Novelty-seeking, cue-conditioning, and attentional bias are processes associated with the development and maintenance of addiction disorders.¹ A team of Cambridge University researchers and others conducted this study to examine these processes in individuals who met diagnostic criteria for compulsive sexual behaviors (CSB), particularly compulsive use of Internet pornography.² The researchers hypothesized that people with CSB would exhibit a greater preference for sexual novelty and images they associate with sexual rewards compared to healthy volunteers.

All the subjects in this study were heterosexual males: 22 CSB subjects and 40 comparably aged, healthy volunteers (HV). HV and CSB participants were matched in a 2:1 ratio to increase statistical power. Potential subjects with histories of substance abuse, psychiatric or compulsive disorders, and under the age 18 years of age were excluded. Participants completed two behavioral tasks to determine their preference for novel versus familiar sexual images, as well as their preference for cues conditioned to sexual, monetary, and neutral images. The sexual images used for testing “could be perceived as erotic rather than sexually explicit.”

In the first experiment designed to test preference for novelty, participants were shown pairs of images which included naked women, clothed women, or furniture. Subsequently they were shown more pairs of images, some of which included the familiar images, but with new images added. At this stage subjects were asked to choose an image for the possibility of winning ₤1. What they did not know is that the probability for selecting a “winning” image was 50% for either of the images displayed.

A second test again involved showing the participants paired images. This time the images were of a nude woman or a grey box. After seeing a series of such images, the images were paired with a novel abstract pattern and participants learned to associate the abstract patterns with either sexual or neutral images. Next, the participants were again asked to choose an image for a chance to win ₤1 and were told that the goal was to make as much money as possible. This time, however, they were told that one of the images was associated with a greater probability of winning. What they did not know was that the odds of winning were greater if the participant chose familiar images verses novel ones. The test was also repeated substituting images of money for the sexual images.

Finally, participants (20 CSB; 20 healthy volunteers) performed tasks during which they viewed images of a nude woman, a ₤1 coin, or a neutral grey box during an fMRI scan to assess their neural habituation to sexual, monetary, and neutral images.

The study reported:

• The results of the first text found that CSB subjects were more likely to choose novel sexual images rather than familiar sexual images when the images were paired against a neutral object. In contrast, HVs were more likely to choose a novel image of a neutral human female when paired against pictures of neutral objects.
• In the second test, CSB participants displayed a greater preference for abstract images (cues) that they were conditioned to associate with either sexual images or pictures of money.
• The fMRI task revealed that CSB subjects demonstrated a greater decrease in dorsal anterior cingulate cortex (dACC) and right inferior temporal cortex activity over time when exposed to sexual versus neutral images compared to HVs. This finding is consistent with “habituation,” a condition in which an addict finds a particular stimulus less rewarding over time.³
• Across all participants, novelty preference to repeated sexual images was predicted by greater habituation of daCC activity to sexual images.
• Importantly, there were no differences in sensation-seeking scores between individuals with CSB and HV (sensation seeking is a personality trait describing people who seek excitement, such as through new and intense experiences). This suggests that rather than men with CSB engaging in more compulsive sexual behaviors because they are high sensation seekers, that their desire for novelty stems from a condition response to pornography as a sexual reward.
• The study reported that “CSB individuals have a dysfunctional enhanced preference for sexual novelty…”⁴ Researchers also explained their work showed “experimentally what is observed clinically that CSB is characterized by novelty-seeking, conditioning, and habituation to sexual stimuli in males.”⁵
• These results support and extend the findings of Voon et al., 2014,⁶ and that of Mechelmans et al., 2014.⁷
• Co-author Valerie Voon commented on the study’s results saying, “Our findings are particularly relevant in the context of online pornography… It’s not clear what triggers sex addiction, but the seemingly endless supply of novel sexual images online helps feed their addiction, making it more and more difficult to escape.”⁸