Keywords

2.1 Introduction and Clinical Description

Clinicians and legal professionals are often familiar with psychopathic individuals, who account for a sizable portion of most incarcerated or forensic populations, and whose characteristic interpersonal, affective, and behavioral features distinguish them from other antisocial individuals. Individuals exhibiting those features now associated consistently with the construct of psychopathy are found throughout psychiatric history, although not always under the “psychopathy” label. For example, texts will often trace the concept to Pinel’s (1806) “manie sans delire”, which was characterized by a tendency towards engaging in impulsive and destructive behavior despite otherwise intact reasoning. Similarly, those same impulsive and antisocial features would have been captured by Kraepelin’s “morbid personalities”, Schneider’s “affectionless” personalities, or Millon’s “aggressive personalities”. The recurrence of callous, impulsive, and antisocial behavior as core features of these conceptualizations would also lay the groundwork for the sometimes-controversial association between what we now consider “psychopathy” and criminality and violence. Such associations would be presaged by Rush’s “innate, preternatural moral depravity” (1812, p.112), or Prichard’s (1835) “moral insanity”. Even the later editions of the Diagnostic and Statistical Manual (DSM) of the American Psychiatric Association (i.e., DSM III, III-R, IV, and 5) folded features typical of the psychopathic individual into their diagnosis for Antisocial Personality Disorder (ASPD), the classification most strongly associated with criminal behavior.

Many key features of psychopathy overlap with the characteristics of ASPD. Nevertheless, researchers have consistently argued that, as a result of distinct patterns in prevalence, etiology, and efficacy of intervention, the two constructs can and should be differentiated (e.g., Crego & Widiger, 2015; Verona et al., 2012). Importantly, although the DSM has historically included criteria for ASPD that are also characteristic of the prototypical psychopath (e.g., guiltlessness, impulsivity), these criteria were not meant to identify this subgroup of antisocial individuals, specifically. As a result, the prevalence of ASPD is higher (roughly 2–3 times greater than psychopathy), suggesting there will be many individuals who meet DSM criteria for ASPD who are not psychopathic (Hare & Neumann, 2008; Ogloff, 2006). Further, as the criteria for ASPD grew more behavioral in nature across DSM editions (e.g., conduct disorderpresent before age 15, repeatedly performing acts that are grounds for arrest), there was an associated increase in the likelihood of excluding some individuals who would be considered psychopathic.

Psychopathy represents as a construct distinct from other antisocial syndromes, associated with different causal models and treatment responses (Hare, 2016; Lykken, 1995; Verona et al., 2012). This chapter will provide an overview of the clinical features of psychopathy, with a primary emphasis on those characteristics highlighted by Cleckley (1941/1988) in his seminal work The Mask of Sanity. It will then review the most commonly used diagnostic instruments, including the PCL-R and its progeny, as well as several well-validated, alternate measures of the construct. Throughout, the chapter will consider some of the key points of contention or controversy relevant to assessment of the syndrome, including the underlying structure and potential heterogeneity of psychopathy.

2.1.1 The Mask of Sanity

Several comprehensive clinical descriptions of the psychopathic individual have been presented throughout history. For example, McCord and McCord (1964) emphasized the characteristics of impulsivity, excitement-seeking, guiltlessness, and “warped capacity for love” in their conceptualization of the psychopath, and referenced historical figures such as “Billy the Kid” as early examples of the prototype. Despite these other presentations, Cleckley’s (1941/1988) work, The Mask of Sanity is considered by most to be the first comprehensive clinical description of the psychopathy syndrome and has often served as the standard against which other conceptualizations are measured. Cleckley’s (1941/1988) intention was to facilitate a more clear understanding of a group of patients who “constitute a most grave and constant problem to the hospital and to the community” (p. xi). To that end, he paid considerable attention not only to describing the key aspects of the psychopathic personality, but also to differentiating the syndrome from other psychopathology. While acknowledging that too little is understood regarding psychopathy, Cleckley (1941/1988) was clear that the syndrome can and should be differentiated from other conditions, including psychosis, psychoneurosis, and “ordinary” criminality. In his book, Cleckley presented a set of detailed case histories from which he derived 16 criteria. Among the 16 criteria (see Table 2.1.), six have consistently and particularly influenced current conceptualizations of the psychopathy syndrome.

Table 2.1 Cleckley (1941/1988) criteria for psychopathy
Full size table

Superficial charm and good intelligence. This feature of psychopathy highlights how the often self-defeating behavior exhibited by the psychopathic individual stems neither from a lack of intelligence nor from an inability to interact effectively with others. As Cleckley noted, “The typical psychopath will seem particularly agreeable and make a distinctly positive impression when he is first encountered... signs of affectation or excessive affability are not characteristic. He looks like the real thing.” (p. 338) This feature may be especially important for modern conceptualizations of the “successful psychopath”, who is more likely to be found in the higher reaches of the boardroom than in a prison (e.g., Boddy et al., 2010).

Lack of remorse or shame. It is notable that the psychopathic individual does not express genuine contrition for the antisocial acts he or she commits. When confronted, the psychopathic individual may be unable to articulate the purpose in feeling such remorse. Cleckley wrote: “Usually he denies emphatically all responsibility and directly accuses others as responsible, but often he will go through an idle ritual of saying that much of his trouble is his own fault.… More detailed questioning about just what he blames himself for and why may show that a serious attitude is not only absent but altogether inconceivable to him” (p. 343). Because “lack of remorse” is a criterion for ASPD, this feature is one that can contribute to the difficulty in differentiating psychopathy from ASPD; although, this becomes less challenging when the presence of other features is considered.

Inadequately motivatedantisocialbehavior. Although there is some debate regarding the centrality of criminal behavior to the conceptualization of psychopathy (see Sect. 2.3.1.3), most assessments of the syndrome will include some measure of antisocial behavior. Importantly, Cleckley allowed for a wide range of behaviors in this category, ranging from minor infractions such as lying and cheating, to more serious, aggressive offenses. For Cleckley, what was important was not the type or severity of the acts, but the psychopath’s tendency to “commit such deeds in the absence of any apparent goal at all” (p. 343). Thus, the “inadequately motivated” was the key piece of this criterion; one that distinguished the behavior of the psychopath from the behavior of other criminals.

Poor judgment and failure to learn by experience. Although characterized by “good intelligence”, the psychopathic individual continues to make self-defeating choices. Further, even when the psychopathic individual can explain “what went wrong” in a particular situation (i.e., what he did that may have resulted in the poor outcome), this understanding does not translate to future situations. Cleckley saw this as a key feature, noting: “One important point that distinguishes the psychopath is his failure to learn and adopt a better and more fulfilling pattern of life” (p. 78).

Incapacity for love. Cleckley noted that, although the psychopathic individual may be “capable of fondness, of likes, of dislikes … these affective reactions are, however, always strictly limited in degree” (p. 348). He wrote of one case example, “As his feelings…were discussed, it remained impossible to detect any sort of affective content to which those words might refer. The more one investigated…the more strictly verbal his statements appeared” (p. 86). Psychopathic individuals, as Maslow (1951) would write “have no love identifications with other human beings and can therefore hurt them or even kill them casually, without hate, and without pleasure” (p. 173).

General poverty in major affective reactions. Consistent with their apparent “incapacity for love”, psychopathic individuals generally do not demonstrate those behaviors or attitudes that would be demonstrative of deep, long-lasting emotional experience. Although the psychopathic individual may express himself in ways that suggest that he is experiencing affective reactions (e.g., a short temper, a declaration of affection), there is no “mature, wholehearted anger, true or consistent indignation, honest, solid grief, sustaining pride, deep joy, and genuine despair” (p. 348). This apparent inability to experience deep emotion or to connect emotionally with others is one of the most central features of the disorder, and an important criterion for distinguishing the psychopath from other antisocial individuals (e.g., Cleckley, 1941/1988; Cooke et al., 2006; Lykken, 1995).

In summary, the psychopathic individual can be identified based on certain interpersonal, affective, and behavioral features that have been depicted and well-described in a number of case studies. These features reflect an individual who does not appear to appreciate the negative impact of their behavior on themselves or others. They also describe an individual who fails to form deep, emotional connections, and who engages in self-defeating, reckless behavior despite normal intelligence. As a result, although psychopathic individuals may never voluntarily seek treatment or assistance, they will often come before clinicians as a consequence of their illegal or harmful behaviors.

2.2 Epidemiology

Although the number and types of psychopathyassessment tools has been growing in the past decades, the Psychopathy Checklist-Revised (PCL-R; Hare, 2003) is generally considered to remain among the most influential tools for the assessment of the syndrome, particularly in forensic settings. The PCL-R is composed of 20 items, which are rated as 0 “not applicable to the individual”, 1 “applicable only to a certain extent”, or 2 “applicable to the individual” on the basis of information collected from both interview and file review (Hare, 2003). Although the PCL-R can be conceptualized as a dimensional instrument (e.g., Walters et al., 2007, 2015), a cut score is often used to classify individuals as psychopathic (Hare, 2003). Historically, a cut score of 30 is recommended (Hare, 2003), although researchers- particularly in Europe- have also employed other cut scores (e.g, 25). Overall, the rate of PCL-R assessed psychopathy in offender populations has been reported between 10% and 15% in forensic psychiatric settings, and 15–50% in non-psychiatric prison populations (Hare, 1991, 2003; Herve et al., 2004; Salekin et al., 1998). Rates appear to differ, however, across gender, racial, and cultural groups.

2.2.1 North American Samples Versus European Samples

Evidence for differences in psychopathyprevalence across regions is difficult to interpret. For example, research does suggest that there is a significant difference between the mean PCL-R scores of incarcerated North American offenders (M = 22.1; SD = 7.9) and those of incarcerated European offenders (M = 17.5; SD = 7.3; Sullivan & Kosson, 2006). However, other studies show that the difference in mean scores between psychiatric samples (i.e., patients or inmates in psychiatric or secure hospitals) across North America and Europe are considerably smaller (i.e., a mean of 21.5 (6.9) in North American samples and 22.5(8.0) in European samples). As a result, it has been suggested that the larger differences observed in incarcerated samples may not reflect differences in levels of the syndrome across nations, but instead result from differences in incarceration base rates (Rasmussen et al., 1999) as well as differences in how mentally disordered offenders are classified and placed within different nations’ legal systems (Hobson & Shine, 1998).

2.2.2 Male Samples Versus Female Samples

There are well-documented differences in the mean scores and rates of psychopathy between male and female offender populations (see Verona & Vitale, 2018, for a review). The majority of studies using PCL-based measures (i.e., PCL-R, PCL-YV, PCL-SV) have found lower rates of psychopathy among femaleoffenders compared to males, with reported prevalence rates for female offender samples as low as 6% (Jackson et al., 2002), and several falling between 11% and 17% (e.g., O’Connor, 2001; Warren et al., 2003). These differences also maintain when other measures of the syndrome are used. For example, in a self-report study examining psychopathy in community samples across nations, Neumann et al. (2012) found that levels of psychopathy assessed using the Self Report Psychopathy Scale (SRP) were generally lower for females than for males across world regions. This finding is consistent with differences in the mean scores for males and females that have been reported in institutionalized, undergraduate, noninstitutionalized, and adolescent samples (see Verona & Vitale, 2018).

2.2.3 African American Samples Versus European American Samples

Early reviews based on a relatively limited number of samples suggested differences in mean PCL-R scores across racial groups. Because African American offenders attained higher scores than European American offenders in these studies (e.g., Cooke et al., 2001; Kosson et al., 1990), these data lead some to conclude that psychopathy rates were elevated in this group (Lynn, 2002). However, this conclusion has been strongly challenged, as there has been an important shift in the interpretation of mean scores and rates of psychopathy among African American offender populations. Most notably, in a meta-analysis of 21 studies (n = 8890), only a small (i.e., an average of less than 1 point)—albeit statistically significant—difference in PCL-R total scores across race was found (Skeem et al., 2004), disputing the argument that levels of psychopathy differ in any clinically meaningful way between African American and European American samples.

In summary, rates of psychopathy tend to be higher in offenderpopulations than in community samples. Further, there is good evidence for differences in the rates of psychopathy across region and gender, although the source of these differences is much less clear. These differences may represent differences in the true base rate of the syndrome. However, there is also evidence to suggest that these rates may instead reflect differences in how individuals are moved through the criminal justicesystem (i.e., whether individuals are incarcerated or hospitalized) and what features of the psychopathy syndrome may be most apparent in these populations (i.e., the likelihood of aggressive behavior).

2.3 Assessment of Psychopathy

Although Cleckley’s criteria and case descriptions provided some guidance on how to identify the psychopathic individual, they did not represent a systematic, reliable assessment tool. Following the development of the “Cleckley criteria”, clinicians relied primarily on either case-based “psychopathyprototype” assessments (e.g., Hare et al., 1978) or the use of self-report measures believed to capture the personality traits associated with the syndrome, such as the Socialization (So) subscale of the California Personality Inventory and the Psychopathic Deviate (Pd) scale of the MMPI. However, these methods were limited in diagnostic reliability. In addition, a lack of diagnostic uniformity made it difficult to generalize findings across studies. There was clearly a need for a reliable, widely accepted assessment of psychopathy. That need led to the development of the Psychopathy Checklist and its progeny (i.e., the PCL-R, the Psychopathy Checklist: Screening Version, and the Psychopathy Checklist: Youth Version), which eventually emerged as the most influential diagnostic tool and the standard against which other psychopathyassessment instruments were typically measured (DeMatteo et al., 2014; Fulero, 1995; Hare, 2016).

2.3.1 The PCL and Related Measures

Using Cleckley’s criteria as a standard, Hare first developed the Research Scale for the Assessment of Psychopathy in 1980 (Psychopathy Checklist; Hare, 1980). This early version of the PCL was a 22-item measure that was scored on the basis of a semi-structured interview and review of institutional files. A revised version of the checklist (i.e., PCL-R) that removed two of the original scale items was released in 1991 and the scale has remained unchanged since then (Hare, 1991, 2003). As described in Sect. 2.2, each item on the 20-item checklist is scored using interview and file review as 0, 1, or 2. Items tap the interpersonal (e.g., “superficial charm”), affective (e.g., “lack of remorse or guilt”), and impulsive/antisocial lifestyle (e.g., “irresponsibility, “juvenile delinquency”) features of the syndrome. Scores range from 0 to 40 and although there is taxonometric evidence suggesting the scale indexes a continuous construct (e.g., Walters et al., 2007, 2015), a diagnostic cut-off of 30 is often used in North American, male samples.

The PCL-R rose quickly to prominence, giving researchers both a reliable diagnostic tool, as well as a common vocabulary for describing psychopathy and for comparing results across studies. Not surprisingly, given its wide influence, criticisms have emerged that have challenged the outsized influence of the PCL-R in the field. Questions have arisen surrounding the factor structure of the PCL-R and the components of psychopathy (e.g., Bishopp & Hare, 2008; Cooke et al., 2006), the utility of an assessment tool that requires considerable collateral evidence to rate and score (e.g., Skeem et al., 2011), and the generalizability of the PCL-R across populations (e.g., Cooke & Michie, 1999; Kosson et al., 1990; Verona & Vitale, 2018).

2.3.1.1 The Structure of the PCL-R

On the basis of initial Exploratory Factor Analysis of the PCL-R, early studies seemed to support a correlated, two-factor structure (Harpur et al., 1988) of the instrument. Factor 1 was labeled the “affective/interpersonal factor”, and included items representing many of the deficient emotional and interpersonally manipulative characteristics of the syndrome (e.g., glib/superficial charm, manipulative, callous, shallow affect). Factor 2 included items capturing the psychopathic individual’s antisocial and criminal behavior (e.g., poor behavioral controls, impulsivity, early behavior problems), and became known as the social deviance or “impulsive/antisocial lifestyle” factor. Hare and colleagues (e.g., Hare, 2003, 2016; Neumann et al., 2007) have proposed that psychopathy is best conceptualized as a unidimensional construct. However, research has revealed that there are unique correlates of Factors 1 and 2 (Dolan & Anderson, 2003; Salekin et al., 2004), suggesting that the true relationship between psychopathy and other variables may be obscured if these differential associations are not taken into account.

In one of the first challenges to the two-factor conceptualization of psychopathy, Cooke et al. (2006) argued for a three-factor model that included an “Interpersonal” Factor 1, an “Affective” Factor 2, and a “Lifestyle” Factor 3. The first two factors essentially divided the original Factor 1 into two component parts (i.e., interpersonal and affective). However, this three-factor solution, although a significantly better fit to existing data than the traditional two-factor model (Cooke et al., 2004) also excluded 7 PCL-R items, limiting its relevance to the full PCL-R.

Both the original two-factor model and Cooke’s proposed three-factor structure have since been superseded by a widely-accepted four-facet structure that can be used to model the higher-order two-factor structure (Hare, 2016; Hare & Neumann, 2008; Neumann et al., 2007). These facets are the “interpersonal” facet (including the items glib/superficial charm, grandiose sense of self-worth, pathological deception, conning/manipulative), the “affective” facet (including the items lack of remorse or guilt, shallow affect, callous/lack of empathy, failure to accept responsibility), the “lifestyle” facet (including the items need for stimulation/proneness to boredom, parasitic lifestyle, lack of realistic long-term goals, impulsivity, irresponsibility), and the “antisocial” facet (including the items poor behavioral controls, early behavior problems, juvenile delinquency, revocation of conditional release, criminal versatility).

It is important to note that the debate surrounding the factor structure of the PCL-R is not just relevant for researchers particularly interested in measurement theory. Rather, the debate has important implications for the field’s conceptualization of the psychopathy construct. One implication is the potential heterogeneity of psychopathy, which may be important for understanding differences in psychopathic individuals’ behaviors and responses to treatment. The second is the question of the centrality of criminal and/or violent behavior to our understanding of psychopathy and our prototype of the psychopathic individual.

2.3.1.2 Factors, Facets, and Psychopathy “Subtypes”

As already noted, research reveals differential relationships between the Factors/Facets of the PCL-R and important variables. For example, in their study of sexual offender treatment outcomes, Sewall and Olver (2019) found that the affective facet, specifically, was associated with lower levels of therapeutic progress, whereas the affective and lifestyle facets together predicted treatment noncompletion. In another study, an examination of abuse history showed that whereas sexual abuse history was associated with the interpersonal and lifestyle facets, a history of physical abuse was related to the lifestyle and antisocial facets (Krstic et al., 2016). Factor and facet differences have also been observed in event-related potential (ERP) studies (Anderson et al., 2015; Steele et al., 2016; Venables et al., 2015; Veit et al., 2013), as well as in executive functioning as assessed by performance on the Wisconsin Card Sort (Pera-Guardiola et al., 2016).

Given findings such as these, researchers have noted the utility of considering subtypes of psychopathy (see Hicks & Drislane, 2018; Poythress & Skeem, 2006, for reviews). Most prominent among these has historically been the distinction between “primary” and “secondary” psychopathy. Typically, the primary psychopathy type is characterized by deficits in affective responses, whereas the secondary psychopath will evidence anxiety, depression, and negative emotionality (Dargis & Koenigs, 2018; Karpman, 1948; Lykken, 1995; Newman et al., 2005). Consistent with this distinction, studies using the PCL-R, as well as other psychopathy measures, have identified important differences between these types. For example, compared to the primary psychopathy subgroup, the secondary psychopathy type has been associated with the presence of fewer adaptive traits (i.e., leadership, focus; Bronchain et al., 2020), more self-injury behaviors and thoughts (Fadoir et al., 2019), higher rates of childhood maltreatment (e.g., Dargis & Koenigs, 2018), and lower rates of treatment non-completion (Klein Haneveld et al., 2018).

Despite this evidence for the existence of unique correlates of the Factors/Facets, as well as the increasing interest in distinguishing subgroups of psychopathic individuals, some researchers caution against perceiving any one component of the syndrome to be held superior over the others (e.g., Hare, 2003; Neumann et al., 2007). Rather, these individuals argue that PCL-Rpsychopathy is best conceptualized as a whole and that this “‘whole’ may be greater than the sum of the ‘parts’” (Neumann et al., 2007). Nevertheless, there does appear to be increasing evidence that a failure to examine associations at the factor/facet level or to consider the heterogeneity of the construct may lead to incomplete understanding of psychopathy’s relation to other variables.

2.3.1.3 Criminal Behavior and the PCL-R

The PCL-R was designed for use within institutionalized populations, as evidenced by its inclusion of items directly assessing criminality (e.g., “revocation of conditional release”, “criminal versatility”) as well as the reliance on extensive collateral information. Not surprisingly, scores on the measure are consistently associated with criminal behavior and predict general, violent, and sexual reoffending (Hare, 1996; Hemphill et al., 1998). As a result, the instrument is commonly used for risk assessment, management, and monitoring, particularly in North America. Although these associations have led to an increased use of PCL-R within forensic contexts (Fulero, 1995; Hare, 1998; Hurducas et al., 2014; Neal & Grisso, 2014), they have also been a source of criticism from those who challenge the importance of criminal behavior—and especially violent criminal behavior—as a core feature of psychopathy (e.g., Cooke et al., 2006; Lilienfeld, 1994; Skeem & Cooke, 2010; Skeem et al., 2011).

Although Cleckley (1941/1988) included “inadequately motivated antisocial behavior” among his original criteria, he did not present violent criminal behavior as a necessary component of the syndrome. Rather, he argued that “many persons showing the characteristics of those described here do commit major crimes and sometimes crimes of maximal violence. There are so many, however, who do not, that such tendencies should be regarded as the exception rather than as the rule” (Cleckley, 1941/1988, p. 262). Consistent with Cleckley’s conceptualization, it is noteworthy that among the 7 PCL-R items that were omitted from Cooke et al.’s (2006) three-factor model of the PCL-R were those items specific to criminal or violent behavior.

While the ascendance of the PCL-R and the subsequent factor debates brought this issue to the forefront, the tension between conceptualizations of psychopathy and the role of violence precedes the development of the measure. For example, Lewis (1974) criticized what he called “a preoccupation with the nosological status of the concept … its forensic implications, its subdivisions, limits, [and] the propriety of identifying psychopathic personality with antisocial behavior…” (pp. 137–138). Similarly, Millon (1981) noted: “50 years ago the same issues were in the forefront, notably whether the psychopathic personality was or was not synonymous with overt antisocial behavior” (p. 184).

Researchers have turned to a variety of methods to address their concerns regarding the role of criminality in PCL-Rpsychopathy. As noted earlier, one solution has been to examine separately the contributions of the interpersonal and affective factor/facets and the antisocial/lifestyle factor/facets when studying the syndrome (e.g., Hansen et al., 2007; Patrick et al., 1993; Vaidyanathan et al., 2011). Another approach has been for researchers to develop alternative measures of psychopathy that are not as reliant as the PCL-R on either criminal behavior or corroborating evidence for the rating and scoring of individuals (e.g., Brislin et al., 2015; Lilienfeld & Andrews, 1996). Determining what features are considered “core” to psychopathy is necessary not only for guiding the refinement or development of assessment measures, but also for informing our examinations of these measures across populations. As a result, this debate is directly relevant to the next criticism of the PCL-R, which involves the generalizability of PCL-Rpsychopathyassessment across groups.

2.3.1.4 Generalizability Across Groups

Given the PCL-R’s use in applied clinical and forensic settings, the generalizability of the measure across samples is a highly relevant consideration (e.g., Cooke & Michie, 1999; Kosson et al., 1990; Sullivan et al., 2006; Verona & Vitale, 2018). Much of the early research using the PCL-R was limited to samples of incarcerated, European American males in the US and Canada. Although differences in the expression of psychopathy across gender, cultural, and racial groups would have important implications for the use of the PCL-R in applied settings, there was for many years only limited research on the generalizability of the construct across populations. Fortunately, there was a marked increase in research in these areas in at the turn of the century, with numerous studies focused on the expression and correlates of psychopathy in other groups, particularly femaleoffenders and African-American offenders (see Beryl et al., 2014; Sullivan & Kosson, 2006; Verona & Vitale, 2018 for reviews). However, the results of this research have not always been clear-cut. For example, although evidence supports the reliability of psychopathy assessments among female populations (e.g., Miller et al., 2011a, b; Salekin et al., 1997; Vitale et al., 2002) and across racial and cultural groups (e.g., Vachon et al., 2012), the evidence for the generalizability of behavioral and etiological-relevant correlates of psychopathy is less consistent.

Several key deficits in emotion-related responding have not been demonstrated among African American offenders (e.g., Baskin-Sommers et al., 2011; Lorenz & Newman, 2002; Newman et al., 1997) nor among femaleoffenders (e.g., Anton et al., 2012; Vitale et al., 2011). Similarly, abnormalities in response perseveration and passive avoidance learning that have been reliably demonstrated among psychopathic males have not been reported among psychopathic females (e.g., Vitale et al., 2011). Differences across gender have also been found in laboratory-based assessments of adolescents with high levels of psychopathy traits (e.g., Isen et al., 2010; Vitale et al., 2005; Wang et al., 2012).

Even the well-established associations between PCL-Rpsychopathy and criminal behavior may be limited across samples. For example, Walsh (2013) showed that in a sample of 424 adult male jail inmates, PCL-R scores were a better predictor of violence among European American offenders than among either African American or Latino offenders. Similarly, Edens et al. (2007) reported meta-analytic results suggesting that within ethnically diverse juvenile samples, psychopathy was a weaker correlate of violentrecidivism than within primarily European American samples. Finally, some research provides evidence that psychopathy may be a less powerful predictor of recidivism in incarcerated female samples (Weizmann-Henelius et al., 2015). Notably, other research identifying genderdifferences when using other alternative measures of psychopathy (e.g., Eichenbaum et al., 2019) suggest that these concerns might not be specific to PCL-Rpsychopathy, but may reflect more general limitations in how the psychopathy construct is conceptualized and assessed across groups.

Ideally, these inconsistencies would raise questions about the source of these differences. Is the PCL-R identifying a slightly different syndrome across different groups? Are certain items/facets disproportionately affecting total scores across groups? Some researchers have investigated these differences. For example, Neumann et al. (2012) conducted a large-scale (n = 33,016; 58% female/42% male) self-report psychopathy study across gender and world regions, and found that, in their female sample, Gross Domestic Product per capita (GDPpc) was negatively correlated with the expression of the interpersonal/affective psychopathy traits, suggesting an association between GDPpc and the expression of core psychopathy features. In a different study, Walsh and Kosson (2007) found that Socioeconomic Status (SES) moderated the relationship between psychopathy and crime differently across race, with a significant SES x psychopathyinteraction on recidivism emerging among European American but not African American participants. Taken together, these findings highlight the possibility that the expression of psychopathy may be influenced by macro-level environmental factors such as SES and GDP.

In summary, it is clear that PCL-R assessed psychopathy is an influential construct in the field and particularly within institutional and forensic settings. In the past decades, the assessment landscape has changed, however. Although still at the forefront of psychopathyassessment, there are some debates surrounding the PCL-R’s dominance. These debates include the role of criminal behavior and violence in the conceptualization of the syndrome and limitations of the generalizability of the construct across populations.

The desire of the field to generalize psychopathy findings to alternate samples leads directly to the final challenge to the PCL-R, which is the inability to use the measure to assess psychopathy in noninstitutionalized populations. As a result of this limitation, as well as the concerns surrounding the instrument’s reliance on overt criminal behavior, there is a strong emphasis in the field on the continued development and validation of alternate or self-report measures that focus on psychopathy specifically (as opposed to more general personality traits) and that can be used with noninstitutionalized populations. In the next section, an overview of several of these measures is provided.

2.3.2 Other Measures of Psychopathy

Alternative measures of psychopathy have primarily been developed along two paths. The first path includes measures meant to be used with noninstitutionalized adults. These measures are designed to circumvent the necessity of a lengthy clinical interview and/or the use of extensive, corroborating file information. The second path includes measures that have been developed for use among adolescent populations. These measures are meant to capture the syndrome as it might appear prior to adulthood and place less emphasis on characteristics unlikely to be seen in adolescent samples (e.g., engaging in short-term marital relationships).

2.3.2.1 Self-Report and Other Alternative Measures

Along the first path, two measures that were developed as alternatives to the PCL-R are direct descendants of the original measure. These are the PCL: Screening Version (PCL:SV; Forth et al., 1996), designed to be less reliant on long interviews and extensive files review, and the Self-Report Psychopathy scale (SRP-II, -III; Williams & Paulhus, 2004), designed to provide a pen-and-pencil self-report assessment of the syndrome. The PCL: SV (Forth et al., 1996) was an early variation of the PCL-R, created to assess psychopathy using less information and without formal criminal records. Generally, research suggests that the PCL: SV captures a syndrome similar to the PCL-R. The two measures are highly correlated (with an average correlation of.8) (Cooke et al., 1999) and the PCL: SV exhibits a factor structure and item functioning similar to the PCL-R (Hill et al., 2004). Consistent with its close association to the original PCL-R, the PCL: SV is a good predictor of violent behavior (e.g., Douglas et al., 1999; Skeem & Mulvey, 2001). The Self-Report Psychopathy scale (SRP, SRP-II, SRP-III) was developed by Hare and colleagues (e.g., Hare et al., 1989; Williams et al., 2007) as a self-report measure of the syndrome in adult samples. The SRP-II and SRP-III are reliable (Neal & Sellbom, 2012) and relate in expected ways with correlates of the psychopathy syndrome, including scores on the PCL-R as well as measures of alcohol abuse, narcissism, empathy, Machiavellianism, agreeableness, and conscientiousness (e.g., Paulhus & Williams, 2002; Tew et al., 2015; Zagon & Jackson, 1994; Watt & Brooks, 2012).

Other researchers, wanting to emphasize theoretical conceptualizations of psychopathy distinct from the PCL-R have developed other, independent, measures of the syndrome. These measures were developed on the basis of those traits believed to be central to psychopathy, with less emphasis on the numbers or types of disinhibited behaviors or criminal acts committed by the individual. These have included the Primary and Secondary Psychopathy Scales (SRPS; Levenson et al., 1995), the Psychopathic Personality Inventory (PPI; Lilienfeld & Andrews, 1996), the Triarchic Psychopathy Measure (TriPM; Patrick, 2010), and the Comprehensive Assessment of Psychopathic Personality (CAPP; Kreis et al., 2012).

The SRPS is a 26-item self-report measure developed by Levenson et al. (1995) that has two components: the “primary scale” and the “secondary” scale. Scores on the primary scale are positively correlated with disinhibition and boredom susceptibility and negatively correlated with harm avoidance. Scores on the secondary scale are associated with stress reactions. Scores on the SRPS are correlated with PCL-R scores, substance use, criminal versatility, self-reported delinquency, low-agreeableness, and passive avoidance task performance (Brinkley et al., 2001; Lynam et al., 1999; Sellbom, 2011). More recently, scores on the SRPS have been related to abnormalities in ERP responses in a startle paradigm (De Pacalis et al., 2019) consistent with theories of psychopathy,

The PPI (Lilienfeld & Andrews, 1996) is a 187-item self-report measure with 8 subscales, including Machiavellian Egocentricity, Coldheartedness, Social Potency, Carefree Nonplanfulness, Fearlessness, Impulsive Nonconformity, Blame Externalization, and Stress Immunity. Research shows that the PPI correlates with PCL-R total scores (Poythress et al., 1998), and also with adult and childhood antisocial behavior and institutional misconduct (Edens et al., 2008a, b), measures of emotional empathy (Sandoval et al., 2000), and self-report aggression and dominance (Edens et al., 2001). The PPI has also been associated with abnormalities in affective startle responses (Anderson et al., 2011), in behavioral and neurological responses to incentives (Bjork et al., 2012), and in visual-spatial attention processes (Carolan et al., 2020).

The TriPM is based on the Triarchic Personality Model of Psychopathy (Patrick et al., 2009; Brislin et al., 2015), which places the three traits of meanness, disinhibition, and boldness at the core of the syndrome. Research has consistently shown expected associations with psychopathy-relevant variables. For example, research utilizing the triarchic conceptualization of psychopathy has shown expected correlations with other measures of psychopathy, antisocialbehavior, and self-reported empathy (Sellbom et al., 2015a, b), structural differences in the amygdala (Vieira et al., 2015), deficits in emotion responses (Somma et al., 2015), and behavioral dysregulation (Ribes-Guardiola et al., 2020). However, there is some debate regarding the factor structure of the instrument (e.g., Collison et al., 2016; Roy et al., 2020), as well as the relative importance of all three factors (e.g., Hanniball et al., 2019; Sleep et al., 2019; Shou et al., 2018).

Just as the TriPM was developed to reflect a theoretical model of psychopathy centered around three neurobiologically-based traits, the Comprehensive Assessment of Psychopathic Personality (CAPP; Cooke et al., 2004; Hoff et al., 2012) is a conceptual model of the syndrome built through reference to the clinical and empirical literature. The CAPP includes 33 symptoms that are collected under six domains: Attachment (e.g., detached, unempathic), Behavioral (e.g., reckless, aggressive), Cognitive (e.g., suspicious, intolerant), Dominance (e.g., manipulative, garrulous), Self (e.g., self-justifying, self-aggrandizing), and Emotional (e.g., lacks remorse, lacks emotional depth). A growing body of research supports the utility of the CAPP model, which has been shown to translate across languages (Hoff et al., 2014), to intercorrelate with the PCL-R (Sandvik et al., 2012), and to relate in expected ways to criminal recidivism (Pedersen et al., 2010).

Early tests of the model utilized the CAPP- Institutional Rating Scale (CAPP-IRS; Cooke et al., 2004, 2012). However, the CAPP-IRS was developed for use in institutionalized settings, and its reliance on clinical interviews and extensive file reviews made it both time-intensive and impractical for application to noninstitutionalized populations. As a result, both the CAPP-Self Report (CAPP-SR; Sellbom et al., 2019) and the CAPP Lexical Rating Scale (LRS; Sellbom et al., 2015a, b; Kavish et al., 2020) have been more recently developed. Early results from research with both instruments provide evidence that these measures are reliable and valid assessments of the CAPP model and lay the groundwork for future research in this area.

Consistent with both the TriPM and CAPP models’ emphasis on psychopathic traits, other researchers have developed alternative psychopathy conceptualizations rooted strongly in personality theory. For example, Lynam and colleagues (e.g., Lynam & Derefinko, 2006; Miller & Lynam, 2015) have argued that psychopathy is best conceptualized according to the traditional Five-Factor Model (FFM) of personality, and that psychopathy is easily captured by the traits and facets of personality measures like the NEO-PI-R. Proponents of this approach note that conceptualizing psychopathy in accordance with existing personality traits places the syndrome within the context of well-validated personality theory that is already strongly connected to research in diverse areas, including genetics, development, and neurobiology (Lynam & Derefinko, 2006; Widiger et al., 2012; Widiger & Trull, 2007).

In regards to measurement, Widiger and Lynam (1998) suggested that each item of the PCL-R could be represented by facets within the FFM. Miller et al. (2001) tested this proposal by asking psychopathy experts to generate an FFM profile of the prototypical psychopath on the basis of their understanding and knowledge of the syndrome. Importantly, the profile generated by these experts was similar to that generated by the theorists, which held, for example, that “glibness/superficial charm” would represented by low self-consciousness, and “shallow affect” by low warmth, low positive emotionality, low altruism, and low tender-mindedness.

On the basis of this early work, Lynam and colleagues (Lynam & Widiger, 2001; Miller & Lynam, 2003) went on to calculate the Psychopathy Resemblance Index (PRI), which was a measure of the extent to which an individual resembles the FFM prototype. Research showed that these scores were associated with an earlier age of onset of delinquency, greater criminal versatility, earlier drug use, higher rates of substance abuse, risky sexual behavior, and low internalizing problems (Miller et al., 2001; Miller & Lynam, 2003). Scores were also predictive of performance on psychopathy-related laboratory tasks (i.e., the use of aggressive responses on a social-information task, and less willingness to delay gratification on a time-discounting task) (Miller & Lynam, 2003).

To provide a measure based on the FFM but specific to psychopathy, Lynam et al. (2011) have developed the Elemental Psychopathy Assessment (EPA), which has both short and long forms. The long-form of the scale assesses the 18 traits that have been consistently associated with psychopathy, and which comprise four factors: Antagonism, Emotional Stability, Disinhibition, and Narcissism. In forensic, undergraduate, and community samples, scores on the EPA have correlated with existing psychopathy measures (i.e., SRP-III, PPI-R), as well as with aggressive social cognitions, antisocial personality features, romantic infidelity, alcohol use, and antisocial behavior (Collison et al., 2016; Lynam et al., 2011; Miller et al., 2011a, b; Miller et al., 2014; Wilson et al., 2011).

2.3.2.2 Measures for Use with Juvenile Samples

Developing separately from those measures meant to assess psychopathy in noninstitutionalized populations were measures designed to assess the construct among juvenile samples. Interest in reliable and valid assessments of the syndrome in these samples has only heightened in light of evidence for stability in psychopathic traits across childhood and adolescence (Hawes et al., 2018; Hemphälä et al., 2015; Lopez-Romero et al., 2014). A measure derived from the PCL is among those that have been established for use with adolescents. However, as in adult samples, other measures developed separately from the PCL have also grown in prominence.

The PCL: YV (Forth et al., 2003) is a modified version of the PCL-R that can be used with adolescents ages 12–18 (Forth et al., 2003). Research has demonstrated reliability of the measure in both male and female samples (e.g., Bauer et al., 2011), although there is some evidence for differential item functioning across gender (Tsang et al., 2015) and ethnicity (Tsang et al., 2014). Importantly, the measure also relates to criterion variables in ways that are consistent with PCL-R research with adults. For example, relative to adolescents with low scores, adolescents with high scores on the instrument commit more and more violent crimes and show lower levels of familial attachment (Kosson et al., 2002).

The PCL: YV, like the PCL-R, requires a lengthy interview procedure and is best utilized in institutional settings. As a result, more easily administered measures of psychopathy for juveniles have been developed. Primary among these has been the Antisocial Process Screening Device (APSD; Frick & Hare, 2001), a 20-item rating scale that can be used as a self-report measure or as a teacher and parent report measure. The ASPD has been widely utilized, and research has shown that scores on the measure are reliably associated with many of the personality traits and laboratory deficits exhibited by psychopathic adults. For example, high scores on the APSD delineate a group of individuals who exhibit higher rates of conduct problems and police contacts, and stronger family histories of antisocial behavior than groups characterized by lower scores (Christian et al., 1997; Fung et al., 2010; Munoz & Frick, 2007; Pechorro et al., 2014). Higher scores on the APSD are also associated with decreased empathy, perspective taking, and fearfulness (Blair et al., 2001).

The ASPD captures the interpersonal (e.g., superficial charm, lack of empathy), emotional (e.g., shallow affect), and behavioral (e.g., reckless antisocial behaviors, impulsivity) characteristics of psychopathy. Over time, particular interest has emerged in the callous/unemotional (CU) traits assessed by the measure, which may serve to distinguish those adolescents who are most closely similar to our conceptualization of an adult psychopathic individual. For example, laboratory studies have demonstrated that adolescents characterized by high scores on the CU traits exhibit abnormal neural responses (e.g., Sebastian et al., 2012), performance deficits on a task requiring them to modify an initial reward-oriented response strategy in light of increasing rates of punishment (e.g., O’Brien & Frick, 1996), reduced interference on a Picture-Word Stroop, and deficits in passive avoidance on a go-no-go task (Vitale et al., 2005)—all deficits associated with psychopathy in adults.

The Youth Psychopathic Traits Inventory (YPI and YPI-Short Form; Andershed et al., 2002) and YPI–Child Version (YPI-CV) are alternatives to the ASPD. The YPI has been shown to be moderately correlated with factors of the PCL: YV (Andershed et al., 2007), and other self-report measures of psychopathy (Cambell et al., 2009; Gillen et al., 2019). Further, the measure has been associated with key correlates of psychopathy, including conduct problems and proactive aggression (Leenarts et al., 2017; Rucevic, 2010; van Baardewijk et al., 2011), as well as self-reported antisocial attitudes and impulsivity (Campbell et al., 2009; Eisenbarth & Centifanti, 2020). However, results are mixed. Some studies have not found expected associations with criminal behavior or substance use (Colins et al., 2015; Shepherd & Strand, 2015) and others have provided only weak evidence that the measure captures key personality features of psychopathy (i.e., callous-unemotional traits) (Oshukova et al., 2015).

In summary, there is evidence that measures such as the PCL: YV, the ASPD, and—potentially—the YPI, capture a syndrome among adolescents that is similar to adultpsychopathy. Further, assessments of juvenile psychopathy appear to be relatively stable across adolescence (e.g., Lynam et al., 2009; Neumann et al., 2011). That does not mean that the field is without controversy, however. For example, it is not apparent that psychopathyassessments in adolescents have the same utility in forensic contexts as assessments made for adults (Cauffman et al., 2009), suggesting that caution is required when these assessments are made in certain applied settings. Consistent with this caution, given the historic association between psychopathy and increased dangerousness and poor treatment response (e.g., Edens, 2006; Lykken, 1995), some critics have also argued that the psychopathy label may result in decreased attention to intervention and treatment for youth with this classification.

2.4 Conclusions and Recommendations

Psychopathy is a recognizable syndrome that is associated with significant negative effects for both the psychopathic individual, whose callous, irresponsible, manipulative, and sometimes aggressive behavior often results in punitive consequences, as well as for those persons who become their unwitting victims. The need to understand psychopathy derives from the desire to control better the behavior of these individuals in order to lessen the occurrence of harmful behaviors and their consequences. Despite a rich clinical history, psychopathy remains a somewhat controversial classification. Distinct from those disorders included in the various editions of the Diagnostic and Statistical Manual of the American Psychiatric Association (e.g., DSM-5; APA, 2013), psychopathy has been captured via numerous methodologies, from relatively subjective diagnoses based on clinical impressions to highly structured diagnostic rating scales. The emergence of the PCL-R in the early 1990’s brought a new focus to psychopathyassessment, as the field rapidly adopted the instrument for use in both research and clinical/forensic contexts.

However, dissatisfaction with the limits of the PCL-R include concerns about its generalizability across diverse samples, the inability to apply it easily to noninstitutionalized populations, and more fundamental disputes over the nature of the psychopathy construct as assessed by the measure. These issues have resulted in a more varied assessment landscape in recent years. Measures built on theoretical models such as the TriPM and the CAPP-SR, instruments geared towards assessing the construct in adolescents including the APSD and YPI, and approaches rooted in general personality theory especially as reflected in the EPA, are all increasingly represented in the literature. This growing diversity in assessment tools brings its own challenges, however.

As researchers continue to pursue alternative methods of psychopathyassessment, it will be important to determine the extent to which these different instruments capture a similar construct. When the measures do diverge, it is important to clarify which components or characteristics of psychopathy are represented, and which aspects of the syndrome are not. In the absence of this clarity, the shared vocabulary the field has benefited from in recent decades will be diminished. Research should also continue to focus on the generalizability of results using these different measures across populations, and to try to determine, when differences do arise, whether they represent differences in the application or performance of the measure, differences in the composition of the samples, or fundamental differences in the expression of the psychopathy syndrome. Ideally, researchers would employ more than one psychopathyassessment measure in their studies, which would better enable direct comparisons across instruments. The importance of and interest in the psychopathy construct is unlikely to diminish in the near future. Developing, validating, and clarifying the limitations of measures of the construct will continue to be a necessary undertaking, as these tools will serve as the foundation on which all studies of the causes, consequences, and treatments for psychopathy will be built.