Study links male ejaculate to personality traits


Maggie Willard

Tara DeLecce

Taylor McDaniel, Staff Reporter

While certain psychological research may be cut and dry, in more ways than one, that criteria does not apply to a recent paper published in the “Personality and Individual Differences” journal on the relationship between human ejaculate quality and major personality dimensions by members of the psychology department at Oakland University. 

One of said members includes Tara DeLecce, a postdoctoral researcher and special lecturer. DeLecce cited her involvement as a postdoc after data collection was wrapped up as a “bit of an accident” as initially the research was part of a broader study on sperm competition. 

“[Sperm competition] is the idea that males of many species will adjust their semen quality to be better so that they can compete with other sperm of rival males that may already be in a woman’s reproductive tract,” DeLecce said. 

Flyers were put up on the bulletin boards on campus as one way to prompt participants into the study. The men had to be heterosexual and in sexually-active, committed relationships in order to take part. 45 total men were included in the analysis that DeLecce and other members of the psychology department, such as Dr. Lisa Welling, completed. 

“A lot of my work focuses on hormonal mechanisms involved in interpersonal relationship behaviors and mate choice, so I was interested in other biological markers and human sexuality, such as psychological sources of variation in ejaculate quality,” Welling said via email on her involvement in the paper. 

Participants of the study were given a written story of different scenarios that would prime sperm competition. The control condition plot was the significant other spent all of their finances gambling while the experimental was their partner had cheated on them and that they were having sexual relations for the first time since. 

The men would masturbate on two separate occasions, thinking about one of the scenarios for each time, and collect the ejaculate. The sample had to be taken to the lab on campus within an hour, before the sperm would begin to die, according to DeLecce. 

However, the data revealed that there was no significant difference in ejaculate quality between the two scenarios. Ejaculate quality was analyzed in a SQA-V machine in the semen lab via light beam analysis. 17 different parameters were measured including velocity, concentration, and motility, which has its own subsections. 

Although the sample size was smaller than preferred, the team welcomed any figures they could obtain. 

“It’s hard to get this type of data,”  DeLecce said. “We collected everything we could possibly get.” 

Body measurements, shoulder-to-hip ratio, testes size, IQ measures and personality tests were just a few of the figures collected from the participants. The team used HEXACO Personality Inventory, measuring six main facets in terms of personality, standing for: Honesty-humility; Emotionality; eXtraversion; Agreeableness; Conscientiousness; Openness to Experience. Statistically, the test has proven to perform well, according to DeLecce. 

It was discovered throughout the study that there was a high correlation between personality measures and sperm quality, specifically a negative relationship between agreeableness and ejaculate quality. 

While there are some theories as to why this relationship may exist, a disclaimer that DeLecce strongly stands by is the fact that there is much more research to be done. It cannot definitively be said that a lack of agreeableness is linked to a high sperm count, just that there happened to be a correlation, not even a strong one, in this particular study. 

“It could be that we needed a larger sample size or that it was just a weird fluke,” DeLecce said. 

Research studies such as these can potentially help with idiopathic infertility, or no explained cause for infertility. 

“[Idiopathic infertility] has been on the rise in the past 50 years,” DeLecce explained.
“If we could better understand these different relationship level dynamics that could potentially be affecting infertility it could help and have some uses.”