The relationship between infidelity risk and oral sex: An independent replication of Pham and Shackelford (2013) and Pham et al. (2013)

In two studies, Pham and Shackelford (2013) and Pham et al. (2013) analyzed the relations between oral sexual behavior and partner infidelity risk in heterosexual couples. They found that indicators of partners' risk of infidelity were significantly associated with men's, but not women's interest in, and time spent performing oral sex after controlling for relationship length, relationship satisfaction and duration of sexual intercourse. We conducted a preregistered close replication of the methods and analyses of these studies using two distinct samples. In both samples, partner infidelity risk was not significantly associated with greater interest in and duration of oral sex for men or for women. The associations between infidelity risk and oral sexual behaviors were not significantly different between men and women, consistent with the original research. Exploratory analyses showed participants who suspected their partners of being unfaithful had significantly lower scores on the partner infidelity risk measure than those who did not hold those suspicions in Sample 1, while no significant difference emerged in Sample 2. These findings challenge the validity of the original partner infidelity risk measure. Overall, the current study offers contradictory evidence for the proposed evolutionary explanation for the adaption of oral sexual behaviors in humans. •Oral sex has been suggested to be an adaptation to detect unfaithful partners.•Oral sex has been shown to be related to partner infidelity risk for men, not women.•Only null results regarding this association were replicated for women.•A statistical error was identified in the original article.•Support for this proposed evolutionary explanation of oral sexual behavior is mixed.