Lie Detection Analysis
Lie detection analysis is also referred to as polygraph testing. The evaluation is usually conducted to ascertain if a person is telling the truth or lying about their knowledge, or direct involvement, in a specific event. Typically, the event is a crime that has been committed. A polygraph machine is attached to the person's body. The apparatus has the capability of measuring certain physiological features of the subject and records the data.
Other People Are Reading
-
Function
-
The process of lie detection analysis involves using a combination of medical devices to monitor and record physiological differences in the body. Usually, sensors may be attached to the suspect's body, which may include the chest, abdomen, arms and legs. The individual is then ask a series of questions associated with the crime and unrelated materials that the examiner has knowledge of.
When an answer is given, the machine records the pulse rate, blood pressure, rhythm of breathing and level of perspiration. The information is then transferred to graph paper. The readings that are recorded on the questions related to the investigation and to other materials are compared. Any deviations in the response may be indicative of deception.
-
History
-
The first modern machine, which measured multiple physiological factors, was invented by a medical student at the University of California. John Larson's invention analyzed a person's blood pressure, respiration and the passage of electricity through the skin. In 1924, law enforcement authorities began using lie detection analysis in its interrogation and investigation of suspects in criminal cases. In 1926, Leonarde Keller introduced a more sophisticated machine that incorporated the features of Larson's device as well as versions by other inventors.
Theories
-
The basic theory behind lie detection analysis is that when an individual is not telling the truth, the deception engenders a particular level of stress and anxiety. This condition causes multiple, involuntary, physiological reactions as the person becomes increasingly nervous about the lying. The physiological change that occurs includes items, such as sweating, accelerated heartbeat and variations in the rhythm of breathing.
Currently, researchers are working on a form of lie detection analysis that uses an electronic tablet to measure features of a person's handwriting to determine if they are lying. It evaluates factors, such as the length of time the writing instrument is on the tablet compared to in the air; the width and length of the strokes and the pressure exerted on the tablet. The claim is that the elements of a person's handwriting, who is being deliberately deceptive, changes when compare to honest responses.
Types
-
Lie detection analysis consists of three basic approaches: Control Question Test (CQT), Directed Lie Test (DLT) and Guilty Knowledge Test (GKT). A CQT evaluates the person's physiological feedback to questions pertaining to the actual crime to the answer given to question regarding any previous wrongdoings. The result of this evaluation can lead to either prosecution for a crime or exoneration.
A DLT attempts to reveal deception by assessing physical changes in the body when an individual is instructed to intentionally tell a lie when responding to questions. The GKT method makes comparisons to responses to multiple-choice questions related to the crime. Hidden within the choices are facts about the case known only to law enforcement investigators.
Misconceptions
-
A lie detector analysis is not used to "detect lies." The device is used to determine if a person is being deceptive. Also, from a legal standpoint, law detection analysis has little legal standing. Typically, the results of polygraph testing are not admissible in judicial proceedings. In the majority of states, the results of a lie detection analysis cannot be admitted into the court records without a prior condition being met. In addition, the prosecution and defense must agree to allow admission of the results before the start of the trial. Currently, the State of New Mexico is the only jurisdiction that allows polygraph tests to be admitted into the court records without these requirements.
-
References
- Photo Credit "New York's First Lady" is Copyrighted by Flickr user: hmerinomx (Henry Merino) under the Creative Commons Attribution license.
