The utility of polygraph with mentally disordered sex offenders

Collins, Nikki (2019). The utility of polygraph with mentally disordered sex offenders. University of Birmingham. Foren.Psy.D.

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Abstract

The use of post-conviction polygraph testing with sex offenders is used worldwide. However, to date there is no known study that has examined the utility of polygraph with mentally disordered sex offenders, which is the focus of this current thesis.
An introduction to polygraph outlines how the tool works, the three test types and the suggested psychological theories, that attempt to explain the psychophysiological responses observed in polygraphy.
Chapter 2 is a systematic literature review of the utility of polygraph post-conviction sex offender tests (PCSOT) with sex offenders in general, focussing on the areas of assessment, treatment and management. The review highlights key findings relating to recidivism, risk, disclosures, polygraph outcome and perceptions of the polygraph. Further to this, the review suggests that polygraph enhances the assessment of sexual offenders by leading to increased disclosures (victims, offences and sexual risk behaviours).
Additionally, this thesis introduces the Violence Risk Scale, Sex Offender version (VRS-SO) as a sexual risk assessment tool. A critique of this assessment considers the reliability and validity of the tool. The VRS-SO is used in the empirical study of this thesis, which investigates the use of polygraph with mentally disordered sex offenders in a high secure forensic setting. The key significant findings are that using polygraph with mentally disordered sex offenders was effective in eliciting more information about behaviours associated with risk. Specifically, eliciting an increase in the number of high risk behaviours; a broader range of paraphilic behaviours; the number of victims; the number of inappropriate sexual fantasies; the reported level of masturbation to inappropriate sexual fantasies and the use of pornography. Offenders were also asked about their experience of polygraph. Thematic analysis of their responses suggested four main themes of risk, truthfulness, impact and knowledge. Finally, implications of this thesis are considered in addition to future research into the utility of polygraph.

Type of Work:

Thesis (Doctorates > Foren.Psy.D.)

Award Type:

Doctorates > Foren.Psy.D.

Supervisor(s):