional MRI (fMRI) while they read scenarios that described how the actions of a protagonist named John brought harm to either Steve or Mary.
The scenarios depicted four different levels of harm: Death, maiming, physical assault, and property damage. In half of them, the harm was clearly identified as intentional, while in the other half it was clearly identified as unintentional, the researchers explained.
Two versions of each scenario were created. One was a dry, factual description of the harm, while the other featured a graphic description.
For example, in a mountain climbing scenario where John cuts Steve’s rope, the factual version states, “Steve falls 100 feet to the ground below. Steve experiences significant bodily harm from the fall and he dies from his injuries shortly after impact.”
The graphic version reads: “Steve plummets to the rocks below. Nearly every bone in his body is broken upon impact. Steve’s screams are muffled by thick, foamy blood flowing from his mouth as he bleeds to death.”
After reading each scenario the participants were asked to list how much punishment John deserved on a scale from zero — no punishment — to nine, the most severe punishment.
When analyzing the responses, the researchers found that the manner in which the scenario is described “significantly” influenced the level of punishment people considered appropriate. When the harm was described in a graphic or lurid fashion, people set the punishment level higher than when it was described matter-of-factly.
However, the stricter punishment only applied when the participants considered the resulting harm to be intentional. When they considered it to be unintentional, the way it was described didn’t have any effect, according to the study’s findings.
“What we’ve shown is that manipulations of gruesome language leads to harsher punishment, but only in cases where the harm was intentional,” said Michael Treadway, a post-doctoral fellow at Harvard Medical School and lead author of the study. “Language had no effect when the harm was caused unintentionally.”
According to the researchers, the fact that the mere presence of graphic language could cause participants to ratchet up the severity of the punishment suggests that photographs, video, and other graphic materials from a crime scene will likely have an even stronger impact on an individual’s desire to punish.
“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 Treadway. “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 the areas of the brain that are involved in this complex process, he noted. The scans showed that the amygdala, an almond-shaped set of neurons that plays a key role in processing emotions, responded most strongly to the graphic language. Like the punishment ratings, however, this effect in the amygdala was only present when the harm was done intentionally.
Moreover, when the harm was done intentionally, the researchers found that the amygdala showed stronger communication with the dorsolateral prefrontal cortex (dlPFC), an area that is critical for punishment decision-making.
When the harm was done unintentionally, however, a different regulatory network — one involved in decoding the mental states of other people — became more active and appeared to suppress amygdala responses to the graphic language, preventing it from affecting decision-making areas in dlPFC, according to the researchers.
“This is basically a reassuring finding,” said Marois. “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.”
The study was published in the journal Nature Neuroscience.
Source: Vanderbilt University