"Neuroscience of Internet Pornography Addiction: A Review and Update" - Excerpt critiquing Prause et al., 2015
- Link to original paper - "Neuroscience of Internet Pornography Addiction: A Review and Update" (2015)
Excerpt critiquing Prause et al., 2015:
Another EEG study involving three of the same authors was recently published . Unfortunately, this new study suffered from many of the same methodological issues as the prior one . For example, it used a heterogeneous subject pool, the researchers employed screening questionnaires that have not been validated for pathological internet pornography users, and the subjects were not screened for other manifestations of addiction or mood disorders.
In the new study, Prause et al. compared EEG activity of frequent viewers of Internet pornography with that of controls as they viewed both sexual and neutral images . As expected, the LPP amplitude relative to neutral pictures increased for both groups, although the amplitude increase was smaller for the IPA subjects. Expecting a greater amplitude for frequent viewers of Internet pornography, the authors stated, “This pattern appears different from substance addiction models”.
While greater ERP amplitudes in response to addiction cues relative to neutral pictures is seen in substance addiction studies, the current finding is not unexpected, and aligns with the findings of Kühn and Gallinat , who found more use correlated with less brain activation in response to sexual images. In the discussion section, the authors cited Kühn and Gallinat and offered habituation as a valid explanation for the lower LPP pattern. A further explanation offered by Kühn and Gallinat, however, is that intense stimulation may have resulted in neuroplastic changes. Specifically, higher pornography use correlated with lower grey matter volume in the dorsal striatum, a region associated sexual arousal and motivation .
It’s important to note that the findings of Prause et al. were in the opposite direction of what they expected . One might expect frequent viewers of Internet pornography and controls to have similar LPP amplitudes in response to brief exposure to sexual images if pathological consumption of Internet pornography had no effect. Instead, the unexpected finding of Prause et al.  suggests that frequent viewers of Internet pornography experience habituation to still images. One might logically parallel this to tolerance. In today’s world of high-speed Internet access, it is very likely that frequent consumers of Internet pornography users view sexual films and videos as opposed to still clips. Sexual films produce more physiological and subjective arousal than sexual images  and viewing sexual films results in less interest and sexual responsiveness to sexual images . Taken together, the Prause et al., and Kühn and Gallinat studies lead to the reasonable conclusion that frequent viewers of internet pornography require greater visual stimulation to evoke brain responses comparable to healthy controls or moderate porn users.
In addition, the statement of Prause et al.  that, “These are the first functional physiological data of persons reporting VSS regulation problems” is problematic because it overlooks research published earlier [262,263]. Moreover, it is critical to note that one of the major challenges in assessing brain responses to cues in Internet pornography addicts is that viewing sexual stimuli is the addictive behavior. In contrast, cue-reactivity studies on cocaine addicts utilize pictures related to cocaine use (white lines on a mirror), rather than having subjects actually ingest cocaine. Since the viewing of sexual images and videos is the addictive behavior, future brain activation studies on Internet pornography users must take caution in both experimental design and interpretation of results. For example, in contrast to the one-second exposure to still images used by Prause et al. , Voon et al. chose explicit 9-second video clips in their cue reactivity paradigm to more closely match Internet porn stimuli . Unlike the one-second exposure to still images (Prause et al. ), exposure to 9-second video clips evoked greater brain activation in heavy viewers of internet pornography than did one-second exposure to still images. It is further concerning that the authors referenced the Kühn and Gallinat study, released at the same time as the Voon study , yet they did not acknowledge the Voon et al. study anywhere in their paper despite its critical relevance.