Psychopathy (pronounced /saikopath in General American), not to be confused with psychosis, is a term derived from the Greek psyche (mind) and pathos (suffering), and was once used to denote any form of mental illness. Currently, psychopathy is defined in psychiatry as a condition characterized by lack of empathy or conscience, and poor impulse control or manipulative behaviors.
Though in widespread use as a psychiatric term, psychopathy has no precise equivalent in either the DSM-IV-TR, where it is most strongly correlated with antisocial personality disorder, or the ICD-10, where it is correlated with dissocial personality disorder. Robert Hare is working to have psychopathy listed in the DSM-V as a separate disorder.
In current clinical use, psychopathy is most commonly diagnosed using Hare's Psychopathy Checklist-Revised (PCL-R). Hare describes psychopaths as "intraspecies predators who use charm, manipulation, intimidation, and violence to control others and to satisfy their own selfish needs. Lacking in conscience and in feelings for others, they cold-bloodedly take what they want and do as they please, violating social norms and expectations without the slightest sense of guilt or regret." "What is missing, in other words, are the very qualities that allow a human being to live in social harmony."
Research into a group of individuals that could be described as psychopathic was first completed by Philippe Pinel almost 200 years ago. Pinel described patients as "insane without delirium," which he characterized as a lack of restraint and remorselessness for their actions. Pinel felt that his patients were morally neutral, reflecting his humanistic approach to mental illness.
The next most distinctive work on psychopaths was done in 1941 by Hervey M. Cleckley in his book The Mask of Sanity (significantly expanded in the second edition of 1950). Cleckley offered a broad range of case histories, from all corners of society, all of which showed patients with the common characteristic of "emotional emptiness." Cleckley probed the psychopath's attitudes and thought patterns in search of a meaning for their unusual behaviour; however, according to Robert Hare, Cleckley's most important contribution was in providing the framework of emotion for most future research into this disorder.
What is a psychopath?
A psychopath is defined as a person having no concerns for the feelings of others and a complete disregard for any sense of social obligation. They seem egocentric and lack insight of any sense of responsibility or consequence. Their emotions are thought to be superficial and shallow, if they exist at all. They are considered callous, manipulative, and incapable of forming lasting relationships, let alone showing any kind of meaningful love. They typically never perform any action unless they determine it can be beneficial for themselves.
Since psychopaths cause harm through their actions, it is assumed that they are not emotionally attached to the people they harm; however, according to the PCL-R Checklist, psychopaths are also careless in the way they treat themselves. They frequently fail to alter their behavior in a way that would prevent them from enduring future discomfort. Dr. Joseph Newman contends that the behavior displayed by psychopaths is the result of "an inability to process contextual cues." 
It is thought that any emotions which the primary psychopath exhibits are the fruits of watching and mimicking other people's emotions. They show poor impulse control and a low tolerance for frustration and aggression. They have no empathy, remorse, anxiety or guilt in relation to their behavior. In short, they truly are devoid of conscience. However, they understand that society expects them to behave in a conscientious manner, and therefore they mimic this behavior when it suits their needs.
Most studies of psychopaths have taken place among prison populations.
Cleckley defined psychopathy thus:
It has been shown that punishment and behavior modification techniques do not improve the behavior of a psychopath. They have been regularly observed to respond to both by becoming more cunning and hiding their behavior better. It has been suggested that traditional therapeutic approaches actually make them, if not worse, then far more adept at manipulating others and concealing their behavior. They are generally considered to be not only incurable but also untreatable.
Psychopaths also have a markedly distorted sense of the potential consequences of their actions, not only for others, but also for themselves. They do not, for example, deeply recognize the risk of being caught, disbelieved or injured as a result of their behaviour.
Psychopathy has quite separate legal and judicial definitions that should not be confused with the medical definition. Various states and nations have at various times enacted laws specific to dealing with psychopathic offenders, and many of these laws are active, on statute, today:
- Washington State Legislature defines a "Psychopathic personality" to mean "the existence in any person of such hereditary, congenital or acquired condition affecting the emotional or volitional rather than the intellectual field and manifested by anomalies of such character as to render satisfactory social adjustment of such person difficult or impossible".
- California enacted a psychopathic offender law in 1939  that defined a psychopath solely in terms of offenders with a predisposition "to the commission of sexual offenses against children." A 1941 law  attempted to further clarify this to the point where anyone examined and found to be psychopathic was to be committed to a state hospital and anyone else was to be sentenced by the courts.
- In the U.K. "Psychopathic Disorder" is legally defined in the The Mental Health Act (uk)  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."
Types of psychopathy
Cleckley also distinguished between two types of psychopathy: primary and secondary. Primary psychopathy was defined as the root disorder in patients diagnosed with it whereas secondary psychopathy was defined as an aspect of another psychiatric disorder or social circumstances. Today, primary psychopaths are considered to have mostly Factor 1 traits from the PCL-R (arrogance, callousness, manipulativeness, lying) whereas secondary psychopaths have a majority of Factor 2 traits (impulsivity, boredom proneness, irresponsibility, lack of long-term goals) .
Mealey uses the term "primary psychopathy" to differentiate between psychopathy that is biological in origin and "secondary psychopathy" that results from a combination of genetic and environmental influences. Lykken prefers sociopathy to describe the latter.
Sellbom and Ben-Porath (2005) describe the distinction succinctly:
- Some people who engage in violent behavior possess psychopathic personality traits, such as callousness, grandiosity, and fearlessness, and presumably engage in such conduct because they care little about others. Others are impulsive and experience considerable anger, anxiety, and distress and may commit violent acts as a reaction to negative emotions, which are sometimes referred to as "crimes of passion." Indeed, the distinction between primary and secondary psychopathy (including so-called neurotic psychopathy) has long been noted in the psychopathy literature (Karpman, 1947; Lykken, 1995).
This distinction closely resembles the distinction between instrumental and impulsive/reactive crime/violence in the field of criminology.
Primary psychopaths show a lack of anticipatory anxiety to threats and an apparent extreme emotional underreactivity. Occasional outbursts of emotion may be exhibited, but in a backdrop of emotional coldness, psychiatrists consider these a manipulative tactic.[How to reference and link to summary or text]
Primary psychopaths' behavior is thought to be rooted in their inability to comprehend emotionally the consequences of their actions and an inability to form empathic bonds with others, even family. Since primary psychopaths do not experience the feelings that would usually inhibit other people's antisocial impulses, they do whatever is most expedient for getting what they want.[How to reference and link to summary or text]
For the primary psychopath, especially prominent are the Factor 1 (in the two-factor model) PCL-R items of callousness/lack of empathy, shallow affect, lack of remorse or guilt, inability to accept responsibility for own actions, grandiose sense of self-worth, glibness/superficial charm, pathological lying, conning/manipulativeness.[How to reference and link to summary or text]
On the MMPI-2 Restructured Clinical Scales (RC), primary psychopathy (as measured by the Psychopathic Personality Inventory, Factor 1) is negatively correlated with RC2 (low positive emotions), RC7 (dysfunctional negative emotions), RC4 (antisocial behavior), and RC9 (hypomanic activation). On the MMPI-2 Personality Psychopathology Five (PSY-5) scales, primary psychopathy was positively correlated with AGGR(ession) (specifically, grandiosity and interpersonal dominance, and instrumental aggression) and DISC(onstraint) (specfically, fearlessness) while being negatively correlated with NEGE (negative emotionality) and INTR(oversion).
Newman et al. found measures of primary psychopathy to be negatively correlated with Gray's behavioral inhibition system, a construct intended to measure behavioral inhibition from cues of punishment or nonreward.
Secondary psychopaths show normal to above-normal physiological responses to potential threats. Their crimes tend to be unplanned and impulsive with little thought of the consequences . They have hot tempers and are prone to reactive aggression. They experience normal to above-normal levels of anxiety but are nevertheless highly stimulus seeking and have trouble tolerating boredom. Their lifestyle may lead to depression and even suicide.
For the secondary psychopath especially prominent are the Factor 2 (in the two-factor model) PCL-R items of impulsivity, weak behavioral controls, irresponsibility, lack of realistic long-term goals, proneness to boredom/need for stimulation, parasitic lifestyle, early behavioral problems, juvenile delinquency, and revocation of conditional release (breaking probation).
Sellbom and Ben-Porath (2005) found that secondary psychopathy (as measured by the Psychopathic Personality Inventory, Factor 2) shows opposite correlations to primary psychopathy in many cases. On the MMPI-2 RC, secondary psychopathy is positively correlated with RC4 (asb), RC7 (dne), and RC9 (hpm). It was also found to be correlated with the MMPI-2 PSY-5 scales of AGGR(ession) and DISC(onstraint).
Newman et al. found measures of secondary psychopathy to be positively correlated with Gray's behavioral activation system, a construct intended to measure sensitivity to cues of behavioral approach.
Diagnostic Criteria, The PCL-R Test
- Main article: Psychopathy Checklist-Revised (PCL-R)
The PCL-R has allowed for a differentiation of individuals with psychopathy and antisocial personality disorder (APD).
In contemporary research and clinical practice, psychopathy is most commonly assessed with the PCL-R (Hare, 1991), which is a clinical rating scale with 20 items. Each of the items in the PCL-R is scored on a three-point (0, 1, 2) scale according to two factors. PCL-R Factor 2 is associated with reactive anger, anxiety, increased risk of suicide, criminality, and impulsive violence. PCL-R Factor 1, in contrast, is associated with extroversion and positive affect. Factor 1, the so-called core personality traits of psychopathy, may even be beneficial for the psychopath (in terms of nondeviant social functioning). A psychopath will score high on both factors, whereas someone with APD will score high only on Factor 2.
Both case history and a semi-structured interview are used in the analysis.
Psychopathy's Relationship with other Mental Health Disorders
Psychopathy, as measured on the PCL-R, is negatively correlated with all DSM-IV Axis I disorders except substance abuse disorders. Psychopathy is most strongly correlated with DSM-IV antisocial personality disorder. PCL-R Factor 1 is correlated with narcissistic personality disorder and histrionic personality disorder. PCL-R Factor 2 is particularly strongly correlated to antisocial personality disorder and criminality.
PCL-R Factor 2 is associated with reactive anger, anxiety, increased risk of suicide, criminality, and impulsive violence. PCL-R Factor 1, in contrast, is associated with extroversion and positive affect.
The official stance of the American Psychiatric Association as presented in the DSM-IV-TR is that psychopathy and sociopathy are obsolete synonyms for antisocial personality disorder. The World Health Organization takes a similar stance in its ICD-10 by referring to psychopathy, sociopathy, antisocial personality, asocial personality, and amoral personality as synonyms for dissocial personality disorder.
Among laypersons and professionals, there is much confusion about the meanings and differences between psychopathy, sociopathy, antisocial personality disorder, and dissocial personality disorder.
The difference between sociopathy and psychopathy, according to Hare, may "reflect the user's views on the origins and determinates of the disorder." Most sociologists, criminologists and even some psychologists believe the disorder is caused by social conflicts, and thus prefer the term 'sociopath.' Those who believe as Hare does, that a combination of psychological, biological, genetic and environmental factors all contribute to the disorder are more likely to use the term 'psychopath'.
David T. Lykken proposes that psychopathy and sociopathy are two distinct kinds of antisocial personality. He holds that psychopaths are born with temperamental differences such as impulsivity, cortical underarousal, and fearlessness that lead them to risk-seeking behavior and an inability to internalize social norms; sociopaths, on the other hand, have relatively normal temperaments; their personality disorder being more an effect of negative sociological factors like parental neglect, delinquent peers, poverty, and extremely low or extremely high intelligence. Both personality disorders are, of course, the result of an interaction between genetic predispositions and environmental factors, but psychopathy leans towards the hereditary whereas sociopathy tends towards the environmental.
- Main article: Antisocial personality disorder
Comparing psychopathy to antisocial personality disorder is a continuing source of debate within the psychological community. The official stance of the American Psychiatric Association as presented in the DSM-IV-TR is that psychopathy and sociopathy are obsolete synonyms for antisocial personality disorder (APD). The World Health Organization takes a similar stance in its ICD-10 by referring to psychopathy, sociopathy, antisocial personality, asocial personality, and amoral personality as synonyms for dissocial personality disorder.
Hare and others take the stance that psychopathy as a syndrome should be considered distinct from the DSM-IV's antisocial personality disorder construct. even though APD and psychopathy were intended to be equivalent in the DSM-IV. However, those who created the DSM-IV felt that there was too much room for subjectivity on the part of clinicians when identifying things like remorse and guilt; therefore, the DSM-IV panel decided to stick to observable behaviour, namely socially deviant behaviours. As a result, the diagnosis of APD is something that the "majority of criminals easily meet." Hare goes further to say that the percentage of incarcerated criminals that meet the requirements of APD is somewhere between 80 to 85%, whereas only about 20% of these criminals would qualify for a diagnosis of psychopath. This twenty percent, according to Hare, accounts for 50% of all the most serious crimes committed, including half of all serial and repeat rapists. According to FBI reports 44% of all police officer murders in 1992 were committed by psychopaths.
One study found that only 20 percent of those diagnosed with APD qualified as psychopath on the PCL-R.
Another study using the PCL-R to examine the relationship between antisocial behaviour and suicide found that suicide history was strongly correlated to PCL-R Factor 2 (reflecting antisocial deviance) and was not correlated to PCL-R factor 1 (reflecting affective functioning). Given that APD relates to Factor 2, whereas psychopathy relates to both factors, this would confirm Hervey Cleckley's assertion that psychopaths are relatively immune to suicide. Sufferers of APD, on the other hand, have a relatively high suicide rate.
Pseudopsychopathic personality disorder
It has been suggested that people can suffer apparently psychopathic personality changes from lesions or damage of the brain's frontal lobe. This is sometimes called Pseudopsychopathic personality disorder or Frontal lobe disorder.
One well-known and dramatic case was that of Phineas Gage, a 19th century railroad work supervisor. According to Renato M. E. Sabbatini, an explosive charge was set. When it detonated, a steel rod was accidentally driven through Gage's skull from his left cheek to above the right brow.
Incredibly, he survived for many years. According to the common account, his personality changed completely. He became abusive, aggressive, deceitful, irresponsible and incapable of insight and planning (a poor sense of consequence). Computerised reconstruction of the possible brain damage suggest that, from his known injuries he seemed likely to have had a lesion on the ventromedial frontal cortex.
However, Malcolm Macmillian's recent research into the Gage case shows evidence that many of the so-called "psychopathic" features were never documented by physician John Harlow, the primary source, or the Harvard physicians who examined him intensively in Boston. No police records or newspaper accounts can be found for Gage's alleged, drunken behavior or violence, nor any record of his mother complaining to Dr. Harlow, despite being in contact for years.
Macmillan suggests that claims of deceitfulness, social coarsening and loutish behavior, in Harlow's report to the medical society, lack justification. His research also showed that Gage was able to hold steady work in two locations. His drifting from job to job happened at the end of his life when he developed seizures, eventually succumbing to status epilepticus in front of his family. Macmillan concluded that, at worst, Gage was probably guileless and lacked social skills. A hotel guest, basically a stranger, convinced him to travel to Chile and manage a Concord stagecoach, a difficult cognitive-motor task, which he apparently mastered.
Psychopathy is not normally diagnosed in children or adolescents, and some jurisdictions explicitly forbid diagnosing psychopathy and similar personality disorders in minors. Psychopathic tendencies can sometimes be recognized in childhood or early adolescence and, if recognised, are diagnosed as Conduct disorder. It must be stressed that not all children diagnosed with conduct disorder grow up to be psychopaths, or even disordered at all, but these childhood signs are found in significantly higher proportions in psychopaths than in the general population. Conduct disorder, as well as its two other overlapping subcategories Attention Deficit Hyperactivity Disorder and Oppositional Defiance Disorder, can sometimes develop into adult psychopathy. However, conduct disorder "fails to capture the emotional, cognitive and interpersonality traits - egocentricity, lack of remorse, empathy or guilt - that are so important in the diagnosis of psychopathy."
Children showing strong psychopathic precursors often appear immune to punishment; nothing seems to modify their undesirable behavior. Consequently parents usually give up, and the behavior worsens.
The following childhood indicators are to be interpreted not as to the type of behavior, but as to its relentless and unvarying occurrence. Not all must be present concurrently, but at least a number of them need to be present over a period of years:
- An extended period of bedwetting past the preschool years that is not due to any medical problem.
- Cruelty to animals beyond an angry outburst.
- Firesetting and other vandalism. Not to be confused with playing with matches, which is not uncommon for preschoolers. This is the deliberate setting of destructive fires with utter disregard for the property and lives of others.
- Lying, often without discernible objectives, extending beyond a child's normal impulse to not be punished. Lies are so extensive that it is often impossible to know lies from truth.
- Theft and Truancy.
- Aggression to peers, not necessarily physical, which can include getting others into trouble or a campaign of psychological torment.
The three indicators — bedwetting, cruelty to animals and firestarting, known as the MacDonald triad — were first described by J.M. MacDonald as indicators of psychopathy. Though the relevance of these indicators to serial murder etiology has since been called into question, they are considered relevant to psychopathy.
The question of whether young children with early indicators of psychopathy respond poorly to intervention compared to conduct disordered children without these traits has only recently been examined in controlled clinical research. The findings from this research are consistent with broader evidence - pointing to poor treatment outcomes. 
Discrete taxon vs. continuous dimension
As part of the larger debate on whether personality disorders are distinct from normal personality or extremes on various dimensions of normal personality is the debate on whether psychopathy represents something "qualitatively different" from normal personality or a "continuous dimension" shading from normality into severely psychopathic. Marcus, John, and Edens performed some statistical analysis on previously attained PCL–R and PPI scores and concluded that psychopathy may best be conceptualized as having a "dimensional latent structure" like depression.
In contrast, the PCL–R sets a score of 30 out of 40 for North American male inmates as its cut-off point for a diagnosis of psychopathy.
Perceptual/emotional recognition deficits
In a 2002 study, Kosson, Suchy, et al. asked psychopathic inmates to name the emotion expressed on each of 30 faces; compared to controls, psychopaths had a significantly lower rate of accuracy in recognizing disgusted facial affect but a higher rate of accuracy in recognizing anger. Additionally, when "conditions designed to minimize the involvement of left-hemispheric mechanisms" were used, psychopaths had more difficulty accurately identifying emotions. This study did not replicate Blaire, et al. (1997)'s findings that psychopaths are specifically less sensitive to nonverbal cues of fear or distress.
In a 2002 experiment, Blair, Mitchell, et al. used the Vocal Affect Recognition Test to measure psychopaths' recognition of the emotional intonation given to connotatively neutral words. Psychopaths tended to make more recognition errors than controls with a particularly high rate of error for sad and fearful vocal affect.
Hiatt, Schmitt, and Newman conducted a 2004 experiment to test their hypothesis of overselective attention in psychopaths using two forms of the Stroop color-word and picture-word tasks: with color/picture and word separated and with color/picture and word together. They found that in the separated Stroop tasks, psychopaths performed significantly worse than controls; however, on standard Stroop tasks, psychopaths performed equally well as controls. When split into low-anxious and high-anxious groups, low-anxious psychopaths and low-anxious controls showed less interference on the separated Stroop tasks than their high-anxious counterparts; for low-anxious psychopaths, interference was very nearly zero. They conclude that the inability to integrate contextual cues depends on the cues' relationship to "the deliberately attended, goal-relevant information."
- Psychopathy Checklist-Revised (PCL-R)
- Conduct disorder
- Oppositional defiant disorder
- Antisocial personality disorder
- Serial killer
- Narcissistic personality disorder
- Sadistic personality disorder
- Fictional portrayals of psychopaths
- Malignant narcissism
- ↑ Hare, R. D. Psychopathy and Antisocial Personality Disorder: A Case of Diagnostic Confusion, Psychiatric Times, February 1996, XIII, Issue 2 Accessed June 26, 2006
- ↑ Hare, Robert D, Psychopaths: New Trends in Research. The Harvard Mental Health Letter, September 1995
- ↑ Hare, Robert D. Without Conscience: The Disturbing World of Psychopaths Among Us, (New York: Pocket Books, 1993) pg 2.
- ↑ Hare, Robert D. Without Conscience: The Disturbing World of Psychopaths Among Us, (New York: Pocket Books, 1993) pg 25.
- ↑ Cleckley, Hervey. The Mask of Sanity, pg 92.
- ↑ Hare, Robert D. Without Conscience: The Disturbing World of Psychopaths Among Us, (New York: Pocket Books, 1993) pg 19.
- ↑ Newman, J Psychos need a little sympathy Wired News
- ↑ 8.0 8.1 8.2 Cleckley, H, 1941 The Mask of Sanity (pdf Download 1.38mb)
- ↑ Washington State Legislature Revised Code of Washington (RCW) Accessed June 26, 2006
- ↑ Statutes and Amendments to the Codes of California 1939, page 1783, ch. 447, enacted June 6, 1939
- ↑ Statutes and Amendments to the Codes of California 1941, page 2462, ch. 884, enacted June 28, 1941.
- ↑ The Mental Health Act (UK) Reforming The Mental Health Act, Part II, High risk patients Accessed June 26, 2006
- ↑ Karpman, Ben, M.D. "The Myth of the Psychopathic Personality." The American Journal of Psychiatry, 104:523-534 (March 1948). Accessed January 16, 2007.
- ↑ 14.0 14.1 Lykken, David T. The Antisocial Personalities (1995).
- ↑ Mealey, L. (1995). The sociobiology of sociopathy:An integrated evolutionary model. Behavioral and Brain Sciences, 18, 523–559.
- ↑ 16.0 16.1 16.2 Sellbom, Martin; Ben-Porath, Yossef S.; et al. Journal of Personality Assessment, 85(3), 334-343.
- ↑ 17.0 17.1 17.2 Newman, Joseph P.; MacCoon, Donald G.; Vaughn, Leah J.; Sadeh, Naomi. "Validating a Distinction Between Primary and Secondary Psychopathy With Measures of Gray's BIS and BAS Constructs." Journal of Abnormal Psychology. 2005, Vol. 114 (2), pp. 319-323.
- ↑ Davison, G.C., Neale, J.M., Blankstein, K.R., & Flett, G.L. (2002). Abnormal Psychology. (Etobicoke: Wiley)
- ↑ Hare, Robert D. Without Conscience: The Disturbing World of Psychopaths Among Us, (New York: Pocket Books, 1993) pg 23.
- ↑ Hare, R. D. Psychopathy and Antisocial Personality Disorder: A Case of Diagnostic Confusion, Psychiatric Times, February 1996, XIII, Issue 2 Accessed June 26, 2006
- ↑ Hare, Robert D. Without Conscience: The Disturbing World of Psychopaths Among Us, (New York: Pocket Books, 1993) pg 25.
- ↑ Hare, Robert D. Without Conscience: The Disturbing World of Psychopaths Among Us, (New York: Pocket Books, 1993) pg 25-30.
- ↑ Rutherford, M.J., Cacciola, J.S., & Alterman, A.I. (1999). "Antisocial Personality Disorder and Psychopathy in Cocaine-Dependent Women," American Journal of Psychiatry, 156. pp. 849-856
- ↑ Joiner, Thomas E. "Psychopathy, Antisocial Personality, and Suicide Risk," Journal of Abnormal Psychology 110 August 2001. pp 462-470.
- ↑ Sabbatini, Renato M.E. The Psychopath's Brain Accessed June 26, 2006
- ↑ Macmillan, Malcolm, An Odd Kind of Fame: Stories of Phineas Gage, MIT Press, 2000
- ↑ Hare, Robert D. Without Conscience: The Disturbing World of Psychopaths Among Us, (New York: Pocket Books, 1993) pg 159.
- ↑ Ramsland, Katherine, The Childhood Psychopath: Bad Seed or Bad Parents?
- ↑ J. M. MacDonald "The Threat to Kill". American Journal of Psychiatry, 125-130, 1963
- ↑ Hawes, D. J., & Dadds, M. R. (2005). The treatment of conduct problems in children with callous-unemotional traits. Journal of Consulting and Clinical Psychology, 73(4), 737-741. 
- ↑ Marcus, David K.; John, Siji L.; Edens, John F. "A Taxometric Analysis of Psychopathic Personality." Journal of Abnormal Psychology. 2004, Vol. 113 (4), pp. 626-635.
- ↑ Kosson, David S.; Suchy, Yana; Mayer, Andrew R.; Libby, John. "Facial Affect Recognition in Criminal Psychopaths." Emotion. 2002, Vol. 2 (4), pp. 398-411.
- ↑ Blair, R. James R; Mitchell, Derek G.V.; Richell, Rebecca A.; Kelly, Steve; Leonard, Alan; Newman, Chris; Scott, Sophie K. "Turning a Death Ear to Fear: Impaired Recognition of Vocal Affect in Psychopathic Individuals." Journal of Abnormal Psychology. 2002, Vol. 111 (4), pp. 682-686.
- ↑ Hiatt, Kristina D.; Schmitt, William A.; Newman, Joseph P. "Stroop Tasks Reveal Abnormal Selective Attention Among Psychopathic Offenders." Neuropsychology. 2004, Vol. 18 (1), pp. 50-59.
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