What Kind of Porn do Men Prefer?
The science of pornography, sperm competition, and penile plethysmography
What kind of porn do men prefer? That’s a dangerous question: human sexuality is as varied as a rainbow. A rainbow that leads to a bucket of sex toys guarded by a leprechaun in a leather gimp mask. To put it simply, people are filthy. Whack any random words you can think of into a search engine followed by ‘porn’ and hit enter, and you’re bound to get 20 million results. I’ll leave you to test that theory on your office computer…
Point is, can we make scientific predictions about the kind of porn that appeals to most men? Pavol Prokop of Trnava University in Slovakia certainly thinks so. This month he published a paper testing his theory that men prefer pornography with low levels of what scientists call ‘sperm competition’.
What’s sperm competition? Well, let’s take a step back. We all know that in many species, including humans, males compete for sexual access to females. Think rutting stags or rhinos that pummel each other into submission with their antlers and horns, or birds of paradise that try to impress females with their bright plumage and funky dance moves. What sperm competition theory says is that this male-male rivalry extends beyond securing a partner, beyond even the sex act itself. The idea is that the sperm compete inside the female to fertilise her egg.
This theory has led to weird and wonderful claims of kamikaze sperm that sacrifice themselves in battle so that their brethren have a better chance of making it to the egg, but it has also explained why some male beetles plug up their mate’s reproductive tracts with a quick-drying glue to prevent other males from depositing their own sperm, and why corkscrew shaped penises or penises with hooks and barbs evolved almost as weapons of war to guarantee conception. There are even some who hypothesise that the glans of the human penis acts as a kind of plunger to remove the semen of other men from a woman’s vagina. Now there’s a nice image…
Anyway, sperm competition theory is definitely a colourful research area, but it has a lot of serious scientists behind it. The point I want to make is, it’s not as crazy as it sounds.
So, Prokop found a list of the most famous female porn stars and downloaded each of their freely available videos. Freely available, mind! No taxpayer money was spent on porn in this study. Prokop was looking for three types of video. One in which the actress had sex with two other women, one in which she had sex with one man, and a third in which she had sex with two men. The reasoning was that each of these scenarios presents different levels of sperm competition.
When there are no men, there’s no sperm, and hence no sperm competition. When there’s one man, there’s sperm but no sperm competition. However, if we think of the male viewer of the video as the second man — the fantasy participant in the scenario — then there is some hypothetical sperm competition. When the actress has sex with two men, however, there is visual evidence of very real sperm competition: two men, two types of sperm, only one likely to lead to conception. Well, let’s be honest, this is porn: none of that sperm is making it anywhere near an egg. But you get the idea.
Prokop’s volunteers were asked to look at screen caps from each porn star’s three videos. They then chose the image that they found most arousing. The results of the study showed that men preferred pictures with a “moderate intensity of sperm competition”, i.e. the pictures showing one woman with one man. This type of image was chosen 600 times by Prokop’s 100 volunteers. Low sperm competition intensity — woman on woman action — was preferred 250 times. Images depicting high sperm competition — a woman with two men — were chosen only 115 times. So men are turned on by some level of sperm competition, but are turned off when that competition gets too strong.
If you’ve been reading closely, I hope you have already spotted one problem with this experiment: like the Armstrong and Reissing study into women’s reasons for having sex, it’s based entirely on self-report. What men say they find most arousing may not match up with that they actually prefer. The men may feel that a preference for viewing lesbian sex or sex involving multiple male partners is wrong somehow, less ‘normal’ or ‘healthy’ than enjoying good old fashioned one-man-one-woman porn. Some scientists use a piece of equipment called a ‘penile plethysmograph’ to record more objective measures of arousal: it’s a kind of rubber band that’s slipped over the penis and hooked up to a computer, to register cold hard data on a man’s turgidity.
Also, when we talk of sperm competition are we really talking about sex in the presence of other men? It could be possible that these straight volunteers weren’t bothered too much by sperm competition, but rather by the sight of multiple naked men.
At any rate, these results contradict those from previous studies that show multiple male videos are much more prevalent online than multiple female videos, and evidence that the number of men interacting with a single woman on a DVD cover is a good predictor of a high sales ranking for that DVD. However, it could just be that men who are turned on most by evidence of sperm competition make up a bigger percentage of the market for porn: if this group of men buys more porn, of course the porn market will grow to match their preferences.
What these men find so arousing about multiple-male-single-female sex remains to be discovered. Perhaps sperm competition exerts some kind of subliminal turn on, or maybe the presence of the superfluous men is arousing for some other reason. Clearly there’s more research to be done, and, as Prokop points out “the evolution of human mating systems is not likely to be resolved in the near future”.
Prokop, P. (2015). Perception of intensity of sperm competition on the part of males. Personality and Individual Differences, 76, 99–103. Read summary
The content of this post first appeared in the Jan 2015 episode of The Psychology of Attractiveness Podcast.
