Lie-detection tools measure the body's involuntary reactions as a person answers questions. Since these reactions must be translated, the information gathered is subjective. Polygraphs--machines used for measuring bodily responses--do not announce whether someone is lying or telling the truth. The results are open to human interpretation, rendering them ineffective in court cases. New tools in lie-detection technology have been developed as of December 2010 and others are in progress.
Polygraph machines work through three different methods. First, a blood pressure cuff is wrapped around the arm of the person being tested. This measures changes in pulse rate and blood pressure during questioning. Next, metal plates are attached to two of the subject's fingers. These will measure reactions through the skin, such as perspiration. Finally, two tubes made of convoluted rubber are wrapped around the subject's chest and stomach. Convoluted rubber is flexible and will stretch around the body of any subject. It also conducts electricity well. These tubes will monitor respiratory patterns during questioning. All nervous system reactions are sent to a computer and saved.
Voice Stress Analysis
Another tool used in lie detection is a Voice Stress Analysis (VSA) machine. This machine came into use in the 1970s. According to the Polygraph Secrets website, enough police departments have purchased these devices to make them the second most used lie detection tools, behind polygraphs. The appeal of the VSA is it lacks components that attach to the subject and works with live speech or on a voice recording. The voice sample is played on a computer, where certain software is used to detect the body's vocal changes under stress.
Analysis of a subject's facial expressions and reactions during questioning is a form of lie detection that has been researched for years. Researchers believe facial reactions called micro-expressions occur and these reactions convey the true emotional response the subject is trying to hide. These micro-expression often occur within a split second, as a flash of surprise or fear in the eyes or an unintentional tightening of the lips or mouth. Facial and body language experts analyze video of the subject frame by frame. According to the Polygraph Secrets site researchers are working to automate this analysis, which would greatly speed up the process.
Brain Imaging is a lie detection tool that measures the amount of blood sent to different areas of the brain during questioning. The process is called Functional Magnetic Resonance Imaging (FMRI). The device uses a magnet that works with software to track these patterns of blood usage in the brain. The theory behind this process is that more blood appears in a specific area of the brain when that area is in use and that different areas are used when someone lies than when they tell the truth. Practical uses of FMRI, however, have yet to be demonstrated.
- American Polygraph Association: Frequently Asked Questions/What Is a Polygraph
- Polygraph Secrets: Voice Stress Analysis
- Polygraph Secrets: Facial Analysis
- Polygraph Secrets: Brain Imaging
- New Age Industries: Convoluted PTFE Tubing
- Science Daily: Lying Is Exposed By Micro-Expressions We Can't Control
Facial analysis is a lie detection method that involves carefully watching and interpreting facial expressions. While people who are lying are usually...
Information on Lie Detection
Police and security agencies commonly use several lie detection methods to determine if a person is a criminal or to help in...
How to Detect Micro Expressions
Do you ever wonder what someone is really feeling or thinking when they tell you one thing? Do you sometimes wonder if...
About Forensic Technology
The field of forensic technology continues to grow significantly due to advances in the science and technical fields and increasing emphasis on...
Lie Detection Law
Lie detectors purport to ascertain whether a person lies by gauging how their body reacts to a question. However, lie detectors are...
How to Pass a Polygraph - 10 Tips
The police have asked you to take a polygraph test. What should you do and how can you pass a lie detector?
Skill Assessment Tools
A person's skills and interests are oftentimes developed through education in the classroom, work history, special training, hobbies and in everyday living....
Advantages of a Brain MRI
Everyday, brain MRI's are performed on millions of people in the United States to detect medical problems, such as bleeding in the...
How to Build a Lie Detector
Are you curious to see if your loved one is lying to you? Are you trying to make a cool gadget for...
Careers in Lie Detection
Careers in Lie Detection. Companies ranging from those in the retail industry to the federal government utilize lie detection services. Lie detection...