Although psychopathy may be viewed as an evolutionary adaptation that serves the individual well, it typically is construed as a personality disorder, or a chronic, inflexible, and maladaptive pattern of relating to the world. Most conceptualizations of psychopathy emphasize traits of emotional detachment, including callousness, failure to form close emotional bonds, low anxiety proneness, remorselessness, and deceitfulness. However, the most widely used measure of psychopathy goes beyond these traits to assess repeated involvement in antisocial behavior. The Revised Psychopathy Checklist (PCL-R) was developed with criminal offenders and weighs past antisocial behavior as strongly as traits of emotional detachment in diagnosing psychopathy. Predominant use of the PCL-R and offender samples has established a large research literature on unsuccessful psychopathy. Relatively little is known about individuals with traits of emotional detachment who escape contact with the legal system; express their psychopathic tendencies in a manner that does not conflict with the law; or even attain success in business, political, and other settings. Indeed, most contemporary research and virtually all practical interest in psychopathy revolve around the utility of the PCL-R in forecasting offenders’ violent and antisocial behavior and, to a lesser extent, offenders’ treatment amenability. Recent research challenges the prevailing assumptions that (a) traits of emotional detachment per se predict violence and (b) individuals with psychopathic traits cannot be effectively treated. In this entry, research on these practical issues is reviewed before turning to more fundamental questions about the basic nature and manifestations of psychopathy. Theoretically driven research on the potential mechanisms that underpin the disorder reveal the importance of emotional detachment as a likely manifestation of classic or “primary” psychopathy. Such research also suggests that there may be a “secondary” variant of psychopathy, marked by psychological disturbance and violence potential.

Practical Interest in Psychopathy

A variety of psycholegal issues that arise in the criminal and juvenile justice system call for the identification of individuals who are inalterably dangerous. Increasingly, measures of psychopathy are being applied to inform decisions about the length of offenders’ sentences, their level of institutional supervision, whether they should be released from prison on parole, whether they should receive any treatment, and whether they should be sentenced to death. Psychopathy measures predominantly are used as prosecution tools. As shown in this section, there are reasons to question the assumption that these measures identify individuals who are inalterably dangerous.

Violence Prediction

The most widely used measure of psychopathy is also the number one tool used to assess risk of future violence. In fact, forensic psychologists use the PCL-R to assess risk twice as often as they use tools that were specifically designed as risk assessment tools. This is not the case for other well-validated measures of psychopathy such as the Psychopathic Personality Inventory (PPI). Instead, the diagnostic measure for personality disorders has become the most widely used tool for assessing violence risk, owing to a series of studies indicating that the PCL measures robustly predict violence and recidivism for offenders, forensic patients, and even psychiatric patients. Although the absolute size of this relationship is weak (r ~ .25), the PCL-R is among the strongest single predictors of violence and other criminal behavior, on a level that competes with leading risk assessment tools.

Although this relationship suggests that emotionally detached psychopaths callously use violence to achieve control over and exploit others, recent research suggests otherwise. The lion’s share of the PCL-R’s utility in predicting violence is attributable to its saturation with indices of past violence and criminality. Although there is debate about its factor structure, the original PCL-R model has two moderately correlated scales: The first assesses core interpersonal and affective features of emotional detachment that are central to most conceptualizations of psychopathy; the second assesses impulsivity, irresponsibility, poor anger controls, and antisocial behavior, which some view as peripheral to psychopathy. A meta-analysis of 42 studies indicated that the PCL-R’s antisocial behavior scale is significantly more predictive of violent and general recidivism than its emotional detachment scale. Moreover, three original studies indicate that the emotional detachment scale does not significantly predict future violence, independent of its association with the antisocial behavior scale.

Psychopathy explains the predictive utility of the PCL-R less than do two other factors. First, indices of past violent and criminal behavior naturally are linked with future, like behavior. Information about criminal behavior determines one’s ratings of some PCL-R items and heavily affects one’s ratings of many others. Second, ratings of past violent and criminal behavior appear to capture something trait-like that is clinically useful but not specific to psychopathy. The PCL-R (antisocial or total scores) manifests some incremental utility in predicting future violence and crime, beyond indices of past, like behavior. Recent research suggests that the PCL-R may tap constructs of antagonism or “externalizing” that place individuals at high risk of involvement in violent situations. Antagonism involves suspiciousness, hostility, combativeness, and irritability. Externalizing weaves together traits of aggression and behavioral disinhibition, antisocial behavior, and substance use. Neither construct is specific to psychopathic personality disorder. Both are related to violent and antisocial behavior.

Treatment Amenability

Practical interest in psychopathy revolves around its implications for assessing both violence risk and treatment amenability. The prevailing assumption is that psychopathy cannot be effectively treated. In fact, the results of one early study led many to opine that treatment only “made psychopaths worse”—that is, more likely to re-offend than if they had not been treated. This study was a retrospective matched trial that compared the recidivism rates of mentally disordered offenders released from either a prison or a radical therapeutic community program. The treatment program was active in the 1960s and involved unconventional interventions such as extended nude encounter groups and administration of psychedelics, alcohol, and other drugs to psychopaths to disrupt their defenses, increase their anxiety, and generally make them more accessible to treatment.

Therapeutic pessimism about psychopathy is so deeply entrenched in clinical and forensic circles that it rarely has been subjected to empirical evaluation. To date, no randomized controlled trial has compared the outcomes of psychopathic individuals who do, or do not, receive treatment. Moreover, no published study has examined treatment programs developed particularly for those with psychopathy; instead, treatment for other conditions (mental disorder, substance abuse, or recidivism risk) has been administered “as usual” to those with psychopathy.

Nevertheless, a mounting body of recent quasi-experimental evidence challenges the assumption that individuals with psychopathy do not respond to conventional treatment. This research suggests that psychopathy, like many other personality disorders, complicates the first-line treatment of mental and substance abuse disorders. Simply put, individuals with psychopathy tend to have low treatment motivation, to misbehave in treatment, and to respond more slowly to treatment. However, when provided sufficient “doses” of treatment, those with psychopathy are as likely as anyone else to manifest reduced risk of violence and recidivism.

Three nonexhaustive examples will be provided here. First, a meta-analysis of 44 studies indicated that (a) therapeutic communities were the most common and least effective form of treatment for those with psychopathy and (b) across treatment modalities and definitions of psychopathy, treatment was moderately successful in reducing recidivism for psychopathic individuals (a 62% success rate). Second, a prospective study of approximately 900 civil psychiatric patients indicated that psychopathy did not moderate the effect of outpatient treatment on future violence. Of those who received relatively intensive treatment during one 10-week period, those with psychopathic traits were as likely as those without such traits to show significantly reduced violence potential in the next 10-week period. Third, a prospective study of 381 offenders mandated to substance abuse treatment indicated that treatment involvement significantly reduced risk of recidivism during the year after release, regardless of the effect of psychopathic traits. In the latter two studies, propensity scores were applied to control for the nonrandom assignment of individuals to less versus more intensive treatment. The effects remained moderate and significant. Together, this research suggests that individuals with psychopathy should be recast as high-risk (not hopeless) cases in need of intensive treatment. Correctional research indicates that focusing intensive resources on the highest-risk cases maximizes reduction in recidivism.

Basic Nature and Manifestations of Psychopathy

The relatively recent surge of interest in applying measures of psychopathy has affected our conceptualization of the construct itself. To be certain, use of the PCL-R has advanced the field’s understanding of the nature and manifestations of psychopathy. The ever-increasing momentum of research on psychopathy is largely attributable to the PCL-R’s ability to assess reliably traits such as callousness, facilitate comparison of results across studies, and clarify communication among practitioners and researchers. However, referring to the PCL-R as the “gold standard of psychopathy” signals that the field has mistakenly conflated a measure with a construct. A PCL-R score is no more psychopathy than a Wechsler Adult Intelligence Scale (WAIS-R) score is intelligence.

As research on the PCL-R’s utility in predicting violence has accumulated, the dominant view of psychopathy itself has shifted. Most modern views of psychopathy may be traced to Hervey Cleckley’s influential book The Mask of Sanity (1941). Based on a series of case studies, Cleckley articulated 16 criteria for psychopathy that emphasized traits of emotional detachment. Although the PCL-R is based on Cleckley’s conceptualization, it omits some features that Cleckley viewed as central to psychopathy (e.g., low anxiety) and emphasizes tendencies toward violent and antisocial behavior. Cleckley viewed these tendencies as largely “independent” of the more fundamental manifestations of psychopathy. As the field has come to equate psychopathy with the PCL-R, there has been slippage toward the notion that psychopathy is a violent variant of antisocial personality disorder. Now, psychopaths are called “intraspecies predators,” and criminal behavior has been held up as the “ultimate criterion” for measures of psychopathy.

Notably, this entry focuses on the nature and manifestations of psychopathy among those for whom measures of psychopathy are best validated: adult, Caucasian, male offenders. Questions have been raised about the applicability of the psychopathy construct to juveniles, African Americans (who do not manifest some deficits on laboratory tasks thought prototypic of psychopathy), and women (who do not yield a clear factor structure for measures of psychopathy).

Validation Hierarchy

Predictive utility (which seeks clinical utility) cannot be mistaken for construct validity (which seeks construct identification). To increase the PCL-R’s predictive utility, one could go beyond criminal behavior to include items that assess young age and male gender. This would not, however, necessarily enhance the measure’s validity in assessing psychopathic personality disorder. To advance understanding of the construct, psychopathy must be evaluated against a validation hierarchy dictated by a theory of the disorder.

There are two major groups of theories about psychopathy. The first group begins with Cleckley, who posited that psychopathy is a largely inherited affective deficit that results in self-defeating behavior. Similarly, Robert Hare hypothesizes that this affective deficit involves impaired processing of emotional meanings related to language and may be based on reduced lateralization of verbal processes. The second theoretical group begins with the Fowles-Gray model of psychopathy, which references two constitutionally based motivational systems that influence behavior. The behavioral inhibition system (BIS) regulates responsiveness to aversive stimuli and is associated with anxiety, whereas the behavioral activation system (BAS) regulates appetitive motivation and is associated with impulsivity. According to the Fowles-Gray theory, primary psychopaths possess an intact BAS and a weak BIS, so they do not experience anticipatory anxiety that causes most people to inhibit activity that leads to punishment or nonreward. In a related sense, David T. Lykken’s primary psychopath is fearless. Without the experience of fear to facilitate learning to avoid conditions associated with pain, the primary psychopath has difficulty with avoidance learning. Rather than fearlessness, Joseph P. Newman’s conceptualization emphasizes a lack of anxiety. Specifically, Newman postulates that a cognitive processing or “response modulation” deficit lies at the core of Cleckleyan psychopathy. These individuals are unable to suspend a dominant response set to accommodate feedback from the environment.

Despite the differences among them, most of these theories describe psychopathy as a largely inherited affective or cognitive processing deficit. These theories dictate a validation hierarchy that places pathophysiologic and etiological mechanisms at the top, as they offer the greatest potential for explaining the disorder and potentially altering its course. Although unmodulated, unrestrained, or self-defeating behavior is symptomatic of the disorder, and may be found at lower levels of the validation hierarchy, there is nothing specific to criminal or violent behavior. Indeed, several theories explicitly omit criminal behavior. The question is whether the diagnostic criteria for psychopathy identify a homogeneous group of individuals with clearly delineated deficits and largely genetic pathophysiology.

Deficits and Etiology

The PCL-R has been most thoroughly evaluated in laboratory experiments as comprising the diagnostic criteria for psychopathy. Although these criteria do appear to identify a group of individuals with theoretically relevant deficits, they could be refined to do this better. On the one hand, PCL-R scores are associated with diminished startle response to negative or aversive emotional cues, less autonomic arousal during fear and distress imagery, and greater recall for the peripheral details of aversive images. On the other hand, the PCL-R omits key features of psychopathy, such as low anxiety. Among offenders with high PCL-R scores, only those who also manifest low anxiety show response modulation deficits on a passive avoidance learning task or reduced sensitivity to cues of punishment when a reward-oriented response set is primed. Moreover, the PCL-R overemphasizes antisocial behavior. When PCL-R scale scores are examined, performance on many of these laboratory measures is more strongly linked with the emotional detachment scale than the antisocial behavior scale. Integrating across studies, the core of psychopathy seems to involve emotional detachment, including low anxiety, not antisocial behavior.

Although one might interpret the results of these experiments as evidence that psychopathy is genetically influenced, caution should be exercised in drawing premature inferences because the heritability of these laboratory variables is unclear. To date, no behavior genetic studies of PCL-R psychopathy have been conducted. Nevertheless, several survey studies indicate that childhood maltreatment is more strongly associated with the PCL-R’s antisocial behavior scale than its emotional detachment scale. In keeping with the experimental data, this suggests that emotional detachment is a more theoretically valid indicator of psychopathy than antisocial behavior.

To date, only one behavior genetic study of psychopathy has been conducted with adults or adolescents. In this twin study of more than 600 17-year-olds drawn from the community, a measure of normal personality was used to estimate scores on a promising self-report measure of psychopathy, the PPI. Although the PPI has “Fearless Dominance” and “Impulsive Antisociality” scales that appear somewhat like the two scales of the PCL-R, the PPI is not saturated with indices of violent and antisocial behavior. The study yielded moderate heritability estimates for both scales (h = .45 to .49). The extent to which these results will generalize to the context in which psychopathy is typically studied (i.e., direct assessment of PCL-R psychopathy with offenders) is unclear.

In summary, the criteria for diagnosing psychopathy can identify individuals with clearly delineated deficits, particularly if they are modified to include low anxiety and deemphasize antisocial behavior. At present, it is unclear whether these deficits are largely genetically determined. However, as shown next, the present criteria clearly do not identify a homogeneous group of individuals as psychopathic.


Although psychopathy usually is treated as a unitary construct, Ben Karpman’s seminal theory posits that there are two variants: primary psychopathy is underpinned by an inherited affective deficit, whereas secondary psychopathy reflects an acquired affective disturbance. Primary psychopathy is consistent with classic conceptualizations of psychopathy as a deficit, whereas secondary psychopathy represents a more psychopathological, hostile, and violent variant.

Although the etiological distinctions between them have not been rigorously investigated, there is evidence that primary and secondary variants of psychopathy can be identified. Despite differences in their methodology, three studies have identified— among offenders with PCL-R scores in the range deemed psychopathic—primary and secondary variants. In the first study, model-based cluster analysis was applied to 96 inmates’ scores on a measure of general personality to identify two groups of psychopaths: one emotionally stable (primary) and the other aggressive (secondary). Although the two groups were difficult to distinguish in their psychopathic traits, secondary psychopaths reported more fights, greater alcohol abuse, lower socialization, and higher trait anxiety than primary psychopaths. In the second study, model-based cluster analysis was applied to 124 inmates’ scores on the PCL-R and a measure of trait anxiety to reveal two groups. Relative to primary psychopaths, secondary psychopaths had greater trait anxiety, fewer psychopathic traits, and comparable levels of antisocial behavior. Across validation variables, secondary psychopaths manifested more borderline personality features, poorer interpersonal functioning (e.g., withdrawal, lack of assertiveness), more symptoms of major mental disorder, and greater treatment responsivity than primary psychopaths. A similar approach was used in the third study of 116 juvenile offenders, which also yielded primary and secondary variants. Secondary variants were more likely than primary variants to endorse early childhood abuse.

These recent findings raise fundamental questions about the nature of psychopathy. Are secondary psychopaths still “psychopaths” if the mechanisms that underpin their traits differ from psychopathy as classically construed? The findings may also have substantial practical implications for risk assessment and risk management. Relative to primary psychopaths, secondary psychopaths theoretically are both more prone to violence and more amenable to treatment. The next generation of research holds promise for addressing these key questions, ideally while distinguishing between the practical enterprise of clinical prediction and the pursuit of understanding the psychopathy construct.


  1. Cleckley, H. (1976). The mask of sanity (5th ed.). St. Louis, MO: Mosby.
  2. Lilienfeld, S. O. (2005). Psychopathic Personality Inventory-Revised (PPI-R). Lutz, FL: Psychological Assessment Resources.
  3. Lykken, D. T. (1995). The antisocial personalities. Hillsdale, NJ: Lawrence Erlbaum.
  4. Patrick, C. J. (2006). Handbook of psychopathy. New York: Guilford Press.
  5. Skeem, J., Poythress, N., Edens, J., Lilienfeld, S., & Cale, E. (2003). Psychopathic personality or personalities? Exploring potential variants of psychopathy and their implications for risk assessment. Aggression & Violent Behavior, 8, 513-546.

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