Psychopathy, qu’est-ce que c’est

Psychopathy, qu’est-ce que c’est

A thought experiment

Imagine that you are a respected scientist trying to better understand psychopathy.  What might be different in the brain of a psychopath?  As you look through brain scan after brain scan of psychopathic individuals—many of them convicted kilpet scanlers—you see a pattern.  In brain regions important for impulse control, moral reasoning, and empathy, the psychopathic individuals exhibit less brain activity than is normal.  You delve deeper into these differences, becoming an expert in the field.

Years later, one of the members of your lab confusedly hands you a scan that fits the pattern of a psychopathic individual–the same decreased activity in certain brain circuits.  But the scan is from a control group of supposedly healthy adults.  Your mind races.  Could the scanner have malfunctioned?  Did you just find a criminal who has so far escaped the law?  Or a person on the brink of committing a crime? Should you call the police?  You peel back the cover on the name of the subject.  It is your name.  Your brain looks like that of a violent murderer.

This is the true story of Dr. James Fallon from UC Irvine, who discusses his experience in his book The Psychopath Inside: A Neuroscientist’s Personal Journey into the Dark Side of the Brain, on NPR’s Snap Judgement, and in a TED talk.  As it turns out, his judgment of the scan was spot-on.  James is a psychopath.  And I don’t mean psychopathic on the level of being manipulative and cold-hearted while superficially charming (which he admits to).  I mean psychopathic on the level of knowingly bringing his brother to a cave full of the Marburg virus, a terrifying cousin of Ebola that causes its victims to bleed out from every orifice.  While he was surprised by the scan results, his family was not.  (Thankfully, his brother did not contract the virus.)


Psychopath or sociopath?

So what exactly is psychopathy, and where on the continuum from cold-hearted to exposing-brother-to-Marburg is the diagnosis?  There is actually no official psychopathy diagnosis.  In the DSM (“Diagnostic and Statistical Manual”, the universal book of guidelines in diagnosing mental disorders), psychopathy is included within the diagnosis of antisocial personality disorder (ASPD), which includes criteria such as “failure to conform to social norms with respect to lawful behaviors,” “reckless disregard for safety of self or others,” and “lack of remorse.”

ASPD includes not only psychopathy but sociopathy as well.  While the ASPD diagnostic criteria cover their commonalities, psychopathic individuals are more cold and calculating while sociopathic individuals are more impulsive and easily angered.  Psychopathic individuals are often highly educated and able to perform well at work (like James Fallon), while sociopathic individuals often have difficulty functioning in society and holding down a job.  Psychopathy also is viewed as more genetic (there are apparently seven alleged killers in Fallon’s ancestry, including Lizzie Borden!!).



See no fear, feel no fear

Let’s try another thought experiment. Now imagine that you are walking alone at night, looking down at the sidewalk as you walk, lost in your own thoughts.  Suddenly you walk right into someone.  You look into the other person’s face and see a trace of fear.  You quickly apologize, flash a reassuring smile that you mean no harm, and continue walking.

Instead, imagine the same scenario except that when you look into the other person’s face, you see anger and aggression.  You surmise that he purposefully got in your way to instigate something.  You stop, ready to defend yourself, expecting a fight might occur.

That split-second look into the other person’s face allows you to gauge his state of mind and helps to inform your reaction. It makes sense that interpreting others’ facial expressions is absolutely essential for normal social interactions, and it is well-documented scientifically that those with certain social disorders have difficulty doing this.  Those with ASPD specifically have difficulty in processing fearful expressions [1].  If we return to our scenario, someone with ASPD might be unable to see fear–instead sensing anger in both cases–and might react maliciously even when there was no reason to.

In addition to difficulty in recognizing fear, those with psychopathic traits report less subjective fear in threatening scenarios [2].  This finding extends to both the brain as well as the body’s physiological response.  In one particular MRI study, researchers compared a group of healthy control subjects to a group of criminal offenders who scored highly on the PCL-R, an exam widely used to assess psychopathic traits.  Both groups underwent “fear conditioning” in which they were trained to associate an aversive stimulus (painful pressure) with pictures of neutral faces.

psychopathy fmri

A figure adapted from [3] showing the differences in brain activity between healthy controls and psychopathic individuals during fear conditioning

fMRI data from the healthy subjects showed strong activation of a certain brain circuit related to emotion (the limbic-prefrontal circuit, which includes the amygdala, orbitofrontal cortex, insula, and anterior cingulate), but the psychopathic individuals did not (see image below).  Additionally, the psychopathy group showed less of response in a skin conductance exam, a proxy for sweat and excitement, demonstrating that their bodies as well as their brains were not as responsive to fear [3].


We saw in our second thought experiment that someone unable to recognize fear might react with inappropriate anger in a social context, but there is another very important way in which this disconnect with fear influences behavior: moral decision-making.  Researchers at Georgetown University presented a group of participants with statements designed to evoke one of five emotions: anger (e.g., “You are a disgrace”), disgust (e.g., “I never wash my hands”), fear (e.g., “You better watch your back”), happiness (e.g., “I bought you a present”), and sadness (e.g., “I don’t want to be friends anymore”).  Participants rated how morally acceptable it would be to say these statements to someone else.  The degree to which the participants felt moral permissibility for causing someone else’s fear was predictive of their own score in a psychopathy assessment [4].  This suggests that psychopathic individuals have a deficit in moral reasoning in the context of causing fear, which likely affects their moral decision-making.

Another recent study takes this a step further.  Our brains are incredibly impressive prediction machines, constantly taking into account all of our past experiences, recognizing patterns and statistics, and using this information to calculate the best response to any current situation (read more about this fascinating capability in Jarrett’s post!).

Screen Shot 2017-06-21 at 10.57.02 AM

A figure from [5] showing that, among those who scored highly in an assessment of psychopathy, those less sensitive to regret had a history of more incarcerations

It seems psychopathic individuals have a deficit in this regard as well.  In a gambling task (having nothing to do with judging fearful expressions), psychopathic individuals had an intact emotional response when they “lost” and were shown what other choice could have given them more points–they were upset at losing instead of winning.  However, they showed a deficit in using this retrospective regret to influence future choices within the task.  Not only that, but the degree of maladaptive decision-making in the task was correlated to the incarceration history of the participant [5]!


Don’t judge

Aside from giving us a little peek into criminal minds, these studies reveal something important.  Psychopathic individuals are often labeled as “evil” by society (or conflated with “psycho” or “psychotic”, which are quite different).  We tend to imagine that they thrive on hurting others, that they understand what they are doing and have no regret.  While there is an element of truth to this, their behavior is a result of a real difference in how their brains process incoming information and in how their nervous systems process fear.  While their criminal behavior is obviously not excusable, it is in part explainable by real cognitive deficits.  Also, not all psychopathic individuals are dangerous criminals, and it is likely that a predisposition towards psychopathic traits can be greatly exacerbated by a difficult childhood.  Despite his very questionable decision to bring his brother to a virus-infested cave, as far as we know, our friend Fallon is not a felon.

But I’m probably not trying to go do a postdoc in his lab.




  1. Marsh AA, Blair RJR. Deficits in facial affect recognition among antisocial populations: a meta-analysis. Neuroscience and biobehavioral reviews. 2008;32(3):454-465. doi:10.1016/j.neubiorev.2007.08.003.
  2. Marsh AA, Finger EC, Schechter JC, Jurkowitz IT, Reid ME, Blair RJ. Adolescents with psychopathic traits report reductions in physiological responses to fear. J Child Psychol Psychiatry. 2011 Aug;52(8):834-41. doi:10.1111/j.1469-7610.2010.02353.x. Epub 2010 Dec 14. PubMed PMID: 21155775; PubMed Central PMCID: PMC3116087.
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    Fear and Physical Harm. PLoS One. 2015 May 20;10(5):e0125708. doi:
    10.1371/journal.pone.0125708. eCollection 2015. PubMed PMID: 25992566; PubMed
    Central PMCID: PMC4438873.
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    exhibit but do not avoid regret during counterfactual decision making. Proc Natl
    Acad Sci U S A. 2016 Dec 13;113(50):14438-14443. Epub 2016 Nov 28. PubMed PMID:
    27911790; PubMed Central PMCID: PMC5167137.