Psychologists, perhaps more than other researchers, are known to occasionally push the boundaries of believability with their findings. It’s a hallmark of the discipline. It’s part of what makes psychology so interesting to a general audience, but it also opens the door to some potentially problematic and dodgy science.
"Trust, but verify" might be the correct approach when assessing some of the more dubious findings in psychological research. New research appearing in the journal Personality and Individual Differences sought to do exactly that. A team of psychologists led by Tara DeLecce of Oakland University revisited a fascinating but controversial claim—that male ejaculate quality could be linked to certain personality traits such as self-confidence, extraversion, and social assertiveness.
"Ejaculate quality is a measure of fertility that includes sperm motility, count, concentration, velocity, and morphology," state DeLecce and her team. "Some research has reported relationships between personality dimensions and ejaculate quality, but this research has methodological limitations. […] In the current study, we investigated the relationships between six major personality dimensions and ejaculate quality in a design that offered several methodological improvements over previous research."
To accomplish this, DeLecce and her team recruited 45 men between the ages of 18 and 34 to participate in a multi-phased experiment. To qualify for the study, men had to be in a heterosexual and sexually active relationship. They could not have undergone treatment for infertility in the past nor could they have had a vasectomy.
The experiment took place in three separate sessions. In the first session, participants were asked to take a series of self-report personality tests. During this session, the researchers also collected several body measurements, including height, weight, and BMI. Then, participants were given the materials they would need to collect and transport two masturbatory ejaculates. Participants were informed to abstain from ejaculating for at least 48 hours before each masturbatory session and to return the ejaculate samples to the laboratory within one hour of ejaculation.
Next, the researchers analyzed participants’ sperm quality and assessed its correlation with six core dimensions of personality: honesty-humility, emotionality, extroversion, agreeableness, conscientiousness, and openness to experiences.
Here’s what they found. An initial analysis revealed that both agreeableness and openness to experiences were significantly related to ejaculate quality, such that more agreeable and open men were shown to have lower ejaculate quality. However, a more stringent statistical test that took into account other pieces of information such as age, BMI, and abstinence duration revealed a non-significant association between ejaculate quality and openness to experiences and a weakened association between agreeableness and ejaculate quality. Furthermore, none of the other personality dimensions showed any reliable connection with ejaculate quality.
The authors conclude, "We provided preliminary evidence that agreeableness may be negatively associated with ejaculate quality, although we caution that this relationship warrants replication by future research. The current study adds to a body of evidence indicating that psychological attributes—including major dimensions of personality—may be associated with ejaculate quality."
DeLecce, T., Lopes, G. S., Zeigler-Hill, V., Welling, L. L., Shackelford, T. K., & Abed, M. G. (2020). A preliminary but methodologically improved investigation of the relationships between major personality dimensions and human ejaculate quality. Personality and Individual Differences, 153, 109614.