In addition to the abovementioned concerns that are more broadly related to the assessment of psychopathy, there are also specific concerns about the manner in which criminologists have approached the use of psychopathy to explain involvement in offending. If psychopathy is to become an important construct for developmental criminology, it is critical to avoid these past errors. The effectiveness of psychopathy in contributing to explanations of offending trajectories is dependent upon the extent to which the construct can be captured within different samples and by different measurement tools. In this section data from the Incarcerated Serious and Violent Young Offender Study (ISVYOS) are used to help demonstrate concerns with (a) the manner in which prior empirical studies have measured psychopathy and (b) the types of populations sampled from to obtain data on psychopathy.
Beginning with Farrington’s (2005) advocating for greater efforts to integrate psychopathy into explanations of offending, criminologists have been rather productive. No longer is psychopathy research specific to the field of forensic psychology. Through
these greater efforts there are some directions for moving criminologists’ contribution to psychopathy research forward. It is perhaps due to the enthusiasm to address Farrington’s (2005) recommendations that criminologists have focused less on psychopathy as a construct and more on ways to include measures of ‘psychopathy’ in statistical models. It is also possible that due to this enthusiasm, instead of creating new studies developed with the specific intention of measuring psychopathy, many researchers looked for expedient ways to measure psychopathy within existing criminology-based studies10. This
approach has resulted in critical limitations of the current body of research on psychopathy and offending produced by the field of criminology. These limitations include: (1) conclusions about the predictive validity of psychopathy without the use of appropriately validated measures of the construct and (2) conclusions about the predictive validity of psychopathy made with an almost sole reliance on self-report measures.
Measurement Issues
There is a lengthy process involved in validating a measure of psychopathy within the field of forensic psychology. Twenty years after the development of the PCL-R and its derivatives, the PCL:SV and PCL:YV, debate continues regarding the number of factors that best describe the instrument (e.g., Cooke & Michie, 2001; Cooke, Michie, Hart, & Clark, 2004; Cooke, Michie, & Skeem, 2007; Hare & Neumann, 2005; Harpur, Hare, & Hakstian, 1989; Vitacco, Neumann, Caldwell, Leistico, & van Rybroek, 2006), whether antisocial behavior should be included as one of these factors (e.g., Hare & Neumann, 2010; Skeem & Cooke, 2010), whether the full range of interpersonal and affective symptoms of psychopathy are captured by this instrument (e.g., Cooke et al., 2004; Dawson et al., 2012; Sandvik et al., 2012), and whether the psychopathy construct is most appropriately described as dimensional or categorical (Murrie et al., 2007). These efforts have not been matched by researchers examining psychopathy within the field of criminology, and the absence of studies within criminology designed specifically to measure psychopathy have likely contributed to the lack of emphasis on construct measurement. Of specific concern is that, in some studies, psychopathy has been measured ex post facto, where items from pre-existing instruments designed to measure
10 The term ‘criminology based’ refers to studies published in criminology-oriented journals or by
individuals trained in criminology rather than psychology. For an exception to this chapter’s critique of such studies, see research published from the Pathways to Desistance Study.
other constructs are selected to measure psychopathy because of their resemblance to items from existing measures of psychopathy. In such studies, rather than examine factor structure via confirmatory factor analyses and other analytic strategies typically used to assess the validity of measures (e.g., Cooke & Michie, 2001), criminological studies simply assumed measurement was accurate on the basis of Cronbach’s alpha values. Moreover, concurrent, convergent, and discriminant validity assessments critical to the development of measures such as the PCL:YV were missing from criminological studies.
Another measurement concern is criminology’s almost sole adherence to the use of self-report measures, which do have some advantages, but also a large number of reliability and validity concerns (Hart & Cook, 2012; Lilienfeld & Fowler, 2006). Reliability concerns are largely an issue of method-mode mismatch. For example, given that persistent lying is considered an important symptom of psychopathy (Cleckley, 1976), the risk of inaccuracy within self-report instruments may be highest among the types of individuals whom researchers are most interested in understanding. Even if an instrument includes a measure of social desirability bias, such scales are not designed to capture subtle forms of manipulation that are most likely to be found among individuals with symptoms of psychopathy (Lilienfeld & Fowler, 2006). As further evidence of the method- mode mismatch, self-report instruments are typically completed well within an hour and therefore risk being influenced by the subject’s mood state. On the other hand, expert rating scales typically involve multiple interviews with the subject and incorporate file- based information to cover a broader range of the subject’s personality over their life course (Dawson et al., 2012).
Research Design Issues
Although the expediency of self-report instruments is often viewed as a strength (e.g., Lilienfeld & Fowler, 2006), there is a trade-off between economy and accuracy. Expert rating scales rely on file reviews and interviews with the subject (e.g., the PCL instruments) and allow for the measurement of inter-rater reliability to assess whether the construct is being measured accurately. The latter evaluation method is especially likely to be more accurate due to the inclusion of both subject and collateral informant information. Collateral information is particularly important because those with symptoms of psychopathy typically show a more serious lack of insight compared to non-
psychopaths (Lilienfeld & Fowler, 2006). Unlike self-report instruments that require respondents to answer a specific set of questions within a specific response format, expert rating scales are based on semi-structured interviews that allow the interviewer to re- phrase questions that the offender may have misunderstood or avoided answering directly. The ability to clarify answers is particularly important because the semantic aphasia often associated with individuals with psychopathy implies that they are more likely to misunderstand questions addressing affective deficits (Lilienfeld & Fowler, 2006).
Similar to criminology’s use of ex post facto measures of psychopathy, Hart and Cook (2012) noted that most self-report instruments are not designed to measure psychopathy specifically and thus do not typically capture the full range of symptoms. Hart and Cook (2012) also noted that, unlike expert rating scales, self-report instruments have only low to moderate temporal stability and low to moderate concurrent validity with other measures of psychopathy. With regard to concurrent validity, self-report instruments appear most limited with respect to capturing interpersonal and affective deficits (e.g., Hare, 1985; Harpur et al., 1989; Sellbom, 2011). Most critically for criminological theories, these instruments have not shown sound predictive validity regarding involvement in serious antisocial behavior (Hart & Cook, 2012). Problems with the use of the psychopathy construct also extend to the research design stage, where there have been problems with the misspecification of independent and dependent variables, indicating confusion with manifestations of symptoms of psychopathy. For example, although high rate and versatile substance use is used as an indicator of the stimulation seeking item within the PCL:YV (see Forth et al., 2003), some argue that drug use increases the prevalence of symptoms of psychopathy (e.g., Pardini, Bechtold, Loeber, & White, 2015). An alternative interpretation to Pardini et al.’s (2015) finding is that changes in levels of drug use reflect heterotypic continuity associated with personality disorders like psychopathy.
Another research design limitation that has been characteristic of almost all existing studies on psychopathy in criminology is the reliance on general population samples11. This research design strategy is understandable given that the most influential
criminological longitudinal studies have focused on the development of offending more
11 Of the limitations presented, this limitation is likely affected the most by the lack of new
broadly and therefore emphasize generalizability. However, studying the influence of psychopathy within general population samples where, typically, there is little variance in symptoms of this disorder poses several challenges, even when psychopathy is viewed as a dimensional construct. For example, in the MacArthur Violence Risk Study, 50% of the sample scored either a zero or one on the PCL:SV (Neumann & Hare, 2008). Similarly low scores were observed within the Cambridge Study in Delinquent Development (Piquero et al., 2012). It is also important to consider the construct validity issue that scores on an instrument designed to measure psychopathy do not necessarily reflect symptoms of psychopathy. For example, an individual with a drug addiction may have a parasitic orientation, may be irresponsible, and may engage in reckless behavior. These can all be symptoms of psychopathy, but they also may be consequences of an offender’s drug addiction, and there is little evidence that drug addiction influences the development of symptoms of psychopathy (cf., Pardini et al., 2015). Nevertheless, this drug addicted individual in a community sample would likely score higher on the PCL:SV than at least 50% of participants from the MacArthur Violence Risk Study.
Low average scores on measures of psychopathy in community studies is especially concerning when scores pertaining to interpersonal and affective deficits are not reported. It leads to the question of whether higher scores on the instrument simply reflect higher levels of low self-control (e.g., the lifestyle facet from PCL instruments). For example, despite scores of 16-18 indicating ‘high’ scores on the PCL:SV, only 8% of men from the Cambridge study12 scored ten or higher (Piquero et al., 2012). To what extent are
core interpersonal and affective symptoms represented within this group? In a more recent study, Auty, Farrington, and Coid (2015) reported that men from the Cambridge study averaged a score of 1.17 (out of 12) on Factor One (F1) of the PCL:SV (the interpersonal/affective factor). Even more importantly, scores on this facet ranged from 0- 8, indicating that none of the sample presented with the full range of interpersonal and affective symptoms described by this instrument. Average scores on Factor Two (F2) of the PCL:SV (lifestyle/behavioral factor), although also low, were twice as high compared
12 The contributions made by researchers examining the Cambridge study are enormous, and the
critique here is not meant to be a general critique of the study. Rather, the critique presented is common to many studies in criminology, and the decision to specifically focus on the
to F1 scores. This suggests that within community samples, the individuals identified as scoring ‘high’ on symptoms of psychopathy (e.g., ‘10’ on the PCL:SV in the Piquero et al., 2012 study) may be more reflective of their F2 score than by their score on the factor measuring core symptoms of psychopathy (F1).
To assess this concern, PCL:SV scores amongst individuals (n = 203) from the Incarcerated Serious and Violent Young Offender Study (ISVYOS) were used to examine whether individuals with PCL:SV13 scores that represented the typical ‘high’ score were
more likely to have achieved that score due to higher scores on items reflecting lifestyle and behavioral PCL:SV items (F2) compared to individuals with atypical ‘high’ scores. Based on PCL:SV scores from community data, the vast majority of individuals defined as scoring ‘high’ on the PCL:SV received scores ranging between 10-14 (see Neumann & Hare, 2008; Piquero et al., 2012). Therefore, individuals with scores on the PCL:SV between 10 and 14 were determined to be indicative of the ‘typical’ high scorer and individuals with a score of 15 or greater were determined to be indicative of the ‘atypical’ high scorer. Chi-square measures of association indicated that individuals with typically high PCL:SV scores (n = 64) were significantly (χ2 = 5.81, p < .05) more likely than those
with atypically high PCL:SV scores (n = 108) to have an F2 (lifestyle/behavioral) score that was equal to or greater than their F1 (affective/interpersonal) score (see Figure 3.2). This indicated that individuals with a score that would typically indicate ‘high symptoms of psychopathy’ in a community study would be more likely than individuals with atypically high scores to have their score driven by items reflecting behavioral impulsivity than by interpersonal and affective deficits. To illustrate this concern in another way, the percent of an individual’s total score that was accounted for by F2 was examined. Using independent samples t-tests, individuals with typically high scores on the PCL:SV had a significantly (t (10714) = 3.52, p < .01) higher percentage of their total score accounted for
by F2 compared to individuals scoring atypically high on the PCL:SV (see Figure 3.1).
13 The sample included all young offenders, but the PCL:SV includes an item measuring ‘adult
criminal behavior’. This item was omitted F2 scores were pro-rated. F1 and F2 scores were thus still scored with the same scale range (0-12).
Figure 3.1: Chi-square and t-test analyses indicating that typical ‘high’ scores on the PCL:SV are more likely to be a result of F2 scores than F1
scores compared to atypical ‘high scores’. Note. F2 = Factor Two; F1 = Factor One
When PCL:SV scores are more appropriately treated as dimensional to reflect the dimensionality of psychopathy, similar results are observed. A Pearson correlation was performed on the full sample (n = 203) to examine the correlation between PCL:SV total scores and percent of score accounted for by F2. A significant, moderate, and negative correlation was observed (r = -.470, p < .001). As scores on the PCL:SV decreased, the percent of the total score accounted for by F2 increased. In effect, what may be the basis for these higher psychopathy scores is not core interpersonal and affective symptoms, but measures of criminal behavior, behavioral problems, and impulsivity. Within prior community-based studies of the relationship between psychopathy and offending, conclusions about the predictive validity of psychopathy may instead be more accurately interpreted as the predictive validity of low self-control and prior behavioral problems/criminality. Thus, the concern is that participants in community studies that are purported to typify ‘high psychopathy’ are individuals whose symptom profile is more likely reflective of issues with low self-control than of psychopathy.
0 10 20 30 40 50 60 70 80 90
Percent with F2 score greater than or equal to F1 score
Percent of total sore accounted for by F2
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This does not imply that community-based studies should not attempt to measure psychopathy and study its predictive validity. In agreement with Sellbom (2011), this type of research is needed to move the field of psychopathy research forward. However, the validity concerns discussed can only be fully addressed with larger-scale community studies that capture the full range of symptoms of psychopathy with measurement tools that capture core affective and interpersonal symptoms. For advancing the incorporation of psychopathy into criminological theories, greater attention should be given to ensuring that the psychopathy construct be more fully measured before assessing its predictive validity. Additionally, future research strategies need to account for the rarity of high symptoms of psychopathy in the general population. Once this is done, criminological theories relying on psychopathy as an exploratory construct should focus on a narrower scope of the most serious or criminal behaviors.