Essays - Most men are too small for most women (Part 1/3)
This article discusses issues of penis size based on a fascinating study from 2015 that investigated women's size preferences with 3D-printed penis models.
A fascinating study titled “Women's Preferences for Penis Size: A New Research Method Using Selection among 3D Models” was published in 2015 in the open journal PLOS ONE by researchers at the University of California. It sheds light on women’s preferences when it comes to penis size, among other interesting questions surrounding this topic. In this first part, we delve into the design of the study, the choices made by the researchers, and who the participants were.
3D-printed penis models
What is particularly interesting about this study is that it did not rely on surveys asking women what their ideal penis size was. The problem with such surveys, of course, is the phenomenon of “girl inches”, where women tend to overestimate the size of a penis when they’re trying to guess how long it is in inches. In reality, this is just a byproduct of humans not being very good at guessing the size of things accurately enough, and it is not specific to women.
Another approach that has been used in this type of research is to have women participants look at pictures of penises of different sizes, whether real or simulated, and asking them about their preferences with respect to those images. This is an improvement on simply letting women guess, but it’s still not ideal because an image is only two-dimensional.
The novelty in this study is that the researchers used actual 3D-printed models of penises of different sizes that the participants could not only see, but touch and manipulate with their hands. The researchers did not try to replicate realistic copies of penises, probably because that would be a hell of a lot of work. The excuse they provided in the paper, however, was that realistic models might run the risk of triggering certain participants by evoking negative emotions. Thus, they resorted to simple cylinders with a dome on top to distinguish the base from the tip. The cylinders were blue to avoid any racial connotations.
The researchers made some clever decisions to minimize bias in their study. For example, they did not label the cylinders in any meaningful way that could bias a participant’s view or provide information about its size. They also shuffled the cylinders in three baskets between participants to avoid one’s selection from influencing the next. They also only advertised the project as “a study concerning sexuality” with no mention of penis size. They paid participants $20 for their time volunteering.
What is average?
The authors had to make a choice for the size of each model. Their strategy, a sound one, was to start from the average penis size in terms of length and girth, and then vary both dimensions (length and girth) in both directions (bigger than average and smaller than average). The question then was what was the average size of the penis in the male population?
This question is surprisingly hard to answer from the literature. Let’s only consider penis length to make it simpler. The overwhelming majority of research that aims to ascertain what the average penis length is relies on two methods. The first involves asking men to measure the length of their erect penis themselves and report the measurements. Any man reading this will immediately see the problem with this method: men almost always report overestimates of their real length. Whether this is intentional or unintentional doesn’t matter.
The second method used is the “stretched penis” measurement, whereby a study participant would have his penis stretched in the flaccid state and the length measured would be taken as a reliable predictor of the erect length. In fact, this turns out to be an unreliable indicator. This method sadly survives, however, because it is better than asking men to report their size on their own.
Reading this, you might question why researchers interested in finding out the average penis size wouldn’t just measure the erect penis itself. To do this, you would have to induce erections in participants. The natural way to do this is to have participants view sexually explicit imagery while a nurse stands by waiting for the penis to become erect before measuring it. This would be a truly awkward experimental setting, both for the person doing the measuring and the participants.
But even if you did manage to make it happen somehow, there are unsurmountable obstacles. Think of the participants who would be too anxious to achieve an erection. Think as well of participants who wouldn’t be comfortable enough to show their penises in such a setting, and would thus choose to drop out of the study. This sounds like a recipe for introducing a bias towards a bigger penis size in the participants who go through with the study.
The only other way of doing it is to induce erections pharmacologically by injecting a drug into the penis that does the job. In this setting, you wouldn’t have to worry about social taboos, since no sexual arousal would be involved or needed. Likewise, you wouldn’t have to worry about anxiety or “performance issues” since this is inconsequential on the drug’s guaranteed action of inducing a full erection of the penis.
It turns out that there are very few studies that use this protocol, and those that do have small sample sizes. The reason, we can speculate, is that these drugs are expensive, and nobody seems willing to run a large-scale expensive study just to investigate the distribution of penis size in the population.
One thing that stood out to me in this paper is how the researchers took the average length of the American penis to be 6 inches, which is provably false. The real average length of the penis in the United States lies somewhere between 5 and 5.5 inches, depending a host of factors including ethnicity. (See here and here for example) Interestingly enough, the lead author of the paper is a woman, and one can speculate on her own biases in selecting 6 inches as the average length.
In reply to one reader’s comment online, this lead author defended her choice: “Our figures only included erect models. Most of the data reported on penis size are for flaccid size. These figures are fairly close to average erect sizes in the USA so far as we know them.” In other words, given the lack of adequate research into proper erect size, the researchers went with the average erect size “as they knew it”.
In any case, this choice did not matter, as many models were made. The researchers took the “average” length and girth, and varied both of them with 10 increments of 0.5 inch in both directions. This meant there were 100 possible models they could produce, but this would obviously overwhelm the participants in the study. For this reason, they decided to sample a third of the space of possible measurements. In other words, they randomly selected 33 models out of the 100 possibilities of combined length and girth measurements.
Lesbians attracted to men
The sample size in this study was very small. Only 75 women participated in total and not all of them answered all the questions. The women were white, Asian, Hispanic, and Black, in different proportions. Their mean age was around 24. On average, the women had 3.2 intercourse partners in the last year, while they had an average of 6 partners in their lifetime.
This might seem odd at first, but it looks like most of the women were young university students, so one can speculate that most of their intercourse partners had been recent experiences within the year prior to the study. The women “touched” on average 6.8 penises in their lifetime, which is higher than the average number of intercourse partners, indicating that the women had some sexual partners that they didn’t have intercourse with.
One big problem with the study is that the authors didn’t exclude women who identified as “lesbian” or even “asexual”. Indeed, only 36 women out of the 75 identified as heterosexual; 10 identified as bisexual; 8 as lesbian; 6 as asexual; 3 as queer; and the remaining 11 “did not identify”. A rigorous study would have only kept the heterosexual and bisexual women, but the authors disagreed.
The authors wrote: “Recall that participants were required to report attraction to men to participate, thus a ‘Homosexual/Lesbian’ self-identity did not preclude attraction to men.” It seems like the authors meant to say that a lesbian self-identity did not preclude attraction to an easily made $20.
This is troublesome, especially because the data that were made available don’t contain the question on sexual orientation, and therefore it’s impossible to re-do the analysis of the results excluding certain groups that should have been excluded in the first place.
One can believe what the authors gave as a justification, or one can speculate that the authors preferred to keep a big sample size (n = 75) rather than cut it down to what it should have been (n = 46 heterosexual and bisexual women), which could have compromised the study’s reliability.