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A substantial number of studies exploring the PCSOT rely on comparison between what is known about an offender prior,

and subsequent to, polygraph testing. In many cases, there are no contemporaneous control or comparison group in which participants did not undergo polygraph testing. This design inherently weakens any conclusions drawn from such studies, as it prevents efforts to quantify the influence of extraneous and secondary variables. For example, without an appropriately matched control group, it is difficult conclude with confidence whether individuals would have made such disclosures even in the absence of the PCSOT for example because of changes in supervision or treatment impact (Hindman & Peters, 2001). Similarly, without a comparison or control group, conclusions regarding rates of recidivism must also be interpreted with caution, as offences and breaches may occur without detection. Furthermore, the probability of a serious sexual offender being reconvicted for a sexual or violent crime is relatively low (Grubin, 1998). In some studies, recidivism was limited to a short time period e.g. 5 years (McGrath et al., 2007), which may not cover a sufficient time period to monitor reconvictions (Mann et al., 2010).

In some studies, polygraphed offenders were concurrently receiving treatment for their sexual offending (e.g. Wilcox et al., 2005). In such cases, it is difficult to ascertain whether a

decrease in reoffending/ risk engagement or disclosure is due to the positive impact of therapeutic engagement, or to the polygraph examination, especially given that research indicates that successful engagement in sexual offender treatment alone reduces recidivism and disclosure (Hanson et al., 2002). An integral part of a number of sexual offender treatments involves encouraging attendees to speak openly and honestly about their offences and eradicate the influence of cognitive distortions, such as denial and minimisation (Perkins, 2014). Such therapeutic aims are likely to encourage disclosure.

Another limitation of PCSOT research is that sample sizes are often relatively small (e.g. Wilcox et al., 2005) and rely on voluntary participation (Rosky, 2012). Research in the area is therefore inevitably underpowered. Moreover, for this reason, group differences may be strongly affected by the presence of outliers (Gannon et al., 2008). Studies are also characterised by substantial drop out rates (e.g. Grubin et al., 2004), which further limit the generalisability of the findings. For example, it is possible that voluntary participants who see a study through to completion represent a more compliant subgroup of offenders, who are more likely to disclose information. Such

respondents may be more suggestible to experimenter influences, or demonstrate a desire to please their treatment supervisor and polygraph examiner, or generally include less serious offenders. For example, Gudjonsson and Sigurdsson (2000) found offenders who molested children demonstrated higher levels of social desirability. With regards to the ‘Big Five’ personality traits, Egan et al. (2005) found sexual offenders against children scored higher on measures of Agreeableness and Conscientiousness compared to generic mentally disordered offenders or control groups. Some studies have also shown evidence of selection bias; for example, a study in support of the PCSOT (Kokish et al., 2005) eliminated from the sample any offender who had an outcome of ‘deception indicated’ on a prior polygraph test.

A further research limitation is the use of self-report to measure the accuracy and utility of the PCSOT (e.g. Grubin & Madsen, 2006; Kokish et al., 2005;). Self-report data are characterised by a number of weaknesses including social desirability, self-serving biases, and barriers to recall (Maxfield & Babbie, 2014). These biases may be particularly strong for sexual offenders who have a significant vested interest in presenting themselves favourably (Huizinga & Elliot, 1986).

Relying on self-report fails to acknowledge the absence of an incentive for an offender to admit dishonesty.

In an attempt to encourage disclosure, polygraphed offenders can be granted immunity for their self-reported offences (e.g. Hindman & Peters, 2001). This immunity alone may account for the increase in risk-related disclosures, both because they are protected from consequential punishment and the fact that this provides more freedom to tell the interviewer what they think they want to hear (Gannon et al., 2008). Unfortunately, no previous PCSOT study has included a condition to control for the effects of immunity.

3.8. Conclusion

The PCSOT has demonstrated its usefulness in encouraging disclosures amongst sexual offenders under investigation or in the community. Such disclosure provides fuller histories of deviant sexual behaviour, admissions of previously unknown offences and victims, and increased disclosure of other high- risk behaviours (Madsen et al., 2004). This can assist professionals in gaining a more accurate understanding of the offender, and the risk they pose to others. It appears that a range of emotional and cognitive processes interact to produce

changes in arousal recorded by the polygraph, including autobiographical memory, differential salience (altering threat responses depending on the extent of the perceived threat), attentional processing, and the cognitive effort associated with lying (Grubin, 2016) However, there are a number of concerns with the PCSOT which warrant further attention including its poor theoretical basis, and vulnerability to false-positive and false-negative errors. In addition, as is noted in the earlier systematic review (Chapter 2), a substantial number of studies researching this tool are of poor methodological quality. This suggests that in its current state, the PCSOT should be used as an information facilitator as opposed to a source of hard evidence for influencing sentencing decisions.

Rationale for Chapter 4

Chapter 3 highlighted the benefits and challenges associated with using the polygraph in clinical practice and legal proceedings. Chapter 4 goes beyond this descriptive piece to investigate a paradigm known in social psychology as ‘the bogus pipeline.’ The study explores the bogus pipeline effect experimentally, assessing the rates of disclosure of socially undesirable behaviour amongst individuals attached to a deception indicator machine. Chapter 3 discusses a number of limitations of the polygraph, and the bogus pipeline effect has been cited as one of these, as critics state that the machine’s ability to achieve the truth is grounded in subjects’ believability of its infallibility. Chapter 4 goes on to explore the veracity of the bogus pipeline effect in polygraphy, and under which (if any) circumstances it operates.

Chapter Four

The Bogus Pipeline Effect on the Disclosure of Cheating Behaviour

4.1. Introduction

The polygraph (also referred to as a lie detector or deception indicator test) has become a popular cultural icon in modern society, frequently gaining coverage in the media and providing a topic of debate both amongst a range of professionals and members of the general public. The debate around this topic and the validity of the paradigm can be considerable (Iacono, 2008).

Polygraph examinations utilise devices, which record autonomic arousal, which is believed to indicate deceptive behaviour. Over time the machine has evolved from an analogue to a more efficient digital instrument (Kanable, 2010). A typical polygraph examination will include a pre-test phase during which the polygraph procedure is explained to the examinee, and each question collaboratively reviewed. The pre-test interview ensures that examinees have a sound understanding of the upcoming questions, and the negative implications of acting deceptively. A practice test is sometimes utilised in order to increase a participant’s familiarity with the procedure, and demonstrate its accuracy (Raskin & Honts, 2002).

The American Polygraph Association (APA) claims that the polygraph tests performed by their members are accurate more than 90 percent of the time (American Polygraph Association, 2011). However, there are inconsistencies in the literature regarding such figures. Unfortunately, a substantial number of existing studies exploring the measure’s accuracy have been criticised for their methodological flaws (Cross & Saxe, 2001).