About this time last year I sat in a conference room in a hotel in New York surrounded by lawyers, homicide and vice cops, and journalists, while an academic demonstrated the wonders of a new lie detector test he was developing – the use of MRI scans to test a person’s truthfulness.  In essence, he was showing us images of the brain and explaining that when the subjects lied, certain parts of their brain glowed red on the scan and that this could be transferred to the use of MRI scans in the criminal justice system, if a person responded to a question and a certain section of their brian glowed red on the screen then they were lying.

As I looked around the room I was amazed at how easily all these delegates who, by nature of their professions should have been overly inquisitive and skeptical, were lapping up this information.  When I raised my hand and asked if anyone else was feeling as uncomfortable as I with these findings, based on tests with those who were not people under criminal investigation, I was greeted with a looks of distain.  With the exception of a homicide cop, no one else in the room seemed to have a problem with the suggestion that this was the ‘future’ of interviewing defendants.

While I accept that I am not scientifically minded and as such can be skeptical of a lot of scientific findings, my main issues with this new lie detector model were that the testing was done on students, in a controlled environment, who had volunteered to take part in the research, they were all at least college level educated, and had been given a script, and had then been told whether they had to lie or tell the truth from the script.  There had been no testing of defendants of low intelligence, placed in the extremely stressful environment of a police interview room, who were sleep deprived, had recently taken illicit or prescribed drugs.  Neither had there been any testing of defendants who had good reason to lie to protect themselves or others, and who knew that they were in danger of facing a lengthy prison sentence.

Even worse, the fact that all of these people, who should have known better than just to accept findings without questioning them, had collectively accepted the findings, made me realize that a jury would be unlikely to question any of the findings.  If the scan showed a brain glowing red, the subject would have lied, and hence the jury would have no reason not to find them guilty.

And that is the reason that the lie detector must be viewed with skepticism, it is rarely tested in the exact environment. I have spoken to many defendants in the USA who have been the subject of a lie detector, many felt scared of the physical element of the test, having wires attached to a cuff on their arm and chest.  The demeanor of the person carrying out the test has a big impact on many defendants, some felt that they were being encouraged to answer in a certain way by the machine operator.  The format of the questions can have a big impact on the answers given by the defendant.  Finally the analysis requires someone to make an assessment of the findings, I have experience of the same defendant answering the same questions in three different tests and each assessor came up with a different conclusion.

In theory, the tests that have been carried out on sex offenders may have produced some results which can be seen as positive, but can they actually also be  determined as truthful?  And if the lie detector is introduced in this area, how long will it be before it is introduced into the criminal justice system in other areas.    Beware the dazzling effect of the mumbo jumbo…..

Sex offenders to face compulsory lie detector tests