A Comparison of the Abel Assessment for Sexual Interest and Penile Plethysmography in an Outpatient Sample of Sexual Offenders

The assessment of sexual arousal and sexual interest patterns have become significant elements in the detection and treatment of sexual disorders. This study investigated whether there was a relationship between sexual interest (utilizing viewing time) and sexual arousal (utilizing plethysmography) in a clinical sample of sexual offenders with diagnosed pedophilic interests. Thirty nine participants from an outpatient sexual offender treatment program underwent both penile plethysmography and Abel Assessment for Sexual Interest procedures. Results indicated that both the Abel Assessment for Sexual Interest and the penile plethysmograph were able to identify diagnosed pedophiles to a high degree. Overall, the plethysmograph was able to classify correctly 64 percent of the participants as true positives, while the Abel Assessment for Sexual Interests was able to classify 79 percent of those participating in this study as true positives. The present study goes beyond other analyses to date, however, in providing examination of the conditions in which accuracy in predicting true positives can be significantly enhanced. When a formula is applied to the Abel Assessment graphs to detect for reflexive responders, i.e., those who attempt to employ dissimulation techniques in the Abel assessment protocol, predictive accuracy is affected. The Abel Assessment for Sexual Interest was able to classify correctly almost all of the non‐reflexive responders in the clinical sample, raising the aggregate percentage of 79 percent true positives to 96 percent. Likewise with plethysmography, non‐reflexive responders on the Abel assessment protocol were classified correctly 68 percent of the time, in comparison to 64 percent in the absence of such information. Implications of these findings to psychophysiological assessment of sexual offenders are discussed in context of both viewing time and phallometric approaches. 1 Steven R. Gray, President, Psychological & Consulting Services, Inc. 2 Joseph J. Plaud, Executive Director, Applied Behavioral Consultants, Inc. (www.appliedbehavioralconsultants.com), and Visiting Scholar, Brown University. Correspondence concerning this article should be addressed to either Steven R. Gray, Ed.D., Psychological & Consulting Services, Inc., 1930 S. Alma School Road, Suite C‐201, Mesa, AZ 85210, or to Joseph J. Plaud, Ph.D., BCBA, Research Office, 44 Hickory Lane, Whitinsville, MA 01588‐1356. Electronic mail may be sent via the Internet to [email protected]. Able Assessment vs. Plethysmography GRAY & PLAUD (2005) 2 The assessment of sexual arousal and sexual interest patterns have become significant elements in the detection and treatment of sexual disorders (Abel & Blanchard, 1976; Abel et al., 1998; Alford, Morin, Atkins, & Schoen, 1987; Gaither, Rosenkranz, & Plaud, 1998; Kelly, 1982; Laws & Marshall, 1991; Marshall, 1973, 1979) and sexual dysfunctions (Annon, 1975; LoPiccolo & Stock, 1986; LoPiccolo, Stewart, & Watkins, 1972; Plaud & Holm, 1998). Despite the mixed results of studies investigating the relationship of sexual arousal and sexual interest on human conditioning and sexual offending (OʹDonohue & Plaud, 1994), research has been addressed to understanding the relationship between sexual arousal and classical conditioning (Plaud & Martini, 1996; Rachman, 1966; Rachman & Hodgson, 1968), operant conditioning (Cliffe & Parry, 1980; Kantorowitz, 1978; Rosen, 1973; Rosen, Shapiro, & Schwartz, 1975), and habituation and spontaneous recovery (Koukounas & Over, 1993; Meuwissen & Over, 1990; OʹDonohue & Geer, 1985; OʹDonohue & Plaud, 1991; Plaud, Gaither, Amato‐Henderson, & Devitt, 1997; Smith & Over, 1987) with nondeviant human male samples. In clinical populations, the meta‐analysis of Hanson and Bussiere (1998) clearly implicates the importance of phallometric data because deviant sexual arousal measured through penile plethysmography was the only variable in their analysis with at least a modest (0.32) correlation with sexual recidivism. Abel et al. (1998) describe a non‐phallometric assessment technique based upon viewing time they call the Abel Assessment for Sexual Interest. According to Abel et al. the Abel Assessment for Sexual Interest has the ability to accurately predict sexual interest that is comparable to results typically achieved via plethysmography. They conclude: “In sum, visual reaction time and plethysmography were similar in their ability to predict categorizations” (1998, p. 92). The purpose of this study is to investigate and validate whether there is a relationship between sexual interest (utilizing viewing time) and sexual arousal (utilizing plethysmography) in a clinical sample of sexual offenders. The present investigation will provide for an independent analysis of the Abel Assessment for Sexual Interest and its relationship with plethysmography in the classification of sexual offenders with pedophilic interests. Sexual Arousal and Penile Plethysmography The assessment of male sexual arousal patterns was first investigated by Freund (1963), using a device which recorded changes in penile volume, which was termed phallometry. In this study, Freund was able to classify correctly subjects according to their stated sexual preferences by measuring changes in penile volume in response to stimuli depicting male and female adults and children. In the years that followed researchers developed and tested other types of penile circumference gauges in a general procedure now termed plethysmography (Bancroft, Jones, & Pullan, 1966; Barlow, Becker, Leitenberg, & Agras, 1970; Fisher, Gross, & Zuch, 1965). The circumferential measures such as mercury in rubber or silicone gauges are currently the most commonly used due to practical concerns‐‐they are easier to use and apply and they are more sturdy and reliable than volumetric devices (Howes, 1995). In a review of all of the physiological measures in use at the time (e.g., skin conductance, heart rate, blood pressure, pupillary responses, and temperature), Zuckerman (1971) concluded that penile erection measures were the most sensitive measures of sexual arousal available. Therefore, research conducted over the past forty years has generally supported the conclusion that the plethysmograph is both a reliable and valid means of assessing a maleʹs sexual arousal patterns (Howes, 1995; Maletzky, 1995). Able Assessment vs. Plethysmography GRAY & PLAUD (2005) 3 Sexual Arousal and Sexual Interest Plethysmography measures sexual arousal because the dependent variable is a measure of penile tumescence. Researchers have commonly used the terms sexual interest or sexual preference as substitutes for the term sexual arousal in studies employing plethysmography. For example, Harris and Rice (1996) define plethysmography as a measure of the male erectile response that translates into a scientific measure of men’s sexual preferences. Abel et al. (1998) in a similar fashion define sexual interest as the measure traditionally observed through employing plethysmography. Seto and Lalumiere (2001) specifically use the term sexual interest as the variable being measured in plethysmography, as do Laws et al. (2000). It is clear from even a cursory review of the scientific literature that the terms sexual arousal and sexual interest are being used interchangeably in explaining what plethysmography measures. As a direct physiological measure of penile tumescence, plethysmography can be said to measure sexual arousal, the phallometric definition, or sexual interest, which can also serve a more general term potentially incorporating affective components or cognitive elements into the analysis. If a person is sexually interested in female adults, for example, we may presume a sexual arousal component of that interest amenable to plethysmographic assessment, but we may also be analyzing the cognitive or affective components that participate in the behavior of approaching and engaging female adults in a variety of environmental contexts. Sexual interest may also be measured in ways that go beyond phallometric assessment. For example, direct observation measures of time spent attending to a stimulus, sexual fantasy behavior, self‐report, and other techniques may also address the measurement of sexual interest, as may different physiologically based techniques. One physiology‐based technique advanced as a method to measure sexual interest is viewing time. Long before Freund published his findings using phallometric measures, Rosenzweig (1942) reported a strong relationship between ratings of psychiatric staff members of patients’ interest in sex and the amount of time patients viewed slides depicting sexual versus non‐sexual content. Harris et al. (1996) examined viewing time as an unobtrusive and straightforward measure of sexual interest, and found that viewing time correlated significantly with plethysmography measures. Abel et al. (1998) also reported favorable results utilizing viewing time to distinguish among different categories of pedophilic interest when compared with plethysmography. Abel et al.’s research led to the development of the Abel Assessment for Sexual Interest as a viewing time measure that was investigated in this study of sexual offenders in an outpatient setting. Abel Assessment for Sexual Interest Abel et al. (1990) compared the viewing time of 151 heterosexual and homosexual males viewing 80 slides depicting males and females of various ages. They found that viewing times to slides depicting the patient’s preferred adult gender were significantly greater than viewing times to the non‐preferred gender. Abel et al. (1994) also compared the viewing times of 101 normal, non‐child molesting males with the viewing times of 30 molesters of adolescent boys, 25 molesters of boys under 14 years of age, 57 molesters of adolescent girls and 873 molesters of girls under 14. One hundred sixty slides were presented, half depicting nudes and half depicting non‐nudes in five stimulus categories: adult females, adult males, girls 8‐10 years of age, and boys 8‐10 years of age, plus a neutral category (landscapes). All child molesters had admitted their sexual interest in children. The results showed a high sensitivity and specificity in categorizing those interested in adolescent boys, a moderate sensitivity high specificity for those interested in males under 14; and a high sensitivity for those interested in adolescent girls or girls under 14; but a low specificity for those reporting interest in adolescent girls or girls under 14. Able Assessment vs. Plethysmography GRAY & PLAUD (2005) 4 Abel et al. conclude that the research to date justifies a direct comparison of viewing time with plethysmography as measures of sexual interest (Abel et al., 1998). The present study is a direct investigation of the relationship of viewing time, utilizing the Abel Assessment for Sexual Interest, to plethysmography in an outpatient sample of male sexual offenders.