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History of the Lie Detector Test

Wouldn’t you love it If you could detect the difference between lying and lying? Unfortunately, most traditional methods of detecting lies, such as polygraph machines are no more reliable than chance. While polygraph machines aren’t accurate in determining if a person is lying They can monitor the cardiovascular, respiratory and electrodermal activity with great accuracy!

A Short Overview of Lie Detection Techniques

One of the first methods of lie detection was hypnosis. It has been utilized in official capacity from the 1840s. It was regarded as a form of sleep that is artificially produced experts believed that people in hypnosis were more honest in this naive (and plausible) state. In addition to the questionable ethicality of this procedure it was also not reliable in its results.

In the early 1900s when a doctor administered Scopolamine (or “twilight asleep”) for patients discovered the effect of it on them. It made them disclose confidential details. This led to the development of a field called narcoanalysis, the use of barbiturates, such as sodium pentothal and sodium amytal were administered to those during interrogation to serve to serve as “truth serum”. The theory behind this method was that psychoactives lowered the person’s defenses, which makes people more likely open up. Some types of narcoanalysis used today, however not in all well-established democratic societies.

The History of Lie Detector Test

In 1921 the year 1921, the 1921 California police officer called John A. Larson developed an instrument which could simultaneously track changes in heart rate, blood pressure and respiration. This device was dubbed the polygraph, or more casually called”the lie detector. The mechanism could be traced back to two prior advancements:

The year 1914 was the time that Italian psychotherapist Vittorio Benussi released Die Atmungssymptome der Lüge which was his study of the effects of lying on a person’s breathing function.
It was 1915 when American psychology professor William M. Marston created a continuous systolic blood pressure test to identify deceit

Larson tried his equipment and procedure on actual cases within his own precinct. However, his aide, Leonarde Keeler, refined the test procedures and made the device more portable and also included an element that could measure the galvanic skin reaction of the patient.

The Trial of Lie Detectors

The year 1923 was the first time William M. Marston tried to get the results of the lie detector test accepted as evidence before the court of law. This would later be the case that would become the most famous United States v. Frye. The court ruled against the results of the lie detector which established the Frye test, which could set a standard for admissibility of experts’ evidence on the part of U.S. courts for years to be.

Over 40 decades later in the year 1965 in 1965, the United States Committee on Government Operations conducted the first scientific study of the polygraph device, concluding that it was unreliable in detecting deceit, in a scathing report at the start of this article. However, at this point those who advocated for this test were still going at full speed, unaffected by the committee’s findings.

A different notable change occurred in 1983, when U.S. president Ronald Reagan issued the National Security Decision Directive 84 which allowed federal agencies to utilize polygraphs to conduct their business. In a surprising (and embarrassing) change President Reagan revoked the directive three months later due to an adverse evaluation of the method conducted through Office of Technology Assessment. Office of Technology Assessment.

The Fundamental Science Behind Polygraph Tests

Tests using polygraphs track three physiological reactions that are often linked to deceit:

Cardiovascular activity
Respiratory activity
Electrodermal activity

Cardiovascular Activity

Blood pressure, heart rate and other cardiovascular processes can be affected by the activities that are typically associated with lying, for example, responding to an anticipated or perceived threat (“fight or fight or” reaction) and an increase in mental activity. Polygraphs are used to measure the cardiovascular activity of an arm, wrist or finger cuff fitted with a sphygmomanometer. It is similar to the ones used in medical facilities.

Another method of measuring cardiovascular health is photoelectric plethysmographs. They are attached to the patient’s finger or ear, and transmit infrared radiation through the tissue. Photosensors are then able to measure the light which is reflected, or passes by the body. This is directly linked to the volume of blood it traveled before arriving at the sensor. This permits the physician to monitor changes in blood volume without the necessity of an instrument to measure pressure.

Respiratory Activity

Changes in the respiratory activity of the body could also be a sign of deceit however, since breathing can be controlled through your central nervous system the test is considered to be less reliable.

The respiratory activity is assessed by attaching pneumatic rubber bellows to the abdomen and thorax of the subject. Exhalation and inhalation increase the bellows and cause shifts in the thoracic as well as abdominal circumference. The changes in internal pressure are recorded using the help of a pressure transducer.

Electrodermal Activity

Electrormal activity measurement is believed to be the most reliable and sensitive of the three tests. Why? Skin’s resistance to electrical current as well as conductance are heavily influenced by the glands of the eccirine, that are responsible for producing sweat. They are managed by sympathetic nerve system.

Electrodermal activity is monitored using two electrodes that are attached to the palm or fingers of the subject. A small amount of current is applied to the skin, which determines the conductance of the skin, as well as any changes in addition to its frequency, the intensity of the spontaneous reactions as well as the amplitude of events-related responses and a myriad of other variables.

Deteiving Fraud, Deceiving Results

The polygraph monitors its subjects’ physiological responses in real time using the use of a line graph that contains three values that represent the respiratory, cardiovascular and electrodermal responses. But, how do you know if the results of the physiological tests can be used to answer the psychological issue about whether the person is lying? It is an open question.

One of the biggest difficulties with the accuracy of polygraphs is that the physiological response to the test could vary significantly between people -or even among the same person in different conditions. Furthermore, changes in breathing could affect the rate of their heart and their the galvanic skin reaction. The people who practice breathing and mindfulness techniques may have some control over the physiological reactions (typically to control stress but they could be as deceiving as they can! ).

If polygraph tests are not reliable, what alternatives are more effective in detecting deceit? Criminal justice and law enforcement experts often employ advanced interrogation techniques. In these, the polygraph is employed mostly as a mental aid to the interrogator and not as a real, tried-and-true snare of deceit. Advanced interrogators are even trained in facial microexpressions as well as non-verbal signals. While these methods are difficult to quantify, investigators’ intuitions could be more accurate over “chance”.

Making Better Physiological Testing Devices

Certain blood pressure monitoring instruments aren’t only used to sort of detect if people are lying. Actually, they’re an essential to medical science as blood pressure is generally measured each whenever we go to our doctor’s clinic.

Certain blood pressure measurement devices work using piezoresistive pressure sensors. They are one of the most common MEMS devices that is based on the piezoresistive effect. This is when the resistance to electrical current changes when the application of force to the semiconductor.

When creating the device to monitor blood pressure it is essential that the piezoresistive pressure gauge can accurately measure the blood pressure of the patient and operate within the safest limits that are safe for patients. It is therefore crucial that the designers can describe the workings for these sensors, forecast their behaviour, and evaluate their effectiveness before they’re put on the market.