Lie detectors (also called polygraphs) measure physiological responses to questions like blood pressure, breathing and perspiration. But they can fail because innocent people are often nervous.
Plus, some people have figured out how to beat them. Those include frequent liars like double agents Robert Hanssen and Aldrich Ames. Wired used records and lawsuits to show that not only do polygraph failure rates vary wildly, they also demonstrate racial bias.
The Polygraph
Polygraphs are used by many people to determine whether someone is lying. They work on the premise that liars exhibit increased levels of arousal in response to certain questions, while truth tellers do not.
During a polygraph test, a person’s blood pressure, breathing rate and perspiration are monitored to determine how nervous they are. This is a result of the fight-or-flight system that kicks in when we are afraid or nervous.
While research supports that polygraphs can distinguish a lie from the truth, they are not foolproof. In fact, there are plenty of ways to beat them. Mother Jones reported on a man who made a living by helping liars beat polygraph tests. Similarly, a convicted drug smuggler and child molester were both able to pass their polygraph tests.
Hypnosis
Hypnosis is a trance-like state of relaxation, increased concentration and heightened suggestibility. People who are hypnotized seem to be sleepy and zoned out, but they can still hear and respond to the therapist’s suggestions. Hypnosis has been shown to have medical and therapeutic benefits, including pain relief, and it may help with weight loss, bed-wetting and smoking cessation. It has also been used to ease anxiety before medical procedures, and to reduce hot flashes in menopausal women.For more info I’ll suggest you visit the website UK Polygraph Association.
When someone is hypnotized, different parts of the brain work more independently of each other, and this allows them to be more open to new ideas than they would be in normal consciousness. Researchers have found that hypnosis increases connections between the dorsolateral prefrontal cortex and insula areas of the brain.
Drugs
For most people, being told they have to take a lie detector test is unnerving. Knowing you are being questioned about something that could hurt your future may cause you to feel anxious and nervous, which leads to a rise in heart rate and blood pressure.
These are the typical physiological responses associated with telling a lie, and that’s what the polygraph machine is supposed to pick up on. However, some people are able to control these responses and pass a polygraph test.
The most well known example is Aldrich Ames, who was a mole for the Soviet Union and passed his polygraph tests by simply relaxing. A variety of countermeasures can be employed by those preparing for a polygraph, such as taking sedatives or using antiperspirant to reduce sweating.
Medical Conditions
A lie detector test is a device that monitors several physical indicators like blood pressure, pulse, skin conductivity and respiration during a questioning session. During the testing, an examiner asks a set of questions that are relevant and not irrelevant. The answers to the questions are then compared to see whether you’re lying or not.
Even the most honest people have a hard time telling the truth all the time, especially when they’re dealing with something sensitive or personal. They may even lie about things such as their medical history.
Most private employers are prohibited from requiring job applicants or employees to take a polygraph test. Most states also have laws that prevent the use of lie detector evidence in court. However, despite these limitations, some employers still use them to investigate suspicious activities.
Stress
Many researchers use the term stress to describe a broad range of experiences and situations that have different effects on humans. This reflects the wide scope of activities that fall under the umbrella of stress research, as well as the need for researchers to use consistent language when describing stressor exposures and responses. This is important for building cumulative science and harmonizing around critical theoretical dimensions.
A polygraph tests the involuntary physiological arousal of a subject as they respond to a question or statement. The theory is that people who lie experience a greater arousal, and that this can be measured using a polygraph. However, it is possible to pass a polygraph while lying by increasing your reaction to the control questions or decreasing your response to the test’s relevant questions. Guilty people like Green River Killer Gary Ridgway and Russian mole Aldrich Ames have passed polygraphs while committing crimes.
