What is a Lie Detector Test and How Does It Work?

A polygraph, or a lie detector test, is an experiment used to measure physiological responses to questions in an attempt to determine if someone is telling the truth. The process tests changes in the rate of heartbeats, blood pressure, respiration, and skin conductivity, thereby making appropriate judgments about how the body would react when undergoing specific simulations, which, according to many scientists, vary when someone lies.

The lie detector test basically counts on a general assumption: that physiological responses would indicate the emotional response that a person is undergoing. It is believed that when a person lies, his body acts in automatic ways that are different from when he is telling the truth. These ways include small alterations in heart rate, blood pressure, and even skin moisture, with all monitored closely during the test. A lie detector captures these physiological responses to obtain information a skilled examiner will interpret in respect of accuracy.

How Does a Lie Detector Test Work?

A lie detector test is most often administered in a controlled setting whereby a person being tested is wired to the polygraph device. The device comprises several sensors attached to the respondent’s body to capture his or her physical reactions:

1. Heart Rate: A sensor is held around the chest or finger to check the person’s heart rate. An increased heart rate might indicate stress, in which case the person can lie.
2. Blood Pressure: A cuff is held on the upper arm to check for blood pressure. As in the case of the heart rate, increased blood pressure might also indicate anxiety, which is yet another circumstance in which the person might lie.
3. Respiration: A respiration sensor is placed around the abdomen to measure the breathing patterns. He may tend to change his breathing when he is stressed, which is generally felt by most people while lying on a flat surface.
4. Skin Conductivity: Electrodes are attached to the fingers to monitor sweat production. Sweat production is a sign of nervousness or discomfort and may be caused by lying.

The Lie Detector Test Procedure

The pre-test interview will be given to the test subject, and from this he or she will be asked some relatively simple questions to set a baseline for his or her normal physiological responses. This may involve questions such as “What is your name?” or “Where do you live?” et cetera. Such information is to be used by the examiner in comparing his or her responses in the actual test.

In the course of the experiment, the tester will pose a set of questions-questions some of which may be pertinent to the cause for which one is being tested such as “Did you commit the crime?” for example while others may be neutral or else irrelevant to the case. These questions help the tester distinguish between normal physiological responses and those that may indicate stress related to deception.

Interpreting Results

Physiological data that will be attained after the test will be analyzed by the examiner to determine whether there was a significant change upon the person’s response to certain questions. If noticeable changes in physiological responses occur concerning specific questions, it may indicate that the person has been lying or that he was not truthful. However, a lie detector test is not foolproof. Such factors as anxiety, nervousness, or even medical conditions might influence the results of the test and lead to false positives or negatives.

Limitations of a Lie Detector Test

Lie detector tests have always been aptly meant to decode whether an individual is telling the truth or not. However, it never stays to be the truth. It sometimes also depends on the examiner’s expertise, the person’s emotional state at the time of the test, and the nature or kind of question being asked or rather questions asked. Moreover, in majority cases, the results of lie detector tests are not considered valid in court since, in fact, these are not regarded as proof of guilt or innocence.

Conclusion

In a nutshell, a lie detector test is a means of ascertaining the veracity of an individual by recording physiological responses while a person is asked questions. Even though it provides some sort of information regarding the emotional state of the person who is asked the questions, it is, however, far from an exact science. Thus, the findings are supposed to be analyzed diligently and in combination with other forms of evidence before some form of conclusive judgment can be given.