Psychopathy (//) (or sociopathy (//)) is defined as either an aspect of personality or as a personality disorder, characterized by enduring dissocial or antisocial behavior, a diminished capacity for empathy or remorse, and poor behavioral controls or fearless dominance. There are various definitions which are only partly overlapping and sometimes appear contradictory.
The 4th and 5th editions of the Diagnostic and Statistical Manual of Mental Disorders (DSM) have a diagnosis of Antisocial (Dissocial) Personality Disorder (ASPD), which states: "The essential feature of antisocial personality disorder is a pervasive pattern of disregard for, and violation of, the rights of others that begins in childhood or early adolescence and continues into adulthood. This pattern has also been referred to as psychopathy, sociopathy, or dyssocial personality disorder." Although no psychiatric or psychological organization has sanctioned a diagnosis titled "psychopathy", assessments of psychopathy characteristics are widely used in criminal justice settings in some nations, and may have important consequences for individuals. The term is also used by the general public, in popular press, and in fictional portrayals.
Although American psychiatrist Hervey Cleckley's work on psychopathy probably influenced the initial diagnostic criteria for antisocial personality reaction/disturbance in the DSM, as did American psychologist George E. Partridge's work on sociopathy, in 1980 the somewhat different diagnosis of ASPD was introduced. However, Canadian psychologist Robert D. Hare repopularised the construct of psychopathy in criminology with his Psychopathy Checklist.
- 1 History
- 2 Classification
- 3 Measurement
- 4 Further considerations
- 5 Causes and pathophysiology
- 6 Management
- 7 Epidemiology
- 8 See also
- 9 References
- 10 Bibliography
- 11 External links
The word "psychopathy" is a joining of the Greek words psyche (ψυχή)—meaning soul—and pathos (πάθος)—meaning suffering or feeling. The first documented use is from 1847 in Germany as psychopatisch, and the noun psychopath has been traced to 1885. In medicine, patho- has a more specific meaning of disease (thus pathology has meant the study of disease since 1610, and psychopathology has meant the study of mental disorder in general since 1847. A sense of "a subject of pathology, morbid, excessive" is attested from 1845, including the phrase pathological liar from 1891 in the medical literature).
The term psychopathy initially had a very general meaning referring to all sorts of mental disorders and social aberrations, popularised from 1891 in Germany by Koch's concept of "psychopathic inferiority" (psychopathische Minderwertigkeiten). Some medical dictionaries still define psychopathy in both a narrow and broad sense, such as MedlinePlus from the U.S. National Library of Medicine. On the other hand, Stedman's Medical Dictionary defines psychopathy only as an outdated term for an antisocial type of personality disorder.
The term psychosis was also used in Germany from 1841, originally in a very general sense. The suffix -ωσις (-osis) meant in this case "abnormal condition". This term or its adjective psychotic would come to refer to the more severe mental disturbances and then specifically to mental states or disorders characterized by hallucinations, delusions or in some other sense markedly out of touch with reality.
The slang psycho has been traced to a shortening of the adjective psychopathic from 1936, and from 1942 as a shortening of the noun psychopath, but it is also used as shorthand for psychotic or just mentally crazed in some way.
The label psychopath has been described as strangely nonspecific but probably persisting because it indicates that the source of behavior lies in the psyche rather than in the situation. The media usually uses the term to designate any criminal whose offenses are particularly abhorrent and unnatural, but that is not its original or general psychiatric meaning.
The term sociopathy may have been first introduced in 1909 in Germany by biological psychiatrist Karl Birnbaum and in 1930 in the US by educational psychologist George E. Partridge, as an alternative to, or a subtype of, the concept of psychopathy. It was used to indicate that the defining feature is violation of social norms, or antisocial behavior, and has often also been associated with postulating social as well as biological causation. The element socio had been used in compound words since around 1880.
Hare noted in a 1999 popular science book that sociopathy and psychopathy are often used interchangeably, but in some cases the term sociopathy is preferred because it is less likely than is psychopathy to be confused with psychosis, whereas in other cases which term is used may "reflect the user's views on the origins and determinates of the disorder". Hare contended that the term sociopathy is preferred by those that see the causes as due to social factors and early environment, and the term psychopathy preferred by those who believe that there are psychological, biological, and genetic factors involved in addition to environmental factors. However others point out that Hare appears to really believe that biological factors are predominant. The term sociopathy was originally intended to indicate that social problems are the defining feature, whatever the causes.
The concept of psychopathy has been indirectly connected to the early 1800s with the work of Pinel (1801; “mania without delirium”) and Pritchard (1835; “moral insanity”), although historians have largely discredited the idea of a direct equivalence. The term "psychopathic" was coined toward the end of the 19th century, by the German psychiatrist Julius Koch (1891). In contrast with current usage, Koch applied the term '"psychopathic inferiority" (psychopathischen Minderwertigkeiten) to various chronic conditions and character disorders.
The term 'psychopathic' came to be used to describe a diverse range of dysfunctional or antisocial behavior and mental and sexual deviances, including at the time homosexuality. It was often used to imply an underlying 'constitutional' or genetic origin. Disparate early descriptions likely set the stage for modern controversies about the definition of psychopathy.
The most influential figure in shaping modern American conceptualizations of psychopathy was American psychiatrist Hervey Cleckley. In his classic monograph, The Mask of Sanity (1976), Cleckley drew on a small series of vivid case studies of psychiatric patients at a Veterans Administration hopsital in Georgia to describe the disorder. Cleckley used the metaphor of the “mask” to refer to the tendency of psychopaths to appear confident, personable, and well-adjusted compared to most psychiatric patients, while revealing underlying pathology through their actions over time. Cleckley formulated sixteen criteria to describe the disorder. The Scottish psychiatrist David Henderson had also been influential in Europe from 1939 in narrowing the diagnosis.
The diagnostic category of sociopathic personality in early editions of the Diagnostic and Statistical Manual (DSM) had some key similarities to Cleckley's ideas, though in 1980 when renamed Antisocial Personality Disorder some of the underlying personality assumptions were removed. In 1980, Canadian psychologist Robert D. Hare introduced an alternative measure, the "Psychopathy Checklist" (PCL) based largely on Cleckley's criteria, which was revised in 1991 (PCL-R), and is the most widely used measure of psychopathy. There are also several self-report tests, with "The Psychopathic Personality Inventory" (PPI) being the most popular.
Famous individuals have sometimes been diagnosed, albeit at a distance, as psychopaths. As just one example out of many possible from many countries over many centuries, in a 1972 version of a secret report originally prepared for the Office of Strategic Services in 1943, which may originally have been intended as propaganda, non-medical psychoanalyst Walter C. Langer suggested Adolf Hitler was probably a psychopath. However, others have not drawn this conclusion; clinical forensic psychologist Glenn Walters argues that Hitler's actions do not warrant a diagnosis of psychopathy as he was not always egocentric, callously disregarding of feelings or lacking impulse control, and that there is no proof he couldn't learn from mistakes—though he did show several characteristics of criminality.
Integrating different concepts
There has been effort to reconcile seemingly disparate historical conceptions, operationalizations, and research programs on psychopathy.
The triarchic model suggests that different concepts of psychopathy emphasize three observable characteristics to varying degrees:
- Boldness. Low fear including stress-tolerance, toleration of unfamiliarity and danger, and high self-confidence and social assertiveness. PCL-R measures this relatively poorly and mainly through Facet 1 of Factor 1. Similar to PPI Fearless dominance. May correspond to differences in the amygdala and other neurological systems associated with fear.
- Disinhibition. Poor impulse control including problems with planning and foresight, lacking affect and urge control, demand for immediate gratification, and poor behavioral restraints. Similar to PCL-R Factor 2 and PPI Impulsive antisociality. May correspond to impairments in frontal lobe systems that are involved in such control.
- Meanness. Lacking empathy and close attachments with others, disdain of close attachments, use of cruelty to gain empowerment, exploitative tendencies, defiance of authority, and destructive excitement seeking. PCL-R in general is related to this but in particular some elements in Factor 1. Similar to PPI Coldheartedness but also includes elements of subscales in Impulsive antisociality. Meanness may possibly be caused by either high boldness or high disinhibition combined with an adverse environment. Thus, a child with high boldness may respond poorly to punishment but may respond better to rewards and secure attachments which may not be available under adverse conditions. A child with high disinhibition may have increased problems under adverse conditions with meanness developing in response.
Distinct condition vs. continuum
A crucial issue regarding the concept of psychopathy is whether it identifies a distinct condition that can be separated from other conditions and "normal" personality types, or whether it is simply a combination of scores on various dimensions of personality found throughout the population in varying combinations.
An early and influential analysis from Harris and colleagues indicated a discrete category may underlie PCL-R psychopathy, but this was only found for the behavioral Factor 2 items, indicating this analysis may be related to ASPD rather than psychopathy. Marcus, John, and Edens more recently performed a series of statistical analysis on PPI scores and concluded psychopathy may best be conceptualized as having a "dimensional latent structure" like depression.
Marcus et al. repeated the study on a larger sample of prisoners, using the PCL-R and seeking to rule out other experimental or statistical issues that may have produced the previously different findings. They again found that the psychopathy measurements do not appear to be identifying a discrete type (a taxon). They suggest that while for legal or other practical purposes an arbitrary cut-off point on trait scores might be used, there is actually no clear scientific evidence for an objective point of difference by which to call some people "psychopaths". The Hare checklist was developed for research not clinical forensic diagnosis, and even for research purposes to improve understanding of the underlying issues, it is necessary to examine dimensions of personality in general rather than only this constellation of traits.
Several researchers have argued that there exist two variants of psychopathy. There is also empirical support for separating persons scoring high on the PCL-R into two groups that do not simply reflect Factor 1 and Factor 2. There is at least preliminary evidence of differences regarding cognition and affect as measured in laboratory tests. Different theories characterize these two variants somewhat differently. Compared to "primary" psychopaths, researchers agree that "secondary" psychopaths have more fear, anxiety, and negative emotions. They are often seen as more impulsive and with more reactive anger and aggression. Some preliminary research have suggested that secondary psychopaths may have had a more abusive childhood according to self-reports (which possibly may be inflated in secondary psychopathy), may have a higher risk of future violence, and may respond better to treatment. Blackburn asserted that secondary psychopaths "may be predominantly borderline personalities." Blackburn found that secondary psychopaths qualify more often for diagnoses of borderline personality disorder than do primary psychopaths, who more often qualify for a diagnoses of either antisocial personality disorder and/or narcissistic personality disorder.
Primary psychopathy has been seen as mainly due to genetic factors while secondary psychopathy has been seen as mainly due to environmental factors which also has implications for treatment possibilities. Such proposed environmental factors include an abusive childhood or a society presenting opportunities for cheating. Other researchers have argued that genetics and environment are important for both variants. David T. Lykken, using Gray's biopsychological theory of personality, have argued that primary psychopaths innately have little fear while secondary psychopaths innately have increased sensitivity to rewards. Proponents of the triarchic model described above see primary psychopaths associated with increased boldness and secondary psychopathy as associated with increased disinhibition.
Alternative personality dimensions
Some studies have linked psychopathy to other dimensions of personality. Such personality dimensions may be found throughout the general population to varying degrees, and there are different views as to which dimensions are more central in regard to psychopathy. Examples of these personality dimensions include antagonism (high), conscientiousness (low) and anxiousness (low, or sometimes high). Some have also linked psychopathy to high psychoticism—a theorized dimension referring to tough, aggressive or hostile tendencies. Aspects of this that appear associated with psychopathy are lack of socialization and responsibility, impulsivity, sensation-seeking in some cases, and aggression. Otto Kernberg, from a particular psychoanalytic perspective, believes psychopathy should be considered as part of a spectrum of pathological narcissism, that would range from narcissistic personality on the low end, malignant narcissism in the middle, and psychopathy at the high end. However, narcissism is generally seen as only one aspect of psychopathy as generally defined.
Results of a study on male patients at a maximum-security forensic hospital have also suggested four subtypes of psychopathy: narcissistic, borderline, sadistic, and antisocial. In general, however, antisocial traits are invariably a factor in widely-used psychopathy concepts and measurement tools, rather than simply considered a subtype.
Hare Psychopathy Checklist
Psychopathy is most commonly assessed with the Psychopathy Checklist, Revised (PCL-R) created by the Canadian researcher Robert D. Hare, based on Cleckley's criteria from the 1940s and on research on criminals and incarcerated offenders in Canada. Each of the 20 items in the PCL-R is scored on a three-point scale, with a rating of 0 if it does not apply at all, 1 if there is a partial match or mixed information, and 2 if there is a reasonably good match to the offender. This is said to be ideally done through a face-to-face interview together with supporting information on lifetime behavior (e.g. from case files), but is also done based only on file information. It can take up to three hours to collect and review the information.
|Factor 1||Factor 2||Other items|
Facet 1: Interpersonal
Facet 2: Affective
Facet 3: Lifestyle
Facet 4: Antisocial
The PCL-R is referred to by some as the "gold standard" for assessing psychopathy. High PCL-R scores are positively associated with measures of impulsivity and aggression, Machiavellianism, persistent criminal behavior, and negatively associated with measures of empathy and affiliation. Out of a maximum score of 40, the cut-off for the label of psychopathy is 30 in the United States and 25 in the United Kingdom, although there is little scientific support for these as particular break points. A cut-off score of 25 is also sometimes used for research purposes.
The PCL-R items were designed to be split in two. Factor 1 involves interpersonal or affective (emotion) personality traits and higher values are associated with narcissism and low empathy as well as social dominance and less fear or depression. Factor 2 involves either impulsive-irresponsible behaviors or antisocial behaviors and is associated with a maladaptive lifestyle including criminality. The two factors correlate with each other to some extent. Each factor is sometimes further subdivided in two: interpersonal versus affect items for Factor 1, and impulsive-irresponsible lifestyle versus antisocial behavior items for Factor 2. "Promiscuous sexual behavior" and "many short-term marital relationships" have sometimes been left out in such divisions.
Cooke and Michie have argued that a three-factor structure provide a better model than the two-factor structure. Those items from factor 2 strictly relating to antisocial behavior (criminal versatility, juvenile delinquency, revocation of conditional release, early behavioral problems, and poor behavioral controls) are removed. The remaining items are divided into three factors: Arrogant and Deceitful Interpersonal Style, Deficient Affective Experience, and Impulsive and Irresponsible Behavioral Style. Hare and colleagues have published detailed critiques of the model and argue that there are statistical and conceptual problems.
Because an individual's scores may have important consequences for his or her future, the potential for harm if the test is used or administered incorrectly is considerable. The test can only be considered valid if administered by a suitably qualified and experienced clinician under controlled conditions.
There is also a shorter version of the PCL-R, known as a screening version (PCL-SC), developed for quicker assessments of larger numbers or groups without criminal records. It has only 12 items and a maximum scores of 24 but correlates strongly with the main PCL-R. The corresponding cut-off score is 18.
Hare's concept and checklist have also been criticized. In 2010 there was controversy after it emerged Hare had threatened legal action that stopped publication of a peer-reviewed article on the PCL-R. Hare alleged the article quoted or paraphrased him incorrectly. The article eventually appeared three years later. It alleged that the checklist is wrongly viewed by many as the basic definition of psychopathy, yet it leaves out key factors, while also making criminality too central to the concept. The authors claimed this leads to problems in overdiagnosis and in the use of the checklist to secure convictions. Hare has since stated that he receives less than $35,000 a year from royalties associated with the checklist and its derivatives.
In addition, Hare's concept has been criticised as being only weakly applicable to real-world settings and tending towards tautology. It is also said to be vulnerable to "labeling effects"; to be over-simplistic; reductionistic; to embody the fundamental attribution error; and to not pay enough attention to context and the dynamic nature of human behavior. It has been pointed out that half the criteria can also be signs of mania, hypomania, or frontal lobe dysfunction (e.g., glibness/superficial charm, grandiosity, poor behavioral controls, promiscuous sexual behavior, and irresponsibility).
Some research suggests that ratings made using the PCL system depend on the personality of the person doing the rating, including how empathic they themselves are. One forensic researcher has suggested that future studies need to examine the class background, race and philosophical beliefs of raters because they may not be aware of enacting biased judgments of people whose section of society or individual lives they have no understanding of or empathy for.
Psychopathic Personality Inventory
|PPI–1: Fearless dominance||PPI–2: Impulsive Antisociality||Coldheartedness|
Unlike the PCL, the Psychopathic Personality Inventory (PPI) was developed to comprehensively index personality traits without explicitly referring to antisocial or criminal behaviors themselves. It is a self-report scale that was developed in non-clinical samples (e.g. university students) rather than prisoners, though may be used with the latter. It was revised in 2005 to become the PPI-R (Lilienfeld & Widows) and now comprises 154 items organized into eight subscales. The item scores have been found to group into two overarching and largely separate factors (unlike the PCL-R factors), plus a third factor which is largely independent on scores on the other two:
I: Fearless dominance. From the subscales Social influence, Fearlessness, and Stress immunity. Associated with less anxiety, depression, and empathy as well as higher well-being, assertiveness, narcissism, and thrill-seeking.
II: Impulsive antisociality. From the subscales "Machiavellian" egocentricity, Rebellious nonconformity, Blame externalization, and Carefree lack of planning. Associated with impulsivity, aggressiveness, substance use, antisocial behavior, negative affect, and suicidal ideation.
III: Coldheartedness. From a subscale with the same name.
A person may score at different levels on the different factors, but the overall score indicates the extent of psychopathic personality. Factor I is associated with social efficacy while factor 2 is associated with maladaptive tendencies.
Cleckley clinical profile
In his book The Mask of Sanity, Hervey M. Cleckley described 16 "common qualities" that he thought were characteristic of the individuals he termed psychopaths: The Cleckley checklist formed the basis for Hare's more current PCL-R checklist.
- Superficial charm and good "intelligence"
- Absence of delusions and other signs of irrational thinking
- Absence of "nervousness" or psychoneurotic manifestations
- Untruthfulness and insincerity
- Lack of remorse and shame
- Inadequately motivated antisocial behavior
- Poor judgment and failure to learn by experience
- Pathologic egocentricity and incapacity for love
- General poverty in major affective reactions
- Specific loss of insight
- Unresponsiveness in general interpersonal relations
- Fantastic and uninviting behavior with drink and sometimes without
- Suicide threats rarely carried out
- Sex life impersonal, trivial, and poorly integrated
- Failure to follow any life plan.
Cleckley stated in the first edition of The Mask of Sanity (p. 257) that those he was calling psychopaths were "frankly and unquestionably psychotic", contrary to later classifications of the condition as a personality disorder. He also did not describe them as particularly hostile or aggressive, contrary to more sinister depictions that others later developed. In addition he proposed the existence of a milder and extremely common form of the condition as he judged it: "If we consider, in addition to these patients (nearly all of whom have records of the utmost folly and misery and idleness over many years and who have had to enter a psychiatric hospital), the vast number of similar people in every community who show the same behavior pattern in milder form but who are sufficiently protected and supported by relatives to remain at large, the prevalence of this disorder is seen to be appalling."
DSM and ICD
There are currently two widely established systems for classifying mental disorders—the International Classification of Diseases (ICD) produced by the World Health Organization (WHO) and the Diagnostic and Statistical Manual of Mental Disorders (DSM) produced by the American Psychiatric Association (APA). Both list categories of disorders thought to be distinct types, and have deliberately converged their codes in recent revisions so that the manuals are often broadly comparable, although significant differences remain.
There has never been a diagnosis called "psychopathy" in either the DSM or ICD.[contradiction] The first edition of the DSM in 1952 had a section on sociopathic personality disturbances, then a general term that included such things as homosexuality and alcoholism as well as an "antisocial reaction" and "dyssocial reaction". The latter two eventually became antisocial personality disorder in the DSM and dissocial personality disorder in the ICD. However, traditional and popular conceptions of psychopathy influenced the diagnostic criteria for ASPD, and the DSM states that ASPD is also known as psychopathy. Researchers such as Robert D. Hare and Stephen Hart regard the mainstream psychiatric view as deeply flawed, calling for a return to a traditional model of psychopathy as a distinct disorder.[page needed]
Antisocial personality disorder (ASPD), the criteria of which were based on American psychiatrist Hervey Cleckley's work on psychopathy, is described in the DSM-IV-TR as "... a pervasive pattern of disregard for, and violation of, the rights of others that begins in childhood or early adolescence and continues into adulthood".
A diagnosis of ASPD is based on behavioral patterns, whereas the Hare Psychopathy Checklist also relies on subjective judgments of personality traits. Although Hare wrote that it is possible to obtain reliable and valid measures of the personality traits and behaviors associated with psychopathy, criteria relating to personality traits were excluded from the diagnostic criteria for ASPD in the DSM, in part because it was believed that personality traits were difficult to measure reliably and it was "easier to agree on the behaviors that typify a disorder than on the reasons why they occur". ASPD criteria are thus considered to be strongly associated with Factor 2 items but not as strongly associated with Factor 1 items in the PCL-R. Due to the diagnostic differences, Hare and other critics have argued that psychopathy and ASPD are not synonymous, despite the DSM stating that ASPD is also known as psychopathy.
Although the diagnosis of ASPD covers two to three times as many prisoners as are rated as psychopaths, Hare believes that the PCL-R is better able to predict future criminality, violence, and recidivism than a diagnosis of ASPD. Hare suggests that there are differences between PCL-R-diagnosed psychopaths and non-psychopaths on "processing and use of linguistic and emotional information", while such differences are potentially smaller between those diagnosed with ASPD and without. Hare argued that confusion regarding how to diagnose ASPD, confusion regarding the difference between ASPD and psychopathy, as well as the differing future prognoses regarding recidivism and treatability, may have serious consequences in settings such as court cases where psychopathy is often seen as aggravating the crime.
The DSM-V working party considered a revision of ASPD to be called antisocial/dyssocial personality disorder.[verification needed] There is an 'alternative model' for personality disorders proposed at the end of the DSM-5; this includes 'specifers' which for ASPD could involve: "A distinct variant often termed psychopathy (or “primary” psychopathy) is marked by a lack of anxiety or fear and by a bold interpersonal style that may mask maladaptive behaviors..."
The ICD defines a conceptually similar disorder to psychopathy called dissocial personality disorder, "usually coming to attention because of a gross disparity between behaviour and the prevailing social norms, and characterized by" 3 of 6 specific issues.
There are some traditional personality tests that contain subscales relating to psychopathy, though they assess relatively non-specific tendencies towards antisocial or criminal behavior. These include the Minnesota Multiphasic Personality Inventory (Psychopathic Deviate scale); the California Psychological Inventory (Socialization scale); and the Millon Clinical Multiaxial Inventory (Antisocial Personality Disorder scale). There is also the Levenson Self-Report Psychopathy Scale (LSRP) and the Hare Self-Report Psychopathy Scale (HSRP). However, in terms of self-report tests, the PPI/PPI-R has become the most used in modern psychopathy research on adults.
In terms of simple correlations, the PCL-R manual states an average score of 22.1 has been found in North American prisoners samples, and that 20.5% scored 30 or higher. An analysis of prisoner samples from outside North America found a somewhat lower average value of 17.5. A study also found that psychopathy scores correlated with repeated imprisonment, detention in higher security, disciplinary infractions, and substance misuse. Most correlations were similar to those in other studies.
Psychopathy, as measured with the PCL-R in institutional settings, show in meta-analyses small to moderate effect sizes (r = 0.23 to 0.30) with institutional misbehavior, postrelease crime, or postrelease violent crime with similar effects for the three outcomes. Individual studies give similar results for adult offenders, forensic psychiatric samples, community samples, and youth. The PCL-R is poorer at predicting sexual re-offending. However, this small to moderate effect appears to be due largely to the scale items that assess impulsive behaviors and past criminal history, which are well-established but very general risk factors. The aspects of core personality often held to be distinctively psychopathic, generally show little or no predictive link to crime by themselves. Thus Factor 1 of the PCL-R and Fearless dominance of the PPI-R have smaller or no relationship to crime, including violent crime. In contrast Factor 2 and Impulsive antisociality of the PPI-R are associated more strongly with criminality. Factor 2 has a relationship of similar strength to that of the PCL-R as a whole. The antisocial facet of the PCL-R is still predictive of future violence after controlling for past criminal behavior which, together with results regarding the PPI-R which by design does not include past criminal behavior, suggests that impulsive behaviors is an independent risk factor.
Some clinicians suggest that assessment of the construct of psychopathy does not necessarily add value to violence risk assessment. There are several other risk assessment instruments which can predict further crime with an accuracy similar to the PCL-R and some of these are considerably easier, quicker, and less expensive to administrate. This may even be done automatically by a computer simply based on data such as age, gender, number of previous convictions, and age of first conviction. Some of these assessments may also identify treatment change and goals, identify quick changes that may help short-term management, identify more specific kinds of violence that may be at risk, and may have established specific probabilities of offending for specific scores. PCL-R may continue to be popular for risk assessment because of is pioneering role and the large amount of research done using it. Although psychopathy is associated on average with an increased risk of violence, it is difficult to know how to manage the risk. The concept of psychopathy may perform poorly when attempted to be used as a general theory of crime.
Although high psychopathy scores correlate significantly with violence on average, criminals comprise a heterogeneous group with varying characteristics and high psychopathy scores are not necessarily an underlying trait.
It has been suggested that psychopaths tend to commit more "instrumental" violence than "reactive" violence. One conclusion in this regard was made by a 2002 study of homicide offenders, which reported that the homicides committed by psychopaths were almost always (93.3%) primarily instrumental, while about half (48.4%) of those committed by non-psychopaths were. However, contrary to the equating of this to mean "in cold blood", more than a third of the homicides by psychopaths involved emotional reactivity as well.
In addition, the non-psychopaths still accounted for most of the instrumental homicides, because most of these murderers were not psychopaths. In any case, FBI profilers indicate that serious victim injury is generally an emotional offense, and some research supports this, at least with regard to sexual offending. One study has found more serious offending by non-psychopaths on average than by psychopaths (e.g. more homicides versus more armed robbery and property offenses) and another that the Affective facet of PCL-R predicted reduced offense seriousness.
A large systematic review and meta-regression found that the Hare Psychopathy Checklist performed the poorest out of nine tools for predicting violence. In addition, studies conducted by the authors or translators of violence prediction measures, including the PCL, show on average more positive results than those conducted by more independent investigators.
A 2011 study of conditional releases for Canadian male federal offenders found that psychopathy was related to more violent and non-violent offences but not more sexual offences. For child molesters, psychopathy was associated with more offences. Despite "their extensive criminal histories and high recidivism rate", psychopaths showed "a great proficiency in persuading parole boards to release them into the community." It is purported that high-psychopathy offenders (both sexual and non-sexual offenders) are about 2.5 times more likely to be granted conditional release compared to non-psychopathic offenders."
Some studies have found only weak associations between psychopathy and sexual offending overall. The association is more certain for sexual violence. Psychopaths have on average higher sexual arousal to depictions of rape than non-psychopaths. Rapists, especially sadistic rapists, and sexual homicide offenders have a high rate of psychopathy. Some researchers have argued that psychopaths have a preference for violent sexual behavior.
One study examined the relationship between psychopathy scores and types of aggression expressed in a sample of 38 sexual murderers. 84.2% of the sample had PCL-R scores above 20 and 47.4% above 30. 82.4% of those above 30 had engaged in sadistic violence (defined as enjoyment indicated by self-report or evidence) as compared to 52.6% of those below and total PCL-R and Factor 1 scores correlated significantly with sadistic violence. In considering the challenging issue of possible reunification of some sex offenders into homes with a non-offending parent and children, it has been advised that any sex offender with a significant criminal history should be assessed on the PCL-R, and if they score 18 or higher than they should be excluded from any consideration of being placed in a home with children under any circumstances.
However, there is increasing concern that PCL scores are too inconsistent between different examiners, including in its real world use to evaluate sex offenders, and especially on the evaluation of personality traits.
Terrorists are sometimes called psychopaths, and comparisons can be drawn with traits such as antisocial violence, a selfish worldview that precludes welfare for others, lack of remorse or guilt, and blaming external events. However, such comparisons could also then be drawn more widely, for example to soldiers in wars. In addition, it has been noted that coordinated terrorist activity requires organization, loyalty and ideology; traits such as self-centeredness, unreliability, poor behavioral controls, and unusual behaviors may be disadvantages.
Recently Häkkänen-Nyholm and Nyholm (2012) have discussed the possibility of psychopathy being associated with organised crime, economic crime and war crimes.
It has been speculated that some psychopaths may be socially successful, due to factors such as low disinhibition in the triarchic model in combination with other advantages such as a favorable upbringing and good intelligence. However, there is little research on this, in part because the PCL-R does not include positive adjustment characteristics and most researchers have used the PCL-R on criminals. Some research using the PPI indicate that psychopathic interpersonal and affective traits/boldness and/or meanness in the triarchic model exist in noncriminals and correlate with stress immunity and stability.
Psychologists Fritzon and Board, in their study comparing the incidence of personality disorders in business executives against criminals detained in a mental hospital, found that some personality disorders were more common in the executives. They described the personality-disordered executives as "successful psychopaths" and the personality-disordered criminals as "unsuccessful psychopaths".
Psychopaths may have various other mental conditions. Comorbidity was found in a study to be strongest with antisocial personality disorder but also with histrionic, narcissistic and borderline disorders. A study designed to examine the association between PCL-R scores and assessments of DSM-IV Axis I disorders and diagnoses of DSM-III-R/DSM-IV Axis II disorders, made on the basis of a semi-structured interview, the preferred method of assessment in personality disorder (PD) research, in a sample of forensic psychiatric patients. Participants were 98 male forensic psychiatric patients admitted to the hospital between January 1, 1996, and December 1, 2001. Valid data were obtained from 94 patients. The results indicated that PCL-R psychopathy was most significantly and positively related with antisocial, borderline, narcissistic, and paranoid personality disorders. The most frequently diagnosed Personality Disorder (PD) in the study was ASPD (n = 45), followed by narcissistic PD (n = 26) and borderline PD (n = 24) and last paranoid PD (n = 18). Another study found that psychopathy scores correlated with ASPD, narcissistic, histrionic, and schizoid personality disorders, but not neurotic disorders or schizophrenia. Additionally, the constellation of traits in psychopathy assessments overlaps considerably with ASPD criteria and also with borderline personality disorder, histrionic personality disorder and narcissistic personality disorder criteria.
Psychopathy is associated with substance use disorders. This appears to be linked more closely to antisocial/criminal lifestyle, as measured by Factor 2 of the PCL-R, than the interpersonal-emotional traits assessed by Factor I of the PCL-R.
Attention deficit hyperactivity disorder (ADHD) is known to be highly comorbid with conduct disorder, and may also co-occur with psychopathic tendencies. This may be explained in part by deficits in executive function.
Anxiety disorders often co-occur with ASPD, and contrary to assumptions psychopathy can sometimes be marked by anxiety; however, this appears to be due to the antisocial aspect (factor 2 of the PCL), and anxiety may be inversely associated with the interpersonal-emotional traits (Factor I of the PCL-R).
It has been suggested that psychopathy may be comorbid with several other diagnoses than these, but limited work on comorbidity has been carried out. This may be partly due to difficulties in using inpatient groups from certain institutions to assess comorbidity, owing to the likelihood of some bias in sample selection.
Psychopaths have been considered notoriously amoral – an absence of, indifference towards, or disregard for moral beliefs. There are few firm data on patterns of moral judgment, however. Studies of developmental level (sophistication) of moral reasoning found all possible results – lower, higher or the same as non-psychopaths. Studies that compared judgments of personal moral transgressions versus judgments of breaking conventional rules or laws, found that psychopaths rated them as equally severe, whereas non-psychopaths rated the rule-breaking as less severe.
A study comparing judgments of whether personal or impersonal harm would be endorsed in order to achieve the rationally maximum (utilitarian) amount of welfare, found no significant differences between psychopaths and non-psychopaths. However, a further study using the same tests found that prisoners scoring high on the psychopathy checklist were more likely to endorse impersonal harm or rule violations than non-psychopaths were. Psychopaths who scored low in anxiety were also more willing to endorse personal harm on average.
Assessing accidents, where one person harmed another unintentionally, psychopaths judged such actions to be more morally permissible. This result is perhaps a reflection of psychopaths' failure to appreciate the emotional aspect of the victim's harmful experience, and furnishes direct evidence of abnormal moral judgment in psychopathy.
Dysfunctions in the prefrontal cortex and amygdala regions of the brain are associated with specific learning impairments in psychopathy. Since the 1980s, scientists have linked traumatic brain injury, including damage to these regions, with violent and psychopathic behavior. Patients with damage in such areas resembled "psychopathic individuals" whose brains were incapable of acquiring social and moral knowledge; those who acquired damage as children may have trouble conceptualizing social or moral reasoning, while those with adult-acquired damage may be aware of proper social and moral conduct but be unable to behave appropriately. Dysfunctions in the amygdala and ventromedial prefrontal cortex may also impair stimulus-reinforced learning in psychopaths, whether punishment-based or reward-based. People scoring ≥25 in the Psychopathy Checklist Revised, with an associated history of violent behavior, appear to have significantly reduced microstructural integrity in their uncinate fasciculus—white matter connecting the amygdala and orbitofrontal cortex. There is DT-MRI evidence of breakdowns in the white matter connections between these two important areas.
Additionally, studies suggest inverse relationships between psychopathy and intelligence, including with regards to verbal IQ. However, Hare and Neumann (2008) state that a large literature shows that there is at most only a weak association between psychopathy and IQ. They consider that the early pioneer Cleckley included good intelligence in his checklist due to selection bias since many of his patients were "well educated and from middle-class or upper-class backgrounds" and state that "there is no obvious theoretical reason why the disorder described by Cleckley or other clinicians should be related to intelligence; some psychopaths are bright, others less so." Studies indicate that different aspects of the definition of psychopathy (e.g. interpersonal, affective (emotion), behavioral and lifestyle components) can show different links to intelligence, and it can also depend on the type of intelligence assessment (e.g. verbal, creative, practical, analytical).
Emotion recognition and empathy
Studies by Blair and others suggest psychopaths on average have atypical responses to distress cues (e.g. facial and vocal expressions of fear and sadness), including decreased activation of the fusiform and extrastriate cortical regions, which may partly account for impaired recognition of and reduced autonomic responsiveness to expressions of fear, and impairments of empathy. Studies by Blair on children with psychopathic tendancies have shown such associations. One recent study found that if psychopaths are instructed to empathise with harmed individuals, their empathic reaction (theorized to be via the mirror system) initiates the same way it does for controls, although it remains unclear whether the same overall empathic experience is achieved and whether it is possible to transform the empathy into the more spontaneous response most people have. The underlying biological surfaces for processing expressions of happiness are functionally intact in psychopaths, although less responsive than those of controls. Professor Simon Baron-Cohen suggests that, unlike the combination of both reduced cognitive and affective empathy often seen in those with (classic) autism, psychopaths are aware of the feelings of others when they hurt someone because their cognitive empathy is intact even if affective empathy is not.
Research on psychopathy have largely been done on men and the PCL-R was developed using mainly male criminal samples raising the question how well the results apply to women. There have also been research investigating the sex differences. Men score higher than women on both the PCL-R and the PPI and on both of their main scales. The differences tend to be somewhat larger on the interpersonal-affective scale than on the antisocial scale. Most but not all studies have found broadly similar factor structure for men and women.
Many associations with other personality traits are similar although in one study the antisocial factor was more strongly related with impulsivity in men and more strongly related with openness to experience in women. It has been suggested that psychopathy in men manifest more as an antisocial pattern while it in women manifests more as a histrionic pattern. Studies on this have shown mixed results. PCL-R scores may be somewhat less predictive of violence and recidivism in women. On the other hand, psychopathy may have a stronger relationship with suicide and possibly internalizing symptoms in women. A suggestion is that psychopathy manifests more as externalizing behaviors in men and more as internalizing behaviors in women.
Causes and pathophysiology
Childhood and adolescent precursors
The "Psychopathy Checklist: Youth Version" (PCL:YV) is an adaptation of the PCL-R for 13–18 years old. It is, like the PCL-R, done by a trained rater based on an interview and an examination of criminal and other records. The "Antisocial Process Screening Device" (APSD) is also an adaptation of the PCL-R. It can be administered by parents or teachers for 6–13 year olds or it can be self-administered by 13–18 years olds. High psychopathy scores for both juveniles, as measured with these instruments, and adults, as measured with the PCL-R, have many similar associations with other variables. This include similar predictive ability regarding violence and criminality as well as this mainly being due to the scales measuring impulsive and antisocial behaviors rather than the scales measuring interpersonal and affective features. As for adults, several other measurement tools have similar predictive ability at risk assessment. One difference is that juvenile psychopathy appears to be associated with more negative emotionality such as anger, hostility, anxiety, and depression. Some recent studies have also found poorer ability at predicting long-term, adult offending such as the predictive ability not being better than unaided clinical judgment in one study.
Conduct disorder is a diagnosis with similarities to ASPD. The DSM-IV allows differentiating between childhood onset before age 10 and adolescent onset at age 10 and later. Childhood onset is argued to be more due to a personality disorder caused by neurological deficits interacting with an adverse environment. For many, but not all, is childhood onset associated with what is in Terrie Moffitt's developmental theory of crime is referred to as "life-course- persistent" antisocial behavior as well as poorer health and economic status. Adolescent onset is argued to more typically be associated with short-term antisocial behavior. It has been suggested that the combination of early-onset conduct disorder and ADHD may be associated with life-course-persistent antisocial behaviors as well as psychopathy.
There is evidence that this combination is more aggressive and antisocial than those with conduct disorder alone. However, it is not particularly distinct group since the vast majority of young children with conduct disorder also have ADHD. Some evidence indicates that this group have deficits in behavioral inhibition similar to adult psychopaths. They may not be more likely than those with conduct disorder alone to have the interpersonal/affective features and the deficits in emotional processing characteristic of adult psychopaths. Proponents of different types/dimensions of psychopathy have seen this type as possibly corresponding to adult secondary psychopathy/disinhibition in the triarchic model.
The DSM-V is proposing the specifier "With Significant Callous-Unemotional Traits" which would require at least two out of four of features for at least a year: lacking of remorse/guilt, lacking empathy (callousness), lacking affect, and lacking concern for performance. It has been suggested that this is a subgroup of early onset conduct disorder distinct from the larger group by having less deficits in inhibition, less fear and anxiety, less emotional reactivity and emotional negativity, more boldness and/or meanness, less intellectual impairment, and less exposure to poor parental practices although parental practices do affect outcomes for this group. It has been argued that this group is at increased risk for future of aggressive, criminal, and other antisocial behaviors but it is unclear how much the callous-unemotinal traits contribute to this since this group also often have higher impulsivity and more prior antisocial behavior compared to children with conduct disorder without callous-unemotional traits. Proponents of different types/dimensions of psychopathy have seen this type as possibly corresponding to adult primary psychopathy/boldness in the triarchic model.
There are moderate to high correlations between psychopathy rankings from late childhood to early adolescence. The correlations are considerably lower from early- or mid-adolescence to adulthood. In one study most of the similarities were on the Impulsive- and Antisocial-Behavior scales. Of those adolescents who scored in the top 5% highest psychopathy scores at age 13, less than one third (29%) were classified as psychopathic at age 24.
Three behaviors—bedwetting, cruelty to animals and firestarting, known as the Macdonald triad—were first described by John Macdonald as possible indicators, if occurring together over time during childhood, of future episodic aggressive behavior. However, subsequent research has found that bedwetting is not a significant factor and the triad as a particular profile has been called an urban legend. Questions remain about a connection between animal cruelty and later violence, though it has been included in the DSM as a possible factor in conduct disorder and later antisocial behavior.
A study by Farrington of a sample of London males followed between age 8 and 48 included studying which factors predicted scoring 10 or more on the PCL: SV at age 48. The strongest factors were "having a convicted father or mother, physical neglect of the boy, low involvement of the father with the boy, low family income, and coming from a disrupted family." Other significant factors included poor supervision, harsh discipline, large family size, delinquent sibling, young mother, depressed mother, low social class, and poor housing.
There has also been association between psychopaths and detrimental treatment by peers. Henry Lee Lucas, a serial killer and diagnosed psychopath, was bullied as a child and later said that his hatred for everyone spawned from mass social rejection.
Proponents of the triarchic model described earlier see psychopathy as due to the interaction of an adverse environment and genetic predispositions. What is adverse may differ depending on the underlying predisposition. Thus, persons having high boldness may respond poorly to punishment but may respond better to rewards and secure attachments.
Psychopaths have in laboratory research responded differently to aversive stimuli. They have had weak conditioning to painful stimuli and poor learning of avoiding responses that causes punishment. They have had low reactivity in the autonomic nervous system as measured with skin conductance while waiting for a painful stimulus but not when the stimulus occurs. While it has been argued that the reward system functions normally, some studies have also found reduced reactivity to pleasurable stimuli.
Psychopaths have also had difficulty switching from an ongoing action despite environmental cues signaling a need to do so. One possibility is that this explains the difficulty responding to punishment although it is unclear if it can explain findings such as deficient conditioning. There may also be methodological issues regarding the research.
Neuroimaging studies have found structural and functional differences between those scoring high and low on the PCL-R with a 2011 review by Skeem et al. stating that they are "most notably in the amygdala, hippocampus and parahippocampal gyri, anterior and posterior cingulate cortex, striatum, insula, and frontal and temporal cortex". A 2008 review by Weber et al. stated that psychopathy is associated with brain abnormalities in a prefrontal-temporo-limbic regions that are involved in emotional and learning processes, among others. The amygdala and frontal areas has been suggested as particularly important. People scoring ≥25 in the Psychopathy Checklist Revised, with an associated history of violent behavior, appear to have significantly reduced microstructural integrity in their uncinate fasciculus—white matter connecting the amygdala and orbitofrontal cortex. The more extreme the psychopathy, the greater the abnormality. Psychopathic personality traits, called "acquired sociopathy" can develop due to lesions on the orbitofrontal cortex.
In a recent study of how psychopaths respond to emotional words, the right anterior temporal gyrus, whereby, wide spread differences in activation patterns have been shown across the temporal lobe when criminal psychopaths were compared to "normal" volunteers. This is consistent with the view of clinical psychology.
There is DT-MRI evidence of breakdowns in the white matter connections between these two important areas in a small British study of nine criminal psychopaths. This evidence suggests that the degree of abnormality was significantly related to the degree of psychopathy and may explain the offending behaviors.
Some of these findings are consistent with other research and theories, such as psychopaths having low fear being consistent with changes in the amygdala. Detriments in aversive conditioning and instrumental learning are thought to result from amygdala dysfunction, potentially compounded by OFC dysfunction, but the specific reasons are unknown. The amygdala has also been associated also with positive emotions and there have been inconsistent results in the studies regarding particular areas. "Callous-unemotional" traits in children have also been associated with changes in the amygdala but again there may be methodological issues.
Proponents of the primary-secondary psychopathy distinction and triarchic model discussed earlier argue that there are neuroscientific differences between subgroups of psychopaths supporting their views. Thus the boldness factor in the triarchic model is argued to be associated with reduced activity in the amygdala during fearful or aversive stimuli and reduced startle response while the disinhibition factor is argued to be associated with impairment of frontal lobe tasks. There is evidence that boldness and disinhibition are genetically distinguishable.
Researchers have linked head injuries with psychopathy and violence. Since the 1980s, scientists have correlated traumatic brain injury, including damage to the prefrontal cortex, with psychopathic behavior and an inability to make morally and socially acceptable decisions. Children with early damage in the prefrontal cortex may never fully develop social or moral reasoning and become "psychopathic individuals … characterized by high levels of aggression and antisocial behavior performed without guilt or empathy for their victims." Additionally, damage to the amygdala may impair the ability of the prefrontal cortex to interpret feedback from the limbic system, which could result in uninhibited signals that manifest in violent and aggressive behavior.
Neurotransmitters and hormones
High levels of testosterone combined with low levels of cortisol have been theorized as contributing factors. Testosterone is "associated with approach-related behavior, reward sensitivity, and fear reduction". Cortisol increases "the state of fear, sensitivity to punishment, and withdrawal behavior". Injecting testosterone "shift[s] the balance from punishment to reward sensitivity", decreases fearfulness, and increases "responding to angry faces". Some studies have found that antisocial and aggressive behaviors are associated with high testosterone levels but it is unclear if psychopaths have high testosterone levels. A few studies have found psychopathy to be linked to low cortisol levels.
High testosterone levels combined with low serotonin levels may increase violent aggression. Some research suggests that testosterone alone does not cause aggression but increases dominance-seeking behaviors. Low serotonin is associated with "impulsive and highly negative reactions" which, if combined with high testosterone, may cause aggression if an individual becomes frustrated.
Studies have indicated that individuals with the traits meeting criteria for psychopathy show a greater dopamine response to potential "rewards" such as monetary promises or taking drugs such as amphetamines. This has been theoretically linked to an increased impulsivity.
A 2010 British study found that a large 2D:4D digit ratio, an indication of high prenatal estrogen exposure, was a "positive correlate of psychopathy in females, and a positive correlate of callous affect (psychopathy sub-scale) in males".
One approach to studying the role of genetics for crime is to calculate the heritability coefficient. It describes the proportion of the variance that is due to genetic factors for some characteristic that differs between individuals. The non-heritability proportion can be further divided into the "shared environment" which is the non-genetic factors which make siblings similar while the "non-shared environment" is the non-genetic factors which makes siblings different from another. Studies on the personality characteristics typical of psychopathy have found moderate genetic and moderate "non-shared environmental" influences while none from the "shared environment" A study using the PPI found the two factors fearless dominance and impulsive antisociality to be similarly moderately influenced by genetics and uncorrelated with one another which indicated separate genetic influences.
Genetic factors may generally influence the development of psychopathy while environmental factors affect the specific traits that predominate.
A study on a large group of children found more than 60% heritability for "callous-unemotional traits" and that conduct problems among children with these traits had a higher heritability than among children without these traits.
Studies have suggested a connection between a variant of the monoamine oxidase A (MAO-A) gene (dubbed the "warrior gene") and psychopathy. In the variant, the allele associated with behavioral traits consists of 30 bases, and produces comparatively less MAO-A enzyme. Low MAO-A activity was found to result in a significantly increased risk of aggression and antisocial behavior.
The variant was found to vary widely in demographic prevalence among different ethnic groups. 59% of African-American men, 56% of Maori men and 54% of Chinese men carry the MOA-A 3R genetic variant, compared to 34% of Caucasians, suggesting that the former ethnic groups are more genetically predisposed by the MAO-A gene towards aggression or antisocial tendencies compared to other ethnic groups studied.
Psychopathy is associated with several adverse life outcomes as well as increased risk of early death due to factors such as homicides, accidents, and suicides. This in combination with the evidence for genetic influences is evolutionarily puzzling and may suggest that there are compensating evolutionary advantages. Researchers within evolutionary psychology have proposed several evolutionary explanations. Some psychopaths may possibly be very socially successful. Another is that some associated traits such as early, promiscuous, adulterous, and coercive sexuality may increase reproductive success. A third is that psychopathy represents a frequency-dependent, [clarify]. This may work as long as there are few other psychopaths in the community since more psychopaths means increasing the risk of encountering another psychopath as well as non-psychopaths likely adapting more countermeasures against cheaters.
Criticisms include that it may be better to look at the contributing personality factors rather than treat psychopathy as a unitary concept due to poor testability and a lack of empirical evidence regarding reproductive success of psychopaths. Furthermore, if psychopathy is caused by the combined effects of a very large number of adverse mutations then each mutation may have so small an effect that it escapes natural selection.
Psychopathy has often been considered untreatable. Harris and Rice's Handbook of Psychopathy says that there is little evidence of a cure or effective treatment for psychopathy; no medications can instill empathy, and psychopaths who undergo traditional talk therapy might become more adept at manipulating others and more likely to commit crime. The only study finding increased criminal recidivism after treatment was in a 2011 retrospective study of a treatment program in the 1960s that had several methodological problems likely not approved today. Some relatively rigorous quasi-experimental studies using more modern treatment methods have found improvements regarding reducing future violent and other criminal behavior, regardless of PCL-R scores, although none was a randomized controlled trial. Some other studies have found improvements in risk factors for crime such as substance abuse. No study had in a 2011 review examined if the personality traits could be changed by such treatments. It has been shown in some studies that punishment and behavior modification techniques may not improve the behavior of psychopaths.
In a study where psychopathic criminals were brain-scanned while they watched videos of a person harming another individual, scientists found that psychopaths' empathic reaction (via the mirror system) initiated the same way it did for controls when they were instructed to empathise with the harmed individual, and that the area of the brain relating to pain was activated when the psychopaths were asked to imagine how the harmed individual felt. The research demonstrated how psychopaths could switch empathy on at will and explained how they could be both callous and charming. Although the team who conducted the study believes that it is still unknown how to transform this willful empathy into the spontaneous empathy most people have, they propose it could be possible to bring psychopaths closer to rehabilitation by helping them to activate their “empathy switch”. However, others suggested that despite the results of the study, it remained unclear whether psychopaths' experience of empathy was the same as that of controls, and also questioned whether it was possible to devise therapeutic interventions to make the empathic reactions more automatic.
The PCL-R, the PCL:SV, and the PCL:YV are highly regarded and widely used in criminal justice settings, particularly in North America. They may be used for risk assessment and for assessing treatment potential and be used as part of the decisions regarding bail, sentence, which prison to use, parole, and regarding whether to a youth should be tried as a juvenile or as an adult. There have been several criticisms against this. They include the general criticisms against the PCL-R, the availability of other risk assessment tools which may have advantages, and excessive pessimism regarding prognosis and treatment possibilities.
The interrater reliability of the PCL-R can be high when used carefully in research but tend to be poor in applied settings. In particular Factor 1 items are somewhat subjective. In sexually violent predator cases the PCL-R scores given by prosecution experts were consistently higher than those given by defense experts in one study. The scoring may also be influenced by other differences between raters. In one study it was estimated that of the PCL-R variance, about 45% was due to true offender differences, 20% was due to which side the rater testified for, and 30% was due to other rater differences.
In the United Kingdom, "Psychopathic Disorder" was legally defined in the Mental Health Act (UK), under MHA1983, as, "a persistent disorder or disability of mind (whether or not including significant impairment of intelligence) which results in abnormally aggressive or seriously irresponsible conduct on the part of the person concerned." This term, which did not equate to typical modern concepts of psychopathy, was intended to reflect the presence of a personality disorder, in terms of conditions for detention under the Mental Health Act 1983. With the subsequent amendments to the Mental Health Act 1983 within the Mental Health Act 2007, the term "psychopathic disorder" has been abolished, with all conditions for detention (e.g. mental illness, personality disorder, etc.) now being contained within the generic term of "mental disorder".
In England and Wales, the diagnosis of dissocial personality disorder is grounds for detention in secure psychiatric hospitals under the Mental Health Act if they have committed serious crimes, but since such individuals are disruptive for other patients and not responsive to treatment this alternative to prison is not often used.
"Sexual psychopath" laws
Starting in the 1930s, before the modern concept of psychopathy, "sexual psychopath" laws were introduced by some states until by the mid-1960s more than half of the states had such laws. "Sexual psychopaths" were seen as a distinct group of sex offenders who were not seriously mentally ill but had a "psychopathic personality" that could be treated. This was in agreement with the general rehabilitative trends at this time. Courts sent such sex offenders to a mental health facility for community protection and treatment.
Starting in 1970 many of these laws were modified or abolished in favor of more traditional responses such as imprisonment due to criticism of the "sexual psychopath" concept as lacking scientific evidence, the treatment being ineffective, and predictions of future offending being dubious. There were also a series of cases where persons treated and released committed new sex crimes. Starting in the 1990s several states have passed sexually dangerous person laws, not synonymous with the modern concept of psychopathy, which permit confinement after a sentence has been completed. Psychopathy measurements may be used in the confinement decision process.
A 2008 study using the Psychopathy Checklist: Screening Version (PCL: SV) found that 1.2% of a US sample scored 13 or more which indicates "potential psychopathy". Over half of those studied had scores of 0 or 1 and about two-thirds scored 2 or less. Higher scores were significantly associated with more violence, higher alcohol use, and estimated lower intelligence.
A 2009 British study by Coid et al., also using the PCL: SV, reported a community prevalence of 0.6% scoring 13 or more. The lower prevalence than in the 2008 study may be due to the 2009 sample being more representative of the general population. The scores "correlated with: younger age, male gender; suicide attempts, violent behavior, imprisonment and homelessness; drug dependence; histrionic, borderline and adult antisocial personality disorders; panic and obsessive–compulsive disorders."
PCL-R creator Robert Hare has stated that many (male) psychopaths have a pattern of mating with, and quickly abandoning women, and as a result, have a high fertility rate. These children may inherit a predisposition to psychopathy. Hare describes the implications as chilling. However, empirical evidence regarding the reproductive success of psychopaths is lacking.
- Antisocial personality disorder
- Autistic psychopathy
- Conduct disorder
- Dissocial personality disorder
- Fictional portrayals of psychopaths
- History of psychopathy
- Skeem, J. L.; Polaschek, D. L. L.; Patrick, C. J.; Lilienfeld, S. O. (2011). "Psychopathic Personality: Bridging the Gap Between Scientific Evidence and Public Policy". Psychological Science in the Public Interest 12 (3): 95–162. doi:10.1177/1529100611426706.
- "Hare Psychopathy Checklist". Encyclopedia of Mental Disorders. Retrieved September 4, 2013.
- Delisi, Matt; Vaughn, Michael G.; Beaver, Kevin M.; Wright, John Paul (2009). "The Hannibal Lecter Myth: Psychopathy and Verbal Intelligence in the MacArthur Violence Risk Assessment Study". Journal of Psychopathology and Behavioral Assessment 32 (2): 169–77. doi:10.1007/s10862-009-9147-z.
- Patrick, Christopher (2005). Handbook of Psychopathy. Guilford Press. ISBN 978-1-60623-804-2.[page needed]
- Hare, Robert D. (February 1, 1996). "Psychopathy and Antisocial Personality Disorder: A Case of Diagnostic Confusion". Psychiatric Times 13 (2).
- Hare, Robert D.; Hart, Stephen D.; Harpur, Timothy J. (1991). "Psychopathy and the DSM-IV criteria for antisocial personality disorder". Journal of Abnormal Psychology 100 (3): 391–8. doi:10.1037/0021-843X.100.3.391. PMID 1918618.
- Semple, David (2005). The Oxford Handbook of Psychiatry. Oxford University Press. pp. 448–9. ISBN 0-19-852783-7.
- "Psychopathy", Online Etymology Dictionary Retrieved August 1st 2011
- Online Etymology Dictionary: Psychopathic Retrieved January 21st 2012
- Online Etymology Dictionary: Psychopath Retrieved January 21st 2012
- Online Etymology Dictionary: Pathological Retrieved January 21st 2012
- Medlineplus Psychopath or Psychopathy Retrieved January 21st 2012
- Medilexicon powered by Stedman's, part of Lippincott Williams & Wilkins Psychopath Retrieved January 21st 2012
- Burgy, M. (2008). "The Concept of Psychosis: Historical and Phenomenological Aspects". Schizophrenia Bulletin 34 (6): 1200–10. doi:10.1093/schbul/sbm136. PMC 2632489. PMID 18174608.
- Online Etymology Dictionary: Psychopathic
- "Psycho". Dictionary.com. Retrieved 7 Sept 2013.
- Lykken, David T. (1995). The Antisocial Personalities. ISBN 978-0-8058-1941-0.[page needed]
- Rutter, Steve (2007). The Psychopath: Theory, Research, and Practice. New Jersey: Lawrence Erlbaum Associates. p. 37. ISBN 0-8058-6079-7.
- Online Etymology Dictionary: Socio-
- Hare, Robert D. (1999). Without Conscience: The Disturbing World of the Psychopaths Among Us. New York: Guilford Press. ISBN 1-57230-451-0.[page needed]
- The Psychopath Test. Jon Ronson. Page 225, Riverhead Books 2011
- Current Conceptions of Psychopathic Personality G. E. Partridge, The American Journal of Psychiatry. 1930 July ; 1(87):53-99
- International Handbook on Psychopathic Disorders and the Law, Volume 1, Alan Felthous, Henning Sass, 15 Apr 2008
- Psychopathy in the Treatment of Forensic Psychiatric Patients: Assessment, Prevalence, Predictive Validity, and Clinical Implications Martin Hildebrand, Rozenberg Publishers, 16 Jun 2005
- Epitome of Current Literature: Current Conceptions of Psychopathic Disorder by Partridge, G.E., M. Hamblin Smith, The British Journal of Psychiatry (1930) 76: 838
- Berrios, G.E. (1999). "Classic Text No. 37: J. C. Prichard and the concept of 'moral insanity'". History of Psychiatry 10 (37): 111–26. doi:10.1177/0957154X9901003706. PMID 11623816.
- Berrios, G.E. (1993). "European views on personality disorders: A conceptual history". Comprehensive Psychiatry 34 (1): 14–30. doi:10.1016/0010-440X(93)90031-X. PMID 8425387.
- Bluglass, R (1994). "Who's psychopathic now? A recent report has few new solutions and calls for more research". BMJ 309 (6958): 826. doi:10.1136/bmj.309.6958.826. PMC 2541046. PMID 7950601.
- Antisocial personality disorder – Diagnostic and Statistical Manual of Mental Disorders Fourth edition Text Revision (DSM-IV-TR) American Psychiatric Association (2000) pp. 645–650
- Hare, R. D. (2003). Manual for the Revised Psychopathy Checklist (2nd ed.). Toronto, ON, Canada: Multi-Health Systems.[page needed]
- Craig, Leam; Browne, Kevin; Beech, Anthony R. (2008). Assessing Risk in Sex Offenders. John Wiley and Sons. p. 117. ISBN 0-470-01898-4.
- Langer, Walter C. (1972) . The Mind of Adolf Hitler: The Secret Wartime Report. New York: Basic Books. p. 126. ISBN 978-0-465-04620-1.
- Walters, Glenn D. (2006). "Hitler the Psychopath". Lifestyle Theory: Past, Present, and Future. Nova Publishers. pp. 42–3. ISBN 978-1-60021-033-4.
- Patrick, Christopher J.; Fowles, Don C.; Krueger, Robert F. (2009). "Triarchic conceptualization of psychopathy: Developmental origins of disinhibition, boldness, and meanness". Development and Psychopathology 21 (3): 913–38. doi:10.1017/S0954579409000492. PMID 19583890.
- Harris, Grant T.; Rice, Marnie E.; Quinsey, Vernon L. (1994). "Psychopathy as a taxon: Evidence that psychopaths are a discrete class". Journal of Consulting and Clinical Psychology 62 (2): 387–97. doi:10.1037/0022-006X.62.2.387. PMID 8201078.
- Marcus, David K.; John, Siji L.; Edens, John F. (2004). "A Taxometric Analysis of Psychopathic Personality". Journal of Abnormal Psychology 113 (4): 626–35. doi:10.1037/0021-843X.113.4.626. PMID 15535794.
- Edens, John F.; Marcus, David K.; Lilienfeld, Scott O.; Poythress Jr, Norman G. (2006). "Psychopathic, Not Psychopath: Taxometric Evidence for the Dimensional Structure of Psychopathy". Journal of Abnormal Psychology 115 (1): 131–44. doi:10.1037/0021-843X.115.1.131. PMID 16492104.
- Skeem, Jennifer; Johansson, Peter; Andershed, Henrik; Kerr, Margaret; Louden, Jennifer Eno (2007). "Two subtypes of psychopathic violent offenders that parallel primary and secondary variants". Journal of Abnormal Psychology 116 (2): 395–409. doi:10.1037/0021-843X.116.2.395. PMID 17516770.
- Widiger, Thomas A.; Lynam, Donald R. (2002). "Psychopathy and the Five-Factor Model of Personality". In Millon, Theodore; Simonsen, Erik; Birket-Smith, Morten et al. Psychopathy: Antisocial, Criminal, and Violent Behavior. New York: Guilford Press. pp. 171–87. ISBN 978-1-57230-864-0.
- Zuckerman, Marvin (1991). Psychobiology of personality. Cambridge University Press. p. 390. ISBN 0-521-35942-2.
- Otto F., Kernberg (2004). Aggressivity, Narcissism, and Self-Destructiveness in the Psychotherapeutic Relationship: New Developments in the Psychopathology and Psychotherapy of Severe Personality Disorders. Yale University Press. ISBN 0-300-10180-5.[page needed]
- Murphy, Carolyn; Vess, James (2003). "Subtypes of psychopathy: Proposed differences between narcissistic, borderline, sadistic, and antisocial psychopaths". Psychiatric Quarterly 74 (1): 11–29. doi:10.1023/A:1021137521142. PMID 12602785.
- Cooke, David J.; Michie, Christine (2001). "Refining the construct of psychopathy: Towards a hierarchical model". Psychological Assessment 13 (2): 171–88. doi:10.1037/1040-3522.214.171.124. PMID 11433793.
- Hare, Robert D.; Neumann, Craig S. (2008). "Psychopathy as a Clinical and Empirical Construct". Annual Review of Clinical Psychology 4: 217–46. doi:10.1146/annurev.clinpsy.3.022806.091452. PMID 18370617.
- Hare, Robert D.; Neumann, Craig S. (2005). "The PCL-R Assessment of Psychopathy: Development, Structural Properties, and New Directions". In Patrick, Christopher J. Handbook of Psychopathy. New York: Guilford. pp. 58–88. ISBN 978-1-60623-804-2.
- Minkel, JR (June 17, 2010). "Fear Review: Critique of Forensic Psychopathy Scale Delayed 3 Years by Threat of Lawsuit". Scientific America.
- Walters, Glenn D. (2004). "The Trouble with Psychopathy as a General Theory of Crime". International Journal of Offender Therapy and Comparative Criminology 48 (2): 133–48. doi:10.1177/0306624X03259472. PMID 15070462.
- Dorothy Otnow Lewis, MD, Catherine A. Yeager, MA, Pamela Blake, MD, Barbara Bard, PhD, and Maren Strenziok, MS Ethics Questions Raised by the Neuropsychiatric, Neuropsychological, Educational, Developmental, and Family Characteristics of 18 Juveniles Awaiting Execution in Texas J Am Acad Psychiatry Law 32:408–29, 2004
- Franklin, Karen (2011). "Psychopathy: A Rorschach test for psychologists?". Witness.[self-published source?]
- Miller, A. K.; Rufino, K. A.; Boccaccini, M. T.; Jackson, R. L.; Murrie, D. C. (2011). "On Individual Differences in Person Perception: Raters' Personality Traits Relate to Their Psychopathy Checklist-Revised Scoring Tendencies". Assessment 18 (2): 253–60. doi:10.1177/1073191111402460. PMID 21393315.
- Cleckley, Hervey (1988). "Synopsis and orientation". The Mask of Sanity: An attempt to clarify some issues about the so-called psychopathic personality (5th ed.). Augusta, Georgia: Emily S. Cleckley. pp. 338–9. ISBN 978-0-9621519-0-3.
- DSM-V revision panel T 04 Antisocial Personality Disorder (Dyssocial Personality Disorder). Retrieved January 23, 2012.[dead link]
- WHO (2010) ICD-10: Clinical descriptions and diagnostic guidelines: Disorders of adult personality and behavior
- Patrick, Christopher J, ed. (2005). Handbook of Psychopathy. Guilford Press. pp. 440–3.
- Coid, Jeremy; Yang, Min; Ullrich, Simone; Roberts, Amanda; Moran, Paul; Bebbington, Paul; Brugha, Traolach; Jenkins, Rachel; Farrell, Michael; Lewis, Glyn; Singleton, Nicola; Hare, Robert (2009). "Psychopathy among prisoners in England and Wales". International Journal of Law and Psychiatry 32 (3): 134–41. doi:10.1016/j.ijlp.2009.02.008. PMID 19345418.
- Mills, Jeremy F.; Kroner, Daryl G.; Morgan, Robert D. "Psychopathic Traits". Clinician's Guide to Violence Risk Assessment. Guilford Press. pp. 55–64. ISBN 978-1-60623-985-8.
- Yang, Min; Wong, Stephen C. P.; Coid, Jeremy (2010). "The efficacy of violence prediction: A meta-analytic comparison of nine risk assessment tools". Psychological Bulletin 136 (5): 740–67. doi:10.1037/a0020473. PMID 20804235.
- Heilbrun, Kirk (2005). "Violence Risk: From Prediction to Management". In Carson, David; Bull, Ray. Handbook of Psychology in Legal Contexts. pp. 127–42. doi:10.1002/0470013397.ch5. ISBN 978-0-470-01339-7.
- The Trouble with Psychopathy as a General Theory of Crime Glenn D. Walters. Int J Offender Ther Comp Criminol April 2004 vol. 48 no. 2 133-148, doi 10.1177/0306624X03259472 PMID 15070462
- Neumann, Craig S.; Hare, Robert D. (2008). "Psychopathic traits in a large community sample: Links to violence, alcohol use, and intelligence". Journal of Consulting and Clinical Psychology 76 (5): 893–9. doi:10.1037/0022-006X.76.5.893. PMID 18837606.
- Woodworth, Michael; Porter, Stephen (2002). "In cold blood: Characteristics of criminal homicides as a function of psychopathy". Journal of Abnormal Psychology 111 (3): 436–45. doi:10.1037//0021-843X.111.3.436. PMID 12150419.
- Clin Psychol Rev. 2011 Apr;31(3):499-513. doi: 10.1016/j.cpr.2010.11.009. Epub 2010 Dec 13. A comparative study of violence risk assessment tools: a systematic review and metaregression analysis of 68 studies involving 25,980 participants. Singh JP, Grann M, Fazel S.
- Violence risk meta-meta: Instrument choice does matter: Despite popularity, psychopathy test and actuarials not superior to other prediction methods Karen Franklin, Ph.D. forensic psychologist and adjunct professor, 2011
- Authorship Bias in Violence Risk Assessment? A Systematic Review and Meta-Analysis Jay P. Singh, Martin Grann, Seena Fazel (2013) PLoS ONE 8(9): e72484. doi 10.1371/journal.pone.0072484
- Porter, Stephen; Brinke, Leanne; Wilson, Kevin (2009). "Crime profiles and conditional release performance of psychopathic and non-psychopathic sexual offenders". Legal and Criminological Psychology 14 (1): 109–18. doi:10.1348/135532508X284310.
- Williams, Kevin M.; Cooper, Barry S.; Howell, Teresa M.; Yuille, John C.; Paulhus, Delroy L. (2008). "Inferring Sexually Deviant Behavior from Corresponding Fantasies: The Role of Personality and Pornography Consumption". Criminal Justice and Behavior 36 (2): 198–22. doi:10.1177/0093854808327277.
- Porter, Stephen; Woodworth, Michael; Earle, Jeff; Drugge, Jeff; Boer, Douglas (2003). "Characteristics of sexual homicides committed by psychopathic and nonpsychopathic offenders". Law and Human Behavior 27 (5): 459–70. doi:10.1023/A:1025461421791. PMID 14593792.
- Levenson, Jill S.; Morin, John W. (2000). Treating Non-offending Parents in Child Sexual Abuse Cases. SAGE. p. 7. ISBN 0-7619-2192-3.
- Inter-rater reliability of the PCL-R total and factor scores among psychopathic sex offenders: are personality features more prone to disagreement than behavioral features? John F. Edens, Marcus T. Boccaccini, Darryl W. Johnson (2010)
- Horgan, John (2005). The Psychology of Terrorism. Routledge. p. 49. ISBN 978-0-7146-5262-7.
- Häkkänen-Nyholm, Helinä; Nyholm, Jan-Olof, eds. (2012). Psychopathy and Law: A Practitioners Guide. John Wiley & Sons. p. 177. ISBN 978-0-470-97238-0.
- Board, Belinda Jane; Fritzon, Katarina (2005). "Disordered personalities at work". Psychology, Crime & Law 11 (1): 17–32. doi:10.1080/10683160310001634304.
- Blair, J; Mitchel D; Blair K (2005). Psychopathy, emotion and the brain. Wiley-Blackwell. pp. 25–7. ISBN 0-631-23336-9.
- Nioche, A.; Pham, T.H.; Ducro, C.; De Beaurepaire, C.; Chudzik, L.; Courtois, R.; Réveillère, C. (2010). "Psychopathie et troubles de la personnalité associés : Recherche d'un effet particulier au trouble borderline ?" [Psychopathy and associated personality disorders: Searching for a particular effect of the borderline personality disorder?]. L'Encéphale (in French) 36 (3): 253–9. doi:10.1016/j.encep.2009.07.004. PMID 20620268.
- Hildebrand, Martin; De Ruiter, Corine (2004). "PCL-R psychopathy and its relation to DSM-IV Axis I and II disorders in a sample of male forensic psychiatric patients in the Netherlands". International Journal of Law and Psychiatry 27 (3): 233–48. doi:10.1016/j.ijlp.2004.03.005. PMID 15177992.
- Nedopil, Norbert; Hollweg, Matthias; Hartmann, Julia; Jaser, Robert (1998). "Comorbidity of Psychopathy with Major Mental Disorders". Psychopathy: Theory, Research and Implications for Society. pp. 257–68. doi:10.1007/978-94-011-3965-6_12. ISBN 978-0-7923-4920-4.
- Smith, Stevens S.; Newman, Joseph P. (1990). "Alcohol and drug abuse-dependence disorders in psychopathic and nonpsychopathic criminal offenders". Journal of Abnormal Psychology 99 (4): 430–9. doi:10.1037/0021-843X.99.4.430. PMID 2266219.
- Kantor, Martin (2006). The Psychopathy of Everyday Life. p. 107. ISBN 0-275-98798-1.
- Koenigs, M.; Kruepke, M.; Zeier, J.; Newman, J. P. (2011). "Utilitarian moral judgment in psychopathy". Social Cognitive and Affective Neuroscience 7 (6): 708–14. doi:10.1093/scan/nsr048. PMC 3427868. PMID 21768207.
- Young, Liane; Koenigs, Michael; Kruepke, Michael; Newman, Joseph P. (2012). "Psychopathy increases perceived moral permissibility of accidents". Journal of Abnormal Psychology 121 (3): 659–67. doi:10.1037/a0027489. PMID 22390288.
- "Protect – Watch Your Head". The Franklin Institute Online. The Franklin Institute. 2004. Retrieved July 10, 2013.
- Nature Neuroscience, November 1999[verification needed]
- Archives of General Psychiatry, February 1, 2000[verification needed]
- Blair, R.J.R (2008). "The amygdala and ventromedial prefrontal cortex: Functional contributions and dysfunction in psychopathy". Philosophical Transactions of the Royal Society B: Biological Sciences 363 (1503): 2557–65. doi:10.1098/rstb.2008.0027. PMC 2606709. PMID 18434283.
- Craig, M C; Catani, M; Deeley, Q; Latham, R; Daly, E; Kanaan, R; Picchioni, M; McGuire, P K; Fahy, T; Murphy, D G M (2009). "Altered connections on the road to psychopathy". Molecular Psychiatry 14 (10): 946–53, 907. doi:10.1038/mp.2009.40. PMID 19506560.
- Blair, R.J. (1995). "A cognitive developmental approach to morality: investigating the psychopath.". Cognition.
- Blair, R.J.R. (2003). "Neurobiological basis of psychopathy.". British Journal of Psychiatry.
- "Psychopathy" by Quinton 2006
- Blair, R.J.; E. Colledge, D.G. Mitchell (2001a). "Somatic markers and response reversal: is there orbitofrontal cortex dysfunction in boys with psychopathic tendencies?". Journal of Abnormal Child Psychology.
- Blair, R. J.; D.G. Mitchell, R.A. Richell, et. al (2002). "Turning a deaf ear to fear: impaired recognition of vocal affect in psychopathic individuals". Journal of Abnormal Psychology.
- Stevens, D.; T. Charman, R.J. Blair (2001). "Recognition of emotion in facial expressions and vocal tones in children with psychopathic tendencies". Journal of Genetic Psychology.
- Hogenboom, Melissa (July 25, 2013). "Psychopathic criminals have empathy switch". BBC News. Retrieved July 28, 2013.
- Baron-Cohen, Simon (2011). Zero Degrees of Empathy: A New Theory of Human Cruelty. Penguin UK. Retrieved August 8, 2013.
- http://www.hare.org/scales/pclyv.html/[full citation needed]
- http://www.hare.org/scales/apsd.html[full citation needed]
- MacDonald, John M. (1963). "The Threat to Kill". American Journal of Psychiatry 120 (2): 125–30.
- Weatherby, G. A.; Buller, D. M.; McGinnis, K. (2009). "The Buller-McGinnis model of serial-homicidal behavior: An integrated approach" (PDF). Journal of Criminology and Criminal Justice Research and Education 3: 1–21.
- Skrapec, C. and Ryan, K., 2010-11-16 "The Macdonald Triad: Persistence of an Urban Legend" Paper presented at the annual meeting of the ASC Annual Meeting, San Francisco Marriott, San Francisco, California
- McClellan, Janet (December 2007). "Animal Cruelty and Violent Behavior: Is There a Connection?". Journal of Security Education 2 (4): 29–45. doi:10.1300/J460v02n04_04 (inactive 2010-03-23).
- Scott, Shirley Lynn. "What Makes Serial Killers Tick?". truTV.com. Retrieved 2013-01-10.
- Weber, Sabrina; Habel, Ute; Amunts, Katrin; Schneider, Frank (2008). "Structural brain abnormalities in psychopaths—a review". Behavioral Sciences & the Law 26: 7–28. doi:10.1002/bsl.802.
- Blair, R. J. R. (2003). "Neurobiological basis of psychopathy". The British Journal of Psychiatry 182: 5–7. doi:10.1192/bjp.182.1.5. PMID 12509310.
- Pridmore, Saxby; Chambers, Amber; McArthur, Milford (2005). "Neuroimaging in psychopathy". Australian and New Zealand Journal of Psychiatry 39 (10): 856–65. doi:10.1111/j.1440-1614.2005.01679.x. PMID 16168013.
- Glenn, Andrea L.; Raine, Adrian (2008). "The Neurobiology of Psychopathy". Psychiatric Clinics of North America 31 (3): 463–75, vii. doi:10.1016/j.psc.2008.03.004. PMID 18638646.
- Tikkanen, Roope; Auvinen-Lintunen, Laura; Ducci, Francesca; Sjöberg, Rickard L.; Goldman, David; Tiihonen, Jari; Ojansuu, Ilkka; Virkkunen, Matti (2011). "Psychopathy, PCL-R, and MAOA genotype as predictors of violent reconvictions". Psychiatry Research 185 (3): 382–6. doi:10.1016/j.psychres.2010.08.026. PMC 3506166. PMID 20850185.
- Beauchaine, Theodore P.; Klein, Daniel N.; Crowell, Sheila E.; Derbidge, Christina; Gatzke-Kopp, Lisa (2009). "Multifinality in the development of personality disorders: A Biology × Sex × Environment interaction model of antisocial and borderline traits". Development and Psychopathology 21 (3): 735–70. doi:10.1017/S0954579409000418. PMC 2709751. PMID 19583882.
- Gollan, Jackie K.; Lee, Royce; Coccaro, Emil F. (2005). "Developmental psychopathology and neurobiology of aggression". Development and Psychopathology 17 (4): 1151–71. doi:10.1017/S0954579405050546. PMID 16613435.
- Lee R, Coccaro ER (2007). "Neurobiology of impulsive aggression: Focus on serotonin and the orbitofrontal cortex". In Flannery DJ, Vazsonyi AT, Waldman ID. The Cambridge handbook of violent behavior and aggression. New York: Cambridge University Press. pp. 170–86. ISBN 978-0-521-60785-8.
- Van Goozen, Stephanie H. M.; Fairchild, Graeme; Snoek, Heddeke; Harold, Gordon T. (2007). "The evidence for a neurobiological model of childhood antisocial behavior". Psychological Bulletin 133 (1): 149–82. doi:10.1037/0033-2909.133.1.149. PMID 17201574.
- Buckholtz, Joshua W; Treadway, Michael T; Cowan, Ronald L; Woodward, Neil D; Benning, Stephen D; Li, Rui; Ansari, M Sib; Baldwin, Ronald M; Schwartzman, Ashley N; Shelby, Evan S; Smith, Clarence E; Cole, David; Kessler, Robert M; Zald, David H (2010). "Mesolimbic dopamine reward system hypersensitivity in individuals with psychopathic traits". Nature Neuroscience 13 (4): 419–21. doi:10.1038/nn.2510. PMC 2916168. PMID 20228805.
- Blanchard, Alyson; Lyons, Minna (2010). "An investigation into the relationship between digit length ratio (2D: 4D) and psychopathy". The British Journal of Forensic Practice 12 (2): 23–31. doi:10.5042/bjfp.2010.0183.
- Glenn, Andrea L.; Kurzban, Robert; Raine, Adrian (2011). "Evolutionary theory and psychopathy". Aggression and Violent Behavior 16 (5): 371. doi:10.1016/j.avb.2011.03.009.
- Caspi, A.; McClay, J; Moffitt, TE; Mill, J; Martin, J; Craig, IW; Taylor, A; Poulton, R (2002). "Role of Genotype in the Cycle of Violence in Maltreated Children". Science 297 (5582): 851–4. doi:10.1126/science.1072290. PMID 12161658.
- Frazzetto, Giovanni; Di Lorenzo, Giorgio; Carola, Valeria; Proietti, Luca; Sokolowska, Ewa; Siracusano, Alberto; Gross, Cornelius; Troisi, Alfonso (2007). "Early Trauma and Increased Risk for Physical Aggression during Adulthood: The Moderating Role of MAOA Genotype". In Baune, Bernhard. PLoS ONE 2 (5): e486. doi:10.1371/journal.pone.0000486. PMC 1872046. PMID 17534436.
- Sabol, S. Z.; Hu, Stella; Hamer, D. (1998). "A functional polymorphism in the monoamine oxidase a gene promoter". Human Genetics 103 (3): 273–9. doi:10.1007/s004390050816. PMID 9799080.
- Rod Lea, Geoffrey Chambers, Journal of the New Zealand Medical Association. 2 March 2007. Monoamine oxidase, addiction, and the “warrior” gene hypothesis, Vol 120 No 1250
- "Maori 'warrior gene' claims appalling, says geneticist". News. NZ Herald News. Retrieved 2009-01-27.
- "Scientist debunks 'warrior gene'". News. NZ Herald News. Retrieved 2009-09-11.
- Buss, David M. (2009). "How Can Evolutionary Psychology Successfully Explain Personality and Individual Differences?". Perspectives on Psychological Science 4 (4): 359–66. doi:10.1111/j.1745-6924.2009.01138.x.
- Harris, Grant T.; Rice, Marnie E. (2006). "Treatment of Psychopathy: A Review of Empirical Findings". In Patrick, Christopher J. Handbook of psychopathy. New York: Guilford Press. pp. 555–72. ISBN 978-1-59385-591-8.
- Hogenboom, Melissa (July 25, 2013). "Psychopathic criminals have empathy switch". BBC News. Retrieved July 27, 2013.
- The Mental Health Act (UK) Reforming The Mental Health Act, Part II, High risk patients Accessed June 26, 2006
- Paul Harrison & John Geddes (2005-07-18). Lecture Notes: Psychiatry. Blackwell Publishing. pp. 163–165. ISBN 978-1-4051-1869-9.
- Nathan James, Kenneth R. Thomas, Cassandra Foley. Commitment of Sexually Dangerous Persons. July 2, 2007. Congressional Research Service. http://assets.opencrs.com/rpts/RL34068_20070702.pdf
- Coid J, Yang M, Ullrich S, Roberts A, Hare RD (2009). "Prevalence and correlates of psychopathic traits in the household population of Great Britain". International Journal of Law and Psychiatry 32 (2): 65–73. doi:10.1016/j.ijlp.2009.01.002. PMID 19243821.
- Blair, J. et al. (2005) The Psychopath - Emotion and the Brain. Malden, MA: Blackwell Publishing, ISBN 978-0-631-23335-0
- Cleckley, Hervey M. The Mask of Sanity: An Attempt to Reinterpret the So-Called Psychopathic Personality, 5th Edition, revised 1984, PDF file download.
- Hare, Robert D. (1999). Without Conscience: The Disturbing World of the Psychopaths Among Us. New York: Guilford Press. ISBN 1-57230-451-0.
- Paul Babiak & Robert D. Hare. Snakes in Suits: When Psychopaths Go To Work. HarperCollins, New York, NY. ISBN 978-0-06-114789-0
- Häkkänen-Nyholm, H. & Nyholm, J-O. (2012). Psychopathy and Law: A Practitioners Guide. Chichester: John Wiley & Sons.
- Oakley, Barbara, Ph.D., Evil Genes: Why Rome Fell, Hitler Rose, Enron Failed, and My Sister Stole My Mother's Boyfriend. Prometheus Books, Amherst, NY, 2007, ISBN 1-59102-665-2.
- Michael H. Thimble, F.R.C.P., F.R.C. Psych. Psychopathology of Frontal Lobe Syndromes.
- Widiger, Thomas (1995). Personality Disorder Interview-IV, Chapter 4: Antisocial Personality Disorder. Psychological Assessment Resources, Inc. ISBN 0-911907-21-1.
- Dutton, K. (2012) The Wisdom of Psychopaths ISBN 9780374709105 (e-book)
|Look up psychopathy in Wiktionary, the free dictionary.|
- Handbook of Psychopathy (2007) on Google Books.
- The Mask of Sanity, 5th Edition, PDF of Cleckley's book, 1988
- Without Conscience Official web site of Dr. Robert Hare
- Psychopathy in Psychiatry and Philosophy: An Annotated Bibliography Malatesti, L
- Understanding The Psychopath: Key Definitions & Research
- The Paradox of Psychopathy Psychiatric Times, 2007 (nb: inconsistent access)
- Into the Mind of a Killer Nature, 2001
- Can A Test Really Tell Who's A Psychopath? NPR audio, text and expert panel report, 2011
- What Psychopaths Teach Us about How to Succeed Scientific American, October 2012