Why this tendency is found among extraverts is disputed. Some suggest that extraverts have higher sex drives, and others suggest that they exhibit lower levels of cortical arousal, which they feel the need to constantly stimulate with sex. While extraversion and promiscuity were positively correlated across cultures, they were least correlated with one another in Western cultures.
While Schmitt found no correlation between promiscuity and neuroticism, other studies have (although he notes that in some studies it has been correlated with marital distress and sexual dissatisfaction). He cites other studies noting a higher degree of permissive sexual attitudes, unsafe and riskier sexual practices, as well as one study which found that pregnant and post-partum cocaine users had neuroticism as the single strongest personality-related predictor of risky sexual practices.
He suggests that the reason for this may have to do with neurotics exhibiting lower degrees of impulse control, as well as a tendency to use promiscuity to cope with overwhelming negative affect.
Schmitt notes the tendency of impulsive-sensation seeking, which can be described in terms of a kind of combination of low conscientiousness and low agreeableness, as very highly correlated with promiscuity. Those high in sensation-seeking tend to produce more children and have more partners. Male sensation-seekers in particular are less likely to use protection during sex and more likely to solicit prostitutes.
The personality trait of Machiavellianism, especially among men, tend to be more permissive towards sexual attitudes and tend to be more promiscuous. Schmitt likewise cites Eysenck’s trait of psychoticism as a trait correlated with low agreeableness and low conscientiousness. The latter has likewise correlated psychoticism with permissive sexual practicesa nd attitudes.
He cites another study that found that those with low conscientiousness and low agreeableness showed a greater probability of being unfaithful within the first four years of marriage. Schmitt predicts in his paper that low agreeableness and low conscientiousness will both be correlated with both promiscuity and infidelity. More specifically, he believes that these associations will obtain more with respect to infidelity than promiscuity.
In another study correlating personality traits with sexual promiscuity:
From an evolutionary perspective, large differences in personality between the sexes make perfect sense. Divergent sexual selection pressures on men and women are expected to produce substantial differences in personality traits that influence mating and reproductive strategies. For example, sexual promiscuity is predicted by extraversion, openness to experience, neuroticism (especially in women), positive schizotypy, and the ”dark triad” traits (i.e., narcissism, psychopathy, and Machiavellianism). Negative predictors of promiscuity and short- term mating include agreeableness, conscientiousness, honesty, and autistic-like traits. Relationship instability is associated with extraversion, neuroticism, low agreeableness, and low conscientiousness. In addition to their direct influences on predispositions for sexual promiscuity and relationship instability or sexual monogamy and parental investment, personality traits may also influence competitive tendencies such as status-seeking and risk-taking(Maestripieri, 2012).
Schmitt, David P. The Big Five Related to Risky Sexual Behaviour Across 10 World Regions: Differential Personality Associations of Sexual Promiscuity and Relationship InfidelityEuropean Journal of Personality. Eur. J. Pers. 18: 301-319 (2004). Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/per.520
Maestripieri, Dario (2012). Gender Differences in Personality Are Larger than Previously Thought. Retrieved from: http://www.psychologytoday.com/blog/games-primates-play/201201/gender-di…