Sticking To The Content: Response To "Red Herring: Hook, Line, and Stinker", by Gabe Deem

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I am certainly not alone in my grave concerns about the Nicole Prause & Jim Pfaus ED paper (P&P). Recently, Sexual Medicine Open Access published a Letter to the Editor by Richard A. Isenberg MD, which made many of the same observations as did my critique.

As is customary when a letter critical of a study is published, the study's authors were given a chance to respond. Prause's pretentious response entitled "Red Herring: Hook, Line, and Stinker" not only evades Isenberg's points (and mine), it contains several new misrepresentations and several transparently false statements. In fact, Prause's reply is little more than smoke, mirrors, groundless insults, and falsehoods. On a side note, check out this twitter convo where Prause attempts to substitute insults about Isenberg for substantive replies to his many valid objections:

"@DrDavidLey definitely the most amusing letter I've had the chance to publish. Fun when the first writer cannot spell, math, or think!"

It's unfortunate that she had "fun" instead of actually answering his concerns. She appears to be spinning a Big Fish Story littered with false statements and misrepresentations. I will address Prause's claims in the order of her reply.


The Missing Subjects

Prause begins by boldly claiming that Isenberg was mistaken, and that she had already accounted for 280 participants:

"The author describes “discrepancies” in participant counts, but no discrepancies exist. Table 1 shows all 280 participants, including the subsample with International Index of Erectile Function (IIEF) scores."

This is the first of several false statements by Prause. It is irrefutable that discrepancies existed in her original paper, and these still have not been explained. For example, guess how Prause now claims to get from the 234 subjects Dr. Isenberg counted in the 4 underlying studies to 280, the total subjects she claimed? Simple. She now asserts that a 5th study exists: Moholy and Prause (circled below). This is an unpublished study not mentioned in the original Prause & Pfaus ED paper. No one can see it, so no one can check it or challenge it!

This unpublished paper, which may never be accepted for publication, is now brazenly and improperly tacked onto the existing paper, which has already been published (and supposedly peer-reviewed). How can you publish a study and say it's peer-reviewed, when data it contains and bases its claims on have not been peer-reviewed? Riddle me that.

The original P&P ED paper explicitly states (in error) that all the subjects and data were culled from these four studies (study 1, study 2, study 3, study 4):

"Two hundred eighty men participated over four different studies conducted by the first author. These data have been published or are under review [33–36],"

Either the original ED paper is inaccurate, or the current response tacking on a 5th, unaccepted study is a slight-of-hand.

Why doesn't this mysterious 5th paper add subjects to any other categories in the table? Look below its title in her table (above) and you will see two big fat zeros. Very fishy indeed.

Anyhow, as explained in my original critique, 280 was an empty number, mentioned for headline purposes only. The P&P paper was supposedly about ED in 280 (sic) men, yet it reported erectile functioning scores for a mere 127 men (IIEF). And even that figure (already much lower than the 280 in the headlines) was unsupported by the 4 underlying studies on which the ED paper purports to rest. That is, P&P may have claimed that 127 (or 133) men took the IIEF, but the underlying studies reported only 47 subjects. This glaring discrepancy still has not been explained.

Her table reveals a second sleight-of-hand. Prause now claims that 92 men, from 1 of the 4 studies (Moholy et al), took the IIEF. First problem: that particular study makes no mention of the IIEF. Second, much bigger, problem: that study lists only 61 male subjects (table 1 pg 4). Uh oh, guess 31 fish got away.

Summary of Prause's new assertions:

  1. Prause conjures up a 5th unpublished study no one can check in an attempt to get her subject-count up to 280: Moholy and Prause (under review). This new development directly contradicts P&P ED paper. Suspiciously, the extra 52 men are nowhere else to be found in the original P&P ED paper.
  2. To get to 127 men for the IIEF, Prause announces that 92 missing men were somehow present in Moholy et al. Unfortunately, that study made no mention of the IIEF, and lists only 61 male subjects.

I guess I'll need to add these two additional discrepancies and misrepresentations to the eight in my original critique. By the way, 1 and 2 above render her paragraph that starts with "Secondary analysis..." meaningless.


Each Study Used a Different Arousal Scale

Headlines for the P&P ED paper consistently claimed that porn use increased sexual performance. Shockingly, Jim Pfaus falsely claimed in an TV interview that P&P assessed men's ability to achieve a erection in the lab. Pfaus also falsely stated: "We found a liner correlation with the amount of porn they viewed at home, and the latencies which for example they get an erection is faster."

In reality, the study only asked men to rate their arousal after viewing porn. No erections or latencies were tested. The finding: Men who watched more porn rated their arousal slightly higher than men who watched less porn. That's called sensitization, not "better performance". P&P's claims that porn use leads to greater arousal are dependent upon all four studies using the same arousal scale and the same stimulus. Neither occurred.

Prause tries to explain away the fact that none of her four underlying studies used the same "arousal scale" for porn viewing. Here's what the original P&P ED paper actually said:

"Men were asked to indicate their level of “sexual arousal” ranging from 1 “not at all” to 9 “extremely.”

As Isenberg and I pointed out, only 1 of the 4 underlying studies used a 1 to 9 scale. One used a 0 to 7 scale, one used a 1 to 7 scale, and one study did not report sexual arousal ratings. Even more confusing, the sexual arousal graph in the P&P paper used a 1 to 7 scale. Two glaring mistakes in the original paper.

Instead of apologizing for the original paper's false statements and graph errors, Prause now offers Isenberg a lesson on what researchers might theoretically do with different number scales:

"The author of the letter also made a false statistical statement: “Results from different Likert scales are not poolable”. Of course they are! In fact, there are at least three different methods to pool them."

That's great to know, but there's absolutely no indication that Prause pooled the four different arousal scales. I suspect she didn't as 1) she would have said so, 2) one of the studies had no scale, so couldn't be pooled using any method, and 3) she refused to acknowledge her earlier errors, so why would she acknowledge this one?


Studies Used Different Sexual Stimuli

Not only did the four underlying studies have different arousal scales (or none), they used different stimuli. Two of the studies used a 3-minute film; one study used a 20-second film; and one study used only photos. No researcher can do that and expect valid results. It's well established that films are more arousing than photos. What's shocking is that the original P&P ED paper falsely claims that all 4 studies used sexual films:

"The VSS presented in the studies were all films."

So how does Prause address this conspicuous methodological flaw and her study's false statement? With another false statement, or two, in bold:

"The author also made a false statement that stimuli varied between studies and this was not “controlled”. We assessed and controlled the stimuli as stated in our original article (“sexual arousal reported did not differ by film length, so data were collapsed across studies for this analysis”, p. E4)."

First false statement: Nowhere did Dr. Isenberg say that the stimuli "[were] not controlled."

Second false statement: The stimuli did vary among studies: 3-minute film, 20-second film, photos.

"Controlled for" is meaningless here, and Prause refuses to say how she magically managed to do the impossible: control for some guys viewing photos, while other watched 3-minute porn flicks.


Some of the Subjects Were Gay

Prause begins her next paragraph with yet another false statement:

"Finally, again contrary to the author's claims, there were not “four gay” men in any study.

Dr. Isenberg's only reference to "gay" was a listing of "including 4 gay" in his table under Prause's study "Biases for Affective Versus Sexual Content in Multidimensional Scaling Analysis: An Individual Difference Perspective (2013, Prause, Moholy, Staley). From page 2 of that study.

"A total of 157 (N=47 male, 1 transgender) psychology students over age 18 years participated in exchange for course credit. Most reported being heterosexual. Four males reported being homosexual and four reported being bisexual."

Four gay men, just as Dr. Isenberg stated. It seems Isenberg can "math" good enough to know that 4 means 4.

Why did Dr. Isenberg list 4 gay men in the table? It's well established (and common sense) that gay and straight men have very different brain responses to heterosexual porn. Including gay men, as Prause did, skews the "sexual arousal" results and her resulting correlations. It calls into question her findings.

In brain studies on addiction, or compulsive behaviors, valid results depend upon homogeneous subjects. Put simply, subjects must be the same sex, similar ages, similar IQs and, generally, all right-handed to produce valid results. Prause ignores standard protocols by having males, females and non-heterosexuals all watch heterosexual porn. You can't do that, as many studies confirm significant differences between males and females in response to sexual images (1, 2, 3, 4, 5). 

This is one of various reasons why Prause's 2013 EEG study on porn users was sharply criticized. The study's subjects differed (women, men, heterosexuals, non-heterosexuals), yet they were all shown the same standard male+female porn. This alone invalidates the study's claims that it "debunks porn addiction." Please be aware that Prause has already announced that she has employed this same flaw (mixed subjects) in a study, which she maintains debunks porn addiction once again. From her SPAN Lab website:

What scientist announces on their twitter account and personal website that their single, unpublished study "debunks" an entire field of research?


Hours Per Week Not Defined

This section takes some explaining, but it leads us to another manifestly false statement by Prause. In the following paragraph, Dr. Isenberg explains that P&P failed to fully describe hours per week of porn use. In other words, Prause failed to say if hours per week referred to the previous week, or month, or year, or who knows.

ISENBERG: "The hours-viewed parameter itself is poorly defined. We are not told if the self-report of hours referenced the preceding week, the average over the last year, or was entirely left to subject interpretation. Were there subjects who were previously heavy users who had recently cut down or eliminated their pornography viewing? Absent a well-defined and consistent referent, the porn use data is uninterpretable."

Prause responds by telling us what we already know - that she said "hours per week":

"The author claims we did not adequately describe the sex film view variable. We described that variable at least 13 places in the manuscript. (“weekly average” in abstract; “reported the average number of hours they consumed VSS per week”.....

Again, Dr. Isenberg wanted to know: Are you asking subjects about the "previous week", or "the last year", maybe "since you started watching porn", or some other time-frame? Prause ends her repetitive two-paragraph rant with yet another false statement:

"The question was exactly as described, “How much time per week did you spend using pornography during the past month?” with the response box including the descriptor “hours” for which they could indicate partial hour(s)."

Search the P&P ED paper and you will find no such question (mentioning the past month).

Prause follows up this false statement with two paragraphs arguing that hours per week is an appropriate measure. Dr. Isenberg wasn't commenting on its "appropriateness." He just pointed out that the data cannot be interpreted without knowing how the subjects understood the question. Since she had to make a false claim to respond to Isenberg's point, perhaps Prause's statement is the red herring she refers to in her pompous title.


Many More Variables Than Current Hours Per Week

One of the most common questions posed on recovery forums is, "Why did I develop PIED when my friends watch as much (or more) porn than I do?" Instead of only current hours per week, a combination of variables appears to be implicated in porn-induced ED. Dr. Isenberg highlights the importance of investigating many other variables before claiming, as the authors do, that porn-induced ED is a myth (and he doesn't even mention novelty of watching internet porn, arguably the most important factor):

ISENBERG: "Furthermore, the authors do not report on relevant viewing parameters such as total pornography usage, age of onset, presence of escalation, and extent of sexual activity with partner which may have bearing on male sexual functioning [11,12]."

In the above sentence, Dr. Isenberg cites two studies as examples of research that examined two additional variables: citation 11 employed 'years of porn use', and citation 12 employed 'age started porn use'. Prause spends the next paragraph attacking a straw man, namely, that Dr. Isenberg claimed both studies assessed every single variable he listed. Why didn't she instead explain why she didn't ask her subjects about important variables before drawing her unsubstantiated conclusion that porn isn't the culprit in youthful ED?


Average Erectile Scores Actually Indicate ED

While Prause admits to only a single oversight, it's fitting that she adds yet another misrepresentation to her apology (bold):

"We also recognize that we stated in one place that the IIEF was a “19-item” (p. E3) scale. The scale actually is a 15-item scale. We profusely apologize for this gross oversight, although the scores, results, and conclusions were accurate and indicative of normal erectile function"

As pointed out in my critique, P&P reported an average score of 21.4 out of 30 for the 6-item IIEF (average age 23). This is far from "normal erectile function" in 23-year olds. In fact, this score indicates "mild erectile dysfunction", leaning towards "moderate erectile dysfunction".


Still No Data Correlating IIEF Scores With Porn Use

Isenberg was also concerned that P&P offer inadequate data for their claim that no correlation existed between IIEF scores and hours viewed per week:

ISENBERG: Even more disturbing is the total omission of statistical findings for the erectile function outcome measure. No statistical results whatsoever are provided. Instead the authors ask the reader to simply believe their unsubstantiated statement that there was no association between hours of pornography viewed and erectile function. Given the authors' conflicting assertion that erectile function with a partner may actually be improved by viewing pornography the absence of statistical analysis is most egregious.

Red Herring leaves us hanging on this critical point. We're meant to swallow the authors' conclusions "hook, line and stinker."


Questions Were Raised About P&P's "Strong" Finding

The following excerpt, taken from the second paragraph, claims that Isenberg failed to raise questions about P&P's "strong" finding. Read carefully as Prause alters key words to give the reader a false impression:

"No questions were raised about the strong finding that the more men viewed sex films at home the stronger sexual desire they reported for their partner. In fact, this result was described as 'hardly novel'."

The actual finding? Guys who watched more porn scored higher in their desire to masturbate and have sex with a partner. In the above claim, Prause omitted greater desire to masturbate (presumably to porn), and leads us to believe that the questionnaire stated sexual desire for "their" partner. It didn't. From P&P ED study:

"Men reported their desire for sex with a partner and desire for solitary sex"

Prause added "their" and removed "solitary sex". Since the questionnaire's phrasing was actually "sex with a partner", these porn-loving subjects could have just as easily been fantasizing about sex with their favorite porn star. I suspect many were, as a large percentage of the subjects had no partners (50% in one underlying study).

In reality, higher "desire" to masturbate, or to have sex, might be evidence of sensitization, which is greater reward circuit activation and craving when exposed to porn cues. Sensitization can be a precursor to, or evidence of, addiction.

Two recent Cambridge University studies found that heavy porn users can experience higher desire (cravings), yet also experience erection problems with a partner. Participants' brains lit up when exposed porn, yet 60% of them reported arousal/erectile problems with partners. From the Cambridge study:

"CSB subjects reported that as a result of excessive use of sexually explicit materials.....they experienced diminished libido or erectile function specifically in physical relationships with women (although not in relationship to the sexually explicit material)"

Put simply, there's no basis for claiming that a porn user's higher desire to masturbate and have sex predicts better performance in the bedroom. Remember, the average erection scores for P&P subjects indicated ED.


Prause Tweets & Posts About Her Reply

Here's Prause initially tweeting about her reply to Isenberg's critique:

"Red Herring: Hook, Line, and Stinker" Our fun, published response to the crazy claims made by anti-porn groups

The next day Prause posts this on her SPAN lab website:

Amazing. As you have read above, Isenberg's claims are valid, while Prause makes false statement after false statement. Moreover, she attempts to add an unpublished study after the fact in a desperate ploy to meet her published claim of 280 subjects. She conjures up IIEF subjects who cannot exist by her own earlier admission. Then she calls uro-gynecologist Isenberg a "crazy anti-porn group." Feel free to Google his name. You will see that he has published peer-reviewed studies, yet has never said a word that was anti-porn. Spin without addressing the content.

Why has Sexual Medicine Open Access allowed Prause to publish numerous false statements in both the original P&P paper and her reply to Isenberg? Why weren't Isenberg's questions taken seriously and answered professionally? Why is there no serious investigation into the cause of the sudden jump in ED rates in the last few years? Rates have skyrocketed to around 30% in young men.