Research on the dark triad is used in applied psychology, especially within the fields of law enforcement, clinical psychology, and business management. People scoring high on these traits are more likely to commit crimes, cause social distress and create severe problems for an organization, especially if they are in leadership positions (for more information, see psychopathy, narcissism, and Machiavellianism in the workplace).
All three dark triad traits are conceptually distinct although empirical evidence shows them to be overlapping. They are associated with a callous-manipulative interpersonal style.
- Narcissism is characterized by grandiosity, pride, egotism, and a lack of empathy.
- Machiavellianism is characterized by manipulation and exploitation of others, a cynical disregard for morality, and a focus on self-interest and deception.
- Psychopathy is characterized by continuing antisocial behavior, impulsivity, selfishness, callousness, and remorselessness.
A factor analysis carried out at the Glasgow Caledonian University found that among the big five personality traits, low agreeableness is the strongest correlate of the dark triad, while neuroticism and a lack of conscientiousness were associated with some of the dark triad members.
In 1998, McHoskey, Worzel, and Szyarto provoked a controversy by claiming that narcissism, Machiavellianism, and psychopathy are more or less interchangeable in normal samples. Delroy L. Paulhus and McHoskey debated these perspectives at a subsequent American Psychological Association (APA) conference, inspiring a body of research that continues to grow in the published literature. Paulhus and Williams found enough behavioral, personality, and cognitive differences between the traits to suggest that they were distinct constructs; however, they concluded that further research was needed to elucidate how and why they overlap.
The long-debated "nature versus nurture" issue has been applied to the dark triad. Research has begun to investigate the origins of the dark triad traits. In a similar manner to research on the Big Five personality traits, empirical studies have been conducted in an effort to understand the relative contributions of biology (nature) and environmental factors (nurture) in the development of dark triad traits.
One of the ways in which researchers attempt to dissect the relative influence of genetic and environmental factors on personality (and individual differences more generally) is a broad investigative technique loosely grouped under the heading of "twin studies". For example, in one approach to twin studies, researchers compare the personality scores of monozygotic (MZ) or identical twins reared together to dizygotic (DZ) or fraternal twins reared together. Because both types of twins in this design are reared together, all twin pairs are regarded as having shared a 100% common environment. In contrast, the monozygotic twins share 100% of their genes whereas the dizygotic twins only share about 50% of their genes. Therefore, for any given personality trait, it is possible to parcel out genetic influences by first obtaining the MZ correlation (reflecting 100% common environment and 100% shared genes) and subtracting the DZ correlation (reflecting 100% common environment and 50% shared genes). This difference represents 50% of the genetic influence; doubled, this number is said to account for 100% of the genetic influence, and is one way to derive an index of heritability (sometimes called the heritability coefficient and represented as h2). Similarly, MZ - h2 may be regarded as an estimate of the influence of the common environment. Finally, because individual differences and the environment are supposed to account for the totality of behavior, it is said that subtracting the sum of h2 and the common environment influence from 1 is equal to the influence of unique or non-shared environments.
All three traits of the dark triad have been found to have substantial genetic components. It has also been found that the observed relationships among the dark triad, and among the dark triad and the Big Five, are strongly driven by individual differences in genes. However, while psychopathy (h2 = 0.64) and narcissism (h2 = 0.59) both have a relatively large heritable component, Machiavellianism (h2 = 0.31) has been found to be less heritable.
Compared to biological factors, the influence of environmental factors seem to be more subtle and account for less—yet still significant—variation in individual differences as related to the development of dark triad traits. The influence of non-shared or unique environmental factors (definition and mathematical derivation included above at the end of the "Origins" subsection) accounts for a significant amount of the variance in all 3 dark triad traits (narcissism = 0.41, Machiavellianism = 0.30, psychopathy = 0.32), whereas only Machiavellianism (r = 0.39) has been found to be significantly related to a shared environmental factor. Although it requires substantiation, some researchers have interpreted this latter finding (along with the comparatively lower heritability noted in the section above) to mean that Machiavellianism is the most likely dark triad trait to be influenced by experience. At the very least, this notion about the modifiability of Machiavellianism does make some sense insofar as that the less variance there is attributable to genetic factors, the more variance there must be attributable to other factors, and "other" factors have traditionally been synopsized as environmental or experiential in nature.
Evolutionary theory may also explain the development of dark triad traits. It has been argued that evolutionary behavior predicts not only the development of dark triad personalities, but also the flourishing of such personalities. Indeed, it has been found that individuals demonstrating dark triad personality can be highly successful in society. However, this success is typically short-lived. The main evolutionary argument behind the dark triad traits emphasizes mating strategies. This argument focuses on the notion of life history strategy. Life history strategy proposes that individuals differ in reproductive strategies; an emphasis on mating is termed a "fast life" strategy, while an emphasis on parenting is termed a "slow reproductive" strategy. There is some evidence  that the dark triad traits are related to fast life history strategies; however, there have been some mixed results, and not all three dark triad traits have been related to this strategy. A more detailed approach has attempted to account for some of these mixed results by analyzing the traits at a finer level of detail. These researchers found that while some components of the dark triad are related to a fast life strategy, other components are related to slow reproductive strategies.
Sub-clinical dimensions vs. disordersEdit
In general, clinicians treat these traits as pathological, something that needs to be treated, and inherently undesirable, e.g. socially condemned or personally counter-productive. However, others argue that adaptive qualities may accompany the maladaptive ones. The evolutionary perspective (above) considers the dark triad to represent different mating strategies. Their frequency in the gene pool requires at least some local adaptation.
The everyday versions of these traits appear in student and community samples, where even high levels can be observed among individuals who manage to get along in daily life. Even in these samples, research indicates correlations with aggression, racism, and bullying among other forms of social aversiveness.
Narcissism was discussed in the writings of Sigmund Freud, and psychopathy as a clinical diagnosis was addressed in the early writings of Hervey Cleckley in 1941 with the publication of The Mask of Sanity. Given the dimensional model of narcissism and psychopathy, complemented by self-report assessments that are appropriate for the general population, these traits can now be studied at the subclinical level. In the general population, the prevalence rates for sub-clinical and clinical psychopathy are estimated at around 1% and 0.2%, respectively. Unfortunately, there do not seem to be any reliable estimates of either clinical or sub-clinical narcissism in the general population.
With respect to empirical research, psychopathy was not formally studied until the 1970s with the pioneering efforts of Robert Hare, his Psychopathy Checklist (PCL), and its revision (PCL-R). Hare notes in his book, Without Conscience  that asking psychopaths to self-report on psychologically important matters does not necessarily provide accurate or unbiased data. However, recent efforts have been made to study psychopathy in the dimensional realm using self-reported instruments, as with the Levenson Primary and Secondary Psychopathy Scales, The Psychopathic Personality Inventory, and the Self-Report Psychopathy Scale.
Similarly, assessment of narcissism required clinical interviews, until the popular "Narcissistic Personality Inventory" was created by Raskin and Hall in 1979. Since the NPI, several other measures have emerged which attempt to provide self-report alternatives for personality disorder assessment. In addition, new instruments have been developed to study "pathological" narcissism  as opposed to "grandiose" narcissism, which is what many argue the NPI measures.
Machiavellianism has never been referenced in any version of the Diagnostic and Statistical Manual of Mental Disorders (DSM) for psychological disorders. It has been treated as strictly a personality construct. The original published version of the Mach-IV  is still the most widely used in empirical research.
As noted previously, there is a good deal of conceptual and empirical overlap between the dark triad traits. For example, researchers have noted that all three traits share characteristics such as a lack of empathy, interpersonal hostility, and interpersonal offensiveness. Likely due in part to this overlap, a number of measures have recently been developed that attempt to measure all three dark triad traits simultaneously, such as the Dirty Dozen  and the short dark triad (SD3).
At their root, however, most of these measures are questionnaire-style and require either self-response or observer-response (e.g., ratings from supervisors or coworkers). Both methods can prove problematic when attempting to measure any socially aversive trait as self-responders may be motivated to deceive. A more specific confound might also exist for dark triad traits and Machiavellianism in particular: individuals who are skilled at deceiving and manipulating others should be perceived as low in deceptiveness and manipulation by others, and are therefore likely to receive inaccurate ratings.
Despite these criticisms and the acknowledged commonalities among the dark triad traits, there is evidence that the constructs are related yet distinct.
Named after the philosophy espoused by Niccolò Machiavelli in The Prince, people who score high on this trait are cynical (in an amoral self-interest sense, not in a doubtful or skeptical sense), unprincipled, believe in interpersonal manipulation as the key for life success, and behave accordingly. Scores on measures of Machiavellianism correlate negatively with agreeableness (r= -.47) and conscientiousness (r=-.34). Machiavellianism is also significantly correlated with psychopathy.
Individuals who score high on narcissism display grandiosity, entitlement, dominance, and superiority. Narcissism has been found to correlate positively with extraversion (r = .42) and openness (r = .38) and negatively with agreeableness (r = -.36). Narcissism has also been found to have a significant correlation with psychopathy.
Considered the most malevolent of the dark triad, individuals who score high on psychopathy show low levels of empathy combined with high levels of impulsivity and thrill-seeking. The similarity between psychopathy and antisocial personality disorder have been noted by some researchers. Psychopathy has been found to correlate with all of the Big Five personality factors: extraversion (r = .34), agreeableness (r = -.25), conscientiousness (r = -.24), neuroticism (r = -.34) and openness (r = .24).
The most pronounced group difference is in gender: numerous studies have shown that men tend to score higher than women on narcissism, Machiavellianism, and psychopathy, although the magnitude of the difference varies across traits and the measurement instruments used. One interesting finding related to narcissism—albeit one based on non-representative samples—is that while men continue to score higher than women, it seems that the gender gap has shrunk considerably when comparing cohort data from 1992 and 2006. More specifically, the aforementioned findings indicate that there has been a general increase in levels of narcissism over time among college students of both sexes, but comparatively, the average level of narcissism in women has increased more than the average level of narcissism in men.
There is far less information available on race differences in dark triad traits, and the data that is available is not representative of the population at-large. For instance, a 2008 research study using undergraduate participants found that Caucasians reported higher levels of narcissism relative to Asians. Similarly, another 2008 study using undergraduate participants found that Caucasians tended to score slightly higher than non-Caucasians on Machiavellianism. When attempting to discern whether there are ethnic differences in psychopathy, researchers have addressed the issue using different measurement instruments (e.g., the Self-Report Psychopathy Scale and The Psychopathic Personality Inventory), but no race differences have been found regardless of the measure used. Additionally, when comparing Caucasians and African Americans from correctional, substance abuse, and psychiatric samples—groups with typically high prevalence rates of psychopathy—researchers again failed to find any meaningful group differences in psychopathy. However, in a research conducted by Richard Lynn, a substantial racial difference in psychopathy was found. Lynn proposes "that there are racial and ethnic differences in psychopathic personality conceptualised as a continuously distributed trait, such that high values of the trait are present in blacks and Native Americans, intermediate values in Hispanics, lower values in whites and the lowest values in East Asians."
The focal variable when analyzing generational or cohort differences in dark triad traits has tended to be narcissism, arising from the hypothesis that so-called “Generation Me” or “Generation Entitlement” would exhibit higher levels of narcissism than previous generations. Indeed, based on analyses of responses to the Narcissistic Personality Inventory collected from over 16,000 U.S. undergraduate students between 1979 and 2006, it was concluded that average levels of narcissism had increased over time. Similar results were obtained in a follow-up study that analyzed the changes within each college campus. Trzesniewski & Donnellan (2010) present conflicting evidence and argue that there have not been large changes in disposition or behavioral strategies across generations, although they do note that the current generation is less trusting and more cynical, which are both changes that might be indicative of an increase in Machiavellianism.
In the workplaceEdit
Oliver James identifies each of the three dark triadic personality traits as typically being prevalent in the workplace (see also Machiavellianism in the workplace, narcissism in the workplace and psychopathy in the workplace). Furnham  (2010) has identified that the dark triad is related to the acquisition of leadership positions and interpersonal influence. In a meta-analysis of dark triad and workplace outcomes, Jonason and colleagues (2012) found that each of the dark triad traits were related to manipulation in the workplace, but each via unique mechanisms. Specifically, Machiavellianism was related with the use of excessive charm in manipulation, narcissism was related with the use of physical appearance, and psychopathy was related with physical threats. Jonason and colleagues also found that the dark triad traits fully mediated the relationship between gender and workplace manipulation. The dark triad traits have also been found to be fairly well-represented in upper-level management and CEOs.
Recent studies have found that people who are identified as trolls tend to have dark personality traits and show signs of sadism, antisocial behavior, psychopathy, and Machiavellianism. The 2013 case study suggested that there are a number of similarities between anti-social and flame trolling activities and the 2014 survey indicated that trolling is an Internet manifestation of everyday sadism. Both studies suggest that this trolling may be linked to bullying in both adolescents and adults.
As a mating strategyEdit
Studies have suggested that on average, those who exhibit the dark triad of personality traits have an accelerated mating strategy, reporting more sex partners, more favorable attitudes towards casual sex, lowered standards in their short-term mates, a tendency to steal or poach mates from others, more risk-taking in the form of substance abuse, a tendency to prefer immediate but smaller amounts of money over delayed but larger amounts of money, limited self-control and greater incidence of ADHD symptoms and a pragmatic and game-playing romance style. These traits have been identified as part of a fast life strategy that appears to be enacted by an exploitative, opportunistic, and protean approach to life in general and at work.
The evidence is mixed regarding the exact link between the dark triad and reproductive success. For example, there is a lack of empirical evidence for reproductive success in the case of psychopathy. Additionally, these traits are not universally short-term-oriented nor are they all impulsive. Furthermore, much of the research reported pertaining to the dark triad cited in the above paragraph is based on statistical procedures that assume the dark triad are a single construct, in spite of genetic  and meta-analytic evidence to the contrary.
Several academic studies have found evidence that people with dark triad personalities are judged as slightly better-looking than average on first sight. Two studies have determined that this is because people with dark triad traits put more effort into their appearance, and the difference in attractiveness disappears when "dressed down" with bland clothing and without make up. Two more studies found that only narcissistic subjects were judged to be better-looking, but the other dark triad traits of machiavellianism and psychopathy had no correlation with looks.
The five factor model of personality has significant relationships with the dark triad combined and with each of the dark triad’s traits. The dark triad overall is negatively related to both agreeableness and conscientiousness. More specifically, Machiavellianism captures a suspicious versus trusting view of human nature which is also captured by the Trust sub-scale on the agreeableness trait. Extroversion captures similar aspects of assertiveness, dominance, and self-importance as narcissism. Narcissism also is positively related to the achievement striving and competence aspects of Conscientiousness. Psychopathy has the strongest correlations with low dutifulness and deliberation aspects of Conscientiousness.
The honesty-humility factor from the HEXACO model of personality is used to measure sincerity, fairness, greed avoidance, and modesty. Honesty-Humility has been found to be strongly, negatively correlated to the dark triad traits. Likewise, all three dark triad traits are strongly negatively correlated with Honesty-Humility. The conceptual overlap of the three traits which represents a tendency to manipulate and exploit others for personal gain defines the negative pole of the honesty-humility factor. Typically, any positive effects from the DT and low H-H occur at the individual level, that is, any benefits are conferred onto the beholder of the traits (e.g., successful mating, obtainment of leadership positions) and not onto others or society at large. A study found that individuals who score low in Honesty-Humility have higher levels of self-reported creativity.
Several researchers have suggested expanding the dark triad to contain a fourth dark trait. Everyday sadism, defined as the enjoyment of cruelty, is the most common addition. While sadism is highly correlated with the dark triad, researchers have shown that sadism predicts anti-social behavior beyond the dark triad. Borderline personality disorder and status-driven risk-taking have also been proposed as additions.
Vulnerable dark triadEdit
The vulnerable dark triad (VDT) comprises three related and similar constructs: vulnerable narcissism, factor 2 psychopathy, and borderline personality disorder. A study found that these three constructs are significantly related to one another and manifest similar nomological networks. Although the VDT members are related to negative emotionality and antagonistic interpersonal styles, they are also related to introversion and disinhibition. The study does note however that its findings are based largely on the self-reports of parents of White undergrad students rather than information gleaned from clinical evaluation.
Within the clinical/pathological realm, narcissism can manifest itself in a particularly severe form known as malignant narcissism. Malignant narcissism presents not only with signs and symptoms of grandiose narcissism, but also includes features of paranoia, sadism, aggression, and psychopathy (particularly antisocial behaviors).
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