Critique of “Perceived Addiction to Internet Pornography and Psychological Distress: Examining Relationships Concurrently and Over Time” (2015)

UPDATE 2016: A much more comprehensive analysis of Joshua Grubbs’s claims and studies can be found here – Is Grubbs pulling the wool over our eyes with his “perceived porn addiction” research? (2016)

UPDATE 2017: A new study (Fernandez et al., 2017) tested and analyzed the CPUI-9, a purported “perceived pornography addiction” questionnaire developed by Joshua Grubbs, and found that it couldn’t accurately assess “actual porn addiction” or “perceived porn addiction” (Do Cyber Pornography Use Inventory-9 Scores Reflect Actual Compulsivity in Internet Pornography Use? Exploring the Role of Abstinence Effort). It also found that 1/3 of the CPUI-9 questions should be omitted to return valid results related to “moral disapproval”, “religiosity”, and “hours of porn use.” The findings raise significant doubts about conclusions drawn from any study that has employed the CPUI-9 or relied on studies that employed it. Many of the new study’s concerns and criticisms mirror those outlined in this extensive YBOP critique.

UPDATE 2018: Propaganda piece masquerading as a so-called review by Grubbs, Samuel Perry, Rory Reid & Joshua Wilt – Research Suggests the Grubbs, Perry, Wilt, Reid Review is Disingenuous (“Pornography Problems Due to Moral Incongruence: An Integrative Model with a Systematic Review and Meta-Analysis”) 2018.

UPDATE 2019: Joshua Grubbs confirmed his extreme agenda-driven bias when he joined their allies Nicole Prause, Marty Klein and David Ley in trying to silence Grubbs and other pro-porn “experts” at are engaged in illegal trademark infringement and squatting. Grubbs was sent a cease and desist letter, which were ignored. Legal actions continue to be pursued.

UPDATE 2019: Finally, Grubbs didn’t rely on his CPUI-9 instrument. The CPUI-9 includes 3 “guilt and shame/emotional distress” questions not normally found in addiction instruments – and which skew its results, causing religious porn users to score higher and non-religious users to score lower than subjects do on standard addiction-assessment instruments. Instead, Grubbs’s new study asked 2 direct yes/no questions of porn users (“I believe that I am addicted to internet pornography.” “I would call myself an internet pornography addict.”). Directly contradicting his earlier claims, Dr. Grubbs and his research team found that believing you are addicted to porn correlates most strongly with daily hours of porn use, not with religiousness.

UPDATE 2020: Unbiased researcher Mateuz Gola teamed up with Grubbs. Instead of using Grubbs’s terribly skewed CPUI-9, the study used a single question: “I believe I am addicted to Internet pornography“. This resulted in little or no correlation between religiousness and believe oneself addicted to porn. See: Evaluating Pornography Problems Due to Moral Incongruence Model (2019)


Here are a few of the headlines birthed from this new study by Joshua B. Grubbs, Nicholas Stauner, Julie J. Exline, Kenneth I. Pargament, and Matthew J. Lindberg (Grubbs et al., 2015):

  • Psychology Research Links Distress to Perceived Internet Pornography Addiction
  • Watching Porn Is OK. Believing In Porn Addiction Is Not
  • Perceived Addiction To Porn Is More Harmful Than Porn Use Itself
  • Believing You Have Porn Addiction Is the Cause of Your Porn Problem, Study Finds

In essence the study’s main claim is reported as: “perceived addiction” to pornography is more related to psychological distress than are current daily hours of porn viewing. An excerpt from one of the above articles:

A new study in the journal Psychology of Addictive Behaviors has found that perceived addiction to pornography—that is, “feeling addicted to Internet pornography irrespective of actual pornography use”—is associated with forms of psychological distress including depression, anxiety, anger, and stress. Pornography use itself, the authors found, was “relatively unrelated to psychological distress.”

While the above quote contains inaccuracies which we will explore, let’s take it at face value. The reader is left with the impression that actual porn use is no big deal, but “believing” you are addicted to porn will cause you psychological distress. The take away: It’s perfectly healthy to use porn as long as you don’t believe you are addicted.

Grubbs et al.’s claim, and all the resulting headlines, are built upon this finding: Subjects’ current hours of porn use did not correlate strongly enough (in researchers’ subjective view) with scores on Grubbs’s own porn use questionnaire (the Cyber Pornography Use Inventory “CPUI”). To put it another way, if porn addiction really existed there “should” be, in the authors’ view, a one-to-one relationship between current hours of use and scores on the CPUI. Grubbs et al. also reported that “psychological distress” was related to scores on the CPUI, but not as strongly related to current hours of use.

Here’s the thing: There’s absolutely no scientific basis for declaring the CPUI a measure of “perceived addiction,” and yet that’s what all the inflated headlines rest on! The CPUI was never validated for “perceived” as opposed to “real” addiction.

For Grubbs et al.’s claims and interpretations to be valid, BOTH of the following must be true and supported by actual research:

1) The Cyber Pornography Use Inventory (CPUI) must assess “perceived addiction” to porn but not actual porn addiction.

  • Grubbs himself developed the 9-item CPUI as an inventory of online porn problems, not a “perceived addiction” test. Here he chose to use it in lieu of other validated addiction tests, precisely to create the illusion that he could measure “perceived addiction” rather than addiction. In fact, the CPUI measures the same signs, symptoms and indications of addiction as do standard addiction tests.
  • In the current study, Grubbs et al. use the phrase “perceived porn addiction” synonymously with subjects’ total score on the CPUI, without scientific justification.

2) Internet porn addiction must equal hours of porn viewing.

  • This is refuted by the scientific literature. Internet porn addiction hours of porn viewing.
  • Shockingly, the Grubbs et al. study reveals there actually was a strong correlation between hours of use and the CPUI! From p. 6 of the study:

“Additionally, average daily pornography use in hours was significantly and positively associated with depression, anxiety, and anger, as well as with perceived addiction.”

With respect to the first point, Grubbs developed his own porn addiction questionnaire (CPUI), and then later capriciously declared that it measures only “perceived addiction to porn” – without demonstrating any justification for his recharacterization. (Really!)

With respect to the second point, previous research teams have found that the variable “hours of use” is not correlated with cybersex addiction (or video-gaming addiction). That is, addiction is more accurately predicted by other variables than “hours of use.” That said, as you can see from the above excerpt, Grubbs actually found a significant correlation between hours of use and psychological distress.

We’ll look at details about why Grubbs et al.’s assumptions are neither true nor supportable below, but here’s how the researchers could have described their actual findings without misleading the public:

“Study finds that certain aspects of porn addiction are strongly related to psychological distress and less strongly (but still) related to current hours of use.”

The cliff notes version: Addiction is related to psychological distress, and so are hours of use. So much for the attention-grabbing, misleading headlines spawned by the study.

The CPUI Assesses Neither Actual Porn Addiction, or “Perceived Porn Addiction”

In Grubbs’s initial 2010 paper he validated the his 43-question Cyber-Pornography Use Inventory (CPUI) as a questionnaire assessing certain aspects actual porn addiction, while assessing aspects that have nothing to with addiction (guilt & shame questions). The key for us is that nowhere in the 2010 paper does he use the phrase “perceived addiction”. Excerpts from Grubbs’s original paper confirming his CPUI assesses only real porn addiction:

The previously described models proposed for understanding behavioral addictions were the primary theoretical assumptions used to derive the instrument for this study, the Cyber-Pornography Use Inventory (CPUI), patterned after the Internet Sex Screening Test developed by Delmonico (Delmonico & Griffin, 2008). The CPUI design was based on the principle that addictive behavior is characterized by an inability to stop the behavior, significant negative effects as a result of the behavior, and a generalized obsession with the behavior (Delmonico & Miller, 2003).

The CPUI does indeed show promise as an instrument assessing Internet pornography addiction. Whereas previous instruments, such as the ISST, had assessed only broad-spectrum online sexual addiction, this scale did demonstrate promise in specifically assessing Internet pornography addiction. Furthermore, the items on the previously explained Addictive Patterns scale seem to find some level of theoretical support and potential construct validity when compared with the diagnostic criteria for both Substance Dependence and Pathological Gambling, an ICD.

Finally, five of the items on the Addictive Patterns scale from the original Compulsivity scale seem to directly tap into the individual’s perceived or actual inability to stop the behavior in which they are engaging. Inability to stop a problematic behavior under any circumstances is not only an important diagnostic criterion for both SD and PG, but it can also can be thought of as one of the core elements of both addiction, as manifested in SD, and ICDs (Dixon et al., 2007; Pontenza, 2006). It seems that it is this inability that creates the disorder.

In a 2013 study Grubbs reduced the number of CPUI questions from 43 to 9, and re-labled his actual porn addiction test  a “perceived porn addiction” test. He did so without and explanation, while using the phrase “perceived addiction” 80 times in the 2013 paper. Let’s be very clear – Grubbs did not validate his CPUI as an assessment tool differentiating actual porn addiction from “perceived porn addiction”.

Why did Joshua Grubbs re-label the CPUI a “perceived” porn addiction test?

While Grubbs himself didn’t claim his test could sort perceived from actual addiction, his employment of the misleading term (“perceived addiction”) for scores on his CPUI-9 instrument have led others to assume his instrument has the magical property of being able to discriminate between “perceived” and “real” addiction. This has done enormous damage to the field of porn addiction assessment because others rely on his papers as evidence of something they do not, and cannot, deliver. No test exists that can distinguish “real” from “perceived” addiction. Merely labeling it as such cannot make it so.

Joshua Grubbs said in an email that a reviewer of his second CPUI-9 study caused him and his co-authors of the 2013 study to alter the “porn addiction” terminology of the CPUI-9 (because the reviewer sneered at the “construct” of porn addiction). This is why Grubbs changed his description of the test to a “perceived pornography addiction” questionnaire. In essence an anonymous reviewer/editor at this single journal initiated the unsupported, misleading label of “perceived pornography addiction.” The CPUI has never been validated as an assessment test differentiating actual porn addiction from “perceived porn addiction.“Here’s Grubbs tweeting about this process, including the reviewer’s comments:

Josh Grubbs‏ @JoshuaGrubbsPhD

On my 1st paper on compulsive porn use: “This construct [porn addiction] is as meaningful to measure as experiences of alien abduction: it’s meaningless.”

Nicole R Prause, PhD‏ @NicoleRPrause

You or reviewer?

Josh Grubbs‏ @JoshuaGrubbsPhD

Reviewer said it to me

Josh Grubbs‏ @JoshuaGrubbsPhD  Jul 14

Actually what led to my perceived addiction work, I thought about the comments as revised the focus.

Background on the Josh Grubbs  CPUI-9 and how it badly skews results

In the last few years Dr. Joshua Grubbs has authored a series of studies correlating porn users’ religiosity, hours of porn use, moral disapproval, and other variables with scores on his 9-item questionnaire “The Cyber Pornography Use Inventory” (CPUI-9). In an odd decision that has lead to much misunderstanding of his findings, Dr. Grubbs refers to his subjects’ total CPUI-9 score as “perceived pornography addiction.” This gives the false impression that his CPUI-9 instrument somehow indicates the degree to which a subject merely “perceives” he is addicted (rather than being actually addicted). But no instrument can do that, and certainly not this one.

To say it another way, the phrase “perceived pornography addiction” indicates nothing more than a number: the total score on the following 9-item pornography-use questionnaire with its three extraneous questions about guilt and shame. It doesn’t sort the wheat from the chaff in terms of perceived vs. genuine addiction. Nor does the CPUI-9 assess actual porn addiction.

Perceived Compulsivity Section

  1. I believe I am addicted to Internet pornography.
  2. I feel unable to stop my use of online pornography.
  3. Even when I do not want to view pornography online, I feel drawn to it

Access Efforts Section

  1. At times, I try to arrange my schedule so that I will be able to be alone in order to view pornography.
  2. I have refused to go out with friends or attend certain social functions to have the opportunity to view pornography.
  3. I have put off important priorities to view pornography.

Emotional Distress Section

  1. I feel ashamed after viewing pornography online.
  2. I feel depressed after viewing pornography online.
  3. I feel sick after viewing pornography online.

As you can see, the CPUI-9 cannot distinguish between actual porn addiction and “belief” in porn addiction. Subjects never “labeled themselves as porn addicts” in any Grubbs study. They simply answered the 9 questions above, and earned a total score.

What correlations did the Grubbs studies actually report? Total CPUI-9 scores were related to religiosity (as explained above), but also related to “hours of porn viewed per week.” In some Grubbs studies a slightly stronger correlation occurred between religiosity and total CPUI-9 scores (“perceived porn addiction”) in others a stronger correlation occurred with hours of porn use and total CPUI-9 scores (“perceived porn addiction”).

The media ignored the latter findings and grabbed onto the correlation between religiosity and total CPUI-9 scores (now misleadingly labeled “perceived addiction”), and in the process journalists morphed the finding into “religious people only believe they’re addicted to porn.” The media ignored the just-as-strong correlation between CPUI-9 scores and hours of porn use, and pumped out hundreds of inaccurate articles like this blog post by David Ley: Your Belief in Porn Addiction Makes Things Worse: The label of “porn addict” causes depression but porn watching doesn’t. Here is Ley’s inaccurate description of a Grubbs CPUI-9 study:

If someone believed they were a sex addict, this belief predicted downstream psychological suffering, no matter how much, or how little, porn they were actually using.

Removing Ley’s misrepresentations, the above sentence would accurately read: “Higher scores on the CPUI-9 correlated with scores on a psychological distress questionnaire (anxiety, depression, anger).” Which is how it tends to be for any addiction questionnaire. For example, higher scores on an alcohol use questionnaire correlate with higher levels of psychological distress. Big surprise.

The key to all the dubious claims and questionable correlations: the Emotional Distress questions (7-9) cause religious porn users to score much higher and secular porn users to score far lower, as well as creating a strong correlation between “moral disapproval” and total CPUI-9 score (“perceived porn addiction”).

To put it another way, if you use only results from CPUI-9 questions 1-6 (which assess the signs and symptoms of an actual addiction), the correlations dramatically change – and all the dubious articles claiming shame is the “real” cause porn addiction would never have been written.

To look at a few revealing correlations, let’s use data from the 2015 Grubbs paper (“Transgression as Addiction: Religiosity and Moral Disapproval as Predictors of Perceived Addiction to Pornography“). It comprises 3 separate studies and its provocative title suggests that religiosity and moral disapproval “cause” a belief in pornography addiction.

Tips for understanding the numbers in the table: zero means no correlation between two variables; 1.00 means a complete correlation between two variables. The bigger the number the stronger the correlation between the 2 variables.

In this first correlation we see how moral disapproval correlates powerfully with the 3 guilt and shame questions (Emotional Distress), yet weakly with the two other sections that assess actual addiction (questions 1-6). The Emotional Distress questions cause moral disapproval to be the strongest predictor of total CPUI-9 scores (“perceived addiction”).

But if we use only the actual porn addiction questions (1-6), the correlation is pretty weak with Moral Disapproval (in science-speak, Moral Disapproval is a weak predictor of porn addiction).

The second half of the story is how the same 3 Emotional Distress correlate very poorly with levels of porn use, while the actual porn addiction questions (1-6) correlate robustly with porn use levels.

This is how the 3 Emotional Distress questions skew results. They lead to reduced correlations between “hours of porn use” and total CPUI-9 scores (“perceived addiction”). Next, the sum total of all 3 sections of the CPUI-9 test is deceptively re-labeled as “perceived addiction” by Grubbs. Then, at the hands of determined anti-porn-addiction activists, “perceived addiction” morphs into “self identifying as a porn addict.” The activists have pounced on the strong correlation with moral disapproval, which the CPUI-9 always produces, and presto! they now claim that, “a belief in porn addiction is nothing more than shame!”

It’s a house of cards built on 3 guilt and shame question not found in any other addiction assessment, in combination with the misleading term the questionnaire’s creator uses to label his 9 questions (as a measure of “perceived porn addiction”).

The CPUI-9 house of cards came tumbling down with a 2017 study that pretty much invalidates the CPUI-9 as an instrument to assess either “perceived pornography addiction” or actual pornography addiction: Do Cyber Pornography Use Inventory-9 Scores Reflect Actual Compulsivity in Internet Pornography Use? Exploring the Role of Abstinence Effort. It also found that 1/3 of the CPUI-9 questions should be omitted to return valid results related to “moral disapproval,” “religiosity,” and “hours of porn use.” You see all the key excerpts here, but Fernandez et al., 2018 sums things up:

Second, our findings cast doubts on the suitability of the inclusion of the Emotional Distress subscale as part of the CPUI-9. As consistently found across multiple studies (e.g., Grubbs et al., 2015a,c), our findings also showed that frequency of IP use had no relationship with Emotional Distress scores. More importantly, actual compulsivity as conceptualized in the present study (failed abstinence attempts x abstinence effort) had no relationship with Emotional Distress scores.

Emotional Distress scores were significantly predicted by moral disapproval, in line with previous studies which also found a substantial overlap between the two (Grubbs et al., 2015a; Wilt et al., 2016)…. As such, the inclusion of the Emotional Distress subscale as part of the CPUI-9 might skew results in such a way that it inflates the total perceived addiction scores of IP users who morally disapprove of pornography, and deflates the total perceived addiction scores of IP users who have high Perceived Compulsivity scores, but low moral disapproval of pornography.

This may be because the Emotional Distress subscale was based on an original “Guilt” scale which was developed for use particularly with religious populations (Grubbs et al., 2010), and its utility with non-religious populations remains uncertain in light of subsequent findings related to this scale.

Here’s is the core finding: The 3 “Emotional Distress” questions have no place in the CPUI-9, or any porn addiction questionnaire. These guilt and shame questions do not assess distress surrounding addictive porn use or “perception of addiction.” These 3 questions merely artificially inflate total CPUI-9 scores for religious individuals while deflating total CPUI-9 scores for nonreligious porn addicts.

In summary, the conclusions and claims spawned by the CPUI-9 are simply invalid. Joshua Grubbs created a questionnaire that cannot, and was never validated for, sorting “perceived” from actual addiction: the CPUI-9. With zero scientific justification he re-labeled his CPUI-9 as a “perceived pornography addiction” questionnaire.

Because the CPUI-9 included 3 extraneous questions assessing guilt and shame, religious porn users’ CPUI-9 scores tend to be skewed upward. The existence of higher CPUI-9 scores for religious porn users was then fed to the media as a claim that, “religious people falsely believe they are addicted to porn.” This was followed by several studies correlating moral disapproval with CPUI-9 scores. Since religious people as a group score higher on moral disapproval, and (thus) the total CPUI-9, it was pronounced (without actual support) that religious-based moral disapproval is the true cause of pornography addiction. That’s quite a leap, and unjustified as a matter of science.

YouTube presentation exposing the CPUI-9 and the myth of “perceived addiction”: Pornography Addiction and Perceived Addiction 

Current Hours of Use Are Not Related To Porn Addiction

Grubbs et al.’s conclusion is largely based on a faulty premise: The extent of a porn addiction is best assessed simply by hours of internet porn viewing. As Grubbs et al. did not find a tight enough correlation (in their view) in their subjects, they concluded their subjects merely had “perceived addiction” instead. Two huge holes in the story render Grubbs et al.’s claim highly suspect.

As described earlier, the first gaping hole is that Grubbs et al. actually found a pretty strong correlation between hours of use and the CPUI! From p. 6 of the study:

“Additionally, average daily pornography use in hours was significantly and positively associated with depression, anxiety, and anger, as well as with perceived addiction.”

Stop the presses! This excerpt directly contradicts all the headlines, which claim that pornography use was NOT strongly correlated with psychological distress or “perceived addiction.” Again, whenever you see the phrase “perceived addiction” it actually denotes the subjects’ total score on the CPUI (which is a porn addiction test).

To say all of this another way: Both psychological distress and CPUI scores were significantly correlated with hours of use. Does any journalist or blogger ever read an actual study?

The second hole in this study’s underpinnings, which you could drive a truck through, is that research on internet porn and videogame use (1, 2, 3, 4, 5, 6, 7, 8) has reported that neither addiction correlates with hours of use. The variable ‘hours of use’ is an unreliable measure of addiction, and established addiction assessment tools evaluate addiction using multiple other factors (such as those listed in the CPUI). The following cybersex addiction studies, which Grubbs omitted, report little relationship between hours and indications of addiction:

1) Watching Pornographic Pictures on the Internet: Role of Sexual Arousal Ratings and Psychological-Psychiatric Symptoms for Using Internet Sex Sites Excessively (2011)

“Results indicate that self-reported problems in daily life linked to online sexual activities were predicted by subjective sexual arousal ratings of the pornographic material, global severity of psychological symptoms, and the number of sex applications used when being on Internet sex sites in daily life, while the time spent on Internet sex sites (minutes per day) did not significantly contribute to explanation of variance in Internet Addiction Test sex score (IATsex). We see some parallels between cognitive and brain mechanisms potentially contributing to the maintenance of excessive cybersex and those described for individuals with substance dependence.”

2) Sexual Excitability and Dysfunctional Coping Determine Cybersex Addiction in Homosexual Males (2015)

“Recent findings have demonstrated an association between CyberSex Addiction (CA) severity and indicators of sexual excitability, and that coping by sexual behaviors mediated the relationship between sexual excitability and CA symptoms. Results showed strong correlations between CA symptoms and indicators of sexual arousal and sexual excitability, coping by sexual behaviors, and psychological symptoms. CyberSex Addiction was not associated with offline sexual behaviors and weekly cybersex use time.”

3) What Matters: Quantity or Quality of Pornography Use? Psychological and Behavioral Factors of Seeking Treatment for Problematic Pornography Use (2016)

According to our best knowledge this study is the first direct examination of associations between the frequency of porn use and actual behavior of treatment-seeking for problematic porn use (measured as visiting the psychologist, psychiatrist or sexologist for this purpose). Our results indicate that the future studies, and treatment, in this field should focus more on impact of porn use on the life of an individual (quality) rather than its mere frequency (quantity), as the negative symptoms associated with porn use (rather than porn use frequency ) are the most significant predictor of treatment-seeking behavior.

Relation between PU and negative symptoms was significant and mediated by self-reported, subjective religiosity (weak, partial mediation) among non-treatment seekers. Among treatment-seekers religiosity is not related to negative symptoms.

4) Examining Correlates of Problematic Internet Pornography Use Among University Student (2016)

Higher scores on addictive measures of internet porn use were correlated with daily or more frequent use of internet porn. However, the results indicate that there was no direct link between the amount and frequency of an individual’s pornography use and struggles with anxiety, depression, and life and relationship satisfaction. Significant correlations to high internet porn addiction scores included an early first exposure to internet porn, addiction to video games, and being male. While some positive effects of internet porn use have been documented in previous literature our results do not indicate that psychosocial functioning improves with moderate or casual use of  internet porn.

Thus, from the outset this study and its assertions collapse because its conclusions rest upon equating current hours of use with the level of addiction/problems/distress reported by subjects as a valid measure of addiction.

Why don’t addiction specialists rely on hours of use? Imagine trying to assess addictions by simply asking, “How many hours do you currently spend eating (food addiction)?” or “How many hours do you spend gambling (gambling addition)?” or “How many hours do you spend drinking (alcoholism)?” To demonstrate how problematic hours of use would be, consider alcohol as an example:

  1. A 45-year old Italian man has a tradition of drinking 2 glasses of wine every night with dinner. His meal is with his extended family and it takes 3 hours to complete (lots of yakking). So he drinks for 3 hours a night, 21 hour per week.
  2. A 25 year-old factory worker only drinks on the weekends, but binge drinks both Friday and Saturday night to the point of passing out or getting sick. He regrets his actions and wants to stop, but can’t, drives drunk, gets in fights, is sexually aggressive, etc. He then spends all of Sunday recovering, and feels like crap until Wednesday. However, he spent only 8 hours a week drinking.

Which drinker has a problem? This is why “current hours of use” alone cannot inform us as to who is addicted and who is not.

Finally, we must ask why Grubbs et al. chose to create the CPUI when other, thoroughly validated addiction tests were readily available.

Bottom line: The study’s claims depend upon “current hours of use” being a valid criterion for true addiction. They are not. Moreover, once you get past the abstract, the full study reveals that “current hours of use” is actually related to both psychological distress and CPUI scores!

“Current Hours of Use” Omits Many Variables

A secondary methodological problem is that Grubbs et al. assessed porn use by asking subjects about their “current hours of porn use.” That question is troublingly vague. Over what period? One subject may be thinking “How much did I use yesterday?” another “over the last week?” or “on average since I decided to quit viewing because of unwanted effects?” The result is data that are not comparable can’t be analyzed for the purpose of drawing reliable conclusions.

More important, the “current porn use” question, on which the study’s conclusions rest, fails to ask about key variables of porn use: age use began, years of use, whether the user escalated to novel genres of porn or developed unexpected porn fetishes, the ratio of ejaculation with porn to ejaculation without it, amount of sex with a real partner, and so forth. Those questions would likely enlighten us more about who really has a problem with porn use than simply “current hours of use.”

Grubbs Introduction Distorts Current State of the Research

In the introduction and discussion sections Grubbs et al. toss aside decades of neuropsychological and other addiction research (and related assessment tools) to attempt to persuade readers that the scientific literature shows that internet porn addiction doesn’t exist (and that therefore that all evidence of porn addiction must be “perceived,” not real). A new review shows just how farfetched this contention is. See Neuroscience of Internet Pornography Addiction: A Review and Update, which aligns decades of addiction neuroscience research with recent neuroscience and neuropsych studies on porn users themselves. It concludes (logically and scientifically) that internet pornography addiction is quite real, and in fact a subset of internet addiction (based on more than 100 brain studies, as well as hundreds of other relevant studies).

In their opening paragraphs, Grubbs et al. demonstrate their profound bias by basing their claim about the nonexistence of internet porn addiction on the papers of two self-proclaimed “internet porn addiction debunkers”: David Ley, author of The Myth of Sex Addiction, and former UCLA researcher Nicole Prause, whose work has been formally criticized in the medical literature for weak methodology and unsupported conclusions.

For example, Grubbs et al. rely on a one-sided paper by Ley, Prause and their colleague Peter Finn, which claimed to be a review (that is, an impartial analysis of the existing literature). However, it omitted or misrepresented nearly every study that found negative effects of internet porn use, while also ignoring the dozens of recent internet addiction studies demonstrating addiction-related structural brain changes in internet addicts’ brains. (Line-by-line critique can be found here.)

Equaling telling is Grubbs et al.’s omission of every brain scan and neuropsychological study that found evidence in support of the porn addiction model (over a dozen collected here). Instead of hard science from the many omitted studies, the reader is given an overreaching conclusion:

In sum, there is a fair amount of evidence suggesting that many individuals feel addicted to Internet pornography, even in the absence of a clinically verified diagnosis to subsume such a disorder.

Finally, the only neurological study cited by Grubbs as refuting porn addiction (Steele et al.) actually supports the porn addiction model. Steele et al. reported higher EEG readings (P300) when subjects were exposed to porn photos. Studies consistently show that an elevated P300 occurs when addicts are exposed to cues (such as images) related to their addiction. In addition, the study reported that greater cue-reactivity to porn correlated with less desire for partnered sex. As neither result matched the headlines, Grubbs perpetuated the flawed conclusions of the original authors (the “debunkers of porn addiction”).


Given its unsupported conclusions and biased claims about the non-existence of porn addiction, it seems likely that Grubbs et al. designed this study to meet a specific agenda – to re-label porn addiction as “perceived addiction” and persuade readers that porn use is harmless and they need only worry about believing it can harm. Agnotology mission accomplished!

This saying comes to mind: What the abstract giveth, the full study taketh away. The headlines and claims spawned by Grubbs et al. are not even supported by the underlying study. For much more see: Is Joshua Grubbs pulling the wool over our eyes with his “perceived porn addiction” research? (2016)