Section 3: Assessment
2 Hours


Physiological Tools

Aside from sex offenders, it is hard to imagine any populations within the criminal or juvenile justice field for which physiological assessments are commonly used. Broadly speaking, these tools examine the relationship between an individual’s biological and/or physical responses—in other words, physiological responses—and their thoughts, emotions, and behaviors. Because physiological responses can be difficult for people to control, the use of physiological tools with sex offenders is believed to provide more objective assessment data that is not dependent on the individual’s willingness to self–report.

Three physiological instruments are commonly used in the assessment of sex offenders: the penile plethysmograph, viewing time measures such as the Abel Screen, and the polygraph.45 We’ll discuss each of these very briefly.

Use SlideUse Slide #32: Physiological Tools


The penile plethysmograph assesses deviant sexual arousal in a laboratory setting by measuring the extent to which the penis becomes more full and erect when an individual is exposed to various types of visual and/or auditory stimuli—both non–deviant and deviant. Obviously, the greater the erectile response, the greater the degree of arousal that is thought to exist. With adult sex offenders, this approach is perhaps the most objective measure of deviant sexual arousal. And deviant arousal assessed in this fashion is among the strongest predictors of sexual recidivism with adult sex offenders.46

But over the years, despite its empirical support and its popularity with those who evaluate adult sex offenders, experts have raised concerns about the plethysmograph, such as its intrusiveness, the potentially graphic nature of the stimulus materials, the lack of standardized procedures for how it is administered, inconsistencies in the manner by which responses are scored and interpreted, and—believe it or not—the potential ability of some clients to fake or suppress their responses.47 And these same concerns have been raised regarding the use of the penile plethysmograph with juvenile sex offenders.48 Moreover, there has been only a limited amount of research conducted on its reliability and validity with juvenile sex offenders.49

Some of the research on plethysmography with juvenile sex offenders has, in fact, suggested that this approach can be helpful for assessing deviant arousal with some youth.50 On the other hand, there is evidence that the reliability and validity of its use with juveniles may be affected by youth who are younger, and who deny their offenses.51 And inconsistent findings in the research about the relationship between juveniles’ own sexual victimization experiences and their response patterns on the plethysmograph create even more questions about the use of this tool and what the results really mean.52 As a result, experts have suggested that when conducting assessments of juvenile sex offenders, the plethysmograph should be used cautiously and selectively, keeping in mind some very important caveats.53

Use SlideUse Slide #33: Plethysmography Cautions
Use SlideUse Slide #34: Programs Using Plethysmograph with Juveniles

Again, these include the limited research on its use with juvenile sex offenders and the potential for a number of factors, including age and physical maturity, to impact the reliability and validity of the results. In addition, because of the potential for arousal patterns to be unstable during the period of adolescence, evaluators should consider the age and development of the youth before deciding to use the plethysmograph. And of course, there are concerns about requiring a youth to undergo such an intrusive procedure and one that may expose youth to sexually explicit stimuli.

Perhaps not surprisingly, as you can see, in programs across the country that provide services to juvenile sex offenders, the use of the penile plethysmograph is fairly uncommon.54 These current utilization patterns with juveniles are half of what they were nearly ten years ago!55

Viewing Time

In part due to the concerns about the intrusiveness, explicit stimulus materials, and costs associated with the plethysmograph, viewing time instruments such are the Abel Assessment for sexual interest were designed as an alternative method of assessing deviant sexual interests.

A key feature of the viewing time approach involves the presentation of a series of non–sexually explicit slides of a range of individuals, including young male and female children, adolescents, and adults, all of whom are clothed. There are also some slides that use clothed models to depict paraphiliac acts such as voyeurism, exhibitionism, frotteurism, and sadomasochism. The offender being assessed is responsible for advancing the slides, so the amount of time that elapses before the individual moves to the next slide provides the measure of viewing time. Essentially, the idea behind this assessment approach is that the longer an individual views a specific type of stimulus, the more interested he is. Obviously, then, to maintain the reliability and validity of this assessment method, it is important that the person being evaluated does not know that viewing time is being measured.

Because the Abel Screen is a relatively new measure, compared to the penile plethysmograph, there is less research on its reliability and validity—and there are mixed findings.56 A growing body of literature does suggest that this method of assessing sexual interests is promising, primarily when assessing deviant sexual interests involving children.57 Questions about its use with juvenile sex offenders still remain, primarily because of the limited and mixed research findings that have been published thus far.58

Use SlideUse Slide #35: Viewing Time Cautions
Use Slide #36: Programs Using Viewing Time with Juveniles

You’ll recall that a minority of juvenile programs report using the plethysmograph with their youth. Perhaps because viewing time measures such as the Abel Screen appear to be a promising alternative to the plethysmograph for assessing deviant sexual interests, more programs providing services to juvenile male sex offenders across the country are using them59 —yet these utilization trends are still fairly low, suggesting that reasonable caution is being exercised.


Earlier when we discussed some of the differences between psychosexual evaluations and general psychological evaluations, we made reference to the potential use of the polygraph. Using the polygraph to augment a psychosexual evaluation is probably less common than using the plethysmograph or a viewing time measure such as the Abel Screen for a psychosexual evaluation. Instead, it may be more commonly used as a means of indirectly monitoring treatment and supervision compliance or to facilitate a client’s disclosure of sexual history at later points in the system.

However, since we are talking about the use of physiological tools for assessment purposes right now, and as we have already emphasized the importance of considering assessments beyond the more specific, single “point in time” assessments like the psychosexual evaluation or pre–sentence/pre–disposition report, we will cover the polygraph here as well.

Many of you are probably aware of the growing popularity of the polygraph to aid in sex offender management practices. Specifically, as an assessment tool that measures physiological responses believed to be associated with deception, it has become more and more common as a means of facilitating a sexual history and for assessing compliance with treatment and supervision expectations.

Use SlideUse Slide #37: Polygraph Utilization Trends in Community–Based Programs

Indeed, as you can see, the use of the polygraph for these types of assessment purposes with adult sex offenders has more than doubled over the past decade, and there are similar utilization trends for assessing juvenile sex offenders.60

It should be noted, however, that the polygraph remains a controversial area of practice with sex offenders. This is largely because the polygraph is far from infallible—in fact, its results are inadmissible in criminal cases largely because the polygraph has not been sufficiently demonstrated as a reliable and valid tool by the scientific community, as well as concerns about self–incrimination that may arise during the course of an examination.61 Empirical research on the polygraph continues to be limited, particularly in terms of its reliability and validity for sex offender management purposes.62 Despite the lack of empirical support, practitioners who are proponents of its use find the polygraph to be valuable for increasing disclosures among sex offenders—including youthful sex offenders.63

Use SlideUse Slide #38: Polygraph Cautions

So, if the polygraph is used with juvenile sex offenders, consumers should proceed with caution. Indeed, because the reliability and validity of the polygraph with juveniles has yet to be established—and because there is evidence to suggest that the results can be impacted by some important developmental variables, such as age, intellectual functioning, maturity, and emotions—experts suggest that the polygraph should be used very selectively with juvenile sex offenders.64

Suggested Practice Guidelines for Using Physiological Tools with Juvenile Sex Offenders

At this point, it is probably evident that physiological assessment tools are not “magic bullets,” so to speak. Like all other types of assessment instruments, physiological tools have their own advantages and, of course, their limitations.65 And when considering these tools for juvenile sex offenders, some of the limitations may become more pronounced. Again, that is because of the relatively sparse research that has been conducted on the use of physiological instruments with juveniles and because the associated results can be affected by developmental variables.

To minimize the potential for misuse, suggestions and guidelines have been proposed for the use of these tools with sex offenders.66

Use SlideUse Slide #39: Practice Guidelines: Physiological Measures with Youth

Summary and Recommendations from the Psychosexual Evaluation

Now that we have covered many of the key elements that comprise a psychosexual evaluation and that make it stand apart from a general psychological evaluation, let’s briefly discuss how all of the information could be synthesized into a summary and recommendations section of the psychosexual evaluation report.

Use SlideUse Slide #40: Summary and Recommendations: Psychosexual Evaluation

Remember that when offering recommendations there should always be clear supporting data in the body of the evaluation. And any limitations of the assessment tools used to inform professional opinions must be acknowledged.

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