Development Original subscales The items used in the original version of the PPI were based on a number of
conceptual constructs theorized (by previous researchers such as
Hervey Cleckley and
Robert D. Hare) to be related to psychopathy. It consists of a series of statements to which subjects respond on how accurately the statement describes them using a 4-point
Likert scale ("false, "mostly false", "mostly true", "true").
Factor analysis of the initial 160 items revealed 8 factors: •
Machiavellian egocentricity (ME): A ruthless and self-centered willingness to exploit others •
Social potency (SOP): The ability to charm and influence others •
Coldheartedness (C): A distinct lack of emotion, guilt, or regard for others' feelings •
Carefree nonplanfulness (CN): Difficulty in planning ahead and considering the consequences of one's actions •
Fearlessness (F): An eagerness for risk-seeking behaviors, as well as a lack of the
fear that normally goes with them •
Blame externalization (BE): Inability to take responsibility for one's actions, instead blaming others or rationalizing one's behavior •
Impulsive nonconformity (IN): A disregard for social norms and culturally acceptable behaviors •
Stress immunity (STI): A lack of typical marked reactions to traumatic or otherwise
stress-inducing events Additionally, the PPI also included two special validity scales designed to detect participants who were giving random, inconsistent, or insincere answers. This was to avoid attempts at
malingering, and to eliminate subjects who seemed to have difficulty understanding multiple items.
Revised factors In 2005, the PPI was revised. The new version, called the PPI-R, included a reorganization of the 8 subscales into two (sometimes three) new higher-order factors:
PPI-1: Fearless dominance (FD), consisting of the social potency, stress immunity, and fearlessness subscales. Associated with less anxiety, depression, and empathy as well as higher well-being, assertiveness, narcissism, and thrill-seeking.
PPI-2: Self-centered impulsivity (SCI), consisting of the carefree nonplanfulness, impulsive nonconformity, Machiavellian egocentricity, and blame externalization subscales. Associated with impulsivity, aggressiveness, substance use, antisocial behavior, negative affect, and suicidal ideation. A person may score at different levels on the different factors, but the total score indicates the overall extent of psychopathic personality. Higher scores on factor I are associated with emotional stability and social efficacy, as well as reduced empathy. Higher scores on factor II are associated with maladaptive tendencies, including aggressiveness, substance use problems, negative feelings and suicidal ideation. Scores on the two major factors tend to be only moderately correlated.
Use of coldheartedness Although independent analyses of the PPI's factor structure have shown support for the validity of the new 2-factor model, there is some data that suggests that a 3-factor model may be better. Many analyses of the PPI tend to exclude coldheartedness and focus only on FD and SCI, but some studies have shown the two factors to be less statistically
reliable when coldheartedness is not also considered separately. Thus, some researchers are starting to use it as a distinct third factor in their analyses, as such meanness was a central part of Cleckley's conceptualization of a psychopath (see
The Mask of Sanity). Coldheartedness has also been shown to be distinct from the other two factors when comparing across other
personality models, such as the
Five-factor model (FFM). In particular, coldheartedness has significantly negative correlations with the openness and agreeableness dimensions of the FFM. In 2015, researchers from
Baylor University proposed the connection between psychopaths' coldheartedness and their inability to “catch” the contagious yawning. Those who had more psychopathic qualities were less likely to yawn while watching the yawning clip.
Relationship to other psychopathy theories The fearless dominance and self-centered impulsivity factors are similar to the concepts of
primary and secondary psychopathy. Like primary psychopathy, FD traits are related to a lack of
emotional responsivity but accurate
perception of emotions in others. Conversely, secondary psychopathy and SCI traits are related to difficulties in both emotional perception and
control of negative emotional responses, such as
anxiety, irritation, and aggressiveness.
Validity Construct validity The PPI is based on a personality-centric theory of psychopathy. Thus, to demonstrate
construct validity, the PPI should "be" as a measure of psychopathy is hypothesized to behave according to personality theory of psychopathy. According to this theory, psychopaths should possess a number of specific personality
traits, including low
conscientiousness,
socialization, and
empathy, as well as high
impulsivity and sometimes aggression. Preliminary research suggests that the PPI behaves as the personality theory of psychopathy says it should. For example, one study of 100 male inmates found total PPI scores to be negatively correlated with empathy and positively correlated with aggressive behavior and
borderline personality traits (such as impulsiveness, substance abuse, and unstable personal relationships). Thus, the PPI shows validity as a measure capable of assessing the personality theory of psychopathy.
Criterion validity The PPI demonstrates strong levels of
criterion validity. It shows modest correlations with the PCL, which is considered the "gold standard" of psychopathy assessments. Any discrepancies in scores have been theorized to stem from the fact that the PPI was designed for non-forensic populations and thus focuses more on personality than behavior, while the PCL (designed to assess the disorder in criminals) puts more emphasis on antisocial behaviors in its scoring system. Additionally, each measure uses a different form of data collection (interviews and a review of personal history vs. self-reports), which could also contribute to weaker correlations between the two scores, as discrepancies in the information obtained may result in very different conclusions.
Concurrent validity The PPI exhibits moderate to strong correlations with other measures of psychopathy when used in cross-sectional designs. As stated earlier, the PCL and its derivatives are often used in criminal settings and consists of a semi-structured interview and review of the subject's criminal records. Despite being very different in format, some of the factors of the PPI correlate with the factors of the PCL. One series of studies found moderate correlations between PPI-SCI and PCL Factor 2, which like PPI-SCI examines impulsive and antisocial tendencies. The correlations between PPI-FD and PCL Factor 1 (which both examine interpersonal relations and emotional deficits) were not nearly as strong, but the researchers suggested that this was due to the method variance (self-report vs. interview/file review), and that the correlations were typical for measures of the same construct using different methods. Because of this, it has been suggested that the PPI and interview-based measures of psychopathy like the PCL examine unique aspects of psychopathy while still sharing some overlap.
Gender differences Because of the disproportionately large number of male inmates compared to female, some studies have explored whether the validity of the PPI is affected by the gender of the population. One study used an incarcerated female sample to test this, and found that while the statistical
reliability of the PPI factors was below the normal average for men, the measure proved to be satisfactory at assessing psychopathic traits in comparison to the PCL, the measure most commonly used to assess psychopathy in prison samples. In comparison to other self-report measures, another study compared a female undergraduate sample with an incarcerated female sample. Although the measure correlated well with other self-report measures of psychopathy in both samples, the mean total scores between the two samples was the same, despite prisons normally having a far higher concentration of psychopaths than the general population. This suggests that the PPI has greater difficulty in detecting psychopathic traits in female criminals, possibly due to the expression of psychopathy varying by sex.
Ranking public figures In 2016 psychologist Dr. Kevin Dutton enlisted several historians to rank the psychopathic traits of various US historical and political figures using the 56-item short form of the PPI-R. According to that assessment,
Adolf Hitler scored 169 points,
Donald Trump received 171.
Margaret Thatcher scored 136 points, and
Elizabeth I scored 130.
Jesus and
Saint Paul both scored 157 points. According to Dutton, politicians and business leaders often demonstrate psychopathic qualities. ==Criticism==