Does Erotica by Virtual Reality Improve Sperm Quality
Phase: NA
Conditions: Virtual Reality
Sponsor: Cryos International

Does Erotica by Virtual Reality Improve Sperm Quality?  
 
Study Protocol and Statistical Analysis Plan 
 
NTC no.: N/A 
Date: 27JUN2022 

Sperm samples were donated in private rooms dedicated for the purpose and equipped with a touch 
screen showing erotic material. The men were asked to donate as usual and self-report the amount 
of time (in hours) since their last ejaculation (the abstinence period). Every other donation, donors 
rolled dice to determine whether a VR headset would be used; with the subsequent donation 
performed with the opposite condition. To maximize privacy and minimize stress on the donors, the 
amount of time the donors took to produce a sperm sample (donation period) was recorded as the 
number of seconds from closing the door to the private room to when it was opened again. 
 
Each semen sample was weighed to determine ejaculate volume and allowed to liquify at room 
temperature for up to 1 hour. After liquefaction, aliquots were loaded in duplicate onto Makler 
counting chambers (Sefi-Medical, Israel) and observed at 200x magnification using an Olympus 
CX41 microscope (Olympus, Japan). Measurements of sperm concentration, motility and motile 
sperm concentration were made using a MICROPTIC, S.L. (Barcelona, Spain) Computer Assisted 
Sperm Analysis system with at least 500 cells counted per analysis. No analysis of sperm morphology 
was performed. 
 
Statistical Analyses 
Data was anonymized prior to analyses and no data was excluded (Supplementary Material Table 
S1). We used linear mixed models (LMMs) to assess the relationship between VR-use and ejaculate 
volume, donation period and total motile sperm count (TMSC) for each ejaculate sample, while 
controlling for several factors that might also influence ejaculates: (i) abstinence period, (ii) donor 
age, (iii) donor BMI, (iv) day of the year (season), and (v) location (donation site). In each model, we 
included anonymized donor identity as a random effect to avoid pseudo-replication as each donor 
provided multiple samples. The interaction between VR-use and abstinence period was initially 
included in models as abstinence period is known to increase ejaculate size and quality [16,17] though 
sometimes a decrease has been observed. We considered it to be at least plausible that the influence 
of VR might diminish as abstinence period increased and both ejaculate size and quality approached 
their maxima for each donor. We removed those interaction terms from models when p-values for the 
interactions was >0.20. 
 

To investigate the relative strength of plausible causal relationships among the variables in our 
LMMs, we used piecewise structural equation modeling. To construct this model, we assumed that 
VR use might have a direct effect on ejaculate size, donation period and TMSC, and that ejaculate 
volume and donation period might have direct effects on  
 
We used R version 4.2.0 for analyses, with packages lmer and lmerTest for LMMs. For interaction 
plots we used the sjPlot package. For piecewise structural equation modeling, we used the pSEM 
package with the lme function (nlme package) for mixed models and anonymized donor identity 
nested within location as random effects. To predict the magnitudes of effects from the full LMMs, 
we used the ggpredict function in the ggeffects package. All such effects are reported as mean 
[95%CL] calculated by setting the other predictors in the full models at their mean values.