1. Multidimensional Scaling Analysis of the PCL-R Daz Bishopp. &
Multidimensional Scaling Analysis of the PCL-R Daz Bishopp & Robert Hare Broadmoor Hospital & University of Birmingham Darkstone Research & University of British Columbia
Abstract
Recent studies examining the PCL-R have argued for a range of factorial solutions to describe and explain the dimensions of psychopathy. This study details an empirical analysis of North American PCL-R data for 4630 male offenders, using multidimensional scaling (MDS) as a non-linear alternative to factor analysis. The emergent structure of Hare’s psychopathy psychometric can be interpreted in more than one way and at different levels of specificity. The multidimensional scalograms reveal a set of facets consistent with the two- and four-factor solutions that emerge from the same data. Equally the structure of the PCL-R can be interpreted through personality theory as a set of core traits and behavioral manifestations, consistent with an evolutionary basis for psychopathic tendencies. These analyses provide support for a multidimensional structure within the PCL-R, and suggests that psychopathy can be viewed as an extreme variant of multiple dimensions of personality.
Psychopathy and the Five-Factor Model of Personality
Historical perspectives from Eysenck and Cattell formed the building blocks for contemporary interpretations of personality architecture, such as those described in the five-factor model (FFM) of personality (Costa & McCrae, 1992; Costa & Widiger, 2002) or the alternate Big-5 (Norman, 1967; Goldberg, 1990). The FFM describes personality in terms of five higher-order domains: Openness to experience (O), Conscientiousness (C), Extraversion (E), Agreeableness (A) and Neuroticism (N) each underpinned by further facets. The FFM shows a correspondence to Eysenck’s ENP, although P is posited in terms of conscientiousness. The role of impulsivity within personality remains unclear (Revelle, 1997), and in the FFM the concept is posited as a facet of neuroticism.
There is no explicit psychopathy dimension in the FFM but the construct is interpretable from the sub-facets of the OCEAN domains. Several authors have argued that psychopathy might be understood, in terms of the FFM, as a constellation of low C (irresponsible), low A (aggressive), low N (shallow affect), and facets of high E (adventurous) and low E (cold). Harpur et al., (2002) and Hart and Hare (1994) provided empirical data relating psychopathy, as measured by the PCL–R, to the FFM of personality. Lynam (2002) and Widiger & Lynam (1998) have mapped out in detail the association between each of the PCL-R items and the FFM domains and facets. There is utility in the many personality theories and the constructs described by them, but unfortunately no perspective is universally accepted. Although useful for describing ‘Normal’ personality it may be too restrictive for describing more extreme personality constellations such as psychopathy, or personality disorder.
Multidimensional Scaling Analysis of the PCL-R
Multidimensional Scaling (MDS) procedures have developed from the work of Louis Guttman as a non-linear alternative to factor analysis (Borg & Groenen, 1997; Guttman, 1954; Kruskal & Wish, 1968). These techniques are more flexible than factor analysis as they can be applied to any measure of association, such as those which do not use inter-variable correlation or measures of covariance. Relationships between variables are represented as points in space within a visual scalogram with the distances between points indicating the strength of associations (Euclidian distances).
These techniques are sometimes offered in conjunction with a methodological framework called facet theory, derived from the work of Guttman (Guttman, 1968; Shye, Elizur & Hoffman, 1994). Facet theory emphasises the importance of linking theoretical concepts to empirical structures or facets. Underlying structures (facets) are interpreted theoretically, as with factor analysis, by mapping the MDS content to established theoretical concepts.
Sample and Analyses
The analyses were conducted with the North American SPSS data set for male offenders, described by Hare (2003; see also Bolt et al., 2004). N = The data was analysed using Statistica to provide a range of MDS solutions. As with factor analysis, MDS requires that an appropriate measure of association (correlation) be applied to the raw data matrix. Given that the PCL-R scores are ordinal, a proximity matrix was generated through Statistica, based on an ordinal measure of association. In this case a Goodman-Kruskal Gamma coefficient was selected. The MDS techniques were applied to the resultant association matrix with results presented as scalograms in two and three dimensions using 18 and 20 item datasets.
Results and Discussion
Two sets of MDS analyses were carried out, one using all 20 PCL-R items and the other using the 18 items that form the 4-factor solution (that is, Promiscuous Sexual Behavior and Many Short-term Marital Relationships were excluded). The data were examined in two and three dimensions. The two-dimensional solution for all twenty items is given in Figure 2. The stress index and the coefficient of alienation for the solution was .16 and .18, respectively, indicating a moderate fit.
Figure 1 about here
Introduction
Psychopathy has long been recognised as a part of the human condition, although not necessarily under the contemporary label. The term describes rare individuals who are interpersonally charming but also manipulative, selfish, callous, and socially irresponsible. There is some debate as to whether these facets of ‘character’ (in the classical sense) are a product of personality variations, or whether they represent symptoms of abnormal functioning within a clinical framework. This theoretical tension is one that lies at the heart of differences between psychiatric classifications of disorder and psychological conceptualisations of individual differences.
Psychopathy and Antisocial Personality Disorder
Psychiatric descriptions of psychopathy began to emerge in the C19th. Early clinical observations detailed the now characteristic ‘symptoms’ of an emotionally detached, non-psychotic disorder (Pinel 1806; Pritchard 1835; Koch, 1891; Kraepelin 1909; Schneider, 1923).
During the twentieth century psychopathy became increasingly operationalised as a diagnostic array. (Berrios, 1996; Millon, Simonsen, & Birket-Smith, 1998). Cleckley (1941) outlined criteria for the diagnosis of sociopathic personality disturbance: antisocial reaction in the first edition of the Diagnostic and Statistical Manual (1952).
These features become the basis for both diagnosis and subsequent psychological examination the construct (e.g., Lykken, 1957; Hare, 1970; Blackburn, 1975; Cleckley 1976).
Current conceptualisations of APD in DSM IV appear insufficient to describe the psychological components of psychopathy. Although most psychopaths would meet the criteria for ASPD, very few people with ASPD would meet the criteria for psychopathy.
The current conceptualisations of personality disorder is atheoretical and woefully inadequate. Psychopathy is better described by the combination of antisocial, narcissistic and histrionic features.
The Structure of Personality
Many personality theories and models reflect classical view of Temperaments (from Hippocrates , Galen). Interpersonal theory draws directly on dimensions of Love-Hate and Dominance-Submission, arranged in a circumplex (Leary 1957).
Dominant
Submissive
Friendly
Hostile
Trait Theories
Many theorists suggest that personality variations are based in traits or competencies (Allport & Allport, 1921; Cattell, 1946; Costa & McCrae, 1992; Eysenck, 1947; 1990). The complexity of traits is reflected in the way that they are theoretically organised within a hierarchy of bio-social structures. Put simply, most authors distinguish between primary, or source traits and secondary or surface traits (e.g. Allport, 1966; Cattell & Kline, 1977; Eysenck, 1970). Source traits may be viewed as biological dispositions that are stable over time and generalisable across situations. These are reflected in secondary or surface traits which are behavioural manifestations of the underlying source trait. This distinction may be important for understanding patterns of behaviour and their direct or indirect relationship to core personality structures.
Eysenck
Originally proposed a Temperamental model of personality based on Extraversion and Neuroticism (see below). Eysenck later revised his position on E and N and suggested a third dimension of Psychoticism (Eysenck & Eysenck, 1975). Psychoticism originally represented a continuum of psychotic disorder but now might be viewed as impulsive non-conformity (Eysenck & Eysenck 1995). P has suffered from poor reliablity and conceptual confusion since it does not adequately assess psychosis or psychopathy.
The role of impulsivity in Eysenck’s model and within personality models generally has changed over time. Originally viewed as a facet of extraversion it has since been posited as central to Psychoticism.
Structural Analyses of the PCL-R
A number of recent studies examining the PCL-R used a variety of statistical methods to explore the underlying structures, including factor analysis, structural equation models, item response theory models and multidimensional scaling in this work.
Factor analytic studies of the PCL-R certainly have increased our understanding of the structure of psychopathy. A range of factorial solutions have been distilled from the PCl-R suggesting 2, 3 or 4 factors. Item loadings for each solution is shown in the Table below. The original two-factor solution was based on exploratory factor analysis (EFA) and described Factor 1 in terms of interpersonal and affective features, and Factor 2 as reflecting a socially deviant lifestyle (Hare, 1991; Hare et al., 1990).
Promiscuous Sexual Behavior (item 11) and Many Short-term Marital Relationships (item 17) do not form part of the PCL-R factor structure in any of the extant models. Possibly indicating a distinct sexual behavior facet. It is also possible that items 11 and 17 reflect aspects of sexual and intimate behaviors that are based in idiographic interests, rather than traits. If so they would have a complex relationship with personality structures that may not easily be observed through linear factor analytic models.
Cooke et al. (2004) proposed a model of psychopathy with “plausible causal links between the 3-factor model and antisocial behavior” (p. 347). Although it is not possible to say, with the cross-sectional data used, if antisocial behaviour stems from, or co-exists with, more primary components of psychopathy. Neumann, Vitacco, and Hare (2005) have shown that an equally credible SEM model can be constructed from PCL-R data in which the antisocial variables are “predictive” of the Interpersonal, Affective, and Lifestyle factors.
The debate surrounding the number of factors may be a mute one as it is possible to extract as many factors as one can interpret. Of greater importance is the theoretical interpretations placed on the emergent factors and the sense that this makes to different authors on the subject. Being a strict linear model it may be inappropriate for determining the exact nature of psychopathy as assessed using the PCL-R.
Theoretically Psychopathy has taken two paths…
The psychiatric route in the diagnosis of Antisocial Personality Disorder.
The psychological route of understanding the Psychopathic Personality Dimensions.
Psychobiological Bases of Psychopathy
Psychological thinking has its origins in evolutionary theory.
“The ideal criminal has marked peculiarities of character: his conscience is almost deficient, his instincts are vicious, his power of self-control is very weak, and he usually detests continuous labour” (Galton, 1883, p. 42).
The Darwinian paradigm laid the foundation for understanding variations in personality within a bio-social framework (Darwin, 1872; Galton, 1869; 1871; Spencer 1855). Evolutionary theory helped to explain human variation and diversity, a necessary condition in the race for the ‘Survival of the fittest’. As a consequence individuals are endowed with unique blends of character traits that give rise to personality variations. Some of these variations are inevitably less desirable than others and psychopathy could be viewed in this way – as a frequency dependent evolutionary strategy (Mealey 1995; Lalumière, Harris, & Rice, 2001; Pitchford, 2001). The self-interested psychopath is entirely geared to self-preservation and reproductive success in evolutionary terms (Book & Quinsey, 2003; Harris & Rice). Homo Psychopathiensis may be an extreme variant of otherwise normal personality structures.
On the left hand side of Figure 2 the items associated with a reckless lifestyle and antisocial behavior are clearly visible, consistent with the second factor of the original 2-factor model. The right hand side of the plot likewise shows a correspondence to the interpersonal and affective items of Factor 1. The inclusion of Items 11 (Promiscuous Sexual Behavior) and 17 (Many Short-term Marital Relationships) appears to distort the geometric space, forcing the other items to be more clustered together.
Personality Structures within the PCL-R
Promiscuity
Polygany
Conduct Disorder (Developmental)
Sensation-Seeking
Dominance
Callousness
Lack of Empathy
Emotional Coldness
Criminal Versatility
Impulsivity
Parasitic
Shallow Affect
Conning
Lack Goals
Juvenile delinquency
Early problems
Poor Behavioural Controls
Lack Remorse
Failure Responsibility
Glib
Grandiose
Non Conscientiousness
Revocation of Release
Irresponsible
Lying
Antisocial Behaviour
Need Stimulation
Deception
Primary Trait
Surface Manifestation
A Comparison of PCL-R Factor Solutions
PCL-R Item
2-Factor
Small-3
Big -3
4-Factor 1 2 3 4
1. Glibness/Superficial Charm
2. Grandiose Sense of Self Worth
3. Need Stimulation/Proneness to Boredom
4. Pathological Lying
5. Conning/Manipulative
6. Lack of Remorse or Guilt
7. Shallow affect
8. Callous/Lack of empathy
9. Parasitic Lifestyle
10. Poor Behavioral Controls1 E
11. Promiscuous Sexual Behavior X
12. Early Behavioral Problems1
13. Lack of Realistic Long-term Goals
14. Impulsivity
15. Irresponsibility
16. Failure Accept Responsibility for Actions
17.Many Short-term Marital relationships
18. Juvenile delinquency
19. Revocation of conditional release
20. Criminal versatility
Eysenck’s ENP model
Evolutionary Traits
The biological basis for psychopathy can be viewed in general terms as the product of personality structures. Evolutionary psychology and sociobiology suggests a number of core primate traits that help to explain individual differences (Buss 1991; Gosling & John 1999). While many overlap with similar constructs identified in humans there is some debate as to how many traits are required to fully explain primate or human personality.
Sociability (Extraversion)
Stability (Neuroticism)
Activity (Impulsivity)
Curiosity (Sensation-Seeking)
Dominance (Agency)
Evicence from neurophysiological studies also suggest some inherent deficit in the structures of the brain associated with emotion such as the amygdala (e.g. Blair, 1995). It is difficult to say whether any deficits in brain fucntion related to psychopathy are present at birth or occur as a concequence of a psychopathic lifestyle.
Note: 2-Factor solution from Hare et al. (1990); Small 3-Factor solution from Cook & Michie (2001).
Big 3-Factor solution from Neumann (personal communication, March 7, 2005). 4-Factor solution from Neumann et al. (2005). E = exclusion; X = miss-fit.