COMMENTS: Very few objective, controlled studies have been done on Internet pornography. Important findings in this study are that neither time spent viewing porn on the Internet nor personality factors were associated the level of reported problems with Internet porn use (IAT sex score). Instead, it was intensity of the experience and amount of novelty (different applications opened) that mattered...suggesting that dopamine levels were at play. It has generally been assumed that predisposing personality problems are what make porn addiction possible, but it may be dopamine levels, quite apart from personality.
As it turns out, the level of reported psychological problems (e.g., social anxiety, depression, and compulsivity) appears to be related to how intense the arousal produced, and the number of applications used (degree of novelty). That is just what one would expect with an ongoing addiction. From the study discussion, below:
"Although we did not examine brain correlates of watching Internet pornographic pictures in our study, we found the first experimental evidence for the potential link between subjective reactivity on Internet pornographic stimuli and a tendency toward cybersex addiction."
Cyberpsychol Behav Soc Netw. 2011 Jun;14(6):371-7. doi: 10.1089/cyber.2010.0222. Epub 2010 Nov 30.
General Psychology: Cognition, University of Duisburg-Essen, Forsthausweg 2, Duisburg, Germany. [email protected]
Excessive or addictive Internet use can be linked to different online activities, such as Internet gaming or cybersex. The usage of Internet pornography sites is one important facet of online sexual activity. The aim of the present work was to examine potential predictors of a tendency toward cybersex addiction in terms of subjective complaints in everyday life due to online sexual activities. We focused on the subjective evaluation of Internet pornographic material with respect to sexual arousal and emotional valence, as well as on psychological symptoms as potential predictors. We examined 89 heterosexual, male participants with an experimental task assessing subjective sexual arousal and emotional valence of Internet pornographic pictures.
The Internet Addiction Test (IAT) and a modified version of the IAT for online sexual activities (IATsex), as well as several further questionnaires measuring psychological symptoms and facets of personality were also administered to the participants.
Results indicate that self-reported problems in daily life linked to online sexual activities were predicted by subjective sexual arousal ratings of the pornographic material, global severity of psychological symptoms, and the number of sex applications used when being on Internet sex sites in daily life, while the time spent on Internet sex sites (minutes per day) did not significantly contribute to explanation of variance in IATsex score. Personality facets were not significantly correlated with the IATsex score.
The study demonstrates the important role of subjective arousal and psychological symptoms as potential correlates of development or maintenance of excessive online sexual activity.
Nowadays, the Internet is used in daily life as a very helpful tool. However, some individuals have an inability to control their use of the Internet and may therefore have problems in their everyday life with respect to social relationships, work or academic processes, financial issues, and psychological well-being.1–3 The phenomenon of excessive Internet use is frequently called Internet addiction (e.g., Young,2 Block,4 Chou et al.,5 Widyanto and Griffiths,6 and Praterelli and Browne7), although it has been termed differentially in recent articles.8–11
One form of Internet addiction is excessive cybersex, which seems to be a rising problem, particularly in industrial nations. Some authors claim that cybersex has the highest potential for developing an Internet addiction.8 Negative consequences of excessive cybersex comprise the use of online pornography by employees in the workplace,12 the increased risk of acquiring sexually transmitted diseases in individuals who excessively seek sexual partners through cybersex sites,13 and—as a last example—the potential link between pornography consumption and aggression.14 The importance of considering correlates of excessive cybersex is also emphasized by Kafka.15
Although the topic of cybersex addiction has high clinical relevance, it has been almost neglected in previous research. 16,17 In most of the studies on cognitive or personality correlates of Internet activities in general, online/computer gamers were primarily included in the samples18–20 or no distinction between different online activities has been made.21–24 Studies that particularly investigate experimentally potential mechanisms of cybersex addiction are missing.
Cybersex comprises several active or passive forms, such as seeking sexual partners in real life, sex chats, sex via web camera, and so on. The consumption of cyberpornography is also an important facet of cybersex. Although some information about sociodemographic characteristics of cyberpornography users exist,16,17,25 no empirical study has assessed directly how the consumption of cyberpornography is perceived by users.16 Young26 proposed that the expectation of finding sexual arousal and gratification is one key element of motivation for cybersex (see also Young3). This is principally in accordance with self-reports of subjects who excessively consume cyberpornography.27 However, as has been pointed out by Griffith,28 no strong experimental empirical data exist that support the claims made by Young.3,26 On a theoretical level, it makes sense to assume that subjects addicted to cybersex experience a positive emotional episode accompanied by sexual arousal when consuming cybersex sites. It might also be that subjects who consume cybersex sites excessively have a salience for the incentive in terms of sexual arousal (see the discussion on ‘‘wanting’’ and ‘‘liking’’ as two components of reward, e.g. Berridge et al.29). However, these speculations need to be tested empirically.
On a hypothesized level, we see some parallels between cognitive and brain mechanisms potentially contributing to the maintenance of excessive cybersex and those described for individuals with substance dependence or behavioral addiction (e.g., pathological gambling). For instance, it is known that the brain of subjects with alcoholism or other substance dependence reacts emotionally (activations of the ventral striatum) when being confronted with alcohol- or drug-related pictures.30–32 Other studies also emphasize that craving reactions (cue-reactivity) can be found in subjects with behavioral addictions, such as pathological gambling33 and—most recently—even in subjects who excessively play World of Warcraft19 or other computer games.18 These studies converge to the view that craving reactions on watching addiction-related stimuli are important correlates of the addictive behavior.
The limbic and para-limbic structures mentioned (e.g., ventral striatum) are also involved in sexual behavior and are connected with other brain structures that play important roles in sexual arousal and sexual activity.34–40 Therefore, it seems plausible that those brain regions involved in processing sexual stimuli, and sexual arousal and activity, as well as in craving reactions in individuals with behavioral addictions, are also crucially relevant for development and maintenance of addictive behavior in the context of cybersex.
Aims and hypotheses of the present study
The main aim of the present study was to investigate potential correlates and predictors of subjective complaints in everyday life due to excessive online sexual activities (as a measure of a tendency toward cybersex addiction) in a laboratory experimental setting. As a main potential predictor of these subjective complaints, we concentrated on the subjective evaluation of cyberpornographic pictures, that is, subjective ratings of the pictures’ arousal. We also investigated the degree of psychological symptoms such as social anxiety, depression, and compulsivity. Furthermore, we assessed the usage of specific cybersex applications, as well as several facets of personality (reward sensitivity, shyness).
Given the literature on cue reactivity in substance-dependent individuals and those with specific types of behavioral addiction,18,19,30–33 together with the literature on comorbid psychological symptoms in subjects with behavioral addictions and disorders of impulse control,41–44 we particularly hypothesized that a tendency toward cybersex addiction—in terms of subjectively experienced negative consequences of cybersex in everyday life—is predicted by subjective sexual arousal when watching Internet pornographic material and global severity of psychological symptoms. We also hypothesized that the range of online sexual activities (number of online sex applications used) and the time spent on Internet sex sites additionally predict the degree of self-reported problems in everyday life due to excessive cybersex. The hypotheses are also summarized in Figure 1.
We examined 89 heterosexual male participants (mean age 23.98, SD¼4.09 years). Mean education of the sample was 13.42 years (SD¼1.71). Participants were recruited through a local advertisement and were paid at an hourly rate for participation (10.00 e/hour). The advertisement indicated that heterosexual men are invited to participate in a study on Internet pornography and that the subjects will be confronted with Internet pornographic material. Previous consumption of cybersex sites was not a necessary criterion for participation. Inclusion criteria required that individuals have no history of neurological or psychiatric disease, as determined by a screening. Any substance-related disorders were also exclusion criteria. All participants gave written informed consent prior to the investigation.
A total of 51 participants (57.3%) were in a heterosexual partnership, 35 (39.3%) were single, and 3 (3.3%) did not respond to this question. Mean age at first Internet use was 13.90 (SD¼2.88) years meaning that the average duration of Internet use was 10.08 (SD¼2.88) years. Mean days per week of Internet use for personal reasons was 6.44 (SD¼1.13) and the subjects spent on average 223.87 (SD¼107.88) minutes per day on the Internet (mean Internet use of 26.12 hours per week). Regarding cybersex usage, all 89 subjects reported FIG. 1. Illustration of the hypothesized predictors of cybersex addiction in terms of subjectively experienced negative consequences of online sexual activities in everyday life. 2 BRAND ET AL. that they had used cybersex sites at least once in their life. Mean age at first online sexual activity was 16.33 (SD¼3.56) years. Mean days per week of cybersex use was 2.0 (SD¼1.85, range¼0–7) and the subjects spent on average 36.07 (SD¼31.21, range¼0–150) minutes per day on cybersex sites (72.14 minutes per week, SD¼62.44, range¼0–300). The latter scores are in accordance with that reported previously. 25,45,46
All questionnaires and the experimental paradigm were administered to the participants in a laboratory setting. All tasks and questionnaires were computer-based with the exception of the Symptom Checklist. The whole examination including instructions and debriefing took approximately 75 minutes.
For the assessment of subjective emotional evaluations and arousal experienced while watching Internet pornographic stimuli, we used 40 standardized pictures that either showed a single masturbating women or a male/female couple during sexual intercourse. The sexual behavior was clearly shown on each picture. The women/men shown had an estimated age between 20 and 35 years. In order to make the pictures as comparable as possible to the real world situation, we used a standard browser window in which we pasted the different pictures. In the browser window, the Web site address was standardized with a non-existing webpage (www.sexbild.de). All other information shown (time, programs opened, etc.) was also standardized. On each picture, only one image was shown in the center of the browser window. The images were selected from freely accessible Web sites containing legal content and which were free of charge. The images did not contain any fetish relevant content.
The subjects were asked to rate each image separately with respect to sexual arousal (scale ranging from 1 to 7, where 1¼‘‘no sexual arousal’’ and 7¼‘‘high sexual arousal’’), emotional valence (scale ranging from 1 to 7, where 1¼‘‘negative emotional valence’’ and 7¼‘‘positive emotional valence’’), and representativeness for cyberpornographic material (scale ranging from 1 to 7, where 1¼‘‘the picture is not representative’’ and 7¼‘‘the picture is highly representative’’). The rating of the representativeness of the pictures was included to assure that we had selected material that was representative of the pictures that are consumed in everyday life. The order of picture presentation was randomized. Internal consistencies (Cronbach’s a) of the scales were: sexual arousal rating (a¼0.951), emotional valence rating (a¼0.962), and representativeness rating (a¼0.977).
Subjective complaints in everyday life due to excessive usage of the Internet and potential symptoms of Internet addiction were assessed by a German version of the Internet Addiction Test (IAT).47,48 The original English version was translated into German by a bilingual English/German speaker and retranslated by a second bilingual speaker. In addition, we used a modified version of the IAT in which the terms ‘‘online’’ or ‘‘Internet’’ in the original IAT were replaced by the terms ‘‘online sexual activity’’ and ‘‘Internet sex sites’’ respectively (we termed this modified version IATsex). This IATsex was used to assess subjective complaints in everyday life due to online sexual activities and potential symptoms of cybersex addiction. An example for an item of the original IAT and the modified version (IATsex) is: ‘‘How often do you find that you stay online longer than you intended?’’ (original IAT) and ‘‘How often do you find that you stay on Internet sex sites longer than you intended?’’ (IATsex). Both IAT versions used consist of 20 items, and the scale used ranged from 1 to 5 (‘‘rarely’’ to ‘‘always’’), resulting in a potential score between 20 and 100. Internal consistencies (Cronbach’s a) of these scales were IAT (a¼0.878) and IATsex (a¼0.842).
Participants were asked to indicate how often (on a scale of 0 to 4, where 0¼‘‘never’’ and 4¼’’always when online’’) they use different types of cybersex (e.g., pornographic pictures, videos, literature, sex via web camera, sex chat, searching for sexual partners). They were also asked how often (on a scale of 0 to 4, where 0¼‘‘never’’ and 4¼‘‘always when online’’) they prefer different types of pornographic material (e.g., one single naked or masturbating women, one women having sex with one man, two women and one man, two men and one women, group sex, sex between two women or between two men). Finally, several sexual practices or fetishes (e.g., vaginal, oral, or anal penetration, striptease, leather, fisting, mature, spanking, etc.) were listed, and subjects were asked whether or not they principally have a preference toward these pornographic materials on the Internet (answer mode yes/no; all together 18 practices/fetishes were assessed).
Psychological–psychiatric symptoms were assessed by the Symptom Check List (SCL-90-R),49 which consists of nine subscales: somatization, obsessive– compulsiveness, interpersonal sensitivity, depression, anxiety, anger–hostility, phobic anxiety, paranoid ideation, and psychoticism. In addition, a global severity index can be calculated. Furthermore, we used the German short questionnaire version50 of the BIS/BAS scale51 to assess reward responsiveness and punishment sensitivity. We also assessed shyness and sociability with the Shyness and Sociability Scales by Asendorpf.52
The mean rating scores on the three dimensions were near the middle of the scales’ range: sexual arousal mean¼3.65 (SD¼1.04), emotional valence mean¼3.65 (SD¼0.96), and representativeness mean¼4.88 (SD¼1.16). The IAT scores and the IATsex scores were: IAT mean¼30.67 (SD¼9.2, range 20–66), IATsex mean¼23.66 (SD¼5.56, range 20–56). The mean number of practices for which subjects had a preference when using Internet pornographic websites was 5.61 (SD¼2.86). The IAT and IATsex were correlated highly (r¼0.657, p<0.001). The bivariate correlations between the picture ratings, IATsex, and other variables are shown in Tables 1 and 2.
In order to evaluate further the relationships between IATsex score (as the dependent variable) and the potential predictors of sexual arousal rating, global severity of psychological symptoms, mean overall use of Internet sex applications, and time spent on Internet sex sites (see hypotheses), we calculated a hierarchical regression analysis (all variables centralized).53 The order of variables included in this regression analysis represents the order of hypothesized significance of the predictor variables (see hypotheses). As a first step, sexual arousal rating was a significant predictor of IATsex score (R2¼0.06, F¼5.76, df1¼1, df2¼87, p¼0.018). When adding (second step) the global severity index of psychological symptoms (SCL GSI score) as a predictor, the changes in R2 were significant, resulting in an overall explanation of the IATsex score’s variance of 12.7% (changes in R2¼0.06, changes in F¼6.34, df1¼1, df2¼86, p¼0.014). By entering the mean usage of Internet sex applications as an additional predictor (third step), the changes in R2 were also significant, resulting in an overall explanation of the IATsex score’s variance of 23.7% (changes in R2¼0.11, changes in F¼12.33, df1¼1, df2¼85, p¼0.001). Finally, entering the time in minutes/day spent on Internet sex sites (fourth step) did not significantly contribute to explanation of variance of the IATsex score (changes in R2¼0.004, changes in F¼0.49, df1¼1, df2¼84, p¼0.485; see Table 3 for further values).
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. Subjective arousal ratings, the global severity of psychological symptoms, and the number of sex applications used were significant predictors of the IATsex score, while the time spent on Internet sex sites did not significantly contribute to explanation of variance in the IATsex score.
The finding that subjective sexual arousal ratings while watching Internet pornographic pictures is related to self-reported problems in daily life due to excessive use of cybersex sites may be interpreted in the light of previous studies on cue reactivity in individuals with substance dependency or behavioral addictions. As outlined in the introduction, cue reactivity as a mechanism potentially contributing to the maintenance of addicted behavior has been demonstrated in several patient groups with either substance dependence or behavioral addiction. 18,19,30–33 These studies converge to the view that craving reactions on watching addiction-related stimuli are important correlates of the addictive behavior. Although we did not examine brain correlates of watching Internet pornographic pictures in our study, we found the first experimental evidence for the potential link between subjective reactivity on Internet pornographic stimuli and a tendency toward cybersex addiction.
The relationship between self-reported problems in daily life linked to cybersex (IATsex) and several psychological symptoms is consistent with a previous study by Yang et al.43 in which the SCL-90-R was also used to measure psychological symptoms in subjects with excessive Internet use in comparison to moderate and mild users. However, in the study by Yang et al., no differentiation between specific types of Internet usage (gaming, sex sites, etc.) was made. In our sample, the global symptom severity (SCL GSI), as well as interpersonal sensitivity, depression, paranoid thinking and psychoticism, were correlated particularly with the IATsex score. In contrast, time spent on cybersex sites (minutes per day) was widely unrelated to psychological symptoms. The actual time spent on cybersex sites was also not significantly correlated with the IATsex score. This means that for problems in daily life (e.g., reduced control over online sexual activities, problems with the own partner or in other interpersonal relationships, as well as problems in academic or work life), the time spent on cybersex sites is not predictive.
The results of our study—in particular the correlation between subjective arousal ratings of pornographic material and the reported negative consequences of cybersex in daily life—are in line with Young.26 She proposed that the expectation of finding sexual arousal may be one of the key elements of motivation for online sexual activities.3 Our results indeed emphasize that higher sexual arousal is linked to a tendency toward being addicted to cybersex and related problems in everyday life.
Finally, we have to mention some important limitations of the current study. First, the sample was relatively small. However, one has to keep in mind that subjects enrolled in this investigation were assessed in a laboratory setting with an individual assessment, which makes the data revealed more valid in comparison to studies using online questionnaires because we were able to control for environmental variables that may influence subjects’ responses on the tasks. In addition, we screened for previous psychiatric and neurologic diseases, which also contributes to the homogeneity of the sample. Although we excluded subjects with any substance-related disorder, we did not document current substance use in detail (e.g., alcohol, cannabis). Future studies may address potential correlations between a tendency toward cybersex addiction and consumption of different substances. Second, we freely recruited our participants by advertisements, producing a sample that consisted of ‘‘normal’’ healthy individuals. Accordingly, we had a non-clinical sample, although some of the subjects reported high IATsex scores, which potentially indicate symptom severity that fulfills diagnostic criteria for behavioral addictions.54 Our data need replication with a larger sample and with subjects suffering from sexual addiction. In future studies, potential correlates of cybersex addiction in women and also in homosexual men and women should be investigated. In our study, only heterosexual men were included, and the pornographic stimuli used in the experimental design were selected with and for male eyes. Further studies may use additional pornographic pictures representative for other samples with respect to gender and sexual orientation. Although the limitations mentioned have to be kept in mind, we conclude that our study revealed first reference for the important role of subjective arousal and psychological symptoms as potential correlates of development or maintenance of excessive online sexual activity in heterosexual men. Given the lack of empirical studies on this topic,16,17,28 our current study contributes to filling the gap and will hopefully inspire future research on the very important topic of cybersex addiction.3
Disclosure Statement: No competing financial interests exist.
1. Young KS. Internet addiction: The emergence of a new clinical disorder. CyberPsychology & Behavior 1998; 1: 237–44.
2. Young KS. Internet addiction: A new clinical phenomenon and its consequences. American Behavioral Scientist 2004; 48:402–15.
3. Young KS. Internet sex addiction: Risk factors, stages of development, and treatment. American Behavioral Scientist 2008; 52:21–37.
4. Block J. Issues for DSM-V: Internet addiction. American Journal of Psychiatry 2008; 165:306–7.
5. Chou C, Condron L, Belland JC. A review of the research on Internet addiction. Educational Psychology Review 2005; 17:363–87. Table 3. Hierarchical Regression Analysis with the IATsex Score as the Dependent Variable b T p Main effects ‘‘sexual arousal rating’’ 0.25 2.40 0.018 ‘‘global severity index’’ 0.26 2.52 0.014 ‘‘usage of Internet sex applications’’ 0.34 3.51 0.001 ‘‘min/day on Internet sex sites’’ 0.07 0.70 0.485
6. Widyanto L, Griffiths M. ‘‘Internet addiction’’: A critical review. International Journal of Mental Health & Addiction 2006; 4:31–51.
7. Pratarelli ME, Browne BL. Confirmatory factor analysis of Internet use and addiction. CyberPsychology & Behavior 2002; 5:53–64.
8. Meerkerk GJ, van den Eijnden RJJM, Garretsen HFL. Predicting compulsive Internet use: It’s all about sex! CyberPsychology & Behavior 2006; 9:95–103.
9. Caplan SE. Problematic Internet use and psychosocial wellbeing: Development of a theory-based cognitive–behavioral measurement instrument. Computers in Human Behavior 2002; 18:553–75.
10. Davis RA. A cognitive–behavioral model of pathological Internet use. Computers in Human Behavior 2001; 17:187–95.
11. LaRose R, Lin CA, Eastin MS. Unregulated internet usage: Addiction, habit, or deficient self-regulation? Media Psychology 2003; 5:225–53.
12. Cooper A, Golden GH, Kent-Ferraro J. Online sexual behaviors in the workplace: How can human resource departments and employee assistance programs respond effectively? Sexual Addiction & Compulsivity 2002; 9:149–65.
13. McFarlane M, Sheana S, Rietmeijer C. The Internet as a newly emerging risk environment for sexually transmitted diseases. Journal of the American Medical Association 2000; 284:443–6.
14. Kingston DA, Fedoroff P, Firestone P, et al. Pornography use and sexual aggression: The impact of frequency and type of pornography use on recidivism among sexual offenders. Aggressive Behavior 2008; 34:341–51.
15. Kafka MP. Hypersexual disorder: A proposed diagnosis for DSM-V. Archives of Sexual Behavior 2010; 39:377–400.
16. Do¨ ring NM. The Internet’s impact on sexuality: A critical review of 15 years of research. Computers in Human Behavior 2009; 25:1089–101.
17. Griffiths M. Excessive Internet use: Implications for sexual behavior. CyberPsychology & Behavior 2000; 3:537–52.
18. Thalemann R, Wo¨lfling K, Gru¨ sser SM. Specific cue reactivity on computer game-related cues in excessive gamers. Behavioral Neuroscience 2007; 121:614–8.
19. Ko CH, Liu GC, Hsiao S, et al. Brain activities associated with gaming urge of online gaming addiction. Journal of Psychiatric Research 2009; 43:739–47.
20. Teng C. Personality differences between online game players and nonplayers in a student sample. CyberPsychology & Behavior 2008; 11:232–4.
21. Chak K, Leung L. Shyness and locus of control as predictors of Internet addiction and Internet use. CyberPsychology & Behavior 2004; 7:559–70.
22. Lu H. Sensation-seeking, Internet dependency, and online interpersonal deception. CyberPsychology & Behavior 2008; 11:227–31.
23. Morahan-Martin J, Schumacher P. Incidence and correlates of pathological Internet use among college students. Computers in Human Behavior 2000; 16:13–29.
24. Niemz K, Griffiths M, Banyard P. Prevalence of pathological Internet use among university students and correlations with self-esteem, the general health questionnaire (GHQ), and disinhibition. CyberPsychology & Behavior 2005; 8:562–70.
25. Cooper A, Scherer CR, Boies SC, et al. Sexuality on the internet: from sexual exploration to pathological expression. Professional Psychology: Research & Practice 1999; 30:154–64.
26. Young KS. (2001) Tangled in the web: Understanding cybersex from fantasy to addiction. Bloomington, IN: Authorhouse.
27. Cavaglion G. Cyber-porn dependence: Voices of distress in an Italian internet self-help community. International Journal of Mental Health & Addiction 2009; 7:295–310.
28. Griffiths M. Sex on the Internet: Observations and implications for Internet sex addiction. Journal of Sex Research 2001; 38:333–42.
29. Berridge KC, Robinson TE, Aldridge JW. Dissecting components of reward: ‘‘Liking,’’ ‘‘wanting,’’ and learning. Current Opinion in Pharmacology 2009; 9:65–73.
30. Braus DF, Wrase J, Gru¨ sser S, et al. Alcohol-associated stimuli activate the ventral striatum in abstinent alcoholics. Journal of Neural Transmission 2001; 108:887–94.
31. Garavan H, Pankiewicz J, Bloom A, et al. Cue-induced cocaine craving: Neuroanatomical specificity for drug users and drug stimuli. The American Journal of Psychiatry 2000; 157:1789–98.
32. Gru¨ sser S, Wrase J, Klein S, et al. Cue-induced activation of the striatum and medial prefrontal cortex is associated with subsequent relapse in abstinent alcoholics. Psychopharmacology 2004; 175:296–302.
33. Potenza MN, Steinberg MA, Skudlarski P, et al. Gambling urges in pathological gambling: A functional magnetic resonance imaging study. Archives of General Psychiatry 2003; 60:828–36.
34. Balfour ME, Yu L, Coolen LM. Sexual behavior and sexassociated environmental cues activate the mesolimbic system in male rats. Neuropsychopharmacology 2004; 29: 718–30.
35. Bancroft J. The endocrinology of sexual arousal. Journal of Endocrinology 2005; 186:411–27.
36. Georgiadis JR, Holstege G. Human brain activation during sexual stimulation of the penis. The Journal of Comparative Neurology 2005; 493:33–8.
37. Holstege G, Georgiadis JR, Paans AMJ, et al. Brain activation during human male ejaculation. The Journal of Neuroscience 2003; 23:9185–93.
38. Hu SH, Wei N, Wang Q, et al. Patterns of brain activation during visually evoked sexual arousal differ between homosexual and heterosexual men. American Journal of Neuroradiology 2008; 29:1890–6.
39. Paul T, Schiffer B, Zwarg T, et al. Brain response to visual sexual stimuli in heterosexual and homosexual males. Human Brain Mapping 2008; 29:726–35.
40. Redoute´ J, Stole´ru S, Gre´goire M-C, et al. Brain processing of visual sexual stimuli in human males. Human Brain Mapping 2000; 11:162–77.
41. Brand M, Franke-Sievert C, Jacoby GE, et al. Neuropsychological correlates of decision-making in bulimia nervosa. Neuropsychology 2007; 21:742–50.
42. Yang C. Sociopsychiatric characteristics of adolescents who use computers to excess. Acta Psychiatrica Scandinavia 2001; 104:217–22.
43. Yang C, Choe B, Baity M, et al. SCL-90-R and 16PF profiles of senior high school students with excessive Internet use. Canadian Journal of Psychiatry 2005; 50:407–14.
44. Yen J, Ko C, Yen C, et al. The comorbid psychiatric symptoms of Internet addiction: Attention Deficit and Hyperactivity Disorder (ADHD), depression, social phobia, and hostility. Journal of Adolescent Health 2007; 41: 93–8.
45. Cooper A, Delmonico DL, Griffin-Shelley E, et al. Online sexual activity: An examination of potentially problematic behaviors. Sexual Addiction & Compulsivity 2004; 11: 129–43. 6 BRAND ET AL.
46. Delmonico D, Miller J. The Internet sex screening test: A comparison of sexual compulsives versus non-sexual compulsives. Sexual & Relationship Therapy 2003; 18:261–76.
47. Young KS. (1998) Caught in the net: How to recognize the signs of Internet addiction—And a winning strategy for recovery. New York: John Wiley & Sons.
48. Widyanto L, McMurran M. The psychometric properties of the Internet addiction test. CyberPsychology & Behavior 2004; 7:443–50.
49. Franke GH. (2002) SCL-90-R—Die Symptom-Checkliste von L.R. Derogatis. Go¨ ttingen, Germany: Beltz Test.
50. Hartig J, Moosbrugger H. Die ‘‘ARES-Skalen’’ zur Erfassung der individuellen BIS- und BAS-Sensitivita¨ t: Entwicklung einer Lang- und einer Kurzfassung. Zeitschrift fu¨ r Differentielle und Diagnostische Psychologie 2003; 24:291–308.
51. Carver CS, White TL. Behavioral inhibition, behavioral activation, and affective responses to impending reward and punishment: The BIS/BAS scales. Journal of Personality & Social Psychology 1994; 67:319–33.
52. Asendorpf J. (1997) Schu¨ chternheits- und Geselligkeitsskalen fu¨ r Erwachsene [Shyness and sociability scales for adults]. Berlin: Humboldt-University, Institute of Psychology.
53. Cohen J, Cohen P, West SG, et al. (2003) Applied multiple regression/correlation analysis for the behavioral science. 3rd ed. Mahwah, NJ: Lawrence Erlbaum.
54. Albrecht U, Kirschner NE, Gru¨ sser SM. Diagnostic instruments for behavioural addiction: An overview. GMS Psycho-Social-Medicine 2007; 4:1–11.
Address correspondence to: Matthias Brand, Ph.D. General Psychology: Cognition University of Duisburg-Essen Forsthausweg 2 47057 Duisburg Germany E-mail: [email protected]