In a sample of psychopathic subjects drawn from a temporary job agency, 52% of psychopaths confessed to having attacked a stranger to the point of bruising or drawing blood from the stranger, 42% admitted to having raped at least one person, and 38% said that they had fired a gun at another person (1). Psychopathy, also known as antisocial personality disorder (APD), is of public interest because alarming statistics like these indicate that psychopaths pose a great risk to the population at large (1-4). APD predisposes psychopaths to violent behavior, both because of their categorical inability to empathize with others and their proclivity for dangerous thrill-seeking. Psychopaths have a host of impairments—they have a stunted ability to forge close relationships, they are perceived as callous and manipulative, and they are able to commit atrocities without remorse. These psychopathic qualities make it unsurprising that psychopaths constitute a disproportionate percentage of prison inmates: while an estimated one percent of the general population has APD, it is estimated that more than 35% of prison inmates have APD (2).
Given the criminal appetite associated with psychopathy, there is incentive to diagnose and monitor the psychopathic population in an effort to prevent crime (2,3,5). Predicting and thereby preventing crime is not a new topic. The movie Minority Report is about a futuristic dystopia in which the FBI forms the “Precrime Unit”. The unit is devoted to catching would-be killers moments before the crime, using genetically-engineered savants with visions of the future. While the FBI has announced no plans of breeding humans to prevent crime, there is one up-and-coming field focused on predicting crime: neurocriminology (2,3,5).
Neurocriminology concentrates on studying the brains of criminals, putting the psychopathic brain in the spotlight (2,3). The field seeks to identify those with neurological and genetic predispositions for violent behavior and to hopefully engineer a treatment or prevention strategy (2,3). While the field is still burgeoning, genetic and neurological evidence is making its way into the courtroom, raising ethical questions about how genetics, neurological functioning, and child abuse affect a criminal’s responsibility (2-4,6).
Recent discoveries in neuroscience are relevant to all stages of criminal justice. It is increasingly possible to predict whether a brain is predisposed to criminal activity, and neuroscience is making steps toward predicting what brain activity in criminals correlates with reoffending (2,3,6,7). A 2013 study concluded that criminals with diminished activity in the anterior cingulate cortex, a brain region associated with executive function, were 4.3 times more likely to reoffend while on parole (7). With the increasingly predictive power of neuroscience, it is necessary to examine the ethical implications of allowing neuroscience into courtrooms. Should a person with a neuroanatomical predisposition for killing receive more or less jail time for committing murder? Should a brain scan that predicts, with a small margin of error, that a convicted criminal is likely to revert to violent crime be sufficient grounds to prevent a person’s parole? Should statistics guide sentencing and the granting of parole, or would such a system deny the possibility of free will?
Neuroscience of Psychopathy
Adrian Raine is a leader in neurocriminology as well as a professor at the University of Pennsylvania and chair of their criminology department (6). Raine explores genetic, environmental, and neurological factors that play into violent criminality in his most recent book, The Anatomy of Violence (6). In this book, Raine stipulates that someday all eighteen-year-old men (men because there are nine male murderers for every female murderer) will undergo brain imaging tests to determine their likelihood of succumbing to violent behavior (2,3,5). The reputable criminologist suggests that when neuroscience reaches the point where it can predict a person’s penchant for violence with near certainty, those with a neuroanatomical thirst for blood will be sent away from mainstream society to some equivalent of a holding facility (2). He suggests that this holding facility need not be a prison. It could instead be considered more of a highly regulated sleep-away camp for potentially dangerous individuals (2). This prediction is alarming for ethical reasons and is strongly reminiscent of Minority Report. Perhaps Raine’s hope for a future with confined psychopaths is shaped by his career devoted to studying cold-blooded killers and rapists.
It is little wonder that a man who has spent so much time working with psychopaths hopes for a future without the more dangerous ones on the loose. The psychology of people with APD is chilling; the disorder robs the afflicted of any rich emotion, leaving only the capacity for raw emotions such as fear, anger, boredom, and lust (2,3). Psychopaths are impulsive and irresponsible, which often manifests itself in the form of unprotected sexual promiscuity. Psychopathic irresponsibility is also evidenced by their proclivity for a parasitic lifestyle, where they use their superficial charm to manipulate others into funding their needs and whims (5,7).
One irony of this disorder is that those with APD are often gifted at reading the emotions of others while incapable of experiencing those same emotions themselves (1-3). The psychopathic paucity of emotion can prove advantageous in many arenas. Businessmen who have no reservations about laying off thousands of workers, politicians who feel no twinge of guilt making duplicitous deals—these are just two examples of arenas in which a conscience can be considered a hindrance (8). Psychopathy relegates people to a mechanical existence wherein they consider the emotions of others as no more than a bargaining chip to be played when advantageous. The “successful psychopath” is one who escapes detection, using charm to win people over, all the while satiating his or her craving for stimulation in a variety of ways, sometimes escalating to killing (8).
There are two notable neuroanatomical structures that are deviant in psychopathic brains—the prefrontal cortex (PFC) and the amygdala (1,2,6). The PFC is responsible for executive control, namely inhibition of inappropriate impulses, while the amygdala is critically important in fear conditioning (1). Fear conditioning is tested in lab animals by exposing an animal to an unpleasant or painful situation. The animal is successfully conditioned if it then fears the place in which it experienced the discomfort or any associated stimuli.
Fear conditioning is a simplified version of what happens when people socialize – children learn to avoid a social faux pas by associating social misconduct with discomfort (1). The amygdala and the PFC are critical to this learning process (1,5). A lab rat with a lesioned (surgically removed) amygdala completely loses the ability to learn the associations in fear conditioning. The PFC is involved in fear conditioning in a more subtle way, working by inhibiting the socially unacceptable impulses that have been associated with discomfort. People with APD have been found to have an amygdala that is up to 18% smaller than normal, and studies have found that the psychopathic PFC has a 11% reduction in grey matter (5). These findings point to the theory that APD is a neurodevelopmental disorder that interferes with a person’s ability to experience and learn from negative experiences, specifically negative social feedback (2,5). Raine and his colleagues speculate, “Poor conditioning is theorized to be associated with poor development of the conscience.”
The Merriam-Webster Dictionary defines empathy as “vicariously experiencing the feelings… of others,” and this ability is fundamentally lacking in psychopaths (9). One simple test of empathy measures sympathetic skin conductance response (SCR) while subjects are shows a variety of stimuli (10). The SCR is an electrophysiological indicator of a person’s arousal that measures how much the person is sweating. The SCR test can be used to measure a person’s distress in response to different types of photos, including relaxing photos of nature and more disturbing photos, like a person’s hand getting caught in a closing door (10). The greater a person’s SCR, the greater that person’s distress. The SCR should be low for emotionally neutral scenes, but it should be elevated when, for example, a person sees photos of a needle going into someone’s hand (10). When psychopaths take this test, they exhibit very little change in SCR between the two types of photos (2). They retain a low resting heart rate and a low SCR throughout the photo exhibit, indicating that they are unperturbed when graphically presented with another person’s physical pain.
Feeling another person’s pain may seem like a lofty behavior, but there is neurological evidence that this might be fundamentally important in development (11). The mirror neuron system (MNS) is a circuit of neurons found in monkeys that activates both when an individual performs a specific action, such as making a fist, and when that individual sees another person perform that same specific action (11). The existence of the MNS suggests that “perceiving similarity between self and others” is so adaptive that our neurons force us to feel what others are doing, at least to some degree. The MNS is believed to play a role even in such critical milestones as learning language (12). One theory of language acquisition suggests that mirror neurons propel babies to mimic the movements of their parents’ mouths, expediting their understanding of the relationship between different labiodental configurations and phonemes (12). While there is currently very little literature addressing language development in those with APD, the theory that psychopaths have a dysfunctional MNS is popular and under investigation (2,12).
Between SCR tests, fMRIs scans, and other behavioral measures, there are many different ways of diagnosing psychopathy (2,6). Now the question becomes: how can psychopaths who are likely to commit acts of violence be preempted? And in this new age of neuroscience, how will neurological aberrations be treated in the courtroom? While it is difficult to speculate about how neuroscience will integrate into law in twenty years, there are two recent court cases from the past five years that represent two different roads that neurolaw can take.
Neuroscience in Court
A schoolteacher went to the emergency room complaining that he had a nearly irresistible urge to rape his landlady (13). Doctors were suspicious – this was a man who was scheduled go on trial the very next day for molesting his young stepdaughter, and this resembled a ploy to escape trial (13). While the doctors deliberated over how to deal with the man they suspected was faking symptoms, the patient propositioned the nurses publicly and shamelessly in the waiting room. Doctors noticed that the patient walked with a stiff gait and neglected to notice objects in his left field of vision. This was not a ruse; the unnatural gait and hemispatial neglect were sufficient grounds to order an MRI, which brought to light an egg-sized tumor that the patient had developed. The tumor was pressing on the patient’s prefrontal cortex, the part of the brain associated with inhibition, which explained why the patient could not put a lid on his vivid and violent sexual fantasies (13).
The discovery of this man’s tumor revolutionized his defense. Yes, he had made sexual advances on his stepdaughter, who was just a child (13). But this was a man who had no prior criminal record, who had experienced no pedophilic urges prior to developing this tumor. Once doctors removed his tumor, the patient abruptly lost all pedophilic urges and was profoundly ashamed of his tumorous conduct. The surgery corrected this man’s behavior for a while, but when the patient relapsed into hypersexuality, he discovered that his tumor had reappeared. After the second surgery to remove the tumor, the patient’s libido returned to socially acceptable levels and his wife allowed him to move back in with her (13).
This appears to be a cut and dry case of a tumor driving a man to criminal conduct, and the results of the defendant’s MRI were clearly important to his defense (13). But consider another court case that hinged on genetic testing, tried in 2007 in Italy (14). Abdelmalek Bayout murdered Walter Perez in a bar brawl because Perez had insulted Bayout’s kohl makeup. Bayout confessed to his crime, one that would typically have resulted in a sentence of about twelve years in prison. Bayout’s lawyer, however, negotiated a significantly lighter sentence because genetic tests showed that Bayout carried five genes that correlated with violent behavior (14). One of the genes that Bayout carried, monoamine oxidase (MAO-A), has come to be known as “The Warrior Gene,” because expression of this gene is correlated with elevated levels of aggression and violence. The association between this gene and aggression is still poorly understood – the correlation between MAO-A and aggression varies between ethnic groups, and yet the defendant’s ethnicity was not tested (14). Nature published an article questioning not only the methodology behind the defense’s explanation of genetic predisposition, but also the wisdom of promulgating defense strategies based on “genetic determinism”. The defendant, who confessed to murdering someone over an insult, was relieved of one year of his sentence on the grounds that his genes predisposed him to react to stressful situations with violence (14).
More Questions to Consider
The two cases described above seem different. In one, a tumor transformed a previously model citizen into a child molester. In another, the results of a genetic test relieved a murderer of one year of his sentence. Bayout will be released one year earlier than he would be if he were not a carrier of the Warrior Gene, and he will still have a proclivity towards violence when released, if we are to believe that genes so closely determine so complex a behavior as violence (13). If one of these defenses seems more acceptable than the other, what exactly is the difference?
It is difficult to map out what types of neurological tests or genetic predispositions belong in a courtroom, and it is then even more difficult to determine how such data should affect a verdict. With neuroscience discovering increasingly more about the criminal mind, a revolution in criminal law might be on the horizon. One company offers lie detection services called “No Lie MRI,” and while that technology has not been allowed in court to date, there are serious questions to consider (15,16). If it becomes possible to put a murder suspect in an MRI, ask him if he is the killer, and determine based on the scan’s results whether he is lying or not, is that a violation of the American right to plead the fifth amendment? Will murder suspects have a right to protect themselves from brain scans?
The roles of insanity and remorse in the death penalty are additional factors to consider. In a 2002 court case, Atkins v. Virginia, the Supreme Court ruled that an insane person could not be put to death. When a psychopath is found guilty of murder, should he or she be able to plead insanity and thus escape the death penalty? When a defendant can persuade the judge of his or her genuine remorse, the judge is legally urged to spare that person of the death penalty. Since psychopaths are inherently incapable of remorse, should they go through an adjusted sentencing process? These are just some of the questions we must consider as neuroscience generates more and more information.
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http://archpsyc.jamanetwork.com/article.aspx?articleid=481571 (8 August, 2013)
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3. E. Lerner, Can Science Predict Criminal Behavior? (2011). Available at
http://www.upenn.edu/pennnews/current/2011-03-24/research/can-science-predict-criminal-behavior (9 August, 2013)
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