The polygraph (also known as a ‘lie detector’) is a tool used to measure blood flow and heart rate changes to determine if someone is dishonest. It does not recognize lies but instead records when people become physiologically aroused due to changes in the autonomic nervous system.
The polygraph is used as both an investigative tool and a lie-detection device. The polygrapher usually works like a trained psychologist or psychiatrist who has experience with Pensée Mode protocols (a special typeface used in evaluating honesty).
The examiner attempts to establish a psychological set in the examinee and observe any kind of arousal to a particular question being asked. It could be a result of fear of being caught in a lie, enhanced cognitive processing, or a matter of emotional salience.
Polygraph Examination; The Fundamentals:
Polygraph examinations usually take place in two stages. In the first stage, the examiner asks a few questions that limit the answer to only yes and no while the candidate is attached to the machine.
There is a small post-test interview in the second stage, and it is usually held when the charts have been evaluated. The whole process approximately takes two to three hours. Finally, a polygraph examination is a well-established procedure for assessing truthfulness.
Polygraph testing has been found to be an effective way of increasing reliability when interviewing sex offenders. When they are asked about relevant information, nearly 40% will show high-severity behavior and 14 times more likely than expected.
Moreover, a polygraph examination is often an important part of law enforcement’s investigation into crimes. The device is also used to monitor the activities and compliance levels of sex offenders on probation.
What does the Polygraph Examinations Really Measure?
The polygraph examination aims to trigger and measure only one thing: anxiety.
A psychologist at Brandeis University, Leonard Saxe, states, ‘All these physiological measures are simply associated with fear and anxiety, and people are anxious sometimes when they are telling the truth, and they can be not anxious sometimes when they are lying. So the more practiced you are at lying, the less anxiety is associated with it’.
To sum up his saying, we can conclude that sometimes the examination can be correct and sometimes also be wrong. Moreover, some more studies have suggested that they might naturally feel anxiety when someone is accused of a crime.
The tests that determine if someone’s telling the truth cannot always work because many factors are involved in determining this type of thing, including their emotional responses during mock trials.
Polygraph tests have been found to be an ineffective way of measuring whether or not someone has committed a crime or not. The American Psychological Association and National Research Council both recommend against using polygraphs in investigations because there is not enough evidence showing their effective working.
The Procedure of the Polygraph Examinations:
The polygraph machine was first developed in America in the early 20th century as a way to detect the blood pressure of the examinee, but it soon evolved into an all-encompassing device that monitored not just one’s physical state but also emotional reactions.
The different versions of this invention exist because researchers were trying out various features. The latest machine is equipped to even detect sweat rates, breathing rates, and pulse beats per minute (PPM).
Polygraph examination relies on these three kinds of physiological responses. But the author of ‘The Truth Machine: A Social History of the Lie Detector, Geoffrey Bunn, states, ‘There was never any complete theory of the ‘physiology of the lie,’ and the three measures — blood pressure, respiration, and sweating — are all different physiological systems.”
Nonetheless, the Control Question Technique was developed in the 1950s and ’60s to help investigators catch criminals. The technique uses vague threats like, “Have you ever stolen from a friend?” plus specific questions related directly to determine whether or not one committed the crime.
The examinees will also be reminded that the machine is able to extract the truth from the lie, and they will be threatened to answer truthfully. The idea behind this is that because these questions are vague and hard to answer entirely truthfully, they will arouse some baseline anxiety in response.
If the person did not commit the crime, then his/her levels of stress would actually go down when answering these control questions. But if he/she did commit one, then it will trigger an even greater level of anxiety, and it will be clearly reflected through physiological responses.
So, to finally figure out if the person in question is telling a lie or truth is simply by comparing the individual’s responses on control questions and the relevant ones.
If the anxiety level is higher on the control question, then he/she is innocent, and if the physiological response on the relevant question is higher, then he/she is guilty.
Why are the Polygraph Examinations Still in Practice?
Polygraph tests are still used to some extent in the U.S., despite the 1988 legal ban and 1998
court ruling that the polygraph examination’s results are inadmissible in federal courts. But there is a loophole in that.
This ban is manipulated by federal employers, law enforcement agencies and others. But the question prevails: if this kind of examination is not effective, why is it still being used?
One reason could be that the examinees are tricked into believing that their lies can be detected by the machine and examiner who does the trick well enough, sometimes leading them to confess. Leonard Saxe calls this process a ‘theater of interrogation.’
The polygraph has been used for both deterrence and detection of sex offenders. If a person believes that they will be subject to accurate lie tests, then committing crimes suddenly looks like going back to prison, surely, is not it?
It does not matter whether the test actually works; what matters is how perceived effectiveness can lead them to think twice about committing a crime while on release from imprisonment.
Saxe also says, ‘People want to believe in a just world. And in a just world, people
cannot get away with lying. My impression from speaking with some polygraphers is that they believe what they are doing is accurate. Some even say things like, God gave us this tool to make a better world’.
So, it can be concluded that along with science, there are also factors involved like religion and mythical behind using this examination.
The Bottom Line:
Polygraph examinations have been a popular tool in the United States and other countries for quite some time now. Polygraphers find them to be reliable when conducting a trial on examinees. The use of polygraph testing in criminal justice is becoming more and more prevalent, especially with sex offenders.
It has been proven to provide effective results, so there is no reason not to use this tool when dealing with forensic and legal cases.