Critique of “The Emperor Has No Clothes: A Review of the ‘Pornography Addiction’ Model”, David Ley, Nicole Prause & Peter Finn (2014)

I provide 2 updated “Reality Checks” before we get to the 2014 critique.

Reality check#1: Neurological & epidemiological studies that refute nearly every claim in Ley et al., 2014:

See Questionable & Misleading Studies for highly publicized papers that are not what they claim to be.):

  1. Porn/sex addiction? This page lists over 55 neuroscience-based studies (MRI, fMRI, EEG, neuropsychological, hormonal). They provide strong support for the addiction model as their findings mirror the neurological findings reported in substance addiction studies.
  2. The real experts’ opinions on porn/sex addiction? This list contains 30 recent literature reviews & commentaries by some of the top neuroscientists in the world. All support the addiction model.
  3. Signs of addiction and escalation to more extreme material? Over 60 studies reporting findings consistent with escalation of porn use (tolerance), habituation to porn, and even withdrawal symptoms (all signs and symptoms associated with addiction).
  4. An official diagnosis? The world’s most widely used medical diagnostic manual, The International Classification of Diseases (ICD-11), contains a new diagnosis suitable for porn addiction: “Compulsive Sexual Behavior Disorder.”
  5. Debunking the unsupported talking point that “high sexual desire” explains away porn or sex addiction: At least 30 studies falsify the claim that sex & porn addicts “just have high sexual desire”
  6. Porn and sexual problems? This list contains over 40 studies linking porn use/porn addiction to sexual problems and lower arousal to sexual stimuli. The first 7 studies in the list demonstrate causation, as participants eliminated porn use and healed chronic sexual dysfunctions.
  7. Porn’s effects on relationships? Over 80 studies link porn use to less sexual and relationship satisfaction. (As far as we know all studies involving males have reported more porn use linked to poorer sexual or relationship satisfaction.)
  8. Porn use affecting emotional and mental health? Over 85 studies link porn use to poorer mental-emotional health & poorer cognitive outcomes.
  9. Porn use affecting beliefs, attitudes and behaviors? Check out individual studies – over 40 studies link porn use to “un-egalitarian attitudes” toward women and sexist views – or the summary from this 2016 meta-analysis: Media and Sexualization: State of Empirical Research, 1995–2015. Excerpt:

The goal of this review was to synthesize empirical investigations testing effects of media sexualization. The focus was on research published in peer-reviewed, English-language journals between 1995 and 2015. A total of 109 publications that contained 135 studies were reviewed. The findings provided consistent evidence that both laboratory exposure and regular, everyday exposure to this content are directly associated with a range of consequences, including higher levels of body dissatisfaction, greater self-objectification, greater support of sexist beliefs and of adversarial sexual beliefs, and greater tolerance of sexual violence toward women. Moreover, experimental exposure to this content leads both women and men to have a diminished view of women’s competence, morality, and humanity.

  1. What about sexual aggression and porn use? Another meta-analysis: A Meta‐Analysis of Pornography Consumption and Actual Acts of Sexual Aggression in General Population Studies (2015). Excerpt:

22 studies from 7 different countries were analyzed. Consumption was associated with sexual aggression in the United States and internationally, among males and females, and in cross-sectional and longitudinal studies. Associations were stronger for verbal than physical sexual aggression, although both were significant. The general pattern of results suggested that violent content may be an exacerbating factor.

“But hasn’t porn use reduced rape rates?” No, rape rates have been rising in recent years: “Rape rates are on the rise, so ignore the pro-porn propaganda.” See this page for over 100 studies linking porn use to sexual aggression, coercion & violence, and an extensive critique of the often-repeated assertion that an increased availability of porn has resulted in decreased rape rates.

  1. What about the porn use and adolescents? Check out this list of over 280 adolescent studies, or tor these reviews of the literature: review#1, review2, review#3, review#4, review#5, review#6, review#7, review#8, review#9, review#10, review#11, review#12, review#13, review#14, review#15, review #16. From the conclusion of this 2012 review of the research – The Impact of Internet Pornography on Adolescents: A Review of the Research:

Increased access to the Internet by adolescents has created unprecedented opportunities for sexual education, learning, and growth. Conversely, the risk of harm that is evident in the literature has led researchers to investigate adolescent exposure to online pornography in an effort to elucidate these relationships. Collectively, these studies suggest that youth who consume pornography may develop unrealistic sexual values and beliefs. Among the findings, higher levels of permissive sexual attitudes, sexual preoccupation, and earlier sexual experimentation have been correlated with more frequent consumption of pornography…. Nevertheless, consistent findings have emerged linking adolescent use of pornography that depicts violence with increased degrees of sexually aggressive behavior. The literature does indicate some correlation between adolescents’ use of pornography and self-concept. Girls report feeling physically inferior to the women they view in pornographic material, while boys fear they may not be as virile or able to perform as the men in these media. Adolescents also report that their use of pornography decreased as their self-confidence and social development increase. Additionally, research suggests that adolescents who use pornography, especially that found on the Internet, have lower degrees of social integration, increases in conduct problems, higher levels of delinquent behavior, higher incidence of depressive symptoms, and decreased emotional bonding with caregivers.

  1. For a debunking of nearly every naysayer talking point and cherry-picked study see this extensive critique: Debunking “Why Are We Still So Worried About Wat­­ching Porn?”, by Marty Klein, Taylor Kohut, and Nicole Prause (2018). How to recognize biased articles: They cite Prause et al., 2015 (falsely claiming it debunks porn addiction), while omitting over 50 neurological studies supporting porn addiction.

Reality Check#2 – Authentic reviews of the literature & commentaries countering the rest of the Ley/Prause/Finn claims:

  1. For a thorough review of the neuroscience literature related to Internet addiction subtypes, with special focus on internet porn addiction, see – Neuroscience of Internet Pornography Addiction: A Review and Update (2015). The review also critiques two recent headline-grabbing EEG studies which purport to have “debunked” porn addiction.
  2. Sex Addiction as a Disease: Evidence for Assessment, Diagnosis, and Response to Critics (2015), which provides a chart that takes on specific criticisms and offers citations that counter them.
  3. Should Compulsive Sexual Behavior be Considered an Addiction? (2016) – Review of the literature by top addiction neuroscientists at Yale & Cambridge Universities
  4. Compulsive Sexual Behaviour as a Behavioural Addiction: The Impact of the Internet and Other Issues (2016) – Expands on the above review.
  5. Neurobiological Basis of Hypersexuality (2016) By neuroscientists at the Max Planck Institute
  6. Cybersex Addiction (2015) – By the German neuroscientists who have published the greatest number of studies on cybersex addiction
  7. Is Internet Pornography Causing Sexual Dysfunctions? A Review with Clinical Reports (2016) – An extensive review of the literature related to porn-induced sexual problems. Involving US Navy doctors, the review provides the latest data revealing a tremendous rise in youthful sexual problems. It also reviews the neurological studies related to porn addiction and sexual conditioning via Internet porn. The doctors provide 3 clinical reports of men who developed porn-induced sexual dysfunctions
  8. Integrating psychological and neurobiological considerations regarding the development and maintenance of specific Internet-use disorders: An Interaction of Person-Affect-Cognition-Execution model (2016) – A review of the mechanisms underlying the development and maintenance of specific Internet-use disorders, including “Internet-pornography-viewing disorder”
  9. Searching for clarity in muddy water: future considerations for classifying compulsive sexual behavior as an addiction (2016) – Excerpts: We recently considered evidence for classifying compulsive sexual behavior (CSB) as a non-substance (behavioral) addiction. Our review found that CSB shared clinical, neurobiological and phenomenological parallels with substance-use disorders. Although the American Psychiatric Association rejected hypersexual disorder from DSM-5, a diagnosis of CSB (excessive sex drive) can be made using ICD-10. CSB is also being considered by ICD-11.
  10. Sexual Addiction chapter from Neurobiology of Addictions, Oxford Press (2016)
  11. Neuroscientific Approaches to Online Pornography Addiction (2017) – Excerpt: In the last two decades, several studies with neuroscientific approaches, especially functional magnetic resonance imaging (fMRI), were conducted to explore the neural correlates of watching pornography under experimental conditions and the neural correlates of excessive pornography use. Given previous results, excessive pornography consumption can be connected to already known neurobiological mechanisms underlying the development of substance-related addictions.
  12. Is excessive sexual behaviour an addictive disorder? (2017) – Excerpts: Research into the neurobiology of compulsive sexual behaviour disorder has generated findings relating to attentional biases, incentive salience attributions, and brain-based cue reactivity that suggest substantial similarities with addictions. We believe that classification of compulsive sexual behaviour disorder as an addictive disorder is consistent with recent data and might benefit clinicians, researchers, and individuals suffering from and personally affected by this disorder.
  13. The Proof of the Pudding Is in the Tasting: Data Are Needed to Test Models and Hypotheses Related to Compulsive Sexual Behaviors (2018) – Excerpts: Among the domains that may suggest similarities between CSB and addictive disorders are neuroimaging studies, with several recent studies omitted by Walton et al. (2017). Initial studies often examined CSB with respect to models of addiction (reviewed in Gola, Wordecha, Marchewka, & Sescousse, 2016b; Kraus, Voon, & Potenza, 2016b).
  14. Promoting educational, classification, treatment, and policy initiatives Commentary on: Compulsive sexual behaviour disorder in the ICD-11 (Kraus et al., 2018) – Excerpts: The current proposal of classifying CSB disorder as an impulse-control disorder is controversial as alternate models have been proposed (Kor, Fogel, Reid, & Potenza, 2013). There are data suggesting that CSB shares many features with addictions (Kraus et al., 2016), including recent data indicating increased reactivity of reward-related brain regions in response to cues associated with erotic stimuli (Brand, Snagowski, Laier, & Maderwald, 2016; Gola, Wordecha, Marchewka, & Sescousse, 2016; Gola et al., 2017; Klucken, Wehrum-Osinsky, Schweckendiek, Kruse, & Stark, 2016; Voon et al., 2014.
  15. Compulsive Sexual Behavior in Humans and Preclinical Models (2018) – Excerpts: Compulsive sexual behavior (CSB) is widely regarded as a “behavioral addiction,” and is a major threat to quality of life and both physical and mental health. In conclusion, this review summarized the behavioral and neuroimaging studies on human CSB and comorbidity with other disorders, including substance abuse. Together, these studies indicate that CSB is associated with functional alterations in dorsal anterior cingulate and prefrontal cortex, amygdala, striatum, and thalamus, in addition to decreased connectivity between amygdala and prefrontal cortex.
  16. Sexual Dysfunctions in the Internet Era (2018) – Excerpt: Among behavioral addictions, problematic Internet use and online pornography consumption are often cited as possible risk factors for sexual dysfunction, often with no definite boundary between the two phenomena. Online users are attracted to Internet pornography because of its anonymity, affordability, and accessibility, and in many cases its usage could lead users through a cybersex addiction: in these cases, users are more likely to forget the “evolutionary” role of sex, finding more excitement in self-selected sexually explicit material than in intercourse.
  17. Neurocognitive mechanisms in compulsive sexual behavior disorder (2018) – Excerpt: To date, most neuroimaging research on compulsive sexual behavior has provided evidence of overlapping mechanisms underlying compulsive sexual behavior and non-sexual addictions. Compulsive sexual behavior is associated with altered functioning in brain regions and networks implicated in sensitization, habituation, impulse dyscontrol, and reward processing in patterns like substance, gambling, and gaming addictions. Key brain regions linked to CSB features include the frontal and temporal cortices, amygdala, and striatum, including the nucleus accumbens.
  18. A Current Understanding of the Behavioral Neuroscience of Compulsive Sexual Behavior Disorder and Problematic Pornography Use – Excerpt: Recent neurobiological studies have revealed that compulsive sexual behaviors are associated with altered processing of sexual material and differences in brain structure and function. Although few neurobiological studies of CSBD have been conducted to date, existing data suggest neurobiological abnormalities share communalities with other additions such as substance use and gambling disorders. Thus, existing data suggest that its classification may be better suited as a behavioral addiction rather than an impulse-control disorder.
  19. Ventral Striatal Reactivity in Compulsive Sexual Behaviors (2018) – Excerpt: Among currently available studies, we were able to find nine publications (Table 1) which utilized functional magnetic resonance imaging. Only four of these (3639) directly investigated processing of erotic cues and/or rewards and reported findings related to ventral striatum activations. Three studies indicate increased ventral striatal reactivity for erotic stimuli (3639) or cues predicting such stimuli (3639). These findings are consistent with Incentive Salience Theory (IST) (28), one of the most prominent frameworks describing brain functioning in addiction.
  20. Online Porn Addiction: What We Know and What We Don’t—A Systematic Review (2019) – Excerpt: As far as we know, a number of recent studies support this entity as an addiction with important clinical manifestations such as sexual dysfunction and psychosexual dissatisfaction. Most of the existing work is based off on similar research done on substance addicts, based on the hypothesis of online pornography as a ‘supranormal stimulus’ akin to an actual substance that, through continued consumption, can spark an addictive disorder.
  21. Occurrence and development of online porn addiction: individual susceptibility factors, strengthening mechanisms and neural mechanisms (2019) – Excerpt: The long-term experience of online pornography has led to the sensitization of such people to online pornography-related clues, which has led to a growing sense of craving, compulsive use of online pornography under the dual factors of temptation and functional impairment. The sense of satisfaction gained from it is getting weaker and weaker, so more and more online pornography is needed to maintain the previous emotional state and become addicted.
  22. Occurrence and development of online porn addiction: individual susceptibility factors, strengthening mechanisms and neural mechanisms (2019) – Excerpt: The long-term experience of online pornography has led to the sensitization of such people to online pornography-related clues, which has led to a growing sense of craving, compulsive use of online pornography under the dual factors of temptation and functional impairment. The sense of satisfaction gained from it is getting weaker and weaker, so more and more online pornography is needed to maintain the previous emotional state and become addicted.
  23. Theories, prevention, and treatment of pornography-use disorder (2019) – Excerpt: Compulsive sexual behavior disorder, including problematic pornography use, has been included in the ICD-11 as impulse control disorder. The diagnostic criteria for this disorder, however, are very similar to the criteria for disorders due to addictive behaviors… Theoretical considerations and empirical evidence suggest that the psychological and neurobiological mechanisms involved in addictive disorders are also valid for pornography-use disorder.
  24. Self-perceived Problematic Pornography Use: An Integrative Model from a Research Domain Criteria and Ecological Perspective (2019) – Excerpt: Self-perceived problematic pornography use seems to be related to multiple units of analysis and different systems in the organism. Based on the findings within the RDoC paradigm described above, it is possible to create a cohesive model in which different units of analysis impact each other (Fig. 1). These changes in internal and behavioral mechanisms among people with SPPPU are similar to those observed in people with substance addictions, and map into models of addiction.
  25. Cybersex addiction: an overview of the development and treatment of a newly emerging disorder (2020) – Excerpts: Cybersex addiction is a non-substance related addiction that involves online sexual activity on the internet. Nowadays, various kinds of things related to sex or pornography are easily accessible through internet media. In Indonesia, sexuality is usually assumed taboo but most young people have been exposed to pornography. It can lead to an addiction with many negative effects on users, such as relationships, money, and psychiatric problems like major depression and anxiety disorders.
  26. Which Conditions Should Be Considered as Disorders in the International Classification of Diseases (ICD-11) Designation of “Other Specified Disorders Due to Addictive Behaviors”? (2020) – Excerpts: Data from self-report, behavioral, electrophysiological, and neuroimaging studies demonstrate an involvement of psychological processes and underlying neural correlates that have been investigated and established to varying degrees for substance-use disorders and gambling/gaming disorders (criterion 3). Commonalities noted in prior studies include cue-reactivity and craving accompanied by increased activity in reward-related brain areas, attentional biases, disadvantageous decision-making, and (stimuli-specific) inhibitory control.
  27. The Addictive Nature of Compulsive Sexual Behaviours and Problematic Online Pornography Consumption: A Review – Excerpts: Available findings suggest that there are several features of CSBD and POPU that are consistent with characteristics of addiction, and that interventions helpful in targeting behavioural and substance addictions warrant consideration for adaptation and use in supporting individuals with CSBD and POPU…. The neurobiology of POPU and CSBD involves a number of shared neuroanatomical correlates with established substance use disorders, similar neuropsychological mechanisms, as well as common neurophysiological alterations in the dopamine reward system.
  28. Dysfunctional sexual behaviors: definition, clinical contexts, neurobiological profiles and treatments (2020) – Excerpts: Porn addiction, although distinct neurobiologically from sexual addiction, is still a form of behavioral addiction….The sudden suspension of porn addiction causes negative effects in mood, excitement, and relational and sexual satisfaction….The massive use of pornography facilitates the onset of psychosocial disorders and relationship difficulties…
  29. What should be included in the criteria for compulsive sexual behavior disorder? (2020) – Excerpts: The classification of CSBD as an impulse control disorder also warrants consideration. … Additional research may help refine the most appropriate classification of CSBD as happened with gambling disorder, reclassified from the category of impulse control disorders to non-substance or behavioral addictions in DSM-5 and ICD-11. … impulsivity may not contribute as strongly to problematic pornography use as some have proposed (Bőthe et al., 2019).
  30. Decision-Making in Gambling Disorder, Problematic Pornography Use, and Binge-Eating Disorder: Similarities and Differences (2021) – Excerpts: Similarities between CSBD and addictions have been described, and impaired control, persistent use despite adverse consequences, and tendencies to engage in risky decisions may be shared features (37••, 40). Individuals with these disorders often show impaired cognitive control and disadvantageous decision-making [12, 15,16,17]. Deficits in decision-making processes and goal-directed learning have been found across multiple disorders.

The Critique of Ley et al., 2014 (David Ley, Nicole Prause, Peter Finn)

On February 12th, 2014, “The Emperor Has No Clothes: A review of the ‘Pornography Addiction’ model” (“No Clothes“) appeared in the “Current Controversies” section of Current Sexual Health Reports. The journal’s editors were persuaded by its authors (“Ley et al.”) that “No Clothes” was an objective review, such that no opposing viewpoint was needed to convey a full picture of the controversy over porn addiction to the journal’s readers.

Alas, this “review” is anything but objective. In fact, it wasn’t a true review of the literature. Genuine reviews describe what databases were searched and name the keywords and phrases used in the search. Instead, Ley et al. constitutes a new low in the manipulation of academic writing to serve a shallow sexual political agenda. For years, a determined clique of sexologists have been ignoring the burgeoning findings of neuroscientists who study adolescents, behavioral addiction and sexual-conditioning, which, together, would swiftly advance the field of sexology from its Dark Ages into the light of modern science. Here these flat-earth sexologists endeavor to breathe life into their obsolete talking points via a polemic posing as a scientific review.

Their current mission? To inflate and prop up an illusion that “Frequent porn users can’t be addicts because they’re just impulsive, sensation-seeking people with high libidos.” Never mind that addiction itself produces symptoms that make addicts more impulsive (hypofrontality), desperate for sensation (desensitization) and prone to cravings (which Ley et al. do their best to confound with high sexual desire).

As we will explain below in laborious detail, the authors of this “objective” review:

  1. dismiss all published studies showing ill effects from porn use on the grounds that they are “merely” correlational, and then proceed to cite as support for their pet theories various correlational studies. We’ll share many of the relevant studies Ley et al. found unworthy of mention.
  2. cherry-pick random, misleading lines from within studies, failing to report the researchers’ actual opposing conclusions.
  3. defend their dismissal of addiction on the basis of studies that are as much as 25 years old, ignoring numerous recent, contradictory studies/reviews that reflect the current consensus of experts.
  4. cite numerous studies that are entirely irrelevant to the claims made.
  5. do not acknowledge (or analyze) dozens of brain studies on internet addicts. All show hard evidence that stimulation via the internet is addictive for some users and causes the same fundamental addiction-related brain changes seen in substance addicts. A current list appears at the end of this critique.
  6. ignore the first publicized brain-scan study performed on internet porn addicts/controls at Cambridge University (now published), which dismantles their conclusions.

Anyone familiar with the writings of the first two authors of this review, Ley and Prause, would be unsurprised. These lead authors have already disqualified themselves as impartial reviewers. David Ley, a clinician and frequent talk-show guest with no neuroscience background, is the author of The Myth of Sex Addiction. Nicole Prause, a Kinsey grad who heads SPAN Lab, churns out studies that, in her sole estimation, single handedly disprove the existence of porn addiction. Her flawed work has been exhaustively critiqued, and her interpretations questioned.

Why would these authors engage in this kind of distortion? Based on some of their statements at the end of “No Clothes,” one wonders if their evident bias arises from uncritical “sex positivity.” They seem to conflate Internet porn use with sex, even though today’s internet porn is proving “sex negative” for many young viewers due to a range of porn-induced sexual dysfunctions. Somehow the authors deceive themselves that people who are concerned about the effects of internet porn dislike sex or do not respect individual freedom and diverse sexual tastes. It’s also likely that their egos, as well as their professional and business success, are now tied to their position.

Update: Much has transpired since January, 2014. UCLA did not renew Nicole Prause’s contract (early 2015). No longer an academic Prause has engaged in multiple documented incidents harassment and defamation as part of an ongoing “astroturf” campaign to persuade people that anyone who disagrees with her conclusions deserves to be reviled. Prause has accumulated a long history of harassing authors, researchers, therapists, reporters and others who dare to report evidence of harms from internet porn use. She appears to be quite cozy with the pornography industry, as can be seen from this image of her (far right) on the red carpet of the X-Rated Critics Organization (XRCO) awards ceremony. (According to Wikipedia the XRCO Awards are given by the American X-Rated Critics Organization annually to people working in adult entertainment and it is the only adult industry awards show reserved exclusively for industry members.[1]). It also appears that Prause may have obtained porn performers as subjects through another porn industry interest group, the Free Speech Coalition. The FSC subjects were allegedly used in her hired-gun study on the heavily tainted and very commercial “Orgasmic Meditation” scheme. Prause has also made unsupported claims about the results of her studies and her study’s methodologies. For much more documentation, see: Is Nicole Prause Influenced by the Porn Industry?

In any event, one reason that reviews like Ley et al. survive and flourish is that journalists, and apparently uninformed peer reviewers, seldom investigate the dubious evidence on which they rest. Sadly, actual, knowledgeable experts in the field of addiction don’t have time for correcting such distortions. In fact, the type of journal in which “No Clothes” appeared is generally off their radar. Certainly, the silence of addiction experts should not be taken as agreement here. For example, we asked a world expert on DeltaFosB what he thought of David Ley’s review-related comments to a journalist about DeltaFosB:

The model for hypersexuality in rats, which is where Delta FosB has been studied, is homosexual behavior. The only way right now to study Delta FosB in humans as it might relate to sexuality would require us considering homosexuality and homosexual behavior as evidence of a Delta FosB brain change consistent with addiction. Again, we are terming male homosexual behavior as a disease.

The expert said Ley’s comments sounded like a “bad Saturday Night Live parody.”

For the record, no ΔFosB research ever involved gay rats. It’s inconceivable that anyone would propose studying ΔFosB’s role in addiction in humans by using homosexuals. Ley’s remarks appear to be nothing but more of his inflammatory hype calculated to distract his audience by raising the specter of homophobia without a shred of justification. How could the peer reviewers let similar remarks in the review itself make it to press? Astounding.

Why do Ley, Prause and Finn take such pains to discredit ΔFosB? Because it is one element of the abundant hard-science evidence that addictions are biological realities, not theoretical constructs as they claim. Chemical addictions and behavioral addictions (including, of course, sexual behavior addictions) arise from alterations in the same fundamental brain pathways and mechanisms. See “Natural Rewards, Neuroplasticity, and Non-Drug Addictions” (2011)

In fact, it has even been suggested that someday ΔFosB levels may reveal how severely someone is addicted and where s/he is in the process of recovery. In short, the existence of the ΔFosB research puts an end to the fanciful views expressed by Ley et al. on the subject of addiction. Hence their desire to distract readers from considering the implications of ΔFosB.

Ley Prause & Finn’s appalling ignorance of the basic science of addiction is also demonstrated at the outset of their masterwork. They declare that only opioids can cause addiction. Not nicotine, not alcohol, not cocaine, not gambling, not internet…only opioids. One wonders how a peer reviewer could ever have blessed such a preposterous assertion, which flies in the face of decades of medical research done by genuine addiction neuroscientists. If such obvious addictions as nicotine or cocaine don’t meet these reviewers’ whimsical criteria for addiction, it’s evident that no amount of scientific evidence will convince them that internet porn addiction is real. How can such a “review” be taken seriously?

Nevertheless, we will examine some of their far-fetched assertions in order of appearance. Their overall strategy is to deny the extensive evidence showing that addiction is a biological reality with well established elements, and then arbitrarily list their own (random) criteria for porn addiction for which they demand evidence. Repeatedly they declare that, as “no evidence exists” for these arbitrarily selected elements, addiction is not present. In effect, they create a virtual “straw army,” which they purport to knock down, but which an addiction neuroscientist would know was irrelevant to establishing the presence of addiction. Alas, they may deceive readers who lack an extensive background in addiction.

Those who would like to follow along can read the full text of the “No Clothes”. Headings are taken from the review itself, and direct quotations from the review are underlined and italicized.


Ley et al. claim ‘Pornography addiction’ is one label that has been used specifically to describe the high-frequency viewing of sexual images. Just to clarify, as ASAM, the American Society of Addiction Medicine (3000+ top addiction doctors and researchers) and others have emphasized, all addiction is a primary disease (not a symptom of other pathologies as Ley et al. imply in “No Clothes”). It’s marked by specific addiction-related brain changes in addition to well established behaviors that reflect those changes, such as continued use despite negative consequences.

While pornography addiction may involve high levels of viewing, studies show that length of time spent is not the key determinant of problematic porn use. Rather, it’s degree of arousal and number of applications opened (the thirst for novelty). See 123Watching pornographic pictures on the Internet: role of sexual arousal ratings and psychological-psychiatric symptoms for using Internet sex sites excessively.” (2011)

Excerpts: Time spent on Internet sex sites (minutes per day) did not significantly contribute to explanation of variance in [addiction test] score. …

The finding … may be interpreted in the light of previous studies on cue reactivity in individuals with substance dependency or behavioral addictions.

Another study also found cue reactivity (a measure of addiction), not frequency of use, was most relevant for problematic users: “Cybersex addiction: Experienced sexual arousal when watching pornography and not real-life sexual contacts makes the difference” (2013)

Excerpts: The results show that indicators of sexual arousal and craving to Internet pornographic cues predicted tendencies towards cybersex addiction in the first study. Moreover, it was shown that problematic cybersex users report greater sexual arousal and craving reactions resulting from pornographic cue presentation.

The results support the gratification hypothesis, which assumes reinforcement, learning mechanisms, and craving to be relevant processes in the development and maintenance of cybersex addiction. (emphasis added)

In other words, these studies don’t support the idea that porn users are just folks with high libidos who can’t get enough action in real life and have to make up for the shortfall with porn use. Rather, problematic porn users show hyper-reactivity to cues, just as other addicts do. Incidentally, the Cambridge University brain study on porn addicts found the same hyper-reactivity to cues, and no evidence of higher sexual desire in the addicts tested. Even more ominously, another new study by addiction neuroscience experts on porn users’ brains, found drug-like brain changes even in moderate porn users. See “Brain Structure and Functional Connectivity Associated with Pornography Consumption: The Brain on Porn.”

Ley et al. state that scientists investigating high-frequency sexual behaviors rarely describe these behaviors as an addiction (37 % of articles) [2] First, Ley et al. are now talking about “sexual behaviors,” in general, not studies that screened problematic porn users, so their percentages are irrelevant.

Citation 2 affirms that different studies use different nomenclature for various behavioral addictions. This is not unusual in the mental health field. For example, bi-polar disorder has been called by many names, but it is still the same disorder. Even the DSM-5 uses different ways to describe addictions. So what? The DSM’s confounding terminology probably says more about the politics of the DSM board and work groups than about the physiological reality of addiction.

Naturally, these authors (as well as some others in the sexology field) openly reject sexual-behavior addiction, and sometimes all behavioral addictions, as “pseudoscience.” Their position is evident to anyone familiar with the literature they churn out. Tobacco executives still reject nicotine addiction too. In fact, it’s amazing that 37% of the studies reviewed used the term ‘addiction’, as flat-earth sexology researchers (including Prause) who produce academic articles on the subject have taken great pains to avoid both ‘addiction’ and the screening of addicted subjects (which is required procedure in true addiction research).

Next our audacious authors claim that most scientists have overtly rejected the addiction model [3, 4]. This is untrue, and neither of their citations remotely supports the claim that “most” scientists have “overtly rejected” the addiction model for sexual behavior addictions. Nor does either citation relate to research by addiction neuroscientists, who have publicly concluded the opposite.

Eric Nestler PhD, head of Nestler Lab (Molecular Psychiatry) at Mount Sinai’s Icahn School of Medicine writes about addiction:

It is likely that similar brain changes occur in other pathological conditions which involve the excessive consumption of natural rewards, conditions such as pathological over-eating, pathological gambling, sex addictions, and so on.

From ASAM’s press release:

CHEVY CHASE, MD, August 15, 2011 – The American Society of Addiction Medicine (ASAM) has released a new definition of addiction highlighting that addiction is a chronic brain disorder and not simply a behavioral problem involving too much alcohol, drugs, gambling or sex.

Citation 3 is from 2000. “Sexual disorders not otherwise specified: compulsive, addictive, or impulsive?” It basically says that the DSM should include diagnostic criteria for the disorder underlying the various labels:

Excerpt: Growing evidence supports the existence of a discrete syndrome characterized by recurrent and intense sexually arousing fantasies, sexual urges, or behaviors involving patterns that fall outside the definition of paraphilia. We suggest that the DSM-IV category of sexual disorders be modified to include explicitly diagnostic criteria for a disorder characterized by hypersexual symptoms.

Citation 4 in no way rejects the notion of sex addiction. (“Should Hypersexual Disorder [HD] be Classified as an Addiction?“) In fact, it says that “available data suggest that considering HD within an addiction framework maybe appropriate and helpful.” (emphasis added) In short, the reality is the opposite of “overtly rejecting” the addiction model, the proposition for which Ley et al. cited these items.

Also consider this review, which Ley et al. apparently missed: “Sexual Addictions” (2010)

Excerpts: A number of clinical elements, such as the frequent preoccupation with this type of behavior, the time spent in sexual activities, the continuation of this behavior despite its negative consequences, the repeated and unsuccessful efforts made to reduce the behavior, are in favor of an addictive disorder. …

The phenomenology of excessive nonparaphilic sexual disorder favors its conceptualization as an addictive behavior, rather than an obsessive-compulsive, or an impulse control disorder. (emphasis added)

Ley et al. then cite DSM-5, which has affirmed that pathological gambling is an addiction disorder in the wake of decades of solid science, but has not yet added internet addiction or internet porn addiction. This is not surprising as the dozens of brain studies on internet addictions are fewer and more recent than the majority of gambling studies–and the DSM-5 is notoriously slow and political rather than scientific.

Ley et al. use deceptive wording to imply that the DSM cited the following in support of its position, “To include [internet porn addiction] as an addiction would require published scientific research that does not exist at this time.” However this statement was only made to Ley et al. via personal communication from Charles O’Brien chair of the DSM-5 Work Group on Substance-Related and Addictive Disorders. It seems likely, however, that the DSM will eventually include sexual behavior addictions, because the research on all internet addictions is mounting and it lines up with the research on substance and gambling addictions. Said the same Charles O’Brien in 2013,

The idea of a non-substance-related addiction may be new to some people, but those of us who are studying the mechanisms of addiction find strong evidence from animal and human research that addiction is a disorder of the brain reward system, and it doesn’t matter whether the system is repeatedly activated by gambling or alcohol or another substance.

Moreover, Dr. Richard Krueger, work group member who helped revise the sexual disorders section of the DSM-5, has little doubt porn addiction is real and will eventually garner enough attention to be recognized as a mental illness.

Recklessly disregarding both (1) the DSM’s declaration that gambling is an addictive disorder (i.e., a behavioral addiction) and (2) years of conclusive addiction-neuroscience demonstrating that addictions, behavioral and chemical, are fundamentally one disorder, our anti-science authors next gratuitously dismiss all behavioral addictions (including gambling).

First, they dismiss food addiction ignoring extensive research on the subject and citing both 5, research funded by the sugar industry, specifically World Sugar Research (sponsored in part by Coca-Cola), and 6 “Obesity and the brain: how convincing is the addiction model?” The latter actually makes a decent argument, but its authors cherry pick, and its conclusions need to be considered in light of the many contradictory studies, such as “Obesity and addiction: neurobiological overlaps” and “Common cellular and molecular mechanisms in obesity and drug addiction.”

Next Ley et al. dismiss internet addiction citing 7, a study from 2001. However, almost all of the internet addiction studies have been done in the last 4 to 5 years. The more recent work eviscerates Ley et al.’s position that internet addiction isn’t genuine. These ~180 brain studies are listed at the end of this critique.

Ley et al. next dismiss gambling addiction, citing 8, which is ancient history from 25 years ago. At the same time they ignore the many studies that demonstrate brain changes in gambling addicts akin to those in drug addicts’ brains, as well as the position of the DSM itself. See “Similarities and differences between pathological gambling and substance use disorders: a focus on impulsivity and compulsivity” (2012) and “Neurobiology of gambling behaviors.” Frankly, it is difficult to avoid drawing the conclusion that Ley et al. themselves are “pseudoscientists.”

In support of their claim that “the emperor is not wearing any clothes,” Ley et al. throw in a cite to a 1991 manifesto by the APA’s president 9, which appears to have no relevance to anything at all.

Next, Ley et al. take offense at the word “pornography” in addiction studies, citing 11, a law review article that is not remotely related to addiction. They call for less biased language citing 12, an item that has nothing to do with porn-terminology guidelines.

Ley et al. then make the jaw-dropping claims that pornography use does not appear to be increasing despite increased availability, and VSS viewing in the USA has remained remarkably steady (near 22%) since 1973. The only support for these mind-bending statements is citation 20, an analysis that relies primarily on years of replies to a single question in a government survey of adult women conducted by personal interview. The question, first asked in 1973, is “Have you seen an X-rated movie in the last year? (0=no; 1=yes).”

The researchers then compared percentages of all adult women who said “yes” to seeing an X-rated movie (which was only possible in a theater back then) with percentages of women who say they watch internet porn flicks today. They reach the staggering conclusion that average porn-watching in women of all ages hasn’t changed much.

This is a classic apples-and-oranges sleight of hand. First, an X-rated film in the 70s (think “Last Tango In Paris“) might not be X-rated today. More to the point the percentage of 1973-women watching the equivalent of today’s hardcore porn would have been virtually 0%. In contrast, the rate of young women who watched an X-rated film in 2010 was 33%. In effect, that’s an increase from zero to one-in-three, and up from one-in-five in 1993. Hardly stable.

Second, “X-rated film” watching says nothing about other forms of (potentially addictive) online erotic stimulation, which some of today’s internet-erotica users over-consume, such as streaming video clips of hardcore porn, web cam use, today’s compelling written erotica, endless novel stills or animated porn such as hentai.

Moreover, what do X-rated film-viewing stats have to do with pornography addiction? Would a poll asking who had a drink in the last year be relevant in a review about alcohol addiction?

If Ley et al. believe porn rates are salient to their analysis, why didn’t they cite research that included men? Why didn’t they isolate digital natives, who appear to be most at risk for internet porn overconsumption, based on the fact that they make up the overwhelming majority of online recovery forum membership? Why didn’t they compare quantities of porn viewed? Why instead do they trot out this meaningless survey as sole support for their claim that porn viewing rates are 22% and stable? Consider some of the conflicting research that they ignored, how the stats might differ from porn use among emerging adults in 1973:

Generation XXX: Pornography Acceptance and Use Among Emerging Adults (2008)

Excerpt: Nearly 9 out of 10 (87%) young men and nearly one third (31%) of young women reported using pornography.

Prevalence and correlates of sexual behaviors among university students: a study in Hefei, China (2012)

Excerpt: Males reported more sexual fantasies (84.6%), solitary masturbation (70.3%), and using pornographic videos (86.3%). Note: porn is officially banned in China.

Gender differences in pornography consumption among young heterosexual Danish adults (2006).

Excerpt: In Denmark 97.8% of males and 79.5% of females watched pornography among 1002 people aged from 18–30 years old.

X-Rated: Sexual attitudes and behaviors associated with U.S. early adolescents’ exposure to sexually explicit media (2009)

Excerpt: Average age 13.5: Two-thirds (66%) of males and more than one-third (39%) of females had seen at least one form of sexually explicit media in the past year.

Adolescents’ Exposure to Sexually Explicit Material on the Internet (2006)

Excerpt: 71% of the male adolescents and 40% of the female adolescents had been exposed to some kind of online sexually explicit material in the 6 months prior to the interview.

Pornography Consumption, Sexual Experiences, Lifestyles, and Self-rated Health Among Male Adolescents in Sweden (2013)

Excerpt: Almost all boys, 96% (n = 453), had watched pornography. Frequent users of pornography (everyday) (10%, n = 47) differed from average users (63%, n = 292) and nonfrequent users (27%, n = 126).

Does Viewing Explain Doing? Assessing the Association Between Sexually Explicit Materials Use and Sexual Behaviors in a Large Sample of Dutch Adolescents and Young Adults (2013)

Excerpt: Online cross-sectional survey study of 4,600 young people, 15–25 years of age … found that 88% of men and 45% of women had consumed SEM in the past 12 months.


  • A 2016 cross-sectional, longitudinal study of 2600+ adults 18 or older found that in 2006, “39% of American adults in Wave 1 viewed some sort of pornographic materials in the previous 12 months. Consistent with previous research, almost three times as many men (59%) viewed pornography as women (20%).”
  • And a 2014 study conducted by phone reported that a representative sample of 20,094 men and women aged 16-69 revealed that 63% of the men and and 20% of the women had looked at pornography in the past year.

Ley et al. next offer estimates of men and women reporting out of control sexual experiences. Empirical estimates from nationally representative samples are that 0.8 % of men and 0.6 % of women report out of control sexual behaviors that interfere with their daily lives [23].

This statement demonstrates Ley et al.’s complete lack of integrity. First, their estimates rest on citation 23, a study that is not about porn use. The researchers specifically stated that, “We had not asked about pornography.” It was about sexual experiences, fantasies and urges. In other words, this study has no place in a “porn addiction” review, and all of the artful statistical chicanery that follows is meaningless.

That said, it’s worth noting that Ley, Prause and Finn shamelessly cherry-picked from the (irrelevant) study’s results. Nearly 13% of men and 7% of women reported out of control sexual experiences, but Ley et al. ignored those percentages and only mentioned that 0.8% of men and 0.6% of women reported that their “actual sexual behavior had interfered with their lives.” Porn use is not sex. Problematic porn use therefore exists in some people who believe that no “actual sexual behavior [is] interfering with their lives.”

Ley et al. next make the groundless leap that problematic porn use is always a subset of “actual sexual behavior that interferes with users’ lives,” and estimate that porn problems might affect 0.58 % of men and 0.43 % of women in the USA. Unbelievable. Ley et al.’s own source (see discussion of 24 below) says that experts estimated (in 2012) that 8–17% of Internet pornography users were addicted.

In contrast with the Ley et al.‘s trivial estimates, the researchers in “Viewing Internet Pornography: For Whom is it Problematic, How, and Why?” found that,

approximately 20%–60% of the sample who view pornography find it to be problematic depending on the domain of interest. In this study, the amount of viewing did not predict the level of problems experienced.

Ley et al.’s purposefully misleading calculations also assume that everyone with porn addiction seeks treatment. In fact, it’s likely that only a small percentage do. For example, consider the millions of smokers who attempt to quit every year and the millions who have quit over the last several decades. It’s likely that those who struggled without professional help far outnumbered those who sought it. Once again, one wonders how a peer reviewer, or co-author Finn, could let slip such deceptive reasoning.

Positive Effects of VSS Use

Ley, et al. claim that Most people who view VSS believe that it improves their attitudes towards sexuality [25] and improves their quality of life [26]. The studies Ley et al. cite as proof that porn’s effects are beneficial (24, 25, 26) are unconvincing. The first (24) actually offers evidence of the ill effects of porn use:

Excerpt: Experts put the percentage of persons with problematic sexually compulsive behavior in reference to viewing sexually explicit material at approximately 8–17% of the population of users (Cooper, Delmonico, & Burg, 2000; Cooper, Scherer, Boies, & Gordon, 1999). This group of users exhibits behavioral indicators of sexual compulsivity (e.g., spending 11 or more hours per week in online sexual pursuits) and reports personal distress and impairment of functioning (e.g., declining performance at work).

Further, the researchers found that possible beneficial uses of “sexually explicit visuals” are largely confined to medical and educational audiences.

The second study (25) is primarily a marketing survey of people who like porn (e.g., “Which of the following practices do you like to be present in pornography?”), peppered with a few questions about attitudes toward women. It was funded in part by the porn industry itself. As part of the lengthy survey, a sole ambiguous question asked “What effect has pornography had on your attitudes towards sexuality?” What does this question, or its possible answers (“Large positive effect,” “small negative effect,” etc.) even mean? Isn’t this like asking people at a rave whether rave participation has had a positive or negative effect on their attitude toward ecstasy?

Self-perceived effects of pornography consumption” (26) also relies purely on porn users’ self-perceptions (rather than a comparison with non-users or ex-users). Its questions were skewed to always find porn use beneficial because of all the non-standard sex acts porn users learn about. Its conclusion? The more pornography you use, the more real you believe it is, and the more you masturbate to it, the more positive its effects in every area of your life. Wow! Not even a bell curve there folks. Senior psychology professor and reviewer John Johnson called this questionnaire “a psychometric nightmare,” yet Ley et al. treat it as authoritative. See this critique of the study.

Frankly, many of the “benefits” claimed by Ley et al. turn out to be negatives for today’s young porn users. Here are some of their examples of how porn users might profit:

  1. greater likelihood of anal and oral sex [27] and a greater variety of sexual behaviors [28].

So, more is an unqualified benefit? In “Does pornography influence young women’s sexual behavior?” (2003), Swedish researchers found that of 1000 women polled at a family planning clinic, 4 out of 5 has consumed pornography. About half had experienced anal intercourse, and the majority found it a negative experience. Condom use was only 40%, presenting a risk of spreading STIs. Among young Swedish men visiting a similar clinic, 99% had consumed porn and half had had anal intercourse. Only 17% always used condoms during anal sex. Both genders said that watching porn had influenced their behavior.

According to Mount Sinai: “It is believed that an increased number of people are engaging in sexual activity with multiple partners and engage in oral sex practices and as a result are contracting HPV in the head and neck region, resulting in [at least a four- to five-fold increase in the number of oropharynx cancers in the US].”

  1. This increased breadth of sexual behaviors could arise by increasing a person’s feeling of empowerment to suggest new sexual behaviors or by normalizing the behaviors [29].

“Normalizing sexual behaviors” ultimately proves alarming to many young porn users because, in their unending quest for novelty, they so easily escalate to bizarre fetish porn that doesn’t have anything to do with their earlier sexual tastes. Some go far into this spiral before they begin questioning whether what they’re watching is “normal.”

  1. VSS can also promote pleasant feelings in the moment, such as happiness and joy [30, 31].

What porn user doesn’t have “pleasant feelings” during use, just as many people enjoy drinking? Shouldn’t users be more informed about the potential longer-term effects of their porn use? Incidentally, citation 31 is Prause’s own shaky research: “No Evidence of Emotion Dysregulation in “Hypersexuals” Reporting Their Emotions to a Sexual Film.” See a critique of that study: “Study: Porn Users Report Narrower Emotional Range.”

  1. VSS may provide a legal outlet for illegal sexual behaviors or desires.

Really? Are Ley et al. then advocating watching child porn and creating a demand for more of it?

In any case, progression appears to work the opposite way in some users. Instead of simply providing an outlet for innate sexual preferences, internet porn may create preferences. Thanks to their unending quest for novel sexual stimulation online, some porn users report escalating to bestiality porn or underage porn, both of which are illegal in some jurisdictions.

In “Does deviant pornography use follow a Guttman-like progression?” researchers investigated whether desensitization (leading to a need for more extreme material) occurred in individuals who engage in adult pornography at a young age. They found that,

Excerpt: individuals with a younger “age of onset” for adult pornography use were more likely to engage in deviant pornography (bestiality or child) compared to those with a later “age of onset”.

Ley et al. then proceed to associate declines in crime with increased porn use, and imply a causal link between the two citing correlational data (based not on actual studies, but on notoriously inaccurate government statistics). If such data have a place in this review, then we call upon Ley et al. to redo their entire review to incorporate the dozens of correlational studies associating porn with ill effects. (See the list at the end of this critique, as well as various overlooked studies we cite within the body of this critique.)

Ley et al. write: A large longitudinal study controlling for baseline attitudes and behaviors identified that VSS use accounted for only 0–1 % of the variance in gender role attitudes, permissive sexual norms, and sexual harassment in boys or girls [12]. Ley et al. paint a rather misleading picture of the total findings in citation 12 (“X-Rated: Sexual attitudes and behaviors associated with U.S. early adolescents’ exposure to sexually explicit media” (2009).)

Excerpt: Of all the variables in the models, exposure to sexually explicit media was one of the strongest predictors, even after controlling for demographics, pubertal status, sensation seeking, and the baseline measure of the sexual attitude (if relevant). Thus, these analyses suggest that exposure to sexually explicit media should be considered an important factor in the sexual socialization of early adolescents. …

One of the most troubling findings in this study is that exposure was related to not only early oral sex and sexual intercourse for both males and females but also perpetration of sexual harassment by adolescent males. (emphasis added)

Addiction Model (update: List of Neurological Studies on Porn Users)

Addiction is not, as Ley et al. brashly insist, a theoretical construct. Addiction is perhaps the most studied and best elucidated of all mental disorders. It can be induced in animals and is currently studied right down to the cellular, molecular, and epigenetic mechanisms that physically and chemically change in the brain in response to chronic overconsumption. Addiction is, in fact, the very opposite of a theoretical construct. It’s a physiological reality that applies to both chemical and behavioral addictions.

Again, Ley et al. go to amazing lengths to try to convince themselves and their readers that the slow-moving DSM-5 physicians who are finally beginning to bring the DSM into line with current research by creating a behavioral addiction category–didn’t really mean it: While there seems to be a consensus that addiction is a useful construct to describe opiate dependence [39], the usefulness of ‘addiction’ to describe the excessive use of any drug [40], compulsive gambling [41], and excessive video game playing [42] has raised many concerns.

The citations they tuck into their stunning assertion deserve a closer look. 39, 40 and 41 were published in 1996, 1986 and 1989, respectively. All predate the lion’s share of the research on each of the addictions named. Ley et al. were forced to reach back into the depths of time because modern hard-science studies do not support Ley et al.’s “concerns” about the science of addiction.

Citation 42 relates to videogaming (which has burst on the scene more recently than gambling, of course) and it points to a 2008 item. However, this item predates all but 3 of the ~160 existing brain studies on internet/videogame addicts. As a body, the intervening studies demonstrate that internet addictions also belong in the behavioral addiction category. In short, Ley et al. resort to subterfuge to support their outdated views.

Next, Ley et al. present their unique definition of porn addiction drawn from thin air, and begin to trot out their straw army, a long list of random “proofs” they claim are vital before one can consider porn addiction to exist. As part of this exercise they totally disregard ASAM’s public statements and the decades of hard science that refute their position. Repeatedly, they imply that porn addiction has been studied in the ways they list and found to be absent.

This is not the case. The first two brain studies on porn users done by addiction neuroscientists are now out and their conclusions dismantle the assertions of Ley et al. The first one had already been described in the press before Ley et al. published this review, and they were perfectly aware that it found the same kinds of solid evidence of addiction seen in substance addicts, gambling addicts and internet addicts. One would think that if Ley et al. were indeed taking an objective look at the possible existence of internet porn addiction, they would devote much attention to the ~60 brain studies on internet addiction and internet videogame addiction. Surely those studies are highly relevant to internet porn addicts as well, particularly given ASAM’s consensus that all addictions are fundamentally one disease.

Again, it’s worth noting that Ley et al. proclaim opioids to be the only legitimate addiction–or in their artful lingo, the only “dependence for which an addiction construct is useful.” No one agrees with them. Not the DSM, not ASAM, not the medical profession generally. They may, in fact, be the only 3 people on the planet clinging to this unsupportable position. Or perhaps they hope their empty assertions will fool unsuspecting journalists.

Ley et al. suggest that porn addiction’s existence needs to be supported by proof of negative consequences that cannot be ascribed to other causes. As far as we know, very few studies have even attempted to look at the kinds of severe symptoms porn users report in online forums: erectile dysfunction, delayed ejaculation, anorgasmia, morphing sexual tastes, depression, anxiety, social anxiety, decreased motivation for positive activities, less attraction to real partners, concentration problems, etc. Nor is it easy for porn users to connect porn use with their symptoms until they stop using porn (remove the key variable) for an extended period. Such experiments are difficult to design and execute, and impossible to do with adolescents even though they are the most likely to be adversely affected because their brains are more susceptible to addiction.

As far as we know, only one study has asked porn users to stop porn…for a mere three weeks. Those researchers saw a significant increase in subjects’ desire to remain in a committed relationship, compared with controls who kept using. In short, it’s far too soon to assume that there are no negative consequences from internet porn use itself, especially in light of both the demonstrable problems stemming from overconsumption of internet generally, and the dozens of correlational studies about porn use showing associations with harm.

Negative Consequences of High Use of VSS – High VSS Use Associations with Health-Risk Behaviors

Ley et al. imply that causation studies have been done, and that No study has demonstrated a direct, causal link between VSS use and health-risk behaviors. In fact, no one knows what causal studies would reveal about porn use and health-risk behaviors, because no causal studies have been done. There are only 2 ways to determine causality neither of which seems likely to be undertaken with respect to health risks and porn: 1) Have two matched groups, in which one group uses porn and the other does not. 2) Remove porn for an extended period and see the results.

In the interim, correlation studies are the strongest formal evidence available, and dozens of them show associations between porn use and health-risk behaviors. (See list at end of critique.) Bear in mind that Ley et al. themselves freely cite correlation studies when they like the results.

Negative Consequences of High Use of VSS – Erectile Dysfunction and High VSS Use?

Why does this section exist? As of February, 2014 no published studies have ever considered porn use as a variable in connection with erectile dysfunction. There is nothing to review. Why are Ley et al. once again creating the false impression that the relationship between ED and porn has been formally studied and found to be absent? Why are they citing ED studies that never raised porn as a possible cause, let alone removed porn use as a variable to see if it would help (as it has thousands of young men with unprecedented ED who report their results online)?

Update: Co-author Nicole Prause is obsessed with debunking porn-induced ED, having waged a 3-year war against this academic paper, while simultaneously harassing and libeling young men who have recovered from porn-induced sexual dysfunctions. See: Gabe Deem #1, Gabe Deem #2, Alexander Rhodes #1, Alexander Rhodes #2, Alexander Rhodes #3, Noah Church.).

Ley et al. admit that two European studies have found a startling increase in ED in young men. However, neither belongs in “No Clothes.” The researchers in those studies didn’t think to poll their subjects about internet porn use. They could only theorize that the increases in youthful ED might be stemming from factors such as smoking, drug use, depression or poor health. As an aside, smoking is at an historic low, and it only causes ED problems in longtime smokers who develop arterial disease. Commenting about these two studies, urologist James Elist said that Internet porn was the primary cause of ED in young men:

recreational drugs, smoking, and mental health seem, compared to internet porn consumption, to be making up rather the smaller portion of elements being responsible for early onset ED.

Next Ley et al. hypothesize that porn can’t cause ED because the brains of men with and without ED showed no differences during VSS viewing in (63). Actually citation 63 is irrelevant to the discussion of ED and porn. It only examined cerebral cortex activity, not the limbic regions that govern desire and erections. Incidentally, Ley et al. ignored another study that did find differences in cerebral activation between those with psychogenic ED and controls: “The role of left superior parietal lobe in male sexual behavior: dynamics of distinct components revealed by FMRI.” Note: ‘Psychogenic ED’ is a term for ED, such as porn-related ED, which cannot be explained by organic causes such as vascular damage.

Ley et al. (and their reviewers) apparently overlooked the next two studies as well, which revealed significant differences (in the limbic brain regions that control sexual excitement and erections) when researchers compared control subjects with subjects who had psychogenic ED.

In their determination to dismiss internet porn as a possible cause of unprecedented youthful ED, Ley et al. even vilify masturbation and orgasm. (The irony of this position taken by the champions of “high sexual desire” is noteworthy.) They prefer to theorize about these two time-honored, normal activities, rather than consider the glaring possibility that high-speed internet porn, a brand new stimulus that has only been present for the blink of an eye in evolutionary terms, might be a factor.

They reach the remarkable conclusion, supported by no urologist, that chronic ED in young men is a function of masturbation, or, alternatively, the refractory period. The latter is particularly droll in light of the fact that it sometimes takes 2-12 months for guys to get their erections back even after quitting porn/masturbation. That’s some refractory period!

Persistent porn-induced ED in young men caught the medical profession by surprise, but this year doctors have finally begun to acknowledge it. Harvard urology professor and author of books on men’s health Abraham Morgentaler, MD said,

“It’s hard to know exactly how many young men are suffering from porn-induced ED. But it’s clear that this is a new phenomenon, and it’s not rare.”

And urologist and author Harry Fisch, MD writes bluntly that porn is killing sex. In his book The New Naked, he zeroes in on the decisive element – the internet:

It “provided ultra-easy access to something that is fine as an occasional treat but hell for your [sexual] health on a daily basis.

Dr. Fisch continues:

I can tell how much porn a man watches as soon as he starts talking candidly about any sexual dysfunction he has. … A man who masturbates frequently can soon develop erection problems when he’s with his partner. Add porn to the mix, and he can become unable to have sex. …

Moreover, in the new Cambridge study on 19 porn addicts’ brains, researchers remarked three times that more than half of their subjects reported ED/arousal problems with real partners that were absent during porn use. For example,

CSB [compulsive sexual behavior] subjects reported that as a result of excessive use of sexually explicit materials, they had lost jobs due to use at work (N = 2), damaged intimate relationships or negatively influenced other social activities (N = 16), experienced diminished libido or erectile function specifically in physical relationships with women (although not in relationship to the sexually explicit material) (N = 11), used escorts excessively (N = 3), experienced suicidal ideation (N = 2) and using large amounts of money (N = 3; from £7000 to £15000). (emphasis added)

Finally, Ley et al. say something with which we totally agree, although we don’t know if young men with limp members would appreciate Ley et al.’s label of “non-pathological.” The researchers acknowledge that learning, another term for which would be ‘sexual conditioning,’ might be contributing to youthful ED. We totally agree that young porn users may be wiring their sexual response to screens and novelty-on-demand instead of people, such that performance with a real person is alien and not arousing. This, of course, does not preclude some of these ED sufferers from also being addicts.

What Ley et al. fail to mention is that sexual conditioning (learning) and porn addiction appear to hijack some of the same mechanisms in the brain. In other words, sexual conditioning and addiction are surprisingly closely related phenomena as a biological matter. It’s illogical to entertain sexual conditioning as a possible cause of porn-related problems and still insist that addiction-related brain changes cannot also be at work in some users.

Chronic ED stemming from Pavlovian conditioning via screens is powerful evidence that internet porn is a supernormal stimulus quite unlike static porn in terms of its effects. ED was not a challenge for youthful porn users who could only gaze upon brothel murals or magazines.

In short, Ley et al.’s admission that porn can cause ED via sexual conditioning (learning) is quite close to an admission that porn can also cause addiction–although they seem to be unaware of this. Addiction is merely another example of pathological learning, equally related to Pavlovian conditioning. As researchers said in “Initiation and maintenance of online sexual compulsivity: Implications for assessment and treatment“:

Excerpt: Sexually compulsive behavior on the Internet is now a widely recognized problem. … Factors that serve to maintain compulsive online sexual behavior include classical conditioning and operant conditioning [i.e., Pavlovian conditioning].

Addicted or not, when young men with porn-related ED quit using porn they generally experience a long period of low libido, non-responsive genitals and sometimes mild depression. Happily, thousands of ex-porn users have gradually resolved their sexual health problems (ED, delayed ejaculation, anorgasmia, loss of attraction to real partners and morphing porn-fetish tastes) simply by quitting. Their informal experiment suggests causality, even if further research would be needed to establish it.

Negative Consequences of High Use of VSS – Failure to Inhibit VSS Use

In support of their claim that Far more people report a feeling of inability to control their VSS use, than actually report life difficulties resulting from their use [23], Ley et al. again cite a study that did not ask about pornography use. (See above discussion of citation 23.) They also conclude that No data currently support the notion that ‘porn addicts’ have difficulty inhibiting their VSS use.

In any case, what study has asked porn users to stop using porn so their difficulties could be observed? Not one that we know of. That said, Ley et al. overlook a wide range of correlation studies that suggest that some porn users have difficulty inhibiting use. Consider the following:

Internet sex addiction treated with naltrexone (2008)

Excerpt: Malfunctioning of the brain’s reward center is increasingly understood to underlie all addictive behavior. Prescribed for treating alcoholism, naltrexone blocks opiates’ capacity to augment dopamine release. This article reviews naltrexone’s mechanism of action in the reward center and describes a novel use for naltrexone in suppressing a euphorically compulsive and interpersonally devastating addiction to Internet pornography.

Predicting compulsive Internet use: it’s all about sex! (2006)

Excerpt: The objective of this research was to assess the predictive power of various Internet applications on the development of compulsive Internet use (CIU). The study has a two-wave longitudinal design with an interval of 1 year. … On a cross-sectional basis, gaming and erotica seem the most important Internet applications related to CIU. On a longitudinal basis, spending a lot of time on erotica predicted an increase in CIU 1 year later. The addictive potential of the different applications varies; erotica appears to have the highest potential. (emphasis added)

Hypersexual behavior in an online sample of males: associations with personal distress and functional impairment.

Excerpt: There were 75.3% (N = 253) who reported feeling distressed due to hypersexual behavior. Functional impairment in at least one life area was specified by 77.4% (N = 270), and most participants (56.2%) reported impairment regarding partner relationships. Personal distress and functional impairment in three areas were associated with a strong motivation for behavior change. Distress was associated with online pornography use, masturbation, and/or sexual contact with changing partners. (emphasis added)

Cybersex Users, Abusers, and Compulsives: New Findings and Implications (2000)

Excerpt: This study empirically examines the characteristics and usage patterns of individuals who use the Internet for sexual purposes. The Kalichman Sexual Compulsivity Scale was the primary tool used to divide the sample (n = 9,265) into four groups: nonsexually compulsive (n = 7,738), moderately sexually compulsive (n = 1,007), sexually compulsive (n = 424), and cybersex compulsive (n = 96); 17% of the entire sample scored in the problematic range for sexual compulsivity. (emphasis added)

Pornography consumption, sexual experiences, lifestyles, and self-rated health among male adolescents in Sweden. (2013)

Excerpt: One third of Swedish 16-year old males who were frequent porn users reported watching more pornography than they actually wanted.

Neuroadaptations to VSS Use

This section trots out a veritable platoon of straw men, who are nothing more than a hand-picked assortment of ‘essential elements’ Ley et al. imply have been studied and found wanting in porn users.

A major building block of their thesis is that  “no data have demonstrated that VSS are different from any other ‘liked’ activity or object“. In other words, sexual stimulation is no different from viewing memorabilia of your favorite football team (as they later suggest). Of course that is nonsense.

First, sexual activity elevates nucleus accumbens dopamine far beyond any other stimulus, such as highly palatable food. Second, sexual stimulation activates its own dedicated set of nucleus accumbens neurons. These same neurons are activated by addictive drugs such as methamphetamine and cocaine, which is why these drugs are so compelling for some users. In contrast, rewards such as food and water activate a separate subset of nucleus accumbens neurons, and there’s only a small percentage of nerve-cell activation overlap between meth and food or water (other natural rewards).

Put simply, we know the difference between watching football and having a mind-blowing orgasm. Speaking of orgasm, ejaculation in male rats can temporarily shrink the reward circuit nerve cells that produce dopamine. This normal event mimics the effects of heroin addiction on these same dopamine nerve cells. This is yet another another example of the uniqueness of sexual stimulation and how it mimics the effects of addictive drugs. Additional recent studies found that sex and addictive drugs not only activate the exact same reward center neurons, but both initiate the same cellular alterations and gene expression. Sex is unique among rewards, and shares many qualities with addictive drugs.

Next, Ley et al. opine that porn can’t cause addiction unless it shifts the brain’s response from ‘liking’ to ‘wanting.’

This appears to fulfill the initial liking present in the development of substance addictions [90] and offers some commonalities with substance reinforcement [91], but in no case has a shift away from liking to wanting or craving been demonstrated.”

In effect, Ley et al. are denying that craving for porn exists. Yet all of these studies suggest craving is present:

Excerpts from the previous item: In light of its similarities with substance abuse and dependence, there is growing support for conceptualizing problematic sexual compulsions as an addictive disorder (Barak & King, 2000; Griffiths, 2001; Meerkerk, Van Den Eijnden, & Garretsen, 2006; Orford, 2001). One element of addiction— and of many impulse control and paraphilic disorders—is the subjective experience of craving. ….The heaviest pornography users reported significantly higher craving. (emphasis added)

More to the point, when researchers finally investigated “liking” versus “wanting” in porn addicts, they found exactly what Ley et al said was missing: a shift away from liking to wanting. A 2014 Cambridge University brain study on porn addicts showed that they experienced cue-induced cravings and greater ventral striatum activation than controls, yet they did not “like” porn any more than the controls. From the study:

Excerpts:Sexual desire or subjective measures of wanting appeared dissociated from liking, in line with incentive-salience theories of addiction [12] in which there exists enhanced wanting but not liking of salient rewards.”

“Compared to healthy volunteers, CSB subjects [porn addicts] had greater subjective sexual desire or wanting to explicit cues and had greater liking scores to erotic cues, thus demonstrating a dissociation between wanting and liking. CSB subjects also had greater impairments of sexual arousal and erectile difficulties in intimate relationships but not with sexually explicit materials highlighting that the enhanced desire scores were specific to the explicit cues and not generalized heightened sexual desire.”

Put simply, compulsive porn users (CSB subjects) in this study aligned with the accepted model of addiction, called incentive motivation or incentive sensitization. Addicts experience strong cravings to use “it” (wanting), yet they do not like “it” any more than non-addicts. Or as some say, “wanting it more, liking it less, yet never satisfied.”

A follow up “attentional bias” study by Cambridge University lent further support to the addiction model of craving porn more without liking it more. The authors concluded:

Excerpt: “These findings converge with recent findings of neural reactivity to sexually explicit cues in CSB in a network similar to that implicated in drug-cue-reactivity studies and provide support for incentive motivation theories of addiction underlying the aberrant response to sexual cues in CSB.”

A 2014 brain scan study by Germany’s Max Planck Institute, published in JAMA Psychiatry, also supports the addiction model of wanting porn more, yet not liking it more. The study found higher hours per week/more years of porn viewing correlated with less reward circuit activity when presented with still images. The study also correlated higher porn use with loss of reward circuit grey matter. From the study:

Excerpt: “This is in line with the hypothesis that intense exposure to pornographic stimuli results in a downregulation of the natural neural response to sexual stimuli.”

Lead author Simone Kühn said

That could mean that regular consumption of pornography more or less wears out your reward system.”

Kühn continued –

We assume that subjects with a high porn consumption need increasing stimulation to receive the same amount of reward.

Kühn says existing psychological, scientific literature suggests consumers of porn will seek material with novel and more extreme sex games.

That would fit perfectly the hypothesis that their reward systems need growing stimulation.

The above findings dismantle the two primary arguments put forth by porn addiction naysayers:

  • That porn addiction is simply “high sexual desire“. Reality: The heaviest porn users had less response to everyday sexual images, thus less “sexual desire.”
  • That compulsive porn use is driven by “habituation”, or becoming easily bored. Reality: Habituation is a temporary effect that doesn’t involve the measurable shrinkage of actual brain structures found in the above research.

Again, with ‘heritability‘ of porn addiction Ley et al. mislead readers by implying that this element is essential to establish addiction (huh?), and that studies have investigated it in porn addicts and found absent. However, no such research has appeared (yet), and its absence is not evidence of anything.

Ley et al.’s superficial understanding of addiction is perhaps most evident in their comments on ΔFosB, a transcription factor that accumulates with overconsumption and can trigger a more lasting set of addiction-related brain changes. First, there is no question that drugs of abuse and natural rewards induce ΔFosB in the nucleus accumbens (NAc) of rodents. The 2001 paper by Nestler, et al. “ΔFosB: A sustained molecular switch for addiction” stated:

ΔFosB may function as a sustained “molecular switch” that helps initiate and then maintain crucial aspects of the addicted state.

Since 2001, study after study has confirmed that consumption of natural rewards (sex, sugar, high-fat, aerobic exercise) or chronic administration of virtually any drug of abuse induces ΔFosB in the nucleus accumbens. Alternatively, ΔFosB can be induced selectively within the nucleus accumbens and dorsal striatum of adult animals. The behavioral phenotype of the ΔFosB-overexpressing rodents resembles animals after chronic drug exposure.

Second, Ley et al. say that ΔFosB works via D1 pathways. That’s not always true. The prominent exceptions are the opiates (e.g., morphine, heroin), which induce ΔFosB equally in D1-type and D2-type neurons. Natural rewards such as sucrose (but not sex) resemble opiates in this regard. Sexual activity induces ΔFosB in D1-type neurons in a pattern similar to cocaine and methamphetamine.

Third, Ley et al. say that ΔFosB’s main role is to reduce dopamine signaling. Actually, ΔFosB’s initial action is to inhibit dynorphin, thus increasing dopamine signaling, although ΔFosB may also ultimately lead to D2 down regulation (decreased signaling). See “Cdk5 Phosphorylates Dopamine D2 Receptor and Attenuates Downstream Signaling” (2013)

Fourth, Ley et al. completely miss ΔFosB’s role in sensitization (inducing cravings). A review covering 15 years of ΔFosB research describes sensitization as ΔFosB’s primary action that induces addiction, both chemical and behavioral.

Excerpts: These data indicate that the induction of ΔFosB in dynorphin-containing medium spiny neurons of the nucleus accumbens increases an animal’s sensitivity to cocaine and other drugs of abuse, and may represent a mechanism for relatively prolonged sensitization to the drugs. …

ΔFosB in this brain region sensitizes animals not only for drug rewards but for natural rewards as well, and may contribute to states of natural addiction.

Sensitization also explains how ΔFosB reinforces sexual reward. In relation to sex, only rodents’ ΔFosB levels have so far been measured. Just a few examples:

Delta JunD overexpression in the nucleus accumbens prevents sexual reward in female Syrian hamsters (2013)

Excerpt: These data, when coupled with our previous findings, suggest that ∆FosB is both necessary and sufficient for behavioral plasticity following sexual experience. Furthermore, these results contribute to an important and growing body of literature demonstrating the necessity of endogenous ΔFosB expression in the nucleus accumbens for adaptive responding to naturally rewarding stimuli.

Natural reward experience alters AMPA and NMDA receptor distribution and function in the nucleus accumbens (2012)

Excerpt: Together, these data show that sexual experience causes long-term alterations in glutamate receptor expression and function in the nucleus accumbens. Although not identical, this sex experience-induced neuroplasticity has similarities to that caused by psychostimulants, suggesting common mechanisms for reinforcement of natural and drug reward.

Natural and Drug Rewards Act on Common Neural Plasticity Mechanisms with ΔFosB as a Key Mediator (2013)

Excerpt: Natural and drug rewards not only converge on the same neural pathway, they converge on the same molecular mediators and likely in the same neurons in the nucleus accumbens to influence the incentive salience and the “wanting” of both types of rewards (sex and drugs of abuse).

So, what of humans? Ley et al. correctly state that there are serious challenges in measuring ΔFosB in humans. It requires fresh corpses. But again, they either deliberately misled their readers or failed to do their homework. They did not report that higher than normal ΔFosB levels have been found in deceased cocaine addicts. This suggests that ΔFosB plays a similar role in reinforcing reward in humans. Instead Ley et al. only pointed to null ΔFosB results in deceased alcoholics. How’s that for cherry-picking? They choose an anomaly in hopes they can deceive their readers that ΔFosB research can’t offer strong support for the concept that all chemical and behavioral addictions are one biological disease.

What accounts for the anomaly? The study on alcoholics only looked at the frontal cortex, not the nucleus accumbens or dorsal striatum, which is where ΔFosB is normally measured in connection with addiction. All the studies that induced addiction-like behaviors and hyper-consumputive states did so by elevating ΔFosB in the nucleus accumbens not the frontal cortex.

In any event, alcoholic corpses would be poor subjects because alcoholics typically experience a slow decline from their chronic condition, which would typically make indulgence in their addiction less feasible and thus make accumulation of ΔFosB less likely near their deaths. In contrast, the cocaine addicts whose ΔFosB levels were measured all died sudden deaths without protracted illness. See “Behavioral and Structural Responses to Chronic Cocaine Require a Feedforward Loop Involving ΔFosB and Calcium/Calmodulin-Dependent Protein Kinase II in the Nucleus Accumbens Shell” (2013)

Excerpt: The cohort was composed of 37 male and 3 female subjects, ranging in age between 15–66 years. All subjects died suddenly without a prolonged agonal state or protracted medical illness. … Here, we present the first evidence that levels of both ΔFosB and CaMKII are increased in NAc of cocaine-dependent humans. These data indicate that our examination of ΔFosB and CaMKII induction by cocaine in rodent NAc is clinically relevant to human cocaine addiction.

Next, Ley et al. make the jump from deception or incompetence…to incoherence. For reasons known only to themselves they begin babbling about male-on-male mounting behavior, claiming that no one can study hypersexuality or ΔFosB without using gay rats, which would “pathologize homosexual behavior.” Huh? This is as uncorroborated as their earlier statements that only opioids can cause addiction.

Perhaps this lively red herring is here to distract readers from contemplating the critically important implications of ΔFosB for sexual addictions. Both amphetamine and sex sensitize the same neurons in the brain, which suggests that of all addictions, sexual behavior addictions may be among the most compelling. Or to state this another way, drug addictions hijack the brain machinery that evolved to drive sexual learning

In short, Ley et al.’s insistence that sexual behaviors can’t become addictive in the face of a supernormal stimulus like internet porn is nothing short of reckless given the evidence that ΔFosB is at work, sensitizing brains, in both sex and addiction. See Pornography addiction – a supranormal stimulus considered in the context of neuroplasticity.”

Alternative Models – Secondary Gain

Next Ley et al. chastise the “lucrative, largely unregulated” pornography and sex addiction treatment industry. However, the internet offers many free porn recovery sites. Very few of the tens of thousands of people on online porn recovery forums see therapists. It’s likely that the vast majority of those who self-identify as porn addicts, however severe their symptoms, do not seek, or spend a dime on, treatment. Only a handful have gone to treatment centers, which tend to specialize in helping those with more pervasive sexual or other behavioral and/or chemical addictions.

In any case, how could treatment cost possibly have a bearing on whether or not porn addiction is a physical reality? If Ley et al. are so bothered about possible bias, they could profitably have spent more time investigating their own.

Ley et al. also argue that religious affiliation gives rise to the “supposed pathology” of porn addiction. Self-polls repeatedly show that the overwhelming majority of young people on porn recovery sites are not religious. For example this self-poll of the largest English-language forum found that only 20% of those polled were seeking to quit porn for religious reasons.

And if moneymaking is a problem in the porn-addiction controversy, what of the lucrative porn industry manipulating its visitors to keep them producing ad (and other) revenue?

And if moneymaking is a problem in the porn-addiction controversy, what of the lucrative porn industry manipulating its visitors to keep them producing ad (and other) revenue? What of author David Ley himself, who presumably charges his clients for his clinical services? What about Ley profiting from his book and Psychology Today blog posts denying the existence of porn addiction? What about Ley profiting from speaking engagements? In fact, David Ley profits from denying sex and porn addiction. At the end of this Psychology Today blog post Ley states:

Disclosure: David Ley has provided testimony in legal cases involving claims of sex addiction.

It should be noted that Nicole Prause also offers her “expert” testimony against “sex addiction”. From her Liberos website (page since removed – see WayBack Machine):

“Sex addiction” is increasingly being used as a defense in legal proceedings, but its scientific status is poor. We have provided expert testimony to describe the current state of the science and acted as legal consultants to help teams understand the current state of the science in this area to successfully represent their client.

Legal consultations and testimony are generally are [sic] billed on an hourly rate.

Prause is attempting to sell her services to profit from the claimed anti-porn addiction conclusions of her two EEG studies (1, 2), even though both studies support the addiction model.

Ley et al.’s sloppiness, or desire to discredit those who treat sex addicts, shows up again when they claim that ‘R. Weiss’ has published an explicitly religious argument against porn viewing. The actual author is D. Weiss. Rob Weiss is a sex therapist and the author of several books, including Cruise Control: Understanding Sex Addiction in Gay Men. This error stands to muddy his reputation with both readers and clients.

VSS Use and Mental Health Problems

In this section Ley et al. claim there’s no evidence that porn use causes mental health problems, suggesting that any such problems necessarily predate porn use. No doubt pre-existing conditions do increase some users’ vulnerability to addiction. Yet therapists are increasingly seeing another type of porn addiction that is not dependent on pre-existing conditions.

They are labeling it in various ways including “opportunity addiction” and “contemporary rapid-onset addiction.” Unlike classical ‘sex addiction,’ this type of addiction is to internet porn and has more to do with early exposure to graphic sexual stimuli via the internet than inherent vulnerabilities, which may or may not be present.

Ley et al. claim that citation 125, “Adolescents’ Exposure to Sexually Explicit Internet Material and Sexual Preoccupancy: A Three-Wave Panel Study” (2008), is evidence that lower life satisfaction causes increased porn use, not the reverse. That may, of course, be true for some users, but let’s look more closely at some of that study’s other, more disturbing findings. The researchers surveyed 962 Dutch adolescents three times over the course of 1 year.

Excerpts: The more frequently adolescents used SEIM [Sexually Explicit Internet Material], the more often they thought about sex, the stronger their interest in sex became, and the more frequently they became distracted because of their thoughts about sex. …

Sexual arousal as a result of exposure to SEIM may cue sex-related cognitions in memory … and may eventually lead to chronically accessible sex-related cognitions, that is, sexual preoccupancy.

Next, Ley et al. state that even when loneliness was strongly predicted by overall Internet use, researchers failed to appropriately statistically control for general Internet use and attributed loneliness to VSS use [126]. Alas, continuing a pattern that is becoming dishearteningly familiar in “No Clothes,” citation 126 has nothing to do with internet porn use: See “When What You See Isn’t What You Get: Alcohol Cues, Alcohol Administration, Prediction Error, and Human Striatal Dopamine.” Shoddy.

Ley et al. then resort to misrepresentation. Others have reached similar conclusions: “the high comorbidity rates in the present sample call into question the extent to which it is possible to speak of Internet sex addiction as a primary disorder. The relevant citation (127) comes from “Internet sex addiction: A review of empirical research,” which was not about internet porn addiction, but rather sex addiction facilitated by the internet. In any case, the statement was not a “conclusion” at all. It was made in reference to only a single study (Schwartz & Southern, 2000) of the many studies the author reviewed. The researcher’s actual conclusion was:

If the cybersex user experiences clinically significant distress or impairment because of their engagement in sexual behaviors on the Internet, it appears relatively safe to claim that s/he suffers from Internet sex addiction.

Granted it is difficult to conduct formal causality studies of the type being carried out informally online by tens of thousands of (mostly) guys who are giving up internet porn and seeing profound mental health benefits (improved concentration, reduced social anxiety and depression, increased motivation and elevated mood). However, researchers have conducted numerous correlation studies that show an association between pathological internet use and mental health problems. In addition to the many studies we discuss specifically herein, we list and describe ~30 relevant studies at the end of this critique, all of which demonstrate mental health risks, or other risks, associated with porn use and none of which made it into Ley et al.’s review.

Ley et al. had better be right that internet porn can’t cause mental health problems, because if they’re mistaken they’re dismissing a serious health concern that has the potential to be quite prevalent in today’s digital natives given their porn use (universal among males, growing among females). In view of the increase in depression and suicide risk in those who spend too much time online, internet porn consumers’ wellbeing may be at risk.

VSS Use and Mental Health Problems – VSS Use Explained by Sex Drive

Here Ley et al. trot out their pet theory that porn users merely have higher libido than other people and simply can’t be expected to scratch their itch without the help of internet porn. Further, Ley et al. insist that somehow this means these high-libido people can’t become addicts. This faulty logic has been refuted in “‘High desire’, or ‘merely’ an addiction? A response to Steele et al.

What do the studies they cite in support of their prized hypothesis actually say?

122Frequent users of pornography. A population based epidemiological study of Swedish male adolescents

Excerpt: The frequent users had a more positive attitude to pornography, were more often “turned on” viewing pornography and viewed more often advanced forms of pornography. Frequent use was also associated with many problem behaviours. (emphasis added)

123 Watching pornographic pictures on the Internet: role of sexual arousal ratings and psychological-psychiatric symptoms for using Internet sex sites excessively

Excerpt: We found a positive relationship between subjective sexual arousal when watching Internet pornographic pictures and the self-reported problems in daily life due to the excessiveness of cybersex as measured by the IATsex.

129Nonaffective motivation modulates the sustained LPP (1,000-2,000 ms)

Irrelevant citation. There is no indication that this study is about porn viewing or sexual desire.

130Effects of transcranial direct current stimulation on risky decision making are mediated by ‘hot’ and ‘cold’ decisions, personality, and hemisphere

Again, an irrelevant citation. There is no mention of porn viewing. Instead researchers used “The Columbia Card Task” as their instrument.

81 – “Dysregulated sexuality and high sexual desire: distinct constructs? (2010)”

Excerpt: Men and women who reported having sought treatment scored significantly higher on measures of dysregulated sexuality and sexual desire.

Incidentally, this team of researchers, headed by young Canadian sexologist Jason Winters, deserves special mention as the first to sneak past actual peer reviewers with the fiction that sexual behavior addicts have no pathology, but are merely people with high libido. Quite a feat, but hardly a step forward for humankind.

52 “Sexual desire, not hypersexuality, is related to neurophysiological responses elicited by sexual images”

This is Prause’s very own creative-writing exercise, which has been extensively extensively critiqued. Contrary to her claims in the press, the study reported greater cue-reactivity for porn correlating to less desire for partnered sex. Put simply: The study found greater brain activation for porn combined with less desire for sex (but not less desire for masturbating to porn). Another example of misrepresenting their references.

Reality: Several valid studies falsify Ley’s claim that compulsive porn use or sex addiction is merely “high sex drive”.

VSS Use and Mental Health Problems – VSS Use Explained by Sensation Seeking

The ineptitude of Ley et al. continues. They claim that Higher need or desire for sensation is predictive of more frequent use of VSS, in both adolescents and adults [12,133, 134]. Yet citation 133 has nothing to do with porn viewing. See “Theta-Patterned, Frequency-Modulated Priming Stimulation Enhances Low-Frequency, Right Prefrontal Cortex Repetitive Transcranial Magnetic Stimulation (rTMS) in Depression: A Randomized, Sham-Controlled Study” Nor does citation 134: “Peripheral endocannabinoid dysregulation in obesity: relation to intestinal motility and energy processing induced by food deprivation and re-feeding

Had they (or their reviewers) investigated the actual literature, they might have found Cybersex addiction: Experienced sexual arousal when watching pornography and not real-life sexual contacts makes the difference” (2013), discussed earlier, which says that cue reactivity (evidence of addiction-related brain changes), not “high desire,” fuels problematic porn use:

Excerpt: Poor or unsatisfying sexual real-life contacts cannot sufficiently explain cybersex addiction.

VSS Use and Mental Health Problems – VSS Use As Effective Affect Regulation

Here Ley et al. make the argument that controlling emotions with porn or distracting oneself with porn is normal and only beneficial. They compare porn to cartoons as a way of improving mood. In making their case, Ley et al. overlook, or misrepresent the significance of, various studies that completely contradict their beliefs, and demonstrate that internet porn use is not “like cartoons” in its effects, or mood-elevating properties:

Differential psychological impact of internet exposure on internet addicts” (2013)

Excerpts: The results showed a striking negative impact of internet exposure on the positive mood of ‘internet addicts’. This effect has been suggested in theoretical models of ‘internet addiction [14], [21], and a similar finding has also been noted in terms of the negative effect of exposure to pornography on internet sex addicts [5], which may suggest commonalities between these addictions. It is also worth suggesting that this negative impact on mood could be considered as akin to a withdrawal effect, suggested as needed for the classification of addictions [1], [2], [27].  …

High internet-users also showed a pronounced decrease in mood following internet use compared to the low internet-users. The immediate negative impact of exposure to the internet on the mood of internet addicts may contribute to increased usage by those individuals attempting to reduce their low mood by re-engaging rapidly in internet use. …

Exposure to the object of the problematic behaviours has been found to reduce mood [26], especially in individuals addicted to pornography [5], [27]. As both of these reasons (i.e. gambling and pornography) for use of the internet are strongly associated with problematic internet use [2], [3], [14], it may well be that these factors may also contribute to internet addiction [14]. Indeed, it has been suggested that such negative impacts of engagement in problematic behaviour may, in themselves, generate further engagement in these high probability problematic behaviours in an attempt to escape these negative feelings [28]. …

It should be pointed out that, as two of the key uses of the internet for a sizable number of internet users are to gain access to pornography and gambling [4], [5], and these latter activities are clearly subject to potentially-addictive states, it may be that any results relating to ‘internet addiction’ are actually manifestations of other forms of addiction (i.e. to pornography or gambling). (emphasis added)

Pornographic picture processing interferes with working memory performance” (136)

Excerpts: Some individuals report problems during and after Internet sex engagement, such as missing sleep and forgetting appointments, which are associated with negative life consequences. One mechanism potentially leading to these kinds of problems is that sexual arousal during Internet sex might interfere with working memory (WM) capacity, resulting in a neglect of relevant environmental information and therefore disadvantageous decision making. …

Results contribute to the view that indicators of sexual arousal due to pornographic picture processing interfere with WM performance. Findings are discussed with respect to Internet sex addiction because WM interference by addiction-related cues is well known from substance dependencies. (emphasis added)

Sexual Picture Processing Interferes with Decision-Making Under Ambiguity

Excerpt: Subjective sexual arousal moderated the relationship between task condition and decision-making performance. This study emphasized that sexual arousal interfered with decision-making, which may explain why some individuals experience negative consequences in the context of cybersex use. (emphasis added)

VSS Use and Mental Health Problems – VSS Use and Sexual Orientation

Here Ley et al. imply that porn problems are especially a “gay and bisexual” thing, as if sexual orientation is relevant to the existence or absence of addiction. Moreover, we wonder if porn watching is still a sexual-minority-only issue among today’s digital-native males. A recent poll of the largest online English-language porn recovery forum showed that 94% of users were heterosexual, and 5% gay or bisexual. With the advent of free, streaming video clips and private smartphones, it is doubtful that young heterosexuals still lag behind other male porn users.

In any case, in this section Ley et al. tumble from carelessness to incompetence. Not one of the six studies they cite has anything to do with their statements. To wit:

Studies examining rates of VSS use in nationally representative samples find higher rates of VSS use in both adolescents and adults who identify as other than heterosexual [133], as do studies of clinical samples [143].

Citation 133 has nothing to do with VSS. It’s about transcranial magnetic stimulation and depression. Citation 143  has nothing to do with VSS. It’s about monkeys: “Male masturbation in free-ranging Japanese macaques.

Trials of DSM-5 hypersexual disorder criteria found that MSM were more than three times as likely to be in such treatment settings, compared with rates of MSM in comparable substance abuse or mental health facilities [144].

Citation 144 has nothing to do with the above statement. It’s “Sleep deprivation: Effect on sleep stages and EEG power density in man” 

Increased use of VSS in these populations may reflect adaptive strategies. MSM may be more likely to seek information and stimuli consistent with their sexual orientation. This may reflect a common component of the ‘coming-out process’ of forming a stable sexual identity [145].

Citation 145 has nothing to do with above statement. It’s “Dieting and binging: a causal analysis

Studies that examine use of VSS in MSM find that these men overwhelmingly endorse these positive benefits from VSS use [146]

Citation 146 has nothing to do with men who have sex with men. It is about 12 and 13-year olds. “Sexual risk taking in adolescence: the role of self-regulation and attraction to risk

VSS Use and Mental Health Problems – Impulsivity

VSS Use and Mental Health Problems – Compulsivity

We will address these sections on ‘impulsivity’ and ‘compulsivity’ together because they are part of the same strategem. Ley et al. seek to re-brand people with problematic porn use as having unalterable “traits” as opposed to reversible pathological learning as a consequence of their interaction with their environment (addiction).

Certainly, some people are more impulsive than others. Innate impulsivity is a risk-factor for developing addiction. But Ley et al. imply that the presence of increased impulsivity mysteriously precludes addiction. This is flat out wrong; impulsivity increases the chance of addiction.

Part of their plan is to split impulsivity from compulsivity. They don’t like the latter because it has been used interchangeably with addiction. With respect to compulsive behavior, the goal of Ley et al. is to re-brand it as “high desire.” More on that in a moment.

Let’s see what the established science has to say about the terms ‘impulsivity’ and ‘compulsivity’. The following comes from “Probing Compulsive and Impulsive Behaviors, from Animal Models to Endophenotypes: A Narrative Review“:

Excerpt: Impulsivity may be defined as ‘a predisposition toward rapid, unplanned reactions to internal or external stimuli with diminished regard to the negative consequences of these reactions.’

In contrast, compulsivity represents a tendency to perform unpleasantly repetitive acts in a habitual or stereotyped manner to prevent perceived negative consequences, leading to functional impairment. (emphasis added)

Historically, ‘impulsivity’ and ‘compulsivity’ were viewed as diametrically opposed, with impulsivity being associated with risk-seeking and compulsivity with harm-avoidance. However, increasingly they are recognized to be biologically linked. That is, they share neuropsychological mechanisms involving dysfunctional inhibition of thoughts and behaviors. (“New developments in human neurocognition: clinical, genetic, and brain imaging correlates of impulsivity and compulsivity“)

So, when someone develops an addiction it’s accepted (by experts) that their impulsivity and compulsivity have been increased by their addiction-related brain changes. Why? Addiction has been shown to change the frontal cortex and striatum causing dysfunctions. Both impulsivity and compulsivity are driven by dysfunctional cortico-striatal neural circuits. See “Probing Compulsive and Impulsive Behaviors, from Animal Models to Endophenotypes: A Narrative Review

Excerpt: Impulsive and compulsive disorders are conspicuously heterogeneous, sharing aspects of impulsivity and compulsivity, and become even more complex and thus more difficult to disentangle over time. For example, for impulsive and addictive disorders, tolerance to reward may develop and the behaviors may persist as a method of reducing discomfort (i.e., they become more compulsive).

Indeed, in animal studies low dopamine D2 receptors, caused by addiction, are associated with impulsivity. (“Low dopamine striatal D2 receptors are associated with prefrontal metabolism in obese subjects: Possible contributing factors“) Moreover, causation has been established in both animal and human addicts. In other words, addiction can cause the impulsivity that Ley et al. prefer to believe is purely a fixed trait, independent of addiction.

To state all of this another way, while ‘impulsivity’ and ‘compulsivity’ can be studied separately, they coexist when one has an addiction. In other words, the research has moved in the opposite direction of the impulsivity-compulsivity split that Ley et al. are pandering. In fact, the DSM recently changed pathological gambling from an “Impulse-Control Disorder” to an “Addictive Disorder” precisely because the research is showing it is an addiction, not a matter of impulsivity. “Addiction, a Disease of Compulsion and Drive: Involvement of the Orbitofrontal Cortex” describes the current model of addiction, which:

invokes both conscious (craving, loss of control, drug preoccupation) and unconscious processes (conditioned expectation, compulsivity, impulsivity, obsessiveness) which result from dysfunction of the striato-thalamo-orbitofrontal circuit.

Interestingly, the citation (147) Ley et al. offer for their untenable position contradicts them. The researchers concluded that problematic internet porn (IP) use is “an addictive problem” and the trait of “impulsivity did not appear to be an important factor differentiating IP users from problematic users or IP users from nonusers.”

Citation 149 investigated the impulsivity of patients with compulsive sexual behaviors, and their brain imaging results were not consistent with impulse control disorders. Citation 150 goes to an unpublished study by Prause herself, “Neural evidence of underreactivity to sexual stimuli in those reporting problems regulating their viewing of visual sexual stimuli.” May we be the first to predict that, once again, she will claim the results disprove porn addiction regardless of underlying data or flaws in study design?

It is important not to let weak claims about “traits,” or agenda-driven research, muddy the water, because many of the brain changes associated with addiction are reversible. Addicts can relearn healthy ‘wanting,’ which means they are empowered to change their circumstances. They can learn to alter the choices they made about how they interact with their environment.

A few words about ‘compulsivity’ as viewed through the eyes of Ley et al.: They deny “the compulsivity model,” instead nurturing the notion that compulsive porn use is just evidence of “high desire.” By the same logic, alcoholics would simply have “high desire” for alcohol, and addicted smokers “high desire” for nicotine. This hypothesis has been challenged in a peer-reviewed journal comment, “‘High desire’, or ‘merely’ an addiction? A response to Steele et al.” Also see the studies we cited above in the section entitled, “Negative Consequences of High Use of VSS – Failure to Inhibit VSS Use.” 


Ley et al. extol the health benefits of porn because it facilitates orgasm. However humanity orgasmed just fine for a long time without any help from internet porn. More important, orgasm appears to be less beneficial in the case of masturbation than in the case of partnered sex, so problematic porn use may be getting in the way of potential benefits.

Ley et al. suggest that young porn viewers may be moving to more extreme porn when they don’t have partners with whom to engage in sexual risk behaviors. Both their supporting citations show that the younger someone is exposed to porn, the more likely s/he will proceed to illegal porn. Citation 153 found that early exposure to sexually explicit material is a risk factor for sexual risk-taking, and, as discussed earlier. 154 found that the younger kids start viewing pornography the more likely they are to view bestiality or child porn.

Ley et al. also point to the benefits of masturbation to porn as a way of reducing risky partnered sexual behaviors, as if no one had the option of self-pleasuring instead of acting out prior to internet porn! Next they warn there’s a risk in “labeling VSS as only addictive.” (Who labeled it as “only addictive?”)

They even go so far as to advocate porn use as “cognitive retraining” citing (155) “Brain training: games to do you good!” Today’s porn is indeed brain training for some users, many of whom report devastating “retraining,” such as loss of attraction to real partners, sexual dysfunctions and morphing sexual tastes that escalate to material inconsistent with their underlying sexual orientation.

Not surprisingly, a German team recently found that porn use may well shrink a part of the brain that appears to become larger and more active in videogamers. Porn-watching is a zombie-like activity that uses few of the skills of videogaming. Could that account for the apparent atrophy?

Ley et al. claim that the concept of porn addiction is driven by the dark hand of “non-empirical forces.” This is comical, given that they left out massive empirical evidence that discounts their hypotheses, and brazenly cherry-picked what supported their agenda from various studies, frequently ignoring actual conclusions.

Next they assure us that the popularity of the term “porn addiction” in the media is simply due to widespread ignorance. In fact, the public appears to be ahead of these sexologists in their recognition that addiction is a real, biological condition. Ley et al. also seem unwilling to consider the possibility that growing recognition of the term ‘addiction’ might, in fact, be evidence that more people are experiencing addictions and sexual dysfunctions caused by porn.

Heading for the finish line, Ley et al. imply that concern about porn addiction is somehow proof of moralistic judgments calculated to suppress sexual expression and stigmatize sexual minorities. In fact, as the concept of porn addiction has gained currency, moral concerns about porn use, suppression of sexual expression and stigmatization of sexual minorities all seem to be declining sharply. Perhaps if Ley et al. were to investigate that correlation they would promptly bring their views on internet porn addiction into alignment with current scientific thought.


Persuasion wasn’t necessary as Current Sexual Health Reports Editor-in-Chief, Michael A. Perelman and Current Controversies Section Editor Charles Moser have since teamed up with Ley and Prause to “debunk” porn addiction. At the February 2015 conference of the International Society for the Study of Women’s Sexual Health, Ley, Prause, Moser and Perelman presented a 2-hour symposium: “Porn Addiction, Sex Addiction, or just another OCD?”. In November 2015 Charles Perelman and Nicole Prause presented together at the Annual Fall Meeting of SMSNA. Nicole Prause’s section was titled “Internet Pornography: Harmful to Men and Relationships?” Let us not forget that the Ley et al. editor, Charles Moser, has been a long-time vocal critic of porn and sex addiction. Also know that Current Sexual Health Reports has a short and rocky history. It started publishing in 2004, and then went on hiatus in 2008, only to be resurrected in 2014, just in time to feature Ley et al.

Porn studies showing adverse effects, which were overlooked by authors, and have not been mentioned above

  1. Adolescent pornographic internet site use: a multivariate regression analysis of the predictive factors of use and psychosocial implications (2009) findings suggested that Greek adolescents who are exposed to sexually explicit material may develop “unrealistic attitudes about sex and misleading attitudes toward relationships” The data indicated a significant relationship between consumption of Internet pornography and social maladjustment. Specifically, adolescents who indicated infrequent use of pornography were twice as likely have conduct issues as those who did not consume pornography at all. Also, frequent consumers were significantly more likely to indicate abnormal conduct issues as well as borderline addictive Internet use
  2. Adolescents’ Exposure to Sexually Explicit Internet Material and Notions of Women as Sex Objects: Assessing Causality and Underlying Processes (2009) Peter and Valkenburg (2009) determined that viewing women as sex objects was related to increased frequency in the consumption of sexually explicit material. It is unclear how adolescent females are impacted by viewing other females, and possibly even themselves, as sex objects. In short, these findings suggest that “adolescents’ exposure to SEIM was both a cause and a consequence of their beliefs that women are sex objects.
  3. Adolescents’ Exposure to Sexually Explicit Internet Material, Sexual Uncertainty, and Attitudes Toward Uncommitted Sexual Exploration: Is There a Link? (2008) Drawing from a sample of 2,343 Dutch adolescents aged 13 to 20, the authors find that more frequent exposure to sexually explicit Internet material is associated with greater sexual uncertainty and more positive attitudes toward uncommitted sexual exploration (i.e., sexual relations with casual partners/friends or with sexual partners in one-night stands)
  4. Adolescents’ Use of Sexually Explicit Internet Material and Sexual Uncertainty: The Role of Involvement and Gender (2010) As adolescents use SEIM more frequently, their sexual uncertainty increases. Equally true for both boys and girls; pornography is confusing for all. As adolescents use SEIM more frequently, they became more strongly involved in the material. Involvement is defined as an intense experiential state during the reception of media content and comprises both affective and cognitive processes Lose track of time; don’t notice surroundings, completely focused.
  5. Adolescents’ Exposure to a Sexualized Media Environment and Their Notions of Women as Sex Objects (2007)  Both male and female Dutch adolescents (13-18) who used more sexually explicit content were more likely to view women as sex objects.
  6. Associations between young adults’ use of sexually explicit materials and their sexual preferences, behaviors, and satisfaction. (2011)  Higher frequencies of SEM use were associated with less sexual and relationship satisfaction. The frequency of SEM use and number of SEM types viewed were both associated with higher sexual preferences for the types of sexual practices typically presented in SEM. These findings suggest that SEM use can play a significant role in a variety of aspects of young adults’ sexual development processes.
  7. Developmental Pathways into Social and Sexual Deviance (2010) Hunter et al. (2010) examined the relationship between exposure to pornography prior to age 13 and four negative personality constructs. This study surveyed 256 adolescent males with a history of sexual criminal behavior; the authors found a relationship between early exposure to pornography and antisocial behavior, likely the result of a distorted view of sexuality and the glorification of promiscuity (Hunter et al., 2010).  Hunter et al. (2010) found childhood exposure to sexually explicit material may contribute “to antagonistic and psychopathic attitudes, likely the depiction of distorted views of human sexuality and glorification of promiscuity” (p. 146). Moreover, these authors argued that because adolescents do not always have the opportunity to counterbalance “real-life experiences with sexual partners. . .. they are especially susceptible to internalization of distorted pornographic images of human sexuality and may act accordingly” (p. 147)
  8. Early sexual experiences: the role of Internet access and sexually explicit material (2008) During the ages of 12 to 17, males with internet reported significantly younger ages for first oral sex, and males and females reported younger ages for first sexual intercourse compared to those without it. Early sexual experiences: the role of Internet access and sexually explicit material.
  9. Emerging Adult Sexual Attitudes and Behaviors Does Shyness Matter? (2013) The more university-age men engage in solitary sexual behaviours of masturbation and pornography the more shyness they report.
  10. Emerging in a Digital World: A Decade Review of Media Use, Effects, and Gratifications in Emerging Adulthood. (2013) The more internet porn university students use the worse the quality of their relationships.
  11. Exposure to internet pornography among children and adolescents a national survey (2005) Those who report intentional exposure to pornography, irrespective of source, are significantly more likely to report delinquent behavior and substance use in the previous year. Further, online seekers versus offline seekers are more likely to report clinical features associated with depression and lower levels of emotional bonding with their caregiver.
  12. Exposure to Internet Pornography and Taiwanese Adolescents Sexual Attitudes and Behavior (2005) This study indicated that exposure to sexually explicit material increased the likelihood that adolescents will accept and engage in sexually permissive behaviors. Determined that exposure to sexually explicit material on the Internet had a greater influence on permissive sexual attitudes than all other forms of pornographic media.
  13. Exposure to sexually explicit Web sites and adolescent sexual attitudes and behaviors (2009) Braun-Courville and Rojas’ (2009) study of 433 adolescents indicated that those who use sexually explicit material are more likely to engage in risky sexual behaviors such as anal sex, sex with multiple partners, and using drugs or alcohol during sex. This study was supported by Brown, Keller, and Stern (2009) who indicated that adolescents who witness high risk sexual practices in sexually explicit material in the absence of education on the potential negative consequences, are more likely to engage in some form of high-risk sexual behavior themselves.
  14. Frequent users of pornography. A population based epidemiological study of Swedish male adolescents (2010) regression analysis showed that frequent users of pornography were more likely to be living in a large city, consuming alcohol more often, having greater sexual desire and had more often sold sex than other boys of the same age. High frequent viewing of pornography may be seen as a problematic behaviour that needs more attention from both parents and teachers
  15. Internet Pornography and Loneliness: An Association? Porn use was associated with increased loneliness.
  16. Mental- and physical-health indicators and sexually explicit media use behavior by adults This 2006 survey of 559 Seattle adults found that porn users, compared to nonusers, report greater depressive symptoms, poorer quality of life, more mental- and physical-health diminished days, and lower health status. Mental- and physical-health indicators and sexually explicit media use behavior by adults.
  17. Nucleus accumbens activation mediates the influence of reward cues on financial risk taking Porn use correlates with increased financial risk-taking.
  18. Pornography and attitudes supporting violence against women: revisiting the relationship in nonexperimental studies (2009) Porn use and violent porn use were both associated with attitudes supporting violence against women.
  19. Pornography and teenagers: the importance of individual differences (2005) They found that a male adolescent who “possesses certain combinations of risk factors determines how likely he is to be sexually aggressive following pornography exposure” (p. 316). Focusing directly on violent sexually explicit material, Malamuth and Huppin (2005) suggest that, not only are these higher risk adolescent males “more likely to be exposed to such media but when they are exposed, they are likely to be changed by such exposure, such as changes in attitudes about the acceptance of violence against women” (p. 323–24).
  20. Pornography Consumption and Opposition to Affirmative Action for Women (2013) Pornography viewing predicted subsequent opposition to affirmative action in both men and women, even after controlling for prior affirmative action attitudes and various other potential confounds.
  21. Pornographic exposure over the life course and the severity of sexual offenses: Imitation and cathartic effects (2011) Findings indicate that adolescent exposure was a significant predictor of the elevation of violence—it increased the extent of victim humiliation.
  22. Pornography use as a risk marker for an aggressive pattern of behavior among sexually reactive children and adolescents (2009) Alexy et al. (2009) studied the pornography consumption patterns of juvenile sexual offenders as they related to various forms of aggressive behavior. Those who were consumers of pornography were more likely to display forms of aggressive behaviors such as theft, truancy, manipulating others, arson, and forced sexual intercourse.
  23. Pornography Viewing among Fraternity Men: Effects on Bystander Intervention, Rape Myth Acceptance and Behavioral Intent to Commit Sexual Assault (2011) The more porn male university students watch the more casual their attitudes toward sexual assault.
  24. Pornography, Relationship Alternatives, and Intimate Extradyadic Behavior (2013) Porn use is linked with increased fooling around on the side in romantically committed individuals.
  25. Pornography’s Impact on Sexual Satisfaction (2006) Porn use reduced satisfaction with intimate partners.
  26. Sexual Addiction among Teens: A Review (2007) It is concluded that there probably does exist a phenomenon of sexual addiction that applies across the life course (including the teenage years), that deserves much more study.
  27. The use of cyberpornography by young men in Hong Kong some psychosocial correlates (2007) participants who reported to have more online pornography viewing were found to score higher on measures of premarital sexual permissiveness and proclivities toward sexual harassmen
  28. Use of Internet Pornography and Men’s Well-Being This 2005 study revealed that depression, anxiety, and real-life intimacy problems are associated with chronic cybersexuality in men.
  29. Variations in internet-related problems and psychosocial functioning in online sexual activities: implications for social and sexual development of young adults. (2004) (Available in full online) Online sexual activities displaced normal relationship development, learned courtship, and romantic behaviours in university students.
  30. X-rated material and perpetration of sexually aggressive behavior among children and adolescents: is there a link? (2011) Ley, Prause and Finn do mention this study, but they attempt to reduce it to evidence of “sensation seeking” in porn users. They didn’t mention that adolescents who are intentionally exposed to violent pornography appear to be six times more likely to commit acts of sexual aggression than those who had no exposure or were exposed to non-violent pornography
  31. Young adult women’s reports of their male romantic partner’s pornography use as a correlate of their psychological distress, relationship quality, and sexual satisfaction. 2012 Results revealed women’s reports of their male partner’s frequency of pornography use were negatively associated with their relationship quality. More perceptions of problematic use of pornography was negatively correlated with self-esteem, relationship quality, and sexual satisfaction.
  32. The effects of gay sexually explicit media on the HIV risk behavior of men who have sex with men. 2013. Overall sexually explicit media consumption was not associated with HIV risk; however participants who watched more bareback sexually explicit media reported significantly greater odds of engaging in risk behavior. The results suggest that a preference for bareback sexually explicit media is associated with engaging in risk behavior.
  33. Use of pornography and self-reported engagement in sexual violence among adolescents (2005). The findings showed that active and passive sexual violence and unwanted sex and pornography were correlated. However, reading pornographic material was more strongly linked to active sexual violence, while being a boy was found to be protective against passive sexual violence. Nevertheless, some effects of viewing pornographic films on passive unwanted sex were also found, especially among girls.
  34. Pornography and sexual aggression: Associations of violent and nonviolent depictions with rape and rape proclivity (1994). Data collected from a sample of 515 college men indicated strong bivariate associations of rape and rape proclivity with use of almost all forms of pornography. Multivariate analysis indicated that the strongest correlates of sexual coercion and aggression, as well as rape proclivity, were exposure to hard‐core violent and rape pornography. Exposure to nonviolent hard‐core pornography displayed no association net of the other variables. Exposure to soft‐core pornography was positively associated with likelihood of sexual force and nonviolent coercive behavior, but negatively associated with likelihood of rape and actual rape behavior.
  35. Attitudinal effects of degrading themes and sexual explicitness in video materials (2000)  Results revealed that men exposed to degrading material, regardless of explicitness, were significantly more likely to express attitudes supportive of rape, while explicitness had no significant main or interactive effect on these attitudes. Further, the interaction of explicitness with degradation was found to impact scores on a measure of sexual callousness.
  36. Pornography Use: Who Uses It and How It Is Associated with Couple Outcomes (2012) Overall results from this study indicated substantial gender differences in terms of use profiles, as well as pornography’s association with relationship factors. Specifically, male pornography use was negatively associated with both male and female sexual quality, whereas female pornography use was positively associated with female sexual quality.
  37. Sexual media use and relationship satisfaction in heterosexual couples (2011) Results revealed that a higher frequency of men’s sexual media use related to negative satisfaction in men, while a higher frequency of women’s sexual media use related to positive satisfaction in male partners.
  38. When is Online Pornography Viewing Problematic Among College Males? Examining the Moderating Role of Experiential Avoidance (2012) The current study examined the relationship of Internet pornography viewing and experiential avoidance to a range of psychosocial problems (depression, anxiety, stress, social functioning, and problems related to viewing) through a cross-sectional online survey conducted with a non-clinical sample of 157 undergraduate college males. Results indicated that frequency of viewing was significantly related to each psychosocial variable, such that more viewing was related to greater problems.
  39. “Bareback” Pornography Consumption and Safe-Sex Intentions of Men Having Sex with Men (2014) The results provide novel and ecologically valid evidence that “bareback” pornography consumption impacts viewer’s inclinations toward sexual risk-taking by lowering their intentions to use protected sex measures. Suggestions are given as to how these findings can be utilized for purposes of intervention and prevention of STI and HIV infections.
  40. Narcissism & Internet Pornography Use (2014) Hours spent viewing Internet pornography use was positively correlated to participant’s narcissism level. Additionally, any porn use predicts higher levels of all three measures of narcissism than those who have never used Internet pornography.

Brain studies of internet addicts and internet videogaming addicts, which were overlooked by authors

Internet addiction brain studies:

  1. Influence of excessive internet use on auditory event-related potential (2008)
  2. Decision-making and prepotent response inhibition functions in excessive internet users (2009)
  3. Gray Matter Abnormalities In Internet Addiction: A Voxel-Based Morphometry Study (2009)
  4. Effect of excessive Internet use on the time–frequency characteristic of EEG (2009)
  5. An event-related potential investigation of deficient inhibitory control in individuals with pathological Internet use (2010)
  6. Impulse inhibition in people with Internet addiction disorder: electrophysiological evidence from a Go/NoGo study (2010)
  7. Differentiation of Internet addiction risk level based on autonomic nervous responses: the Internet-addiction hypothesis of autonomic activity (2010)
  8. Increased regional homogeneity in internet addiction disorder a resting state functional magnetic resonance imaging study (2010)
  9. The research of event-related potentials in working memory of the juvenile internet addiction (2010)
  10. Reduced Striatal Dopamine D2 Receptors in People With Internet Addiction (2011)
  11. Microstructure Abnormalities in Adolescents with Internet Addiction Disorder. (2011)
  12. Preliminary study of Internet addiction and cognitive function in adolescents based on IQ tests (2011)
  13. P300 change and cognitive behavioral therapy in subjects with Internet addiction disorder: A 3 month follow-up study (2011)
  14. Male Internet addicts show impaired executive control ability evidence from a color-word: Stroop task (2011)
  15. Deficits in Early-Stage Face Perception in Excessive Internet Users (2011)
  16. Pornographic Picture Processing Interferes with Working Memory Performance (2012)
  17. Effects of electroacupuncture combined psycho-intervention on cognitive function and event related potentials P300 and mismatch negativity in patients with internet addiction (2012)
  18. Abnormal White Matter Integrity in Adolescents with Internet Addiction Disorder: A Tract-Based Spatial Statistics Study (2012)
  19. Reduced Striatal Dopamine Transporters in People with Internet Addiction Disorder (2012)
  20. Abnormal brain activation of adolescent internet addict in a ball-throwing animation task: Possible neural correlates of disembodiment revealed by fMRI (2012)
  21. Impaired inhibitory control in internet addiction disorder: A functional magnetic resonance imaging study. (2012)
  22. Comparison of Psychological Symptoms and Serum Levels of Neurotransmitters in Shanghai Adolescents with and without Internet Addiction Disorder: A Case-Control Study (2013)
  23. Resting-state beta and gamma activity in Internet addiction (2013)
  24. Electroencephalographic (EEG) brainmap patterns in a clinical sample of adults diagnosed with an internet addiction (2013)
  25. Impaired Error-Monitoring Function in People with Internet Addiction Disorder: An Event-Related fMRI Study (2013).
  26. Effects of Internet Addiction on Heart Rate Variability in School-Aged Children (2013)
  27. An Error-Related Negativity Potential Investigation of Response Monitoring Function in Individuals with Internet Addiction Disorder (2013)
  28. Decreased frontal lobe function in people with Internet addiction disorder (2013)
  29. Differential resting-state EEG patterns associated with comorbid depression in Internet addiction (2014)
  30. Brains online: structural and functional correlates of habitual Internet use (2014)
  31. Impaired frontal-Basal Ganglia connectivity in adolescents with internet addiction (2014)
  32. Prefrontal Control and Internet Addiction A Theoretical Model and Review of Neuropsychological and Neuroimaging Findings (2014)
  33. Neural responses to various rewards and feedback in the brains of adolescent Internet addicts detected by functional magnetic resonance imaging (2014)
  34. Internet addictive individuals share impulsivity and executive dysfunction with alcohol-dependent patients (2014)
  35. Disrupted Brain Functional Network in Internet Addiction Disorder: A Resting-State Functional Magnetic Resonance Imaging Study (2014)
  36. Higher Media Multi-Tasking Activity Is Associated with Smaller Gray-Matter Density in the Anterior Cingulate Cortex (2014)
  37. Blunted feedback processing during risk-taking in adolescents with features of problematic Internet use (2015)
  38. Brain structures and functional connectivity associated with individual differences in Internet tendency in healthy young adults (2015)
  39. Examination of neural systems sub-serving facebook “addiction” (2014)
  40. A Short Summary of Neuroscientific Findings on Internet Addictio (2015) PDF
  41. New developments on the neurobiological and pharmaco-genetic mechanisms underlying internet and videogame addiction (2015)
  42. Electroencephalogram Feature Detection and Classification in People with Internet Addiction Disorder with Visual Oddball Paradigm (2015)
  43. Molecular and Functional Imaging of Internet Addiction (2015)
  44. Aberrant corticostriatal functional circuits in adolescents with Internet addiction disorder (2015).
  45. How Has the Internet Reshaped Human Cognition? (2015)
  46. Problematic Internet Usage and Immune Function (2015)
  47. Neural substrates of risky decision making in individuals with Internet addiction (2015)
  48. Relationship between peripheral blood dopamine level and internet addiction disorder in adolescents: a pilot study (2015)
  49. Problematic internet use is associated with structural alterations in the brain reward system in females. (2015)
  50. Working memory, executive function and impulsivity in Internet-addictive disorders: a comparison with pathological gambling (2015)
  51. Disrupted inter-hemispheric functional and structural coupling in Internet addiction adolescents (2015)
  52. Electrophysiological studies in internet addiction: A review within the dual-process framework (2015)
  53. Biological basis of problematic internet use (PIN) and therapeutic implications (2015)
  54. Impaired inhibition and working memory in response to internet-related words among adolescents with internet addiction: A comparison with attention-deficit/hyperactivity disorder (2016)
  55. Deficit in rewarding mechanisms and prefrontal left/right cortical effect in vulnerability for internet addiction (2016)
  56. Functional magnetic resonance imaging of internet addiction in young adults (2016)
  57. Problematic Internet Users Show Impaired Inhibitory Control and Risk Taking with Losses: Evidence from Stop Signal and Mixed Gambles Tasks (2016)
  58. Altered Gray Matter Volume and White Matter Integrity in College Students with Mobile Phone Dependence (2016)
  59. Cue-induced craving for Internet among Internet addicts (2016)
  60. Functional changes in patients with internet addiction disclosed by adenosine stressed cerebral blood flow perfusion imaging 99mTc-ECD SPET (2016)
  61. Respiratory sinus arrhythmia reactivity of internet addiction abusers in negative and positive emotional states using film clips stimulation (2016)
  62. Neurobiological findings related to Internet use disorders (2016)
  63. Texting Dependence, iPod Dependence, and Delay Discounting (2016)
  64. Physiological markers of biased decision-making in problematic Internet users (2016)
  65. The dysfunction of face processing in patients with internet addiction disorders: an event-related potential study (2016)
  66. Internet use: Molecular influences of a functional variant on the OXTR gene, the motivation behind using the Internet, and cross-cultural specifics (2016)
  67. A Two-Stage Channel Selection Model for Classifying EEG Activities of Young Adults with Internet Addiction (2016)
  68. An Affective Neuroscience Framework for the Molecular Study of Internet Addiction (2016)
  69. Electrophysiological studies in Internet addiction: A review within the dual-process framework (2017)

Internet video-game addiction brain studies:

  1. Evidence for striatal dopamine release during a video game (1998)
  2. Dopamine genes and reward dependence in adolescents with excessive internet video game play (2007)
  3. Specific cue reactivity on computer game related cues in excessive gamers (2007)
  4. Brain activities associated with gaming urge of online gaming addiction (2008).
  5. The effect of excessive internet use on N400 event-related potentials (2008)
  6. The effect of methylphenidate on Internet video game play in children with attention deficit hyperactivity disorder (2009)
  7. Computer and video game addiction-a comparison between game users and non-game users (2010)
  8. Bupropion sustained release treatment decreases craving for video games and cue-induced brain activity in patients with Internet video game addiction (2010)
  9. Altered regional cerebral glucose metabolism in internet game overusers: a 18F-fluorodeoxyglucose positron emission tomography study (2010)
  10. Changes in Cue Induced Prefrontal Cortex Activity with Video Game Play. (2010)
  11. Brain correlates of craving for online gaming under cue exposure in subjects with Internet gaming addiction and in remitted subjects. (2011)
  12. Cue induced positive motivational implicit response in young adults with internet gaming addiction (2011)
  13. Enhanced Reward Sensitivity and Decreased Loss Sensitivity in Internet Addicts: An fMRI Study During a Guessing Task (2011)
  14. Brain activity and desire for Internet video game play (2011)
  15. Excessive Internet gaming and decision making: Do excessive World of Warcraft players have problems in decision making under risky conditions? (2011)
  16. The neural basis of video gaming (2011)
  17. Influence of dopaminergic system on internet addiction (2011)
  18. The effect of family therapy on the changes in the severity of on-line game play and brain activity in adolescents with on-line game addiction (2012)
  19. Attentional bias and disinhibition toward gaming cues are related to problem gaming in male adolescents. (2012)
  20. Alterations in regional homogeneity of resting state brain activity in internet gaming addicts. (2012)
  21. Error processing and response inhibition in excessive computer game players: an event-related potential study (2012)
  22. The brain activations for both cue-induced gaming urge and smoking craving among subjects comorbid with Internet gaming addiction and nicotine dependence. (2012)
  23. Brain fMRI study of crave induced by cue pictures in online game addicts (male adolescents) (2012)
  24. Differential regional gray matter volumes in patients with on-line game addiction and professional gamers (2012)
  25. Diffusion tensor imaging reveals thalamus and posterior cingulate cortex abnormalities in internet gaming addicts (2012).
  26. A voxel based morphometric analysis of brain gray matter in online game addicts (2012)
  27. Cognitive biases toward Internet game-related pictures and executive deficits in individuals with an Internet game addiction (2012)
  28. Cortical Thickness Abnormalities in Late Adolescence with Online Gaming Addiction (2013)
  29. Cue reactivity and its inhibition in pathological computer game players (2013)
  30. Decreased functional brain connectivity in adolescents with internet addiction (2013)
  31. Gray matter and white matter abnormalities in online game addiction (2013).
  32. Cognitive flexibility in internet addicts: fMRI evidence from difficult-to-easy and easy-to-difficult switching situations (2013)
  33. Altered default network resting-state functional connectivity in adolescents with internet gaming addiction (2013)
  34. Reduced orbitofrontal cortical thickness in male adolescents with internet addiction (2013)
  35. Reward/punishment sensitivities among internet addicts: Implications for their addictive behaviors (2013).
  36. Amplitude of low frequency fluctuation abnormalities in adolescents with online gaming addiction (2013)
  37. Just watching the game ain’t enough: striatal fMRI reward responses to successes and failures in a video game during active and vicarious playing (2013)
  38. What makes Internet addicts continue playing online even when faced by severe negative consequences? Possible explanations from an fMRI study (2013)
  39. Voxel-level comparison of arterial spin-labeled perfusion magnetic resonance imaging in adolescents with internet gaming addiction (2013).
  40. Brain activation for response inhibition under gaming cue distraction in internet gaming disorder (2013)
  41. Internet gaming addiction: current perspectives (2013)
  42. Altered brain activation during response inhibition and error processing in subjects with Internet gaming disorder: a functional magnetic imaging study (2014)
  43. The prefrontal dysfunction in individuals with Internet gaming disorder: a meta-analysis of functional magnetic resonance imaging studies (2014)
  44. Trait impulsivity and impaired prefrontal impulse inhibition function in adolescents with internet gaming addiction revealed by a Go/No-Go fMRI study (2014)
  45. PET imaging reveals brain functional changes in internet gaming disorder (2014)
  46. Brain correlates of response inhibition in Internet gaming disorder (2014)
  47. Proton magnetic resonance spectroscopy (MRS) in on-line game addiction (2014)
  48. Physiological arousal deficits in addicted gamers differ based on preferred game genre (2014)
  49. Neurophysiological and neuroimaging aspects between internet gaming disorder and alcohol use disorder (2014)
  50. Virtual reality therapy for internet gaming disorder (2014)
  51. Abnormal gray matter and white matter volume in ‘Internet gaming addicts’ (2014)
  52. Altered cingulate-hippocampal synchrony correlate with aggression in adolescents with internet gaming disorder (2014)
  53. Impaired risk evaluation in people with Internet gaming disorder: fMRI evidence from a probability discounting task (2014)
  54. Reduced fiber integrity and cognitive control in adolescents with internet gaming disorder (2014)
  55. Assessment of in vivo microstructure alterations in gray matter using DKI in internet gaming addiction (2014)
  56. EEG and ERP based Degree of Internet Game Addiction Analysis (2014)
  57. Decreased functional connectivity in an executive control network is related to impaired executive function in Internet gaming disorder (2014)
  58. Different resting-state functional connectivity alterations in smokers and nonsmokers with internet gaming addiction (2014)
  59. A selective involvement of putamen functional connectivity in youth with internet gaming disorder (2014)
  60. Similarities and differences among Internet gaming disorder, gambling disorder and alcohol use disorder: A focus on impulsivity and compulsivity (2014)
  61. Differences in functional connectivity between alcohol dependence and internet gaming disorder (2015)
  62. Core brain networks interactions and cognitive control in internet gaming disorder individuals in late adolescence/early adulthood (2015)
  63. Altered gray matter density and disrupted functional connectivity of the amygdala in adults with Internet gaming disorder (2015)
  64. Resting-state regional homogeneity as a biological marker for patients with Internet gaming disorder: A comparison with patients with alcohol use disorder and healthy controls (2015)
  65. Altered reward processing in pathological computer gamers: ERP-results from a semi-natural Gaming-Design (2015)
  66. Striatum morphometry is associated with cognitive control deficits and symptom severity in internet gaming disorder (2015)
  67. Video game training and the reward system (2015)
  68. Decreased Prefrontal Lobe Interhemispheric Functional Connectivity in Adolescents with Internet Gaming Disorder: A Primary Study Using Resting-State fMRI (2015)
  69. Functional characteristics of the brain in college students with internet gaming disorder (2015)
  70. The alteration of gray matter volume and cognitive control in adolescents with internet gaming disorder (2015)
  71. An fMRI study of cognitive control in problem gamers (2015)
  72. Altered resting-state functional connectivity of the insula in young adults with Internet gaming disorder (2015)
  73. Imbalanced functional link between executive control network and reward network explain the online-game seeking behaviors in Internet gaming disorder (2015)
  74. Is the Internet gaming-addicted brain close to be in a pathological state? (2015)
  75. Altered Cardiorespiratory Coupling in Young Male Adults with Excessive Online Gaming (2015)
  76. Altered Brain Reactivity to Game Cues After Gaming Experience (2015)
  77. The Effects of Video Games on Cognition and Brain Structure: Potential Implications for Neuropsychiatric Disorders (2015)
  78. Dysfunction of the frontolimbic region during swear word processing in young adolescents with Internet gaming disorder (2015)
  79. Abnormal prefrontal cortex resting state functional connectivity and severity of internet gaming disorder (2015)
  80. Neurophysiological features of Internet gaming disorder and alcohol use disorder: a resting-state EEG study (2015)
  81. Game addiction (2015)
  82. Decreased functional connectivity between ventral tegmental area and nucleus accumbens in Internet gaming disorder: evidence from resting state functional magnetic resonance imaging (2015)
  83. Compromised Prefrontal Cognitive Control Over Emotional Interference in Adolescents with Internet Gaming Disorder (2015)
  84. Frequency-dependent changes in the amplitude of low-frequency fluctuations in internet gaming disorder (2015)
  85. The inhibition of proactive interference among adults with Internet gaming disorder (2015)
  86. Decreased modulation by the risk level on the brain activation during decision making in adolescents with internet gaming disorder (2015)
  87. Neurobiological correlates of internet gaming disorder: Similarities to pathological gambling (2015)
  88. Brain connectivity and psychiatric comorbidity in adolescents with Internet gaming disorder (2015)
  89. Testing the Predictive Validity and Construct of Pathological Video Game Use (2015)
  90. Impact of videogame play on the brain’s microstructural properties: cross-sectional and longitudinal analyses (2016)
  91. Activation of the ventral and dorsal striatum during cue reactivity in Internet gaming disorder (2016)
  92. Brain connectivity and psychiatric comorbidity in adolescents with Internet gaming disorder (2016)
  93. Frontostriatal circuits, resting state functional connectivity and cognitive control in internet gaming disorder (2016)
  94. Dysfunctional information processing during an auditory event-related potential task in individuals with Internet gaming disorder (2016)
  95. Resting-State Peripheral Catecholamine and Anxiety Levels in Korean Male Adolescents with Internet Game Addiction (2016)
  96. Network-Based Analysis Reveals Functional Connectivity Related to Internet Addiction Tendency (2016)
  97. Altered Functional Connectivity of the Insula and Nucleus Accumbens in Internet Gaming Disorder: A Resting State fMRI Study (2016)
  98. Violence-related content in video game may lead to functional connectivity changes in brain networks as revealed by fMRI-ICA in young men (2016)
  99. Attentional bias in excessive Internet gamers: Experimental investigations using an addiction Stroop and a visual probe (2016)
  100. Decreased functional connectivity of insula-based network in young adults with internet gaming disorder (2016)
  101. Dysfunctional default mode network and executive control network in people with Internet gaming disorder: Independent component analysis under a probability discounting task (2016)
  102. Impaired anterior insular activation during risky decision making in young adults with internet gaming disorder (2016)
  103. Altered Structural Correlates of Impulsivity in Adolescents with Internet Gaming Disorder (2016)
  104. Dysfunctional information processing during an auditory event-related potential task in individuals with Internetgamingdisorder (2016)
  105. Functional characteristics of the brain in college students with internet gaming disorder (2016)
  106. Brain Activity toward Gaming-Related Cues in Internet Gaming Disorder during an Addiction Stroop Task (2016)
  107. Cue-induced Behavioral and Neural Changes among Excessive Internet Gamers and Possible Application of Cue Exposure Therapy to Internet Gaming Disorder (2016)
  108. Neurochemical correlates of internet game play in adolescents with attention deficit hyperactivity disorder: A proton magnetic resonance spectroscopy (MRS) study (2016)
  109. Altered resting-state neural activity and changes following a craving behavioral intervention for Internet gaming disorder (2016)
  110. Exploring the Neural Basis of Avatar Identification in Pathological Internet Gamers and of Self-Reflection in Pathological Social Network Users (2016)
  111. Altered brain functional networks in people with Internet gaming disorder: Evidence from resting-state fMRI (2016)
  112. A comparative study of the effects of bupropion and escitalopram on Internet gaming disorder (2016)
  113. Impaired executive control and reward circuit in Internet gaming addicts under a delay discounting task: independent component analysis (2016)
  114. Effects of craving behavioral intervention on neural substrates of cue-induced craving in Internet gaming disorder (2016)
  115. The topological organization of white matter network in internet gaming disorder individuals (2016)
  116. Altered Autonomic Functions and Distressed Personality Traits in Male Adolescents with Internet Gaming Addiction (2016)
  117. Effects of outcome on the covariance between risk level and brain activity in adolescents with internet gaming disorder (2016)
  118. Changes of quality of life and cognitive function in individuals with Internet gaming disorder: A 6-month follow-up (2016)
  119. Compensatory increase of functional connectivity density in adolescents with internet gaming disorder (2016)
  120. Heart rate variability of internet gaming disorder addicts in emotional states (2016)
  121. Delay discounting, risk-taking, and rejection sensitivity among individuals with Internet and Video Gaming Disorders (2016)
  122. Delay Discounting of Video Game Players: Comparison of Time Duration Among Gamers (2017)