Detecting lies and secrets of the guilty

Evidence from lie detector tests is not admissable in British courts. Sheena Hastings meets the two men whose research may change all that.
Dr John Synnott at the University of Huddersfield, who is conducting research into polygraph (lie detector) tests.Dr John Synnott at the University of Huddersfield, who is conducting research into polygraph (lie detector) tests.
Dr John Synnott at the University of Huddersfield, who is conducting research into polygraph (lie detector) tests.

THE “lie-detector” test played a role in two recent high-profile murder cases in the mid-west of the US.

In Otter County, Minnesota, a father and son were charged with killing their 33-year-old relative, reportedly over drug money he owed them, after failing a polygraph test administered by law enforcement officers early in the investigation.

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A polygraph examination was also used on the father of two young children murdered in their home in St Michael, North Dakota. During the test and interview with FBI agents, he confessed to killing the children. However, this time, the suspect later recanted his evidence and another man was eventually convicted of the stabbings.

Together the two cases show the difficulties surrounding the use of polygraphs. Law enforcement organisations in other parts of the US pooh-pooh the test, citing unreliable results in the past and studies that have discredited it.

But it still has many fans and there are polygraph experts worldwide offering testing for commercial use, such as pre-employment screening.

But the jury is still out on how truly efficient a polygraph can be – and even if it is found to give high-percentage positive results in a lab situation, how can the conditions and methods used there be translated to use in the field, where detectives are dealing with suspected criminals and innocent people in high-risk situations and a very different environment?

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Invented 90-odd years ago, the polygraph was a set of wires attached at one end to the subject’s body and at the other to a machine which translated physiological responses (pulse, breathing, sweat on the finger tips) onto paper.

A series of pens linked to the wires would, theoretically, go into “spike” mode when a subject responded to certain questions that might indicate some sort of deception.

Over the decades many in the area of law enforcement have dismissed the polygraph as at best unreliable and at worst utter nonsense. Among criticisms was the accusation that subjects were often responding to the stressful situation they found themselves in and not to the test itself.

Critics have also discredited the way they were set up and the way data was analysed.

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However, technology moves on and the 21st-century polygraph is more sophisticated and sensitive than ever before, and the science of investigative psychology well developed enough to appraise what, if any, might be the true benefits.

Recent additions to the kit include a sensitive electronic pad under the foot rest, which detects twitching of the body during questioning.

Dr John Synnott and Professor David Canter, two academics at the University of Huddersfield, are presiding over the first of a series of studies that they hope will establish the true worth of the polygraph, in police work and beyond.

To use the language of US crime novels, they say the test has in the past had a “bad rap” and it’s time to find a definitive answer to the question of just how useful a polygraph can be – and what are its potential applications beyond police work.

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John Synnott, who’s leading the project, was not short of student volunteers when he set up the new state-of-the-art equipment and oversaw two postgraduate projects which initially tested it. Learning what is the most systematic way of administering the test have taken up the last three months.

The polygraph, where it has been used as an investigative tool by police – for example in Israel – has never been relied on as a sole means of establishing a suspect or witness’s guilt. Polygraph test material is not currently admissible in criminal courts in the UK.

The test may be most useful in indicating innocence beyond the odds offered by chance, says John Synnott.

“Because studies (done previously) that have found low levels of accuracy/high levels of accuracy have not been done properly or researched appropriately due, for example, to issues relating to the ability to ‘beat the test’ – that is, counter measures for instance, just makes a test inconclusive.”

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He says that, just because the National Academy of Science found flaws in previous research, this doesn’t mean that if used properly by trained individuals following the right methods, there can’t be some some value in the test.

“Our research aims to show this one way or the other – but at least we will know in the end if it is worth further exploration or if it is a waste of time... Our early work has shown that further research into the polygraph is certainly warranted.”

Synnott’s project is supervised by Prof Canter, the man who coined the phrase “investigative psychology” 30 years ago, and has blazed a trail ever since in using psychological methodology to further understanding of a range of areas from how crowds behave to the effects of architecture on human behaviour and offender profiling. He calls this “real world psychology”.

“The polygraph test got a bad rap and rightly so, because it was misused and misunderstood. It was a case of throwing the baby out with the bath water, though, because there are situations where we do have a physiological reaction when we are not telling the truth, such as sweat on the palms and increased heart rate.

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“So it’s perfectly feasible to pick that up, or at very least to pick up that people are not showing the response they would if they were lying.”

Current research concentrates on the “Guilty Knowledge Test” – asking a battery of questions which concentrate on establishing whether a suspect knows something that only the perpetrator of the crime and the police could know, for example that a murder was carried out using a certain specific kind of weapon.

Relying on this use of the test would mean police being able to guarantee that crucial knowledge (in this case information on the weapon) was kept strictly under wraps.

Prof Canter says the polygraph can establish probable innocence but determining guilt is more difficult.

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You can, given the right circumstances and methodology, establish evidence of deception but not to the same degree as innocence – which is a very good reason why polygraph evidence is not admissible in a court of law in this country and many others.

But using it simply to rule out those likely to be innocent could potentially save a lot of police time during investigations.

Huddersfield University, which brought in David Canter as a “super prof” a few years ago to develop an international centre for investigative psychology, has put its own money into buying the polygraph equipment.

“We know it can be misused, and its usefulness is quite subtle and complicated – unlike the Hollywood imagery of sticking wires on someone, asking a few questions, then knowing they are lying within moments.

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“We need to explore the conditions in which it gives better or worse results.

“People are looking for a simple, straightforward magic bullet that anyone can use and it will give yes/no answers, but human beings are never that simple.

“Actually, the best measure of whether someone is telling the truth is how sensible, consistent and plausible what they’re 
saying is.

“You listen carefully to what they’re saying and gauge whether it fits with the known facts and what is known to be possible.”

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Dr John Synott would like more adults from different walks of life and of all ages to volunteer to take part in polygraph research. Email him for information at: [email protected]

For information on Huddersfield University’s MSc and PhD programmes in investigative psychology see www.hud.ac.uk/research/researchcentres/ircip/