Physiological Assessments of Deviant Arousal, Interests, and Preferences

Given the inherent fallibility of self–report, physiological tools have become increasingly popular as an independent and objective enhancement to the assessments of sexually abusive individuals. These types of assessments are particularly valuable when attempting to explore deviant sexual arousal, interests, or preferences. The following are the primary types of physiological assessment approaches used within the sex offender management field:

Phallometry/Penile Plethysmography

The most longstanding, widely employed, and empirically–supported method of assessing deviant sexual arousal, interests, and preferences is phallometry, generally using the penile plethysmograph (Laws, 2003; Marshall & Fernandez, 2003). This process involves exposing an individual to different sets of audio and/or visual stimuli while measuring the physical changes that occur in erectile magnitude. These changes are interpreted as reflecting varied levels of sexual arousal and/or interests; greater levels of arousal to certain stimulus sets relative to others are suggestive of preferences.

Researchers have demonstrated strong associations between phallometric measures of deviant sexual arousal/interests and sexual and violent recidivism, primarily for men who sexually abuse children (Hanson & Bussiere, 1998; Laws, 2003; Marshall & Fernandez, 2003; Rice, Harris, & Quinsey, 1990; Rice, Quinsey, & Harris, 1991). In addition, phallometric assessments of sex offenders against children (and, in some instances, sex offenders against adult women) have revealed greater deviant arousal/interests among those offenders than nonsexual offenders (Abel, Lawry, Karlstrom, Osborn, & Gillespie, 1994; Harris, Rice, Quinsey, Chaplin, & Earls, 1992; Lalumiere & Quinsey, 1994; Laws, 2003; Letourneau, 2002; Marshall & Fernandez, 2003).

Viewing Time

In comparison to phallometric assessment, the use of viewing time procedures is a relatively recent approach to the assessment of sexual interest and, as such, less evidence is available to support its validity and reliability (Letourneau, 2002). With viewing time assessments, the individual views computer–generated slides of children, adolescents, and adults on a screen and enters self–reported ratings of attractiveness for these pictures. Throughout the process, the subject is responsible for advancing to the next slide. The amount of time spent viewing any given picture is believed to provide an objective measure of sexual interest; longer viewing time suggests greater interest (Abel et al., 1994; Abel, Huffman, Warberg, & Holland, 1998; Abel, Jordan, Hand, Holland, & Phipps, 2001).

Some professionals favor viewing time assessments over phallometric assessments as these procedures are far less intrusive and the stimuli are less controversial (Abel et al., 1998). Published reports indicate that viewing time holds promise as a means of assessing deviant sexual interests, particularly with respect to interests in children (Abel et al., 1994, 1998; Letourneau, 2002), although additional independent research is clearly needed.


As an adjunct to the assessment process, the post–conviction or post–adjudication polygraph examination is potentially useful as an indirect assessment of deviant sexual interests through the sexual history disclosure process. Prior to the examination, the offender generally provides detailed information to the polygraph examiner via a sexual history questionnaire and/or interview. During the actual polygraph examination, the subject responds to a limited number of “yes” or “no” questions about the sexual history, at which time the polygraph measures specific physiological changes (e.g., respiration, blood pressure, heart rate) believed to be associated with deception. Using standardized scoring techniques, the polygraph examiner reviews the results and subsequently renders an opinion as to whether the examinee appeared to be candid or deceptive. In the post–examination interview, the polygrapher discusses apparent discrepancies and other areas that may warrant follow–up. Practitioners often indicate that it is during the post–examination process that the most useful information is obtained.

Reports in the literature indicate that greater amounts of information about victims and behaviors are elicited through the polygraph examination process (Ahlmeyer, Heil, McKee, & English, 2000; Heil, Ahlmeyer & Simons, 2003; O’Connell, 2000). Within this context, this sexual history information may assist practitioners with considering deviant interests, either because it corroborates information obtained through other data sources, or because it raises questions that lead to further inquiry or assessment. Despite its growing popularity as an assessment tool with sex offenders, debates over the use of the polygraph continue, with yet unanswered questions regarding its validity and reliability (National Academies of Sciences, 2003) and the impact on sex offender management strategies. If used, the polygraph should be considered as one component of a broader and more comprehensive assessment approach.

Considerations with Juvenile Sex Offenders

The use of phallometric and viewing time assessment techniques is relatively common when conducting evaluations with adult offenders, as is the use of the polygraph to facilitate disclosure for the purpose of obtaining sexual history information (McGrath, Cumming, & Burchard, 2003). Utilization of such technology is less common and more controversial, however, when juveniles are the subjects of the assessment (see, e.g., Fanniff & Becker, 2006a; Hunter & Lexier, 1998; McGrath et al., 2003; Smith & Fisher, 1999).

At present, empirical research on the reliability and validity of these assessment strategies with juvenile sex offenders is lacking (Becker & Harris, 2004; Fanniff & Becker, 2006b; Hunter & Lexier, 1998; Letourneau & Miner, 2005). Moreover, whether the fluidity of juveniles’ development and maturity has an impact on the reliability and validity of these techniques remains an unanswered question. Finally, concerns regarding the intrusive nature of some of these methods and the exposure of juveniles to some of the stimuli have been raised as well (Becker & Harris, 2004; CSOM, 1999; Hunter & Lexier, 1998; Letourneau & Miner, 2005).

In light of these concerns, experts suggest that if such measures are to be incorporated as part of an assessment process with youthful sex offenders, they should be used selectively (Becker & Harris, 2004; Fanniff & Becker, 2006a, 2006b; Hunter & Lexier, 1998). The full informed consent of the juvenile and parent or caregiver should be obtained, ensuring that all parties, including the professionals involved, are aware of the limitations, risks, and caveats associated with the use of such measures. Generally, physiological assessments of sexual arousal, preference, or interest—as well as the use of the polygraph as an assessment tool—should be restricted to older juveniles (i.e., 14 years of age or older) who report deviant sexual interests and/or those juveniles with extensive histories of sexual offending. Under these circumstances, such assessments may be useful for identifying juveniles with emergent paraphilic disorders (Becker & Harris, 2004; Fanniff & Becker, 2006a, 2006b; Hunter & Lexier, 1998).

In summary, while physiological assessments are increasingly common with adult and juvenile sex offenders, they are not without controversy. When considering the use of such assessment tools, a variety of issues warrant attention (ATSA, 2005; Blasingame, 1998; CSOM, 2000, 2002; Laws, 2003):

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