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Lie Detection: A Game of Yes or No

Written by Zoya Khan

The use of the polygraph has done little more than create confusion, ambiguity, and mistakes.—Aldrich Ames

A lie detector is an examination of an oral statement for the purpose of disclosing intentional fraud. Lie Detector can refer to the cognitive process of detecting deception by examining message content and misinformation which can include non-verbal indications. It may also refer to the questioning techniques used and technologies that record body functions to detect truth and falsehood in response.


Lie Detector or polygraph was originally invented in 1921 by John Augustus Larson, a medico at the University of California, Berkeley, and a policeman in the Berkeley Police Department of California. Dr. William Moulton Marston invented an early prototype of the polygraph. He was obsessed with people’s personalities and the secrets that lied within. In 1940, he was hired by Maxwell Charles and him along with his wife created the character ‘Wonder Woman’. The character was based on his wife and his mistress. Wonder Woman was psychologically designed to be the perfect woman with the ability to dominate her opponents with her lasso signifying the truth or by outsmarting them with one punch.


Technology has come a long way since the introduction of polygraph testing in the 20th century. Progress has reshaped the way researchers use tests to detect the perpetrator, and the most recent programs have become digital. Today, lie-detection techniques include AI, machine learning, analytics, and biosensors that don’t even need to touch the topic in question to urge a reading.


Now let us dive into the technology behind Lie Detectors. The sensors can detect changes that occur when a person makes a decision to lie--before the lie is actually articulated. Subjects are given a series of questions that are to be answered truthfully. Thermal imaging uses a heat-sensitive camera to detect increased blood flow around the eyes. According to recent research, when people lie, their eyes give off more heat than when they are telling the truth. Functional Magnetic Resonance Imaging (fMRI) is a technique to measure such brain activity. It is used to detect lying by seeing inside the brain. It tracks blood flow to activated brain areas. The assumption in lie detection is that the brain must exert an additional effort when telling a lie which the regions that do more work get more blood. Such areas light up in scans during the lie studies and hence the lie is detected.


Another approach is known as Brain Fingerprinting in which the subject wears a helmet of electrodes, creating an electroencephalogram (EEG) that records changes in electrical potentials in the brain. The subject is presented with words, phrases, or pictures while the EEG records her brain-wave activity. If the suspect knows the knowledge but lies, a selected brain wave referred to as P300 is elicited. The P300 pattern is activated when the brain recognizes information (or a well-known object) as significant or surprising. The goal is to determine if the subject has the information stored in her brain even though she denies knowing it. These technologies are still under development.


  • The subject may manipulate himself/herself when the questions are asked. For example, Subjects may control their breathing, contraction of sphincter muscles, biting the tongue or inside of the mouth, thinking about horrible things, etc.


  • The validity of a lie detector has long been controversial. The basic problem is theoretical: there is no evidence that any form of immune response is different from deception. An honest person may be nervous when they answer truthfully and an unreliable person may not be worried.


  • A lie detector can sometimes be wrong. Studies conducted on controlled laboratories have found that these tests can usually identify a false positive at a greater rate than chance, but also incorrectly prove that many honest people are lying.



In some countries, polygraphs are used as an interrogation tool with criminal suspects or candidates. Polygraph tests are a kind of a magical instrument that helps detect whether or not a person is lying. It is apparent that the scope of polygraph tests would be quite broad especially in the modern world where people everywhere are subject to different kinds of security threats and terrorist attacks. If the national security departments use polygraph tests, they may be able to identify terrorists who may disguise their identities to deceive government agencies to some extent. Hence, the role of polygraphs tests in maintaining peace, national security, and social stability can be quite denied.

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