Penile Plethysmography Assessments

Penile Plethysmography for the Treatment and Assessment of Sex Offenders

Sex offenders who deny any involvement in deviant sexual behaviour or minimises the degree of his or her deviance are unlikely to respond to treatment efforts and will often re-offend. One of the most effective methods of challenging this denial behaviour is by psychophysiological assessment of sexual arousal patterns. Once confronted with the results of their physiological arousal to inappropriate images, the vast majority of offenders will admit to having such preferences.

The Penile Plethysmograph measures subtle changes in blood flow to the penis in response to visual or audio stimuli. The Centre for Forensic Neuroscience uses both audio material and NRP (Not Real People) visual stimuli sets, based upon the Dost Criteria and meeting the Tanner Criteria (all five stages of represented in both genders) supplied by the Pacific Psychological Assessment Corporation.

This technology can supplement the available evidence when compiling a risk assessment for sexual violence which avoids the reliance upon self-reporting by the offender, and thus can be used for criminal and prison law matters.

Guidelines for the Use of Penile Plethysmography

CFN strictly complies with the British Psychological Society's established guidelines which were published in September 1994:

These brief guidelines are intended to inform good practice in the penile plethysmography assessment, while allowing for the exercise of professional judgement in particular situations. They should be read in conjunction with existing guidelines on professional conduct published by the Society and articles on penile plethysmography assessment in the scientific and professional literature. Responsibility for the supervision of thepenile plethysmography assessment should rest with a psychologist who is eligible to be registered as a Chartered Psychologist. The psychologist should have up-to-date knowledge of relevant practice, legal issues and literature. Staff participating in this work at any level should be adequately briefed and have the option not to be involved should they find the procedure or material distressing.

The penile plethysmography test should be carried out only in the context of an appropriate range of other assessment and treatment procedures or in the course of research that has been professionally and ethically approved by the relevant body. Selection of the stimuli should take into account ethical consideration of how the material was produced or obtained, e.g. if it was under abusive circumstances. Selection of penile plethysmography stimuli (content and mode of presentation) should take into account an appropriate balance between obtaining the best possible assessment and risk of exposing the subject to material which may be therapeutically counter-productive if it is outside their own suspected or known experience. The psychologist should brief the subject on the purpose and procedures involved in penile plethysmography assessment including possible results and their interpretation. He/she should explain limits of confidentiality and likely consequences of participation, non-participation and withdrawal and check that the subject has understood.

Debriefing should be carried out at the end of each assessment.This should include consideration of the impact of the assessment on the client and the need for support and advice. A record that the subject has been properly briefed/debriefed should be kept where appropriate. Stimuli material for penile plethysmography assessment should be kept secure and access limited to those using it for professional purposes. Assessment should only be carried out in appropriate physical conditions with due regard to the standards of safety, privacy, comfort and current hygiene recommendations.