Visual Sexual Stimuli-Cue or Reward? A Perspective for Interpreting Brain Imaging Findings on Human Sexual Behaviors

Abstract

There is an increasing number of neuroimaging studies using visual sexual stimuli (VSS), especially within the emerging field of research on compulsive sexual behaviors (CSB). A central question in this field is whether behaviors such as excessive pornography consumption share common brain mechanisms with widely studied substance and behavioral addictions. Depending on how VSS are conceptualized, different predictions can be formulated within the frameworks of Reinforcement Learning or Incentive Salience Theory, where a crucial distinction is made between conditioned and unconditioned stimuli (related to reward anticipation vs. reward consumption, respectively). Surveying 40 recent human neuroimaging studies we show existing ambiguity about the conceptualization of VSS. Therefore, we feel that it is important to address the question of whether VSS should be considered as conditioned stimuli (cue) or unconditioned stimuli (reward). Here we present our own perspective, which is that in most laboratory settings VSS play a role of reward, as evidenced by: (1) experience of pleasure while watching VSS, possibly accompanied by genital reaction; (2) reward-related brain activity correlated with these pleasurable feelings in response to VSS; (3) a willingness to exert effort to view VSS similarly as for other rewarding stimuli such as money; and (4) conditioning for cues predictive of VSS. We hope that this perspective article will initiate a scientific discussion on this important and overlooked topic and increase attention for appropriate interpretations of results of human neuroimaging studies using VSS.

Keywords: behavioral addictions; compulsive sexual behaviors; incentive salience; neuroimaging; reinforcement learning; sexual behavior; visual sexual stimuli.

Figure 1

(A) Blue bars indicate the number of human studies using neuroscience methods (fMRI, EEG, ERP, PET, MEG or TMS) and visual sexual stimuli (VSS) published between 2000 and 2016 according to PubMed (accessed on March 31st 2016). Red bars indicate the number of neuroscience studies on compulsive sexual behaviors (CSB): 1 in 2013 (Steele et al., 2013), 2 in 2014 (Kühn and Gallinat, ; Voon et al., 2014), 1 in 2015 (Prause et al., 2015), and 3 in 2016 (Banca et al., ; Brand et al., ; Klucken et al., 2016). (B) Number of studies published between 2013 and 2016 interpreting VSS as cue, reward or none of these labels (unspecified). Note that in Oei et al. (2014) VSS were defined both as “reward cues” and “rewarding stimuli”, so it was counted in both categories “Cue” and ”Reward”.

Figure 2

Visual sexual stimuli (VSS) act as cues in real life, but rewards in the lab. According to our perspective, in most real life situations (such as sexual activity with partner or solitary pornography consumption) VSS such as the naked body of a sexually attractive partner or pornographic content play a role of cue (CS). VSS increase sexual arousal and lead to behaviors initializing dyadic or solitary sexual activity and ending with reward—i.e., orgasm (UCS). In contrast, in most laboratory settings sexual activity and orgasm are unavailable. We claim that VSS then play a role of reward (UCS), similarly to some real life situations such as the visit to a strip club. In such contexts, individuals do not expect any other reward than being exposed to VSS, and are willing to exert effort or pay money to receive desired VSS, while being susceptible to conditioning for cues predictive of these VSS. For the purpose of illustration of our ideas this figure presents a simplified representation of real life where other scenarios of VSS use are possible, i.e., pornography consumption may lead to dyadic sexual activity or vice versa. Credits of sample photos: Lies Thru a Lens; Strip club in Montreal, Quebec, in Saint Henri borough; Lola Bel Aire, striptease from Miss Exotic World 2008, CC BY 2.0. For license terms see: CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/).