Do Men Produce Higher Quality Ejaculates When Primed With Thoughts of Partner Infidelity?

Abstract

Sperm competition theory can be used to generate the hypothesis that men alter the quality of their ejaculates as a function of sperm competition risk. Using a repeated measures experimental design, we investigated whether men produce a higher quality ejaculate when primed with cues to sperm competition (i.e., imagined partner infidelity) relative to a control prime. Men ( n = 45) submitted two masturbatory ejaculates-one ejaculate sample for each condition (i.e., sperm competition and control conditions). Ejaculates were assessed on 17 clinical parameters. The results did not support the hypothesis: Men did not produce higher quality ejaculates in the sperm competition condition relative to the control condition. Despite the null results of the current research, there is evidence for psychological and physiological adaptations to sperm competition in humans. We discuss methodological limitations that may have produced the null results and present methodological suggestions for research on human sperm competition.

Life history correlates of human (Homo sapiens) ejaculate quality.

“…The target sample size for the study at conceptualization was 100 men. The target sample size was determined based on the primary aim of the study (within-subjects design; Pham et al, 2018). After 3 years of data collection (and before data analysis), a consensus was reached to stop data collection in May 2016.…”

“…Methodological information relevant to the current study aim is reported here. Full methodological details are also reported in the article by Pham et al (2018). All procedures were approved by the institutional review board of the university where data were collected.…”

“…The current study presents an initial investigation of the association between life history strategies and ejaculate quality in humans. We analyze data from a larger experimental study (Pham et al, 2018) that secured several self-report measures—including a widely used measure of human life history strategy (Figueredo et al, 2006)—and obtained two masturbatory ejaculates from each participant. Using these data, we tested whether life history strategy indicators are associated with ejaculate quality across several clinical parameters.…”

Disengaged, exhaustive, benevolent: Three distinct strategies of mate retention

“…In parallel with previous research on mate retention (Buss et al, 2008; Lopes et al, 2016), this sample included only individuals in a romantic relationship with the opposite sex for at least 3 months. We invited prospective participants through: (1) Amazon Mechanical Turk (MTurk): interested and eligible individuals could access and complete an on-line survey, and those who completed the survey received U$2.50; (2) the Psychology Department Subject Pool at a large Midwestern U.S. university: interested and eligible individuals were provided a link to an online survey, and those who completed the survey received partial course credit upon completion (Lopes et al, 2017); and (3) advertising on bulletin boards on the campus of the same Midwestern U.S. university: interested individuals contacted the researcher, and those who met the participation criteria and agreed to participate were escorted to a private room to answer an in-person survey and received U$25 at the conclusion of the survey (Pham et al, 2018). The current article reports novel analyses of a subset of data from different projects.…”

Of mice and women: advances in mammalian sperm competition with a focus on the female perspective

“…Further, as a potential mechanism of cryptic female choice, exciting new research has demonstrated that sperm chemoattractants produced by eggs may facilitate gamete-mediated 'mate choice' in humans [101]. The study of adaptations to human sperm competition has traditionally bordered the fields of behavioural ecology and evolutionary psychology [102]. Now it seems that this fascinating area of research is reaching into the realm of reproductive biology in relation to the role that the FRT, specifically oviductal fluid and sperm chemoattractants, plays in determining postmating 'mate choice' outcomes.…”