A new study published in Neuron suggests that our ability to respond with outrage toward people who attempt to harm us is seated in a brain region called the ventromedial prefrontal cortex (VMPC).

Patients with damage to this brain area are unable to conjure a normal emotional response to hypothetical situations in which a person tries, but fails, to kill another person. Therefore, they judge the situation based only on the outcome, and do not hold the attempted murderer morally responsible.

The findings support the idea that making moral judgments requires at least two processes — a logical assessment of the intention, and an emotional reaction to it.

Researchers studied a group of nine patients with damage (caused by aneurisms or tumors) to the VMPC, a plum-sized area located behind and above the eyes, associated with regulating emotions. Such patients have difficulty processing social emotions such as empathy or embarrassment, but "they have a perfectly intact capacity for reasoning and other cognitive functions," says Liane Young, a postdoctoral associate in MIT's Department of Brain and Cognitive Sciences and lead author of a paper.

The researchers gave the subjects a series of 24 hypothetical scenarios and asked for their reactions. The scenarios of most interest to the researchers were ones featuring a mismatch between the person's intention and the outcome — either failed attempts to harm or accidental harms.

When confronted with failed attempts to harm, the patients had no problems understanding the perpetrator's intentions, but they failed to hold them morally responsible. The patients even judged attempted harms as more permissible than accidental harms (such as accidentally poisoning someone) — a reversal of the pattern seen in normal adults.

"They can process what people are thinking and their intentions, but they just don't respond emotionally to that information," says Young, ."They can read about a murder attempt and judge it as morally permissible because no harm was done."

Citation: oung et al., 'Damage to Ventromedial Prefrontal Cortex Impairs Judgment of Harmful Intent', Neuron, March 2010; doi:10.1016/j.neuron.2010.03.003