International Overview of Phallometric Testing for Sexual Offending Behaviour and Sexual Risk
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SPECIAL International overview of phallometric PAPER testing for sexual offending behaviour and sexual risk Andrew Bickle,1 Colin Cameron,2 Tariq Hassan,3 Hira Safdar4 and Najat Khalifa5 1Assistant Professor in Forensic with 87 publications in the 1990s, 86 in the Psychiatry, Department of Phallometry is an objective method of 2000s and 88 in the 2010s. Psychiatry, Queen’s University, assessing male sexual arousal. The main Kingston, Canada, Email: [email protected] applications in forensic psychiatry concern the 2National Senior Psychiatrist, evaluation of men charged with or convicted Phallometry and assessment of PCSOs Correctional Service Canada/ of sexual offences, the evaluation of those When employed in clinical forensic psychiatry, Government of Canada 3 with suspected paraphilias not subject to the phallometry should form part of a much broader Associate Professor in Forensic Psychiatry, Department of criminal justice system, risk assessment and sexology assessment. Phallometry response pro- Psychiatry, Queen’s University, measurement of response to sex offender files should only be interpreted by experts (often Kingston, Canada treatment. In some jurisdictions, phallometry forensic psychiatrists and psychologists with spe- 4Assistant Professor, Schulich School of Medicine and Dentistry, is incorporated into legal decisions about cific training), and the results should be used Western University, London, release from custody or discharge from secure only as a supplementary resource to guide clinical Canada hospitals. This paper provides a brief overview impressions.3 Ethically, investigation should focus 5Associate Professor in Forensic Psychiatry, Queen’s University, of the international development of upon PSIs relevant to the presenting issue. Department of Psychiatry, phallometry, considers challenges to its Established sexual behaviour clinics, such as Kingston, Canada broader adoption and discusses future those in Canada and the USA, incorporate phallo- Keywords. Phallometry; penile directions for research and clinical practice. metry into comprehensive clinical evaluations plethysmography; sex offenders; alongside review of objective information, such paedophilia; forensic. as criminal records.4 Thornton et al5 recently First received 12 May 2020 compared phallometry for the assessment of sex- Final revision 28 Dec 2020 Phallometry (also known as penile plethysmogra- ual deviance with structured rating scales, indirect Accepted 12 Apr 2021 phy or penile tumescence testing) is an objective assessment with cognitive tasks and neuroima- doi:10.1192/bji.2021.17 method of assessing male sexual arousal. In foren- ging, concluding that only phallometry and scales sic psychiatry it is primarily deployed in the man- have sufficient evidence base for their clinical use. © The Author(s), 2021. Published by Cambridge University Press on agement of people who have committed sexual Phallometry may be important to the manage- behalf of the Royal College of offences (PCSOs), especially those who have ment of PCSOs because specific sexual response Psychiatrists. This is an Open offended against children. Some clinics utilise profiles predict recidivism3 and phallometric tests Access article, distributed under the terms of the Creative phallometric testing in the management of men are valid indicators of paedophilic interests, both Commons Attribution licence with suspected paraphilias not known to have for PCSOs against children and controls.6 Thus, (http://creativecommons.org/ licenses/by/4.0/), which permits acted upon their problematic sexual interests it is incorporated into the evaluation of PSIs, unrestricted re-use, distribution, (PSIs) to commit offences. Occasionally, phallo- into risk assessment and into measuring response and reproduction in any medium, provided the original work is metry has been used in other settings, such family to sex offender treatment. It is mostly used to properly cited. court proceedings and occupational health. evaluate paedophilia (persistent sexual interest The penile plethysmograph was developed in in prepubescent children) and to a lesser extent Czechoslovakia in the 1950s by the psychiatrist hebephilia (persistent sexual interest in pubescent Kurt Freund. At this time, when homosexuality children), although the latter has been criticised was still illegal in many jurisdictions and regarded as a pathological construct lacking validity.7 Not as a mental disorder, the technology was first all PCSOs against children have these PSIs. directed to identifying homosexual or ‘androphi- There may be other determinants of offending, lic’ desire.1 Although early applications included such as easy availability of victims. Offenders with- aversion therapy to ‘cure’ homosexuality, phallo- out ‘paedohebephilia’ are less likely to recidivate metric evidence of the immutability of sexual for sexual offences against children and may orientation supported the biological basis of have different criminogenic needs. Conversely, homosexuality, and Freund came to lobby suc- many people with paedohebephilic sexual inter- cessfully for decriminalisation in Czechoslovakia.2 ests will not act on them and commit offences. From the mid-1960s, phallometry was used to Some non-offenders will nevertheless meet a assess paedophilia and other PSIs. Freund emi- diagnosis of ‘pedophilic disorder’ within the grated to Canada in 1969 and to date phallometry DSM-58 owing to the marked distress or interper- has received most academic attention in that sonal difficulty it causes them. Phallometry may country, followed by the USA and then other be useful in the assessment and management of countries as set out in Fig. 1. Academic interest this population, so it is paramount that positive in phallometry and offending has remained findings are not equated with criminality. Other remarkably consistent over the past 30 years, non-offender subjects may have paedohebephilic BJPSYCH INTERNATIONAL page 1 of 4 2021 1 Downloaded from https://www.cambridge.org/core. 30 Sep 2021 at 22:59:41, subject to the Cambridge Core terms of use. Other* phallometry, VPP measures changes in blood flow France 4% to the genitals. It utilises a photoelectric transducer UK 2% 2% within a probe akin to a menstrual tampon that is Germany 3% inserted into the vagina. However, the utility of VPP in identifying deviant sexual preferences in clinical forensic practice is limited by relative lack of concordance between genital and subjective sex- ual responses in females.13 USA 22% Procedure Phallometry is conducted in specialist labora- tories. There are two principal technologies: Canada volumetric assessment and circumferential assess- 67% ment. Volumetric assessment entails fitting a sealed tube device over the penis so that changes in length and diameter are detected as air is dis- placed from the tube. This technique is more sen- Fig. 1 sitive to changes in tumescence but has several International academic interest in phallometry for offending behaviour, as measured by disadvantages, including the requirement for affiliation of first and last authors, based on a review of 291 articles identified in PubMed, PsycInfo and Embase using the terms ‘Phallometry’ OR ‘Penile Plethysmography’ OR greater technician training and for the device to ‘Phallometric’. *Australia 0.8%, Czech Republic/Czechoslovakia 0.8%, Netherlands 0.4%, be technician-fitted. In circumferential assess- Republic of Ireland 0.4%, Switzerland 0.4%, Belgium 0.2%, Denmark 0.2%, Portugal 0.2%, ments, a circular gauge of flexible metal or rub- Russia, 0.2%, Singapore 0.2%, unknown 0.2%. ber, which can be fitted over the shaft by the examinee, measures change in penile girth. These are much more commonly utilised than arousal without additional features warranting a volumetric assessments.14 diagnosis of a paraphilic disorder. The examinee’s attention is directed to stimuli In addition, phallometry is sometimes used to that typically include non-sexual stimuli, sexual assess for sexual sadism (persistent and intense sex- scenarios depicting consenting adults and sexual ual arousal from causing or fantasising about the scenarios depicting the PSI under consideration. physical or mental suffering of another person, Some facilities augment their protocols with with or without their consent). However, its clinical ratings by examinees of their level of sexual arousal utility in this area of practice is controversial for two to each scenario. This helps to determine the reli- reasons. First, although the key features of sexual ability of subjective reporting of sexual arousal/ sadism are included in the current editions of the attraction. Stimulus sets commonly include slides, DSM8 and the ICD,9 some commentators regard videos, auditory commentaries or a combination sexual sadism as ‘an elusive concept to define and of these. Allowing for detumescence between stim- measure’.10 Second, the evidence base concerning uli, testing can take several hours to complete.4 the utility of phallometry for the identification of Results from circumferential assessment are sexual sadism is limited, especially when consid- measured in millimetres of change. A minimum ered next to the evidence concerning the identifica- significant change is applied, and scores are tion of paedophilia. It might be surmised that the transformed into either percentage of full erec- minority of violent sexual offenders who have sex- tion or standardised changes in circumference ual sadism are at somewhat at higher risk for recid- using z-scores. This reduces