The first paper contains useful insights about the potential role of sexual conditioning in youthful ED
A better predictor is subjective sexual arousal ratings while watching Internet pornography (cue reactivity), an established correlate of addictive behavior in all addictions [52,53,54]
However, such claims appear to be premature on closer examination of these papers and related formal criticism. However, this publication has come under criticism for various discrepancies, omissions and methodological flaws. For example, it provides no statistical results for the erectile function outcome measure in relation to Internet pornography use. Further, as a research physician pointed out in a formal critique of the paper, the papers’ authors, “have not provided the reader with sufficient information about the population studied or the statistical analyses to justify their conclusion” . Additionally, the researchers investigated only hours of Internet pornography use in the last month. Yet studies on Internet pornography addiction have found that the variable of hours of Internet pornography use alone is widely unrelated to “problems in daily life”, scores on the SAST-R (Sexual Addiction Screening Test), and scores on the IATsex (an instrument that assesses addiction to online sexual activity) [52,53,54,55,56]. There is also increasing evidence that the amount of time spent on Internet video-gaming does not predict addictive behavior. “Addiction can only be assessed properly if motives, consequences and contextual characteristics of the behavior are also part of the assessment” . Three other research teams, using various criteria for “hypersexuality” (other than hours of use), have strongly correlated it with sexual difficulties [15,30,31]. Taken together, this research suggests that rather than simply “hours of use”, multiple variables are highly relevant in assessment of pornography addiction/hypersexuality, and likely also highly relevant in assessing pornography-related sexual dysfunctions.
Our review also included two 2015 papers claiming that Internet pornography use is unrelated to rising sexual difficulties in young men
A second paper reported little correlation between frequency of Internet pornography use in the last year and ED rates 
in sexually active men from Norway, Portugal and Croatia . These authors, unlike those of the previous paper, acknowledge the high prevalence of ED in men 40 and under, and indeed found ED and low sexual desire rates as high as 31% and 37%, respectively. In contrast, pre-streaming Internet pornography research done in 2004 by one of the paper’s authors reported ED rates of only 5.8% in men 35–39 . Yet, based on a statistical comparison, the authors conclude that Internet pornography use does not seem to be a significant risk factor for youthful ED. That seems overly definitive, given that the Portuguese men they surveyed reported the lowest rates of sexual dysfunction compared with Norwegians and Croatians, and only 40% of Portuguese reported using Internet pornography “from several times a week to daily”, as compared with the Norwegians, 57%, and Croatians, 59%. This paper has been formally criticized for failing to employ comprehensive models able to encompass both direct and indirect relationships between variables known or hypothesized to be at work . Incidentally, in a related paper on problematic low sexual desire involving many of the same survey participants from Portugal, Croatia and Norway, the men were asked which of numerous factors they believed contributed to their problematic lack of sexual interest. Among other factors, approximately 11%–22% chose “I use too much pornography” and 16%–26% chose “I masturbate too often” .
Again, intervention studies would be the most instructive. However, with respect to correlation studies, it is likely that a complex set of variables needs to be investigated in order to elucidate the risk factors at work in unprecedented youthful sexual difficulties. First, it may be that low sexual desire, difficulty orgasming with a partner and erectile problems are part of the same spectrum of Internet pornography-related effects, and that all of these difficulties should be combined when investigating potentially illuminating correlations with Internet pornography use.
