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.
Higher scores on factor II are associated with maladaptive tendencies, including aggressiveness, substance use problems, negative feelings and suicidal ideation.
[9] 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).
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.
These included PPI-1 having a strong correlation with measures of Dominance and extraversion, whereas the total score and PPI-2 had no such relationship, but PPI-2 did show a moderate association with substance abuse and anxiety.
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.
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.
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.
[19] 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.[20] According to that assessment, Adolf Hitler scored 169 points, Donald Trump received 171.
This observation caused the researchers to suggest that the FD factor, examined alone, is actually more indicative of the personality of a mentally healthy, well-adjusted individual.
They thus concluded that FD was not a valid factor of psychopathy by itself, as it did not appear to fit into the pathological definitions of psychopathic personality conceptually or empirically.
[22] In response, some of the creators and supporters of the PPI-R defended fearless dominance as a legitimate aspect of psychopathy, arguing that the authors of the meta-analysis were misinterpreting the role and importance of the factor.
Furthermore, the fact that the PCL and PPI-R are designed for different types of sample populations (criminal vs. community), and thus could have very different outcomes and relationships when comparing factors, was reason to doubt the conclusions of the meta-analysis.
They contended that the PPI-R supporters were downplaying the role of anti-social behavior in assessing psychopathy, and that doing so could result in accidentally identifying otherwise normal extroverts as psychopathic.
[24] In the end, most researchers agree that fearless dominance, by itself, is not a sufficient indicator of psychopathy, and that anti-social behavior does need to be a prominent feature regardless of whether the psychopath is a criminal or an ordinary citizen.
Thus, the researchers concluded that the PPI was vulnerable to manipulation by respondents consciously attempting to present themselves in a positive light, which could limit its utility in criminal populations or any situations in which users have a significant motivation to appear well-adjusted.
In relation to psychopathy, individuals possessing psychopathic traits are often more apt to engage in this sort of deception for practical or amusement purposes, and thus may possibly pose a greater risk for malingering than other populations.
However, because the sample did not include any participants meeting criteria for an official diagnosis of psychosis, it is unknown whether those with an actual mental illness would also be classified correctly on the validity scales.