Testing Factor Models of the Psychopathy Checklist: Youth Version and Their Association With Instrumental Aggression

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1 Journal of Personality Assessment ISSN: (Print) (Online) Journal homepage: Testing Factor Models of the Psychopathy Checklist: Youth Version and Their Association With Instrumental Aggression Michael J. Vitacco, Craig S. Neumann, Michael F. Caldwell, Anne-Marie Leistico & Gregory J. Van Rybroek To cite this article: Michael J. Vitacco, Craig S. Neumann, Michael F. Caldwell, Anne-Marie Leistico & Gregory J. Van Rybroek (2006) Testing Factor Models of the Psychopathy Checklist: Youth Version and Their Association With Instrumental Aggression, Journal of Personality Assessment, 87:1, 74-83, DOI: /s jpa8701_06 To link to this article: Published online: 10 Jun Submit your article to this journal Article views: 1129 Citing articles: 77 View citing articles Full Terms & Conditions of access and use can be found at

2 VITACCO, PSYCHOPATHY NEUMANN, AND CALDWELL, INSTRUMENTAL LEISTICO, AGGRESSION VAN RYBROEK JOURNAL OF PERSONALITY ASSESSMENT, 87(1), Copyright 2006, Lawrence Erlbaum Associates, Inc. Testing Factor Models of the Psychopathy Checklist: Youth Version and Their Association With Instrumental Aggression Michael J. Vitacco Mendota Mental Health Institute Madison, Wisconsin Craig S. Neumann Department of Psychology The University of North Texas Michael F. Caldwell Mendota Mental Health Institute Madison, Wisconsin Anne-Marie Leistico Department of Psychology The University of Alabama Gregory J. Van Rybroek Mendota Mental Health Institute Madison, Wisconsin Although there is a documented link between psychopathy and instrumental violence in adult offenders, the association between these constructs has not garnered significant attention in adolescent offenders. In this study, we evaluated the relationship between psychopathy and instrumental aggression in a sample of 122 male adolescents incarcerated in a state facility for serious and chronic offenders. We evaluated the primary (2-, 3-, and 4-factor) models of the Psychopathy Checklist: Youth Version (PCL:YV; Forth, Kosson, & Hare, 2003) and assessed their relationship to a separate 5-item measure of instrumental violence. CFA revealed good model fit for the 3- and 4-factor latent variable models of adolescent psychopathy and a single-factor model reflecting a 5-item measure of instrumental violence. Structural equation modeling results indicate that the 4-factor model accounted for 20% of the variance for instrumental violence. In contrast, the 3-factor model of the PCL:YV accounted for 8%, and the 2-factor model accounted for 5% of the variance associated with instrumental violence. Psychopathy consists of a constellation of personality traits and behavioral indicators defined by affective deficits; interpersonal deceptiveness; and impulsive, antisocial tendencies (Hare, 2003; Hare & Neumann, 2006; Vitacco, Neumann, & Jackson, 2005). This constellation of personality features has demonstrated robust associations with violence in multiple samples including forensic inpatients (Hill, Neumann, & Rogers, 2004), psychiatric outpatients (Vitacco, Neumann, et al., 2005), male and female inmates (Bolt, Hare, Vitale, & Newman, 2004), and adolescent offenders (Kosson, Cyterski, Steuerwald, Neumann, & Walker-Matthews, 2002; Vincent, Vitacco, Corrado, & Grisso, 2003). Notably, the aggression of psychopaths has many distinctive features that include its ongoing persistence and apparent resistance to treatment (Porter, Birt, & Boer, 2001; Serin & Amos, 1995). To provide additional information on youth psychopathy and

3 PSYCHOPATHY AND INSTRUMENTAL AGGRESSION 75 violence, in this article, we evaluate the relationship between three models of the Psychopathy Checklist: Youth Version (PCL:YV; Forth, Kosson, & Hare, 2003) and instrumental aggression. FACTOR STRUCTURE OF THE PCL:YV One of the recent controversies in the psychopathy literature concerns the factor structure of the Psychopathy Checklist Revised (PCL R; Hare, 2003) and its derivatives (i.e., PCL: Screening Version and PCL:YV). For almost 15 years, PCL interview measures were defined by a two-factor structure (Hare, 1991; Harpur, Hakistan, & Hare, 1988) with Factor 1(F 1 ) labeled the Selfish, Callous, Remorseless Use of Others and Factor 2 (F 2 ) labeled Chronic Antisocial Behavior. The two-factor model has been extensively researched in both criminal and forensic patients. However, evidence from studies that have employed confirmatory factor analysis(cfa) has shed doubt on the viability of the two-factor model (Cooke & Michie, 2001; McDermott et al., 2000). In the aftermath of poor results for the two-factor model, two alternative models for PCL measures have been presented. Cooke and Michie (2001) proposed a fundamental change to the factor structure of PCL measures by eliminating items measuring overt antisocial behavior and disaggregating F 1 into two separate facets, thus reducing the original measure to a 13-item, three-factor measure. Cooke and Michie (2001) labeled their factors Deficient Affective Experience, Arrogant and Deceitful Interpersonal style, and Impulsive and Irresponsible Lifestyle. Kosson et al. (2002) tested the threefactor model with a sample of 115 adolescent males on probation and found the model provided generally good fit on indices of absolute fit but less dequate fit on indices of relative fit (p. 104; root mean square error of approximation [RMSEA] =.07, robust comparative fit index [RCFI] =.92). More recently, a four-factor model has been proposed (Forth et al., 2003; Hare, 2003; Hare & Neumann, 2006; Vitacco, Neumann, et al., 2005), which represents the psychopathy construct in terms of interpersonal, affective, lifestyle, and antisocial facets. Vitacco, Salekin, and Neumann (2006) found good model fit for the four-factor PCL:YV model in a sample of 202 justice-involved adolescents (Tucker Lewis Index [TLI] =.96, standardized root mean square residual =.08). Clearly, the factor structure of PCL instruments remains a point of contention (Cooke, Michie, Hart, & Clark, 2004; Neumann, Vitacco, Hare, & Wupperman, 2005) that will continue to stimulate research focusing on the underlying dimensions of psychopathy. PSYCHOPATHIC TRAITS AND AGGRESSION IN ADOLESCENTS The development of clinical factors that provide greater understanding of violent and aggressive behavior in youth is a critical area of study. To be effective, research must accurately distinguish between impulsive juvenile offenders whose antisocial behavior is primarily limited to adolescence (Moffitt & Caspi, 2001) versus those who may evolve into chronic violent offenders (Lynam, 1997). The latter type of offender can have deleterious effects on their respective communities. For instance, Farrington and West (1993) found only 6% of males were responsible for committing approximately 50% of violent crime. These males shared several characteristics in that they began offending at an earlier age, were highly versatile in criminal activities, and offended at a high rate (see Vincent et al., 2003). In attempting to identify potential chronic offenders, the concept of psychopathy has been extended downward to children and adolescents(forth& Burke, 1998; Forth et al., 2003). Despite significant controversy questioning both the developmental appropriateness (Seagrave & Grisso, 2002) and diagnostic validity (Hart, Watt, & Vincent, 2002; Johnstone & Cooke, 2004) of adolescent psychopathy, psychopathy has gained prominence as an effective predictor of risk for shortterm violence in young offenders(catchpole& Gretton, 2003; Corrado, Vincent, Hart, & Cohen, 2004; Gretton, Hare, & Catchpole, 2004). However, the long-term ability of the PCL:YV to predict persistent violence has not been adequately established via longitudinal prospective studies. PSYCHOPATHY AND ITS ASSOCIATION WITH INSTRUMENTAL AGGRESSION IN ADOLESCENTS AND ADULTS Aggression is not a unitary construct with a single etiology. Instead, aggression stems from multiple causes and consists of subtypes, each reflecting a range of pathology. In recognizing the heterogeneity of aggression, Berkowitz (1993) theorized the existence of two primary types: reactive and instrumental. Reactive aggression is defined by failing to inhibit responses to apparent provocation or frustration (see Schmitt & Newman, 1998), whereas instrumental aggression is defined by the presence of planning and the lack of affect (see Meloy, in press). In discussing the differences between reactive and instrumental violence, Cornell et al. (1996) stated Perhaps reactive violence should be considered the most basic form of aggression among criminal offenders, and instrumental violence should be considered a marker of a more pathological development in the ability to use aggression for goal-directed purposes. (p. 788) Viewing instrumental aggression through the lens of the psychopathy construct should provide useful information on the causes of types of aggression. The psychopathy literature has recognized a substantial connection between psychopathic traits and instrumental aggression. Woodworth and Porter(2002) posited that the dominant clinical conception of a psychopath is a dangerous

4 76 VITACCO, NEUMANN, CALDWELL, LEISTICO, VAN RYBROEK person who preys on others across the life span (p. 436). Beyond clinical theory, empirical studies have documented an association between psychopathy and instrumental aggression. Two studies have been especially influential in informing the literature on the nature of psychopathy and instrumental aggression in adult samples. Cornell et al. (1996) completed an important study on the nature of psychopathy and instrumental aggression in 106 male inmates and 50 pretrial forensic referrals with violent histories. In completing their study, Cornell et al. developed an innovative coding system for classifying aggression. Cornell et al. s coding system assessed six distinctive domains: (a) planning, (b) goal directness, (c) provocation, (d) anger, (e) victim injury, and (f) victim relationship. Cornell et al. s results indicate that instrumental offenders were more superficial, manipulative, and lacking in feelings for others and also more impulsive and irresponsible (p. 789). Cornell et al. found that 50% of PCL R items were significantly higher in offenders who had histories of instrumental aggression compared with those with no documented history of instrumental aggression. In a more recent study, Woodworth and Porter (2002) studied psychopathy in a sample of 125 Canadian offenders convicted of homicide. Woodworth and Porter rated each homicide on a continuum from purely reactive to purely instrumental. Results indicated that psychopathic offenders were more likely to commit an instrumental homicide. Zero order correlations revealed that both F 1 (r =.46) and F 2 (r =.31) were related to instrumental homicide; however, after using partial correlations to control for shared variance between the factors, only F 1 (r =.37) remained significantly correlated to instrumental homicide. Similarly, Williamson, Hare, and Wong (1987) evaluated 101 Canadian offenders finding that those with high PCL R scores frequently engaged in aggression that was goal directed and purposeful (e.g., for revenge or financial benefit). Consistent with the downward extension of psychopathy to adolescence, research has begun to analyze the association between psychopathy and instrumental aggression in juvenile offenders. For instance, Murrie, Cornell, Kaplan, McConville, and Levy-Elkon (2004) evaluated the association between psychopathy and instrumental aggression in 113 incarcerated youth. Using a coding system similar to the one developed by Cornell et al. (1996), Murrie et al. found that PCL:YV total scores were correlated (r =.36) with instrumental aggression. Likewise, Kruh, Frick, and Clements (2005) established that young adults (M age = years) who committed unprovoked violence had higher psychopathy scores as measured by the Antisocial Process Screening Device (Frick & Hare, 2001) compared to individuals who committed aggressions in response to provocation. THIS STUDY Recent evidence suggests that psychopathic traits are related to instrumental aggression in adolescents (Kruh et al., 2005; Murrie et al., 2004). In an attempt to extend and replicate previous research on psychopathy, in this study, we had three interrelated goals. First, we evaluated the construct validity of the two-, three-, and four-factor models of the PCL:YV via CFA. This is necessary because there continues to be controversy over which factor structure best suits PCL instruments. Elucidating the factor structure of PCL measures is necessary because the establishment of PCL R underlying dimensions appears central to its construct validation (Rogers, 2001, p. 310). Moreover, understanding construct dimensionality is necessary for proper interpretation of measures and especially critical if dimensions of a multidimensional construct are differentially related to external variables such as violence (Reise, 1999). Given the recency of the PCL:YV s development, these analyses should assist researchers and clinicians in furthering their understanding of adolescent psychopathy. Second, we assessed a five-item measure (i.e., the Aggression Rating Form [ARF]; Cornell et al., 1996) of instrumental aggression. Although previously used in research (Cornell et al., 1996; Murrie et al., 2004), its factor structure has never been subjected to CFA, and its construct validity remains largely unexplored. The third goal was the examination, via structural equation modeling (SEM), of how the three primary factor models of the PCL:YV relate to instrumental aggression. Using external correlates such as aggression in psychopathy research permits one to obtain a fuller understanding of the construct (Reise, 1999). Sample METHOD The sample was composed of juvenile offenders placed in a treatment facility (i.e., Mendota Juvenile Treatment Center) for the most serious and violent adolescent offenders in the State of Wisconsin. All of the adolescents originally began serving their sentences in a Department of Corrections secure juvenile facility; however, they were transferred to the treatment center after continuing to engage in highly disruptive and violent behavior within various state juvenile correctional facilities. The sample consisted of 122 consecutive admissions to the treatment center over the course of 3 years. The participants ranged from 12 to 17 years of age (M = 15.28, SD = 1.20) and consisted of 55 African Americans, 51 Euro-Americans, 10 individuals of mixed ethnicity, and 6 Hispanic Americans. Each participant had complete ratings for all instruments (i.e., there were no missing data for this sample). Adolescents in this sample typically had been arrested by age 11 (M = 11.2, SD = 2.6) and had accumulated an average of 13.6 formal charges (SD = 11.5), about a third of which were crimes against persons (M = 4.6, SD = 5.1). Of the participants, 46% were arrested after hospitalizing or killing their victim.

5 PSYCHOPATHY AND INSTRUMENTAL AGGRESSION 77 Measures PCL:YV. The PCL:YV consists of 20 items designed to assess psychopathic traits in adolescent offenders. Each item is scored on a 3-point gradient ranging from 0 (does not apply at all), 1 (partially applies), to 2 (definitely applies). Scores for the two- and four-factor PCL:YV can range from 0 to 40, and scores for the three-factor model can range from 0 to 26. Unlike its adult counterparts, no diagnostic cut score is provided that categorically classifies adolescents (i.e., psychopath vs. nonpsychopaths). Moreover, there has been significant debate regarding the appropriateness of diagnosing psychopathy in children and adolescents. Given the strong negative connotations associated with mislabeling an adolescent as a psychopath, the authors (Forth et al., 2003) of the PCL:YV explicitly stated It is inappropriate for clinicians or other professionals to label a youth as a psychopath (p. 17). Being mindful of this caution, we treated psychopathy scores as dimensional. ARF. The ARF, a violence coding scheme, was specifically designed to assess the continuum between instrumental and reactive aggression in juvenile offenders. An advanced graduate student assistant, blind to the PCL:YV ratings, scored the ARF. We made the ratings, obtained by file reviews, through reviewing the adolescent s official criminal records, police reports that often included victim statements, institutional records, and reports for all documented aggressive incidents. The coding scheme for the rating scale is based closely on the work of Cornell et al. (1996) who conducted a study on instrumental violence with adult offenders. 1 The ARF was designed to assess five distinct behavioral domains including (a) planning or preparation before the aggression, (b) goal directed the act helped obtain a specific and identifiable goal (e.g., money), (c) the aggressive behavior was unprovoked by the victim, (d) lack of anger during the aggression, and (e) the victim of the aggression was a stranger. Cornell et al. included the level of victim injury in their criteria. High victim injury was thought to indicate reactive aggression. We initially included a coding of this variable but found that it was not internally consistent with the other factors. Although other factors describe the aggressive act(s), victim injury describes the outcome of the aggression and is thus affected by many circumstantial variables. With these issues in mind, we omitted an item measuring victim injury and settled on the rating system we describe here. The rater coded aggression on the following 5-point Likert scale: 1. None: No indications of this characteristic are present in any of the known aggressive acts. 1 Researchers or clinicians interested in using the Instrumental Aggression Rating Measure may contact M. J. Vitacco to obtain a copy of the measure. 2. Seldom: Some incidents include the characteristic, but it is not present in the vast majority of cases. 3. Mixed: The characteristic is present in some aggressions but not in others. 4. Most: The characteristic is present in most aggressions and is only absent in rare exceptions. 5. Always: The characteristic is documented in every known case of aggression. Based on the scoring system covering these five domains, scores for instrumental aggression can range from 5 to 25. The adolescents aggression was rated on a continuum from purely reactive to purely instrumental (Woodworth & Porter, 2002). Procedure We evaluated all admissions for 3 consecutive years for psychopathic traits, symptoms of mental illness, and types of aggression. Each assessment session occurred in a private room within 72 hr of the adolescent s admission into the treatment center. The PCL:YV (Forth et al., 2003) consists of both an in-depth clinical interview and comprehensive file review. Two advanced graduate students conducted the PCL:YV interview (i.e., each could ask questions), subsequent file review, and worked together to obtain a consensus score. Interrater reliability was completed on approximately 1 out of every 8 cases (i.e., 16 cases). For assessing interrater reliability on the PCL:YV, a third rater observed the interview, conducted a separate file review, and generated a score. The third rater did not have access to the consensus generated PCL:YV scores. Given that the information was collected relatively close to intake and aggression was scored based on previous behaviors, the results are considered a postdictive comparison of psychopathy and instrumental aggression. Data Analyses All CFA and SEM analyses were based on the Mplus software (Muthén & Muthén, 2001). The Mplus program is advantageous because it is designed for doing SEM with ordinal as well as continuous variables. In many areas of psychology, individuals are assessed with instruments that employ symptom or trait ratings on an ordinal rather than an interval scale (Everitt & Dunn, 2001). Ratings may involve a determination of whether each symptom or trait is absent (0), present but below a clinical threshold (1), or present at a clinically significant level (2); in such cases, there is no clear interval scale between the ordered ratings. One particular advantage of Mplus is that it provides a robust weighted least squares procedure for parameter estimation, which is appropriate when analyzing ordinal data. As recommended by modeling experts, data file input to the modeling software always involved raw items, appropriately designated as ordinal

6 78 VITACCO, NEUMANN, CALDWELL, LEISTICO, VAN RYBROEK variables; and therefore, a polychoric covariance matrix was the basis for all covariance structure analyses. RESULTS Psychometric Properties of the PCL:YV and ARF The mean PCL:YV score for the entire sample was (SD =5.17;range=14.00to38.00).Thereliabilitydataforallthree models was generally positive with minimally adequate internal consistency and interrater reliability. Table 1 provides the alphas, mean interitem correlations, and interrater reliability, measured by exact agreement intraclass correlations using a one-way random effects model, for all facets and total scores for the two-, three-, and four-factor PCL:YV models. The alpha of the instrumental aggression rating was acceptable (α =.87) with a mean interitem correlation of.57. This sample had engaged in moderate levels of instrumental aggression as demonstrated by their scores on the ARF (M = 11.49, SD = 3.98; range = 5 to 22). The interrater reliability was acceptable (intraclass correlation coefficient =.87; N = 16). Interrater reliability for individual ARF items were as follows: (a) planning or preparation =.70, (b) goal directed =.81, (c) unprovoked by victim =.74, (d) lack of anger during aggression =.79, and (e) limited relationship with victim =.73. Testing Factor Models of the PCL:YV Using CFA, attention was turned to testing the two-, three-, and four-factor models of the PCL:YV (Forth et al., 2003). In evaluating model fit, both relative (e.g., incremental) and absolute fit indexes were used. The two relative indexes used were the comparative fit index (CFI) and the TLI. Traditionally, good model fit was indicated when these indexes were.90 or above, TABLE 1 Reliability Analyses for the PCL:YV Facets and Total Scores Model α MIC ICC Two factor F F Total Three factor Interpersonal Affective Lifestyle Total Four factor a Antisocial Total Note. PCL:YV = Psychopathy Checklist: Youth Version; MIC = mean interitem correlations; ICC = intraclass correlations; F 1 = Factor 1; F 2 = Factor 2. a Four factor includes all factors from the three plus the Antisocial factor. although Hu & Benter (1999) recently recommended good fit at.95. The RMSEA is an absolute fit index with parsimonious model fit evident at values of.08 or lower. Factors were allowed to correlate freely in all models. We initiated testing using the two-factor model proposed by Hare (1991), the original model of PCL instruments. The two-factor model demonstrated unsatisfactory model fit, χ 2 (34, N = 122) = (CFI =.90, TLI =.91, RMSEA =.07). Because other investigators (Kosson et al., 2002; Salekin, Neumann, Leistico, & DiCicco, 2004) have examined a modified version (i.e., without testlets) of the Cooke and Michie (2001) three-factor model, we tested this model. Unlike the two-factor model, this model resulted in good fit, χ 2 (26, N = 122) = (CFI =.95, TLI =.95, RMSEA =.05). As expected, the individual items to factor loadings were remarkably similar to the four-factor model shown in Figure 1. The four-factor PCL:YV model also resulted in good fit, χ 2 (35, N = 122) = (CFI =.95, TLI =.96, RMSEA =.05). Figure 1 displays the standardized parameters for the four-factor model. All individual item loadings and factor correlations were significant (p <.05). In terms of the most robust factor loadings, grandiose sense of self-worth (.99), lack of remorse (.92), callousness (.87), and criminal versatility (.95) demonstrated the best item factor loadings among the respective psychopathy factors. In other words, these specific items were particularly good at assessing their respective latent factors. Unfortunately, the models cannot be compared statistically, as they do not have the same items and covariance matrix. However, the three-factor model is a more saturated model compared to the four-factor model (i.e., 26 vs. 35 degrees of freedom); the four-factor model survives a riskier test of disconfirmation (see Vitacco, Neumann, et al., 2005). Factor Model of the ARF The second study goal was to assess the construct validity of instrumental aggression ratings using CFA. The five instrumental aggression items demonstrated good fit for a single unidimensional factor model (CFI = 1.0, TLI = 1.0, RMSEA =.00). The CFI and TFI indexes, both of which were 1.0, does not indicate perfect fit. Rather, they indicate that there was no suggestion of misspecification of the hypothesized model relative to a baseline or null model (CFI) and that the hypothesized model provided excellent improvement in fit relative to the null (or zero factor) model (TLI). That the RMSEA =.00 is simply a matter of small residuals (i.e., the absolute averaged standardized residuals ranged from.01 to.02). Clearly, the model was able to reproduce the observed data with considerable precision. Figure 2 displays a graphical representation of the instrumental aggression model. Three items were strongly related to Instrumental Aggression factor: goal directed (.91), unprovoked by victim (.95), and lack of anger during aggression (.77). In contrast, planning or preparation (.52) and limited relationship with victim

7 PSYCHOPATHY AND INSTRUMENTAL AGGRESSION 79 FIGURE 1 Confirmatory factor analysis results for the four-factor Psychopathy Checklist: Youth Version model of psychopathy. (.65) were only moderately related to the construct of instrumental aggression. Models of the PCL:YV and Their Association With Instrumental Aggression Our final study goal was to test the relationship between psychopathy and instrumental aggression through the use of SEM. Prior to using SEM, we ran a series of bivariate correlations that analyzed the relationship between PCL:YV facets and the ARF. The correlations for the four- and threefactor model indicated that the interpersonal facet was significantly related to the ARF (r =.20, p =.03); In the four-factor model, the antisocial facet demonstrated a significant negative relationship (r =.24, p =.008) with instrumental aggression. Neither the lifestyle (r =.13) or affective (r =.09) facets were related to instrumental aggression. In addition, when using the two-factor model, neither traditional Factor 1 (r =.16, p =.07) nor Factor 2 (r =.02, p =.82) were significantly related to instrumental aggression. In the next step, we used SEM to further test the relationship between PCL:YV facets and the ARF. We conducted similar model tests with the two-, three-, and fourfactor models of the PCL:YV. We tested the association between the PCL:YV facets and ARF via SEM by regressing the Aggression factor onto the psychopathy factors. As expected, the SEM for the four-factor model resulted in excellent model fit, χ 2 (39, N = 122) = (CFI =.97, TLI =.98, RMSEA =.05) and accounted for 20% of the variance for instrumental aggression. Figure 3 provides a graphical representation of the relationship between the four-factor model of psychopathy and instrumental aggression. Only the interpersonal facet of the PCL:YV positively postdicted instrumental aggression. A critical finding was that the antisocial facet negatively postdicted instrumental aggression. Consistent with the correlational analysis, no other facets were significantly related to instrumental aggression. The three-factor SEM resulted in good fit, χ 2 (31, N = 122) = (CFI =.97, TLI =.98, RMSEA =.05). As shown in Figure 4, this model accounted for 8% of the variance in the Instrumental Aggression factor, and only the Lifestyle factor was related. Finally, despite its unsatisfactory fit, we tested the twofactor model to assess its relationship to instrumental aggression. The two-factor model performed poorly and accounted for only 5% of the variance. In terms of model fit (2-factor PCLYV + ARF), the fit was χ 2 (38, N = 122) = 76.87; CFI =.94, TLI =.95, RMSEA =.10. Clearly, there is a big jump in chi-square between this model and the four-factor with the inclusion of the ARF factor (57.71), and the RMSEA is unac-

8 80 VITACCO, NEUMANN, CALDWELL, LEISTICO, VAN RYBROEK FIGURE 2 Confirmatory factor analysis of the Aggression Rating Form. FIGURE 3 Structural equation modeling results for the fourfactor Psychopathy Checklist: Youth Version and Instrumental Aggression. ceptable. The incremental indexes likely went up because we included the ARF factor, which fits very well. DISCUSSION FIGURE 4 Structural equation modeling results for the threefactor Psychopathy Checklist: Youth Version and instrumental aggression. Over the past several years, accurately defining and measuring the concept of youth psychopathy has taken on greater importance, especially as it relates to understanding violent juvenile offenders. To achieve a better understanding of adolescent psychopathy, in this study, we built on programmatic research relying on SEM (Neumann & Vitacco, 2004; Salekin, Neumann, Leistico, & Zalot, 2004; Vitacco, Neumann, et al., 2005) to evaluate the underpinnings of psychopathy and its relationship with external variables. This study was guided by previous research that has demonstrated a relationship between psychopathic traits and instrumental aggression in adult (Cornell et al., 1996; Woodworth & Porter, 2002) and adolescent (Kruh et al., 2005; Murrie et al., 2004) offenders. Consistent with recent research on the underpinnings of psychopathy, in this study, we demonstrated that psychopathy can be represented in terms of interpersonal, affective, lifestyle, and antisocial dimensions (Hare & Neumann, in press; Hill et al., 2004; Neumann et al., 2005; Vitacco, Neumann, et al., 2005; Vitacco, Rogers, Neumann, Harrison, & Vincent, 2005). Of note, the poor results for the two-factor model are consistent with previous findings (Cooke &

9 PSYCHOPATHY AND INSTRUMENTAL AGGRESSION 81 Michie, 2001; Darke, Kaye, Finlay-Jones, & Hall, 1998; Kosson et al., 2002; McDermott et al., 2000) that have questioned the viability of the two-factor model. Although the three- and four-factor models generated similar fit indexes, the four-factor model accounts for much more variance of the ARF (i.e., instrumental violence). Another key finding from this study is the SEM results showing the positive postdictive relationship between the interpersonal facet of psychopathy and instrumental aggression and the negative postdictive association between the antisocial facet and instrumental aggression. Of particular importance was that the interpersonal facet of psychopathy was no longer significantly related to instrumental violence once the antisocial facet was removed. The different pattern of results between the three- and four-factor model SEMs are similar to the findings of Vitacco, Neumann, et al. (2005), whereby the parameters for the other psychopathy factors take on greater strength when the Antisocial Psychopathy factor is included in the model. We interpret this finding to indicate that the antisocial facet plays a central role in the underlying factor structure of psychopathy (see Hare, 2003; Neumann et al., 2005; Vitacco, Neumann, et al., 2005; Vitacco, Rogers, et al., 2005). Given the associations between instrumental aggression and subsequent violence (Vitaro, Gendreau, Tremblay, & Oligny, 1998), we believed it was necessary to assess the construct validity of the aggression measure. As previously noted, the presence of three features (i.e., goal directed aggression, unprovoked aggression, and lack of anger during aggression) best represented the construct in this sample of adolescents. Notably, this finding is highly consistent with Meloy s (in press) assertion that a principal component of instrumental aggression in adults is the lack of affective arousal. Our findings provide initial support for the generalization of the notion that lack of arousal during aggression relates to instrumental aggression in juvenile offenders. The findings from this study are consistent with recent research that has highlighted the importance of the interpersonal facet of psychopathy in understanding violence. Neumann and Vitacco (2004) employed latent variable growth modeling data (LGM) from the MacArthur Risk Assessment Study (Monahan et al., 2001). LGM enables researchers to predict factors linked to a trait at a discrete time as well as factors that predict its change over time. Neumann and Vitacco discovered that the antisocial facet predicted violence at a 20-week follow-up; however, the interpersonal facet predicted growth of violence at a 7-month follow-up. Similarly, Hill et al. (2004) found that the interpersonal facet predicted institutional violence in a sample of mentally disordered offenders at a 6-month follow-up. High scores on the interpersonal facet of PCL instruments, characterized by a grandiose sense of self-worth, impression management, and deceitfulness, are related to violent and aggressive behavior across multiple samples. One possibility is that individuals with high scores on the interpersonal facet become violent when they feel disrespected or when their perceived status is challenged. Notably, our data provides some support for the threatened egotism hypotheses whereby individuals with high levels of narcissism respond violently when they perceive they are insulted or disrespected (Bushman & Baumeister, 1998; Cale, 2004). Limitations and Recommendations for Future Study The results from this study must be considered in light of some methodological limitations. First, it is unclear how these results will generalize to less severe juvenile samples. Replicating the results in a probation/parole sample or nonreferred youth will be a necessary undertaking in fleshing out the relationship between psychopathy and instrumental aggression. Moreover, it would be helpful to assess these relationships prospectively to fully understand how psychopathic traits in adolescents relate to subtypes of violence. The negative relationship between instrumental aggression and the antisocial facet of the PCL:YV also requires further study. It would be instructive to determine if the negative relationship holds in a sample of offenders whose primary illegal activities are instrumental (e.g., bank robbers). 2 In that instance, antisocial behavior would be saturated with predominantly instrumental offenses, and the negative relationship found between instrumental aggression and the antisocial facet of psychopathy may not hold. The results from this study provide multiple directions for future research. First, the results demonstrate the importance of assessing interpersonal traits when studying aggression. To that end, research must continue to evaluate the theoretical and clinical importance of psychopathy with adolescent offenders. Second, we advocate for further research exploring the relationship between psychopathy and meaningful external correlates (e.g., aggression or intelligence). Future research focusing on IQ and perhaps neurophysiologic functioning (see Morgan & Lilienfeld, 2000) in addition to psychopathy may provide additional information about the nature of aggressive behavior. Finally, applying the construct of psychopathy to adolescents continues to demonstrate promise as a construct with clear linkages to youth violence. It is certainly necessary to understand the facets of psychopathy in adolescents and evaluate how these facets differentially relate to violence if more effective therapeutic interventions are to be developed. CONCLUSIONS The results of this study provide a foundation for linking specific psychopathic traits with instrumental violence. Traits of 2 We thank an anonymous reviewer for this suggestion.

10 82 VITACCO, NEUMANN, CALDWELL, LEISTICO, VAN RYBROEK impression management and grandiose sense of self-worth were positively related to instrumental offending. The difference in facet relationships continues to argue for the presence of psychopathy subtypes (Hicks, Markon, Patrick, Krueger, & Newman, 2004; Murphy & Vess, 2003; Vincent et al., 2003). Reviewing variants of psychopathy through their relationships with external correlates is a promising approach to furthering research aimed at identifying the etiology and pathogenesis of psychopathy. REFERENCES Berkowitz, L. (1993). Aggression, it causes, consequences, and control. New York: McGraw-Hill. Bolt, D. M., Hare, R. D., Vitale, J. E., & Newman, J. E. (2004). A multigroup response theory analysis of the Psychopathy Checklist Revised. Psychological Assessment, 16, Bushman, B. J., & Baumeister, R. F. 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