Daisy Elvin, Head of Operations and Trauma Informed Lead at TONIC.
Research Spotlight: Polygraph Testing
Research Spotlight: Polygraph Testing
Like several of my amazing colleagues at TONIC, I am extremely passionate about conducting research projects and evaluations that seek to enhance support to victims of crime, as well as increasing rehabilitation opportunities for offenders, to improve outcomes and prevent further victimisation. I thought I would use this Research Spotlight to talk about some research I previously conducted into polygraph testing. This feels particularly relevant in light of the recent Victim and Prisoners Act 2024, Police Crime Sentencing and Courts Act 2022, Counter Terrorism and Sentencing Act 2021, and Domestic Abuse Act 2021 - all of which have broadened the scope of offenders in England and Wales who the Secretary of State can impose mandatory polygraph testing on as part of their licence conditions post-release from prison.
I started working for TONIC in 2018 as an Associate Researcher and Analyst, whilst studying for my Masters Degree in Forensic Psychology at the University of Kent’s Centre of Research and Education in Forensic Psychology (CORE-FP). During my MSc, I was lucky enough to have the opportunity to conduct research for my Thesis that was closely linked to the Evaluation of Polygraph Testing by Police to Manage Individuals Convicted or Suspected of Sexual Offending. For more information, please see: https://www.kent.ac.uk/school-of-psychology/downloads/kent_polygraph_report.pdf
My research was in two parts:
Firstly, I paired up with another student on my course to conduct a laboratory experiment Investigating Predictors of Disclosure Timing during Polygraph Examinations.
Secondly, I undertook an in-depth literature review of Why Polygraph Testing does not Consistently lead to Reduced Recidivism for Individuals Convicted of Sexual Offending.
What is a Polygraph?
A polygraph - often referred to as a lie detector test - essentially involves a device that records physiological changes of the autonomic nervous system, using measures such as blood pressure, pulse, respiration, and skin conductivity while a person is asked and answers a series of questions. The hypothesis underpinning the use of the polygraph is that deceptive answers will produce physiological responses that can be differentiated from those associated with non-deceptive answers.
Polygraph examinations are commonly used in the US and are increasingly being used in the UK to monitor individuals convicted of sexual offending on parole or probation. Past research has demonstrated a ‘truth facilitator’ effect, whereby polygraph examinations elicit greater numbers of risk-relevant disclosures, which can be used to facilitate more effective supervision and treatment provision. However, critics remain sceptical of polygraphs, raising concerns regarding ethics, accuracy, validity, standardisation, counter-measures, false confessions, and diminished therapeutic alliance. Furthermore, little is known about the precise mechanisms underlying the cognitive processes during a polygraph examination, and why polygraphs provoke an increased number of disclosures.
Laboratory Experiment using a Bogus Pipeline
In an attempt to further the understanding, my dissertation study investigated whether the stigma associated with a behaviour, as well as an individual’s confidence in the polygraph’s accuracy, affected disclosure timing. The study used an experimental between-subjects design comprising three phases. During the laboratory session, we explored whether participants would make a disclosure about certain behaviours during a bogus pipeline (fake polygraph) procedure and if so, when. The bogus pipeline in this study comprised a genuine Lafayette LX5000 computerised polygraph system that we had borrowed from a local police station, that was paired with a fake onscreen trace, similar in appearance to a standard polygraph output. Apparatus was attached to participants (see picture on the right) and visibly connected to the computer via activity sensors, reinforcing the illusion that physiological responses were being monitored.
We used independent samples t tests, multiple regression, and post-hoc exploratory analysis to interrogate the data collected. Contrary to the hypotheses, stigma corresponding to the respective behaviours and self-reported confidence in the polygraph’s accuracy did not affect disclosure timing.
Literature Review exploring whether Polygraph Testing influences Reoffending
When polygraphs are used with people convicted of sexual offending, the objective is to elicit risk-relevant disclosures to inform and improve their management, with the ultimate aim of reducing the likelihood of reoffending. By conducting a desk-based academic literature review, we wanted to explore whether there was any evidence to support the notion that using polygraphs to monitor people convicted of sexual offending would reduce their risk of reoffending in the future.
By synthesising and evaluating the existing recidivism literature relating to post-conviction sexual offence-related testing (PCSOT), the literature review demonstrated that actually the use of PCSOT lacks robust empirical support beyond the fact that examinations facilitate increased disclosures and can be used as a surveillance tool. The review proposed mechanisms through which polygraphs would be expected to impact offending behaviour and explored potential explanations for why PCSOT has not been found to reduce recidivism. The research suggests that polygraphs may undermine a trusting relationship and may be over-relied upon as a tool to tackle denial or determine risk categorisation, instead of translating disclosures into individualised management. It is clear from this review that there is an need for more rigorous research to assess the effectiveness of PCSOT in terms of treatment and recidivism outcomes, to inform future policies that facilitate empirically driven clinical practice. This piece of work has been published in the journal of Aggression and Violent Behavior and can be accessed here: https://www.sciencedirect.com/science/article/abs/pii/S1359178921001294 I really enjoyed working on these pieces of research and I am collaborating with my co-authors on a second publication.
Written by Daisy Elvin, Head of Operations and Trauma Informed Lead at TONIC.