Polygraphs elicit more risk-relevant disclosures
New (18 March 2020) research from the University of Kent, commissioned by the National Police Chiefs Council concludes that voluntary and mandatory polygraph testing increases the likelihood that individuals convicted or suspected of committing a sexual offence will reveal risk-relevant information.
Research was carried out by Kent’s Centre of Research and Education in Forensic Psychology (CORE-FP) over a two-year period. Information was provided by police officers, including risk-relevant disclosures made by participants, the seriousness of disclosures, and actions taken in response.
The researchers analysed polygraph tests in nine police areas focusing on three categories of sex offenders:
- Strand 1 (Supervisees): 557 individuals convicted of sexual offending and undergoing police supervision who were randomly assigned to polygraph testing (voluntary or mandatory1 depending on police area) or comparison groups.
- Strand 2 (Suspects): 142 individuals suspected of committing online sexual offences and undergoing police investigation who were assigned to polygraph or comparison groups.
- Strand 3 (Applicants): 104 individuals convicted of sexual offending who applied for removal of notification requirements and were assigned to polygraph or comparison groups.
The research compare groups of individuals who were undergoing polygraph testing with comparison groups of individuals who were not and examined in particular the number of risk-relevant disclosures made by the three groups.
Strand 1: Supervisees
- Voluntary or mandatory polygraphed supervisees were equally likely to make RRDs, but voluntary polygraph tests often failed to go ahead.
- Relative to comparisons, supervisees undergoing polygraph testing (voluntary and mandatory) were nearly 6 times more likely to make at least one RRD.
- Supervisees across all levels of risk were more likely to make a RRD than comparisons.
- During polygraph sessions, polygraphed supervisees made more RRDs in the pre-polygraph interview than they did in the post-polygraph interview. Polygraph test results revealing a significant response (i.e., indicative of an untruthful response) were associated with higher levels of post-polygraph interview RRDs.
- Offender managers in the polygraph group rated the helpfulness of the polygraph as over 5 on a 7-point scale; regardless of whether RRDs had been made. The qualitative statements made by Offender Managers in interviews supported this. However, they were concerned about the voluntary nature of the polygraph resulting in test refusal.
Strand 2: Suspects
- Relative to comparisons, polygraphed suspects were over 7 times more likely to make at least one RRD.
- Investigating officers rated polygraphed and comparison RRDs as equally relevant for investigative purposes.
- Investigating officers rated the helpfulness of the polygraph as over 5 on a 7-point scale. However, their statements during interviews suggested some frustration about being unable to use the polygraph as evidence in investigations.
Strand 3: Applicants
- Not one comparison applicant made an RRD, whilst nearly half of polygraph applicants made at least one RRD.
- Applicants who underwent polygraph testing were 42.5 times more likely to make at least one RRD than were comparison applicants.
- Comparison applicants were nearly 5 times more likely than those polygraphed to be successful in their applications for removal of notification requirements.
- Police officers involved in processing removal applications rated the helpfulness of the polygraph as over 6 on a 7-point scale. The qualitative statements made by Offender Managers in their interviews supported this.
Professor Jane Wood, Chartered Forensic Psychologist and project lead said:
Our findings support the police use of polygraph testing, particularly mandatory polygraph testing, as a supportive tool for managing individuals convicted of sexual offences who live in the community. This is because polygraph testing elicits important new information related to risk that would ordinarily remain unknown.
National Police Chiefs’ Council’s Lead for the Management of Sexual and Violent Offenders, Chief Constable Michelle Skeer, said:
‘This research has found that polygraph testing leads to more disclosures from registered sex offenders and recommends the introduction of mandatory tests for convicted sex offenders as being the most effective method of monitoring them by police. We will give this research careful consideration alongside others in policing and the Home Office as the recommendation would require a change in the law.
Policing in the UK has some of the most advanced and effective tools in the world to manage registered sex offenders and every day officers effectively manage the risk posed to the public by such people. This will always be a complex area of work for police and we continue to look at innovative ways, tools and technologies to keep people safe.’