The use of polygraphs in society became quickly popular by the 1960s, with just under 20,000 examinations in the US government (Grubin, 2005). Bull (2004) defined the polygraph as a machine that measures a range of physiological changes that occur in response to a set of unstandardized questions, including, heart and respiration rates, blood pressure, and galvanic response. It is these physiological changes that are believed to be associated with lying (Bull, 2004).
In a legal context, the polygraph can theoretically be used to determine the potential innocence or guilt of an individual. What defines someone as innocent or guilty is the evidence, or lack thereof, collected during an investigation and, of course, the questioning or police interviews of the suspect. Polygraphs can be used within an investigation to establish whether someone is telling the truth or lying in response to a question, as described above. The use of the polygraph in this setting brings about issues regarding its validity and accuracy, especially surrounding potential convictions, being debated throughout the US (Saxe, 1985).
Since its invention in 1921 by John A. Larson (Synnott, 2015), the polygraph has served to have many uses throughout different settings from employment to the media. Use in TV shows such as The Jeremy Kyle Show and the Maury Show have allowed alternative methods of the polygraph to be exposed to the general public. This type of entertainment has managed to reduce the polygraph as simply a method of determining if an individual is lying or telling the truth. This raises the problem surrounding whether a machine that is used for entertainment purposes be used in questions of legality in serious, potentially life-altering situations.
Advantages
Perhaps a main advantage of the polygraph is its ability to reveal the truth of a statement, and potentially aid with the realisation that a suspect may be, in fact, telling the truth.
While not being fully relied upon as evidence, polygraphs can also serve to act as the justification/ validation for decisions made. S
Alongside the rise in popularity of the polygraph came debate about their accuracy (Saxe, 1985).
Indeed, Grubin (2005) quotes an NAS review, suggesting the polygraph has an accuracy of 80% to 90%. The findings of Nelson (2015) have also supported this review
Nelson (2015) has also supported this view, reporting results of
… While these levels of accuracy are still high, they still indicate room for potential error which could impact both guilty and innocent suspect. Despite being able to determine the truth at levels above probability, they are still by no means perfect (NRC, 2003). As the legal standard to convict an individual is that of ‘beyond reasonable doubt’, the current accuracy rating of the polygraph raises questions as to whether this technique can be relied upon to potentially convict an innocent person.
Disadvantages
A main aspect of reliability as a concern of the polygraph is that of false positives, in other words, finding an innocent person guilty. Many studies have researched and demonstrated the accuracy and validity of the machines, with Saxe (1985) reporting a range of 0% to 75% for false positives. A review published by the Bull (2004) found similar results, with between 11% and 47% incorrect classifications for innocent suspects. However, an issue concerning these studies of the polygraph, especially in regard to field studies, stems from the fact that they are not generalisable (Saxe, 1985). In fact, the National Research Council (2003), also reported that the quality of empirical studies was lacking.
Another pressing issue of the polygraph is demonstrated in a suspect’s ability to ‘fool’ the test through the use of countermeasures. Gudjonsson (1983, 1988, as cited in Bull 2004) defined countermeasures as deliberate attempts some guilty suspects use to appear innocent. He identified the ability to suppress or augment the physiological changes and to reduce anxiety as countermeasures some use. Although, as stated by Clifton (1991, as cited in Bull 2004), the use of countermeasures has also been seen in innocent suspects
. Talk about why innocent people use countermeasures
Nelson (2015) stated that the chance of being found deceptive increased when innocent suspects used countermeasures.
Studies into the polygraph test have revealed that these physiological responses associated with lying could also be witnessed when an innocent suspect is anxious of being perceived as lying (National Research Council, 2003). Guilty people worried about detection, innocent worried about..
The mere fact of being hooked up to a polygraph machine and questioned is enough to cause emotional arousal, allowing even an innocent person to appear guilty.
These types of false positives when it comes to the polygraph has also been factored in to studies of reliability.
Alongside[LW2] the possibility of ‘beating’the polygraph comes the subject of inconclusive results. This could potentially stem from the bad techniques used by polygraph analysts and the lack of reliability of the machines themselves. Saxe (1985) reported on this issue, finding a 0% to 25% occurrence of inconclusive results after polygraph testing.
Another topic of debate surrounding polygraphs is whether the evidence from them is enough to be admissible in court, and even for a potential conviction. The Frye Standard (United States v. Frye, 1923) came to be a test in the US to determine if the scientific evidence presented would be admissible in court (Grubin, 2005). This was, however, superseded by the Daubert Standard, once again stating regulations of evidence admissibility (Grubin, 2005). Daniels (2002, as cited in Grubin 2005) found that the use of polygraph evidence had been determined as admissible in 19 US states. Despite this, the polygraph has yet to become a standard part of the interrogation procedure.
Ethical issues are such important factors within psychological investigations. Whether simple physiological responses should be used as grounds for a confession raises many issues with ethics and morality.
((Case study))
The case of Gary Gauger is a prime example of how a polygraph test can fail an innocent. Despite inconclusive results and a forced confession, Gauger faced spending almost three years in prison, nine months of which were spent on death row. S
Despite the harsh realities of a wrongful conviction, this case and others like it can serve as precedent in future proceedings, highlighting the potentialimplications of undergoing a polygraph test. It is also due to cases like this that the need of an improvement in technique for future use.
Conclusion
The future of the polygraph is not clear, despite being around for almost 100 years, it is yet to become a proven technique in detecting deception. In contrast, the first use of DNA in court to aid a conviction (Calandro, 2005) occurred only 33 years after it was first discovered in 1953 by Watson and Crick (Gross, 2014) showing that despite being a fairly new technique, it still showed enough validity to be used in court. Therefore, this raises questions regarding if the polygraph will ever pass the Frye Standard and become admissible in court.
With the advancements in technology of the 21stcentury, it is no surprise that there are potential alternatives in detecting deception. A study by Kozel, Padgett, and George (2004) illustrated certain areas of the brain that showed activity when lying using a MRI scanner. While another study found that use of a fMRI scanner was inconclusive 20% of the time, they also found that combining the certain polygraph parameters and the fMRI results provided a more accurate determination of deception (Gordon et al. 2018). This demonstrates that while polygraphs should not be used as a standalone in detecting deception, it shows the potential for their use in combination with alternatives.
While the possibility of a suspect being able to prove their innocence through a polygraph test might be tempting, the risk of generating afalse positive result is still high. From cases such as that of case study, the consequences of wrongful convictions are shown.
The discussion of whether the polygraph should be used as a common feature during interrogations is one that has yet to come to a conclusion. With a plethora of research both supporting and contradicting the machine, it is no wonder that polygraphs and their use in the conviction of suspects is still a focus of debate within the psychological community.