Can a Lie Detector Test Nail a Cheating Partner?

Deception is one of the foremost causes why couples breakup. Lies, whether driven by infidelity, financial irresponsibility or addictions can tear apart even the most compatible of couples. In keeping with recent advances in technology, there has been a trend of using lie detector tests to find out if a partner is cheating. But then how effective is this and should something like this figure at all in a relationship?

What is a lie detector test?

Lie detection is the practice of determining whether someone is lying and tests which are designed for this purpose are known as lie detector tests.

The most common type of Lie detector test is the polygraph that monitors a person's physiological reactions. This works on the premise that certain functions of the body like heart beat, blood pressure, respiration rate and pupil dilation are not easily controlled by the conscious mind and hence these can give away when a person is under stress such as when he/she is lying.

TIP: Read the guide to prevent a break up or get back with your ex.

How does it work?

A polygraph instrument is basically a combination of medical devices that are used to monitor changes occurring in the body. As a person is questioned about a certain event or incident, the examiner measures changes in the person's heart rate, blood pressure, respiratory rate and electro-dermal activity as in sweatiness of the fingers, in comparison to normal levels. Polygraph tests have been designed to look for significant involuntary responses going on in a person's body when that person is subjected to stress, such as the kind of stress that is associated with deception.

Critics of such lie detector tests point out that these machines cannot specifically detect if a person is lying. This is because the lie detector does not measure truth-telling; instead it only measures changes in blood pressure, breath rate and perspiration rate - physiological changes that can be triggered by a wide range of emotions which may have nothing to do with the subject lying to the questions asked.

However  lie-detector tests continue to be used in a number of areas, underscored by the scientific fact there are certain physiological responses that most people undergo when dealing with a stress situation such as attempting to lie. By asking questions about a particular issue under investigation and examining a subject's physiological reactions to those questions, a polygraph examiner can determine if deceptive behavior is being demonstrated.  thus Fluctuations in physiological response may indicate that person is being deceptive, but in the end, exam results are open to interpretation by the examiner.

Lie detector test in relationships

Till now lie detector tests were used mostly in areas of law enforcement and hiring of professionals. However the popularity of reality TV shows has brought such tests into the living room of viewers, if not right into their bedrooms. In UK, one such show is Jerry Springer TV lie detector show Nothing But The Truth on Sky One in which two couples volunteer to take the test in a bid to win a grand prize of 50,000 sterling pounds. The whole session, including pre and post-test questioning, takes around three hours and polygraphists are trained to look for visual and verbal clues. Only three specific questions can be asked and the test is performed at least three times to gather a correct answer. However an important part of it all is the pre-test interview in which questions are explained in full as well as the implication of certain terms like sexual contact clearly explained. If the subject is found to be lying, there is a post-test interview, where the examiner’s skills of persuading a subject to confess are used.

Another such TV show based on use of lie detector test is “The Moment of Truth,” hosted by Mark Walberg and telecast in USA. This show uses a lie-detector test to determine whether or not contestants are willing to tell the truth for a chance to win half a million dollars. Contestants can walk away with less money at six different levels in the game. Prior to filming, contestants are hooked up to a polygraph machine and asked 50 to 75 personal questions, such as “Have you ever made a sexy video and uploaded to the Internet?” And “Do you think you’ll still be married to your husband five years from now?” Players are asked 21 of those questions during filming. Questions deemed sexually explicit — by Federal Communications Commission standards, anyway — or anything that could harm a minor are supposed to be off-limits1.

However despite the widespread use of lie detection tests in other fields and the claim of TV shows to follow a “scientific” format, the question remains whether at all a lie detector test can nail a cheating partner. Some would say they do, like the Nothing but the Truth Show. One of the episodes2 featured a couple living in Stanmore, North London - customer service adviser Francesca Scott-Downie, 20 and boyfriend Jason Bovell, 32, a decorator. The two had been together for two years; each suspected the other of infidelity and lied in the tests. The polygraph not only showed that they had lied but the truth came out in the post-test confessions where they both admitted they had cheated in the relationship.

However detractors of lie-detection tests claim that such polygraph tests can only measure physiological responses of the subject to a stressful situation – it cannot differentiate by itself between a truth and a lie.

Ultimately though the issue at hand is not so much whether a lie detector test can nail a cheating partner but whether a relationship should be allowed to deteriorate to such an extent that a lie detector tests seems the only option of getting at the truth. When a couple starts considering polygraph test for your relationship, then by definition, either one or both have lost the basic level of trust that is the foundation stone in any relationship. The only way to prevent this from happening is to take an honest look at the issues troubling the relationship and if need be seek the help of a counselor or therapist to put things back on track.


  1. - Contestants face lie detector test on new show
  2. The Sun - Would your love fail lie test?