Measurement of Male Sexual Arousal and Interest Using Penile Plethysmography and Viewing Time

Not all people who engage in sexual violence do so for the same reasons. It appears that some people do so as a consequence of significant social and personal dysfunction, leading to decreased general and sexual self-regulation including poor interpersonal boundaries. There are, however, some people who engage in sexually offensive behavior because they have a strong sexual interest in or, perhaps, even a sexual preference for doing so. Meta-analytic reviews of the predictors of sexual recidivism suggest that clients who demonstrate sexual interest in or preference for engaging in inappropriate sexual behavior are at considerably higher risk for reoffending. At present, there are two main methods used to identify problematic sexual interests and preferences. The penile plethysmograph (PPG) or phallometric test measures changes in penile physiology upon presentation of audiovisual stimuli intended to elicit sexual arousal. As a measure of relative sexual deviance, the PPG is in wide usage throughout Canada, the USA, and other nations; however, concerns exist regarding standardization and psychometric utility. More recently, viewing time measures (VT; e.g., Abel Assessment, Affinity) have been suggested as being helpful in identifying problematic sexual interests. VT methods tend to be used in jurisdictions where ethical and moral concerns exist regarding use of PPG and in situations where PPG cannot be used (e.g., individuals with erectile dysfunction). In this chapter, we present a historical and practical overview of each method (PPG and VT), highlighting strengths and weaknesses. We conclude with a comparative analysis of these two approaches to identifying paraphilic propensities in clients who have sexually offended and make suggestions for future research and practical considerations.