The Frontal Cortex

Morality, Psychopaths and Emotions

On Monday, I posted about some recent imaging work documenting the way the brain distinguishes between “personal” and “impersonal” moral dilemmas. Now comes a new Nature paper from a medley of researchers documenting how damage to a single brain region – the ventromedial prefrontal cortex (VMPO) – erases this fundamental distinction.

Damage to an area of the brain behind the forehead, inches behind the eyes, transforms the way people make moral judgments in life-or-death situations, scientists reported yesterday. In a new study, people with this rare injury expressed increased willingness to kill or harm another person if doing so would save others’ lives.

The findings are the most direct evidence that humans’ native revulsion to hurting others relies on a part of neural anatomy, one that evolved before the higher brain regions responsible for analysis and planning.

“I think it’s very convincing now that there are at least two systems working when we make moral judgments,” said Joshua Greene, a psychologist at Harvard who was not involved in the study. “There’s an emotional system that depends on this specific part of the brain, and another system that performs more utilitarian cost-benefit analyses which in these people is clearly intact.”

It’s an elegant study, although it’s worth remembering that the n is small. But I think this data from neurological patients builds on a growing body of research documenting the crucial importance of emotion when making moral decisions.

Look, for example, at psychopaths/sociopaths. Psychiatrists estimate that 1 percent of the population, and about 25 percent of the prison population, have psychopathic tendencies. This disorder seems largely due to an inability to process emotions. It’s still not clear what brain regions are involved, although attention is currently focused on a defective amygdala/orbitofrontal cortex loop. This anatomical defect has severe consequences. When normal people are shown staged videos of strangers being subjected to pain – like a powerful electrical shock – they automatically generate a visceral emotional reaction. Their hands start to sweat and their blood pressure surges. But psychopaths feel nothing. It’s as if they were watching a blank screen. Most people react differently to emotionally charged verbs like kill or rape than to neutral words like sit or walk, but psychopaths don’t. The words all seem equivalent. When normal people tell lies, they exhibit the classic symptoms of nervousness. Their hands start to sweat and their blood pressure spikes. Lie detectors work by measuring these signals of stress. But psychopaths are able to consistently fool lie detectors. Dishonesty doesn’t make them anxious because nothing makes them anxious. They can lie with impunity.

The absence of emotion is visible in an fMRI machine. After being exposed to fearful facial expressions, the emotional parts of the normal human brain, like the amygdala, show increased levels of activation. So do the cortical parts responsible for recognizing faces. (Fear seems to potentiate our sensations.) As a result, a frightened face becomes a frightening sight; we naturally imitate the feelings of others. The brains of psychopaths respond to these fearful faces with silence. Their emotional areas are unperturbed, and their facial recognition system is even less interested in fearful faces than in perfectly blank stares.

Because psychopaths are unable to process emotions properly, they also don’t understand the innate personal/impersonal moral distinction drawn by most human beings. Most children begin to separate personal transgressions (like hitting somebody) from impersonal transgressions (like talking in class) around the age of three. When asked why acts of personal violence are wrong, young kids will refer to the harm done to the individual. Getting hit hurts. However, when young children are asked why impersonal moral errors are wrong, they typically refer to the social disorder that will inevitably ensue. You can’t talk in class because the teacher is talking. You can’t cut to the front of the line because everybody has to wait their turn.

This elementary distinction has important consequences. When kids are told that it’s now permissible to hit your friend, they still believe that it’s wrong. The act of violence still feels bad; our amygdala has a steady conscience. In contrast, when the rules are changed for impersonal moral violations, they cease to be violations. If the teacher says it’s okay to talk, then it must be okay to talk. The transgression is no longer immoral.

Psychopaths don’t distinguish between personal and impersonal violations. When psychopaths are asked why it’s wrong to hurt somebody, they are much less likely to mention the suffering of another person. Instead, they allude to the pernicious effects of social disorder. Tax evasion is bad for the same reason that murder is bad. Furthermore, when the rules are changed, psychopaths are much more likely to believe that it’s perfectly moral to harm another human being. There is nothing inherently wrong with violence. If the teacher says you can beat somebody up, then you can beat somebody up. Their moral emotions don’t stand in the way.

I certainly don’t mean to imply that these VMPO patients are psychopaths. But their inability to decipher their emotions does leave them with a distinctly consequentialist view of morality:

Those with ventromedial injuries were about twice as likely as other participants to say they would push someone in front of the train (if that was the only option), or suffocate a baby whose crying would reveal to enemy soldiers where the subject and family and friends were hiding.

The difference was very clear for all the ventromedial patients, said Dr. Michael Koenigs, a neuroscientist at the National Institutes of Health who led the study while at the University of Iowa. After repeatedly endorsing killing in these high-conflict situations, Dr. Koenigs said, one patient told him, “Jeez, I’ve turned into a killer.”

Fore more on the etiology of psychopathic tendencies, I’d recommend The Psychopath: Emotion and the Brain, by James Blair, et. al.


  1. #1 Steven
    March 22, 2007


  2. #2 tirta
    March 22, 2007

    i’m interested to take the social identity perspective on this issue of psychopaths. going back to your last post for a bit, i’d say war is natural when you’re talking about out-groups (them) and unnatural when it comes to in-groups (us). using greene’s lingo: when it’s ‘us’, everything tend to be personal, while for ‘them’, the tendency is indeed impersonal. this would also fit nicely with peter singer’s proposal of the expanding moral circle, for those who simply have larger and ever-expanding in-groups.

    now, could it be that psychopaths simply have less people in their in-groups (perhaps only their partner and close relatives — or even no one at all for the extreme cases), thus judging everything as impersonal?

  3. #3 Bravo Romeo Delta
    March 22, 2007


    An important distinction needs to be included here between war and violence, as social actions. The question of whether or not the moral underpinnings against war have a neurological basis isn’t identical to asking if there is a neurological basis to an aversion to violence.

    If one gets sufficiently reductionist, yes, the two are indistinguishable. But that’s contingent on a cartoon-like view of warfare, and such an interpretation obscures a lot of the worthwhile depth to be had in the exploration of the underlying dynamics of warfare.

  4. #4 Susana Delgado
    August 21, 2007

    I wonder if psychopaths would respond when seeing a self-image of pain. Are they able to feel pain? Do they have emotions when they are subject to pain? or their brain is able to separate others’ pain from self-pain.

  5. #5 Houston Injury Attorneys
    March 17, 2011

    In a new study, people with this rare injury expressed increased willingness to kill or harm another person if doing so would save others’ lives.

New comments have been disabled.