Lie-Detecting Methods

Lie-Detecting Methods

When it comes to lie detection, the most commonly used method is the polygraph test. What many people do not realize is there are many different lie detection methods, some simple and some complex. The study of lying and lie detection is intricate, and these methods are the products of years of research and studying.

Facial Analysis

Facial analysis is a lie detection method that involves carefully watching and interpreting facial expressions. While people who are lying are usually able to control the majority of their facial expressions, quick, short-duration facial movements can express the underlying emotions a person is attempting to conceal. These are called micro-expressions, and this detection method is about 80% effective. The problem with this detection method is that the analysis and reading process is time-consuming. A lie detection interview must be videotaped, and then an expert has to analyze the liar's face frame by frame. In the future, it may be possible for computers to automatically analyze expressions, which would make facial analysis a powerful detection method for any situation.

Reaction Time

Research has shown that the act of telling a lie takes more effort and mental concentration than telling the truth. This is because when telling a lie, a person has to create the lie and make sure it doesn't contradict anything he has already said. Telling the truth just involves recounting something that has happened. The extra thinking and creating that comes with telling lies takes time, and even a quick-thinking liar might hesitate slightly. Experts who have been trained in picking up on lies might notice discrepancies in reaction time that can be indicators of lying. This method is not applicable in situations when a person has already created and rehearsed the lies she is telling. While marking reaction times can be effective when the subject is taken off-guard, the reaction time method is not as accurate when the subject has had time to prepare.

Statement Content Analysis

This method involves analyzing a written statement for verb tenses, syntax, emphasis and word choices. For example, if a subject uses past tense to describe a missing person, it may be an indication that the subject knows that the missing person is no longer living. When lying, people may gloss over important information and then write extensively about certain details of no significance in an attempt to draw attention away from the lie. The effectiveness and accuracy of this method has not been determined, but police and other investigators sometimes use this method to get leads or eliminate suspects early in a case.

Brain Imaging

MRI, magnetic resonance imaging, is a medical diagnostic tool used to take images of the inside of the body. The world of lie detecting has found another use for MRIs. Investigators can use functional MRIs to track blood flow and use in the brain. When people are lying, they are thinking creatively, and therefore using a different portion of the brain than when telling the truth. Brain imaging shows when certain lobes of the brain, such as those associated with creative thinking, are in use. This activity is an indicator of lying. The research on this method of lie detection has been promising, but investigators do not yet use brain imaging as a method of lie detection.

Thermal Imaging

Thermal imaging uses thermal cameras and detectors to pick up on subtle changes in body temperature. Typically, lying triggers a slight nervous reaction in people, and nervous reactions include a slight increase of body temperature, especially in areas around the eyes. Thermal cameras pick up on even the slightest changes in body temperature and show when someone is lying or having an emotional reaction to a stimulus. This method is fairly effective, but not commonly used because thermal imaging cameras and the other necessary tools are expensive.