The issue of the reliability of polygraphs has been, and still is widely debated. It is not only of legal interest, but of scientific and social concern as well. The use of polygraph testing has both individual and social consequences and thus holds enough importance in psychology to demand further research and discussion into its validity. The polygraph was first tested by Harvard psychology and law graduate William Marston in the early 1920s. It has been around for nearly 80 years and there are many organisations, websites, books and other media who have something to say about polygraphs.
Various psychologists and academics have carried out studies into the science behind the so-called 'lie-detector' (Ben-Shakhar & Dolev, 1996; Iacono & Lykken, 1997), and it seems that the biggest consumer of polygraphs is the US. Compared to the UK and the rest of Europe, the use of polygraphs in America is immense. It is common practice for government agencies such as the CIA, the National Security Agency and the FBI to use them to screen job applicants. In fact they are accepted there as a way of life. In the UK, their use is much less frequent.
Only the occasional TV show and mainly private investigation companies offer the services of a polygraph for personal research and evidence. Although the polygraph is promoted as being a reliable and useful tool in American public service roles, for every positive group or supporting society of polygraphs there are also a surprising number of anti-polygraph organisations. Some of these have been formed as a result of members of the public being 'stung' by the polygraph: being found guilty when in fact they are completely innocent.
This essay will look at some of the advantages of the polygraph, and will go on to consider exactly how useful it is in contemporary society. It will also discuss the negative impact it has had, in order to ascertain its validity in police investigations today. Our awareness of polygraphs has increased not only due to the high profile cases of people in a position of trust failing the tests, but also because of the appearance of the machine on chat shows, TV crime shows and movies. The portrayal of the polygraph has not always been accurate though.
It has been dubbed a lie-detector by the media when actually it cannot detect lies, only patterns of behaviour which could be triggered by lying. There has also been a lot of controversy surrounding the accuracy of polygraphs in recent years, made worse by the various scandals that have emerged about the US government. There have been several cases where the government has been under pressure to find a suspect guilty and is alleged to have used the polygraph results to make that person's answers 'fit' their requirements, only for them to be found innocent at a later date.
Regardless of why the polygraph is used, the basic concept of how it works remains the same. The polygraph operates by a combination of medical devices measuring changes in our body such as heart rate, blood pressure, respiratory rate and GSR (galvanic skin response), or sweat patterns. Two types of questions are asked by the examiner, control questions such as 'What day is it? ', so that the examiner has an honest answer to compare with, and relevant questions which are about the incident or topic which the examiner is interested in.
It is alleged that when we are telling lies, our body is under abnormal stress and this stress is evident in an increase in sweat, blood pressure or breathing rate. The results of these measurements are recorded on a graph to enable the examiner to see what the person's honest response looks like, in order to compare it with their other responses and thus detect if they are lying. Until now the interest shown in the polygraph in the UK has been minimal. No official organisations have officially recognised its use or purpose.
There are a few companies that offer their services for personal use of a polygraph; however it remains a somewhat mysterious machine that only seems to make an appearance on chat shows. Where criminal investigations are concerned the police have not considered the polygraph as a useful tool as yet, and their application in courts in the UK is currently inadmissible on the grounds that the results of polygraph tests are not accurate enough to prove deception has taken place.
In America only one state, New Mexico, allows for open admissibility of polygraph results, while every other state requires some sort of stipulation to be met prior to admitting polygraph results into record (American Polygraph Association, 2003). Regardless of these rulings, polygraphs are regularly used in many police investigations. In fact it is estimated that more than two-thirds of police departments in America use polygraphs to help solve crimes (Ropeik, 2003). The polygraph tests are also often taken by potential and current employees of the FBI, CIA and National Security agencies.
This has been common practice for many years now, and is so regular that usually nobody objects. In the absence of an alternative, it seems that the FBI believes the tests are the best way of checking a person's honesty, and they will probably continue to be used until another suitable method is realised. Another organisation that believes the polygraph may be better than nothing is the MI5. A senior security source told the press association that MI5 officers were regularly visiting the US to check on the latest lie detector techniques (BBC, 2001).
The detection of traitors selling secrets appears to still be an active issue after the recent scandals of Robert Hanssen and Wen Ho Lee in the US, and so the British security agency seems to be becoming a little concerned about the reliability of their current methods of detecting deception. At a conference entitled the Oversight of Intelligence and Security (2001), the chairman of the Intelligence and Security Committee, Tom King, discussed the importance of the issue of betrayal and said it was actively looking at the possibility of using lie detectors to vet recruits and root out traitors (BBC, 2001).
Another possible use for the polygraph in a criminal setting in the UK is the screening of sex offenders. After a series of successful trials carried out in the North of England in 2002, it was concluded that there may be a place for the polygraph in the monitoring of sex offenders. This was as a result of 3 out of 30 men revealing during the polygraph test that they had unauthorised contact with children whilst on probation.
A UK-based polygraph examiner Bruce Burgess was said to have agreed that the polygraph is as reliable as other methods of catching criminals, and certainly more reliable than handwriting or eye witness. However, as the polygraph is still inadmissible in court, it does not send a positive message out to the public, an opinion shared by Roger Stoodley: a detective who has lead investigations into several child abuse and murder cases. He believes that sex offenders are so deviant that technology cannot keep up with them or effectively monitor them (BBC, 2002).