The FBI teaches you lie detection, people reading and intelligence skills

Chapter 25 Lie Detector Baby: Lie Detector (1)
Polygraph technology is a technology developed based on psychological research, and its main method is to use a polygraph to detect people's mental activities.In developed countries such as Europe and the United States, polygraph technology is quite mature, and the use of polygraphs is also quite common.This chapter will show you the principle and application of the polygraph commonly used by the FBI—the polygraph.

§§§ Section [-] Interpretation of lie detector

The modern polygraph is made up of sensor, host computer and microcomputer three parts.The sensor is connected to the body surface of the subject to collect the change information of the subject's physiological parameters; the host is an electronic component that converts the analog signal collected by the sensor into a digital signal after processing; the microcomputer stores and analyzes the input digital signal, To obtain the result of the lie detection.

Take the milky white PG-7 multi-parameter psychological tester on the market as an example. This lie detector is only the size of a 32-carat book and consists of three parts: a sensor, a host computer and a microcomputer.The polygraph sensor has 3 tentacles: the galvanic skin sensor worn on the human finger, which is a stainless steel electrode, is used to measure changes in skin resistance; the pulse and blood pressure sensor is a pressure-sensitive sensor or sphygmomanometer, worn In the human wrist or arm, the changes of the human pulse and blood pressure are measured; the respiratory sensor is a stretch sensor, which is tied to the human chest to measure the changes of the human respiration.The role of the host is to convert the analog signal collected by the sensor into a digital signal after processing, and input it into the computer.Then the microcomputer stores and analyzes the input digital signal, and obtains the result of the lie detection experiment.

Polygraph technology is a kind of psychological testing technology. The so-called psychological testing technology is a process of analyzing the character's psychology by combining bioelectronics and psychology with the help of computer means.According to the theory of psychology, everyone, without exception, will leave an indelible mark on the mind after experiencing a special event.

As time goes on after committing the crime, the perpetrator will repeatedly replay various scenes during the crime in his mind, pondering the traces he may leave, and even cannot restrain the thoughts of repeated pondering.Therefore, whenever someone mentions some details of the crime scene, the imprint of the perpetrator will be exposed through various biological reactions such as breathing, pulse and skin due to shock.After this subtle reaction is recorded by the test instrument, it will be gathered to form a conclusion of either knowing or participating.Because of this, polygraph testing of suspects allows both yes and no answers, as well as silence.According to our understanding, the psychological testing technology of the Testing Center of the Public Security University has gone through more than 1000 actual criminal cases, and the suspect exclusion rate has reached 100%, and the confirmation rate has reached more than 80%.

In fact, the lie detector cannot directly detect people's hearts, but prepares a series of questions in advance according to the content to be investigated, and then asks the tested person one by one, and uses the polygraph to record and analyze the physiological reactions of the tested person. And the conclusions drawn.

There are three main types of questions involved in polygraph detection: neutral questions that have nothing to do with the investigation event, related or theme questions that are related to the investigation event, and criterion or control questions that are not directly related to the investigation event and the person under test will definitely lie.

Polygraph experts generally do not face the person being tested, but focus their energy on the map on the computer monitor, and pay attention to the facial expression of the person being tested from the corner of their eyes.Furthermore, the tone of the polygraph expert does not have any emotion, but a mechanical voice, so that the best test results can be obtained.

Modern science has proved that some physiological changes do occur when people tell a lie, some of which can be observed with the naked eye, such as a series of unnatural human body movements such as scratching their ears and cheeks, shaking their legs and feet.There are also some physiological changes that are not easy to detect, such as: abnormal breathing rate and blood volume, respiratory depression and breath holding; rapid pulse, increased blood pressure, increased blood output and changes in composition, resulting in obvious pale or pale skin on the face and neck. Redness; increased secretion of sweat glands under the skin, resulting in sweating of the skin, sweating first between the eyes or on the upper lip, especially in the fingers and palms; dilated pupils of the eyes; contraction of the stomach, abnormal secretion of digestive juices, resulting in dry mouth, tongue, and lips; muscle Nervous, trembling, leading to stuttering.Because these physiological parameters are dominated by the autonomic nervous system, they are generally not controlled by human consciousness, but autonomous movements. A series of conditioned reflexes will appear under external stimuli.None of this can escape the "eyes" of the lie detector.

Modern lie detector is also called "multifunctional physiological scanning recorder", which generally measures four aspects of human physiological changes, namely blood pressure, heart rate, respiration and skin resistance (caused by the secretion of sweat on the skin surface).The physiological changes in these four aspects are controlled by the autonomic nervous system and are not easily affected by human consciousness, so they can better reflect the emotional state of people.During the lie detection process, the four sensors are connected to the corresponding parts of the subject's body, and then a series of questions are asked to him.The physiological changes of the autonomic nervous system caused by emotional changes in the process of answering the interrogation will be carefully recorded by the polygraph.

Based on the recorded results, the lie detector can analyze the emotional state and changes of the subjects when answering the corresponding questions (especially key questions), and infer whether they are telling a lie or the truth.

§§§ Section [-] Use of polygraph
Polygraph technology is a technology developed based on psychological research, and its main method is to use a polygraph to detect the psychological activities of the person being tested.In developed countries such as Europe and the United States, polygraph technology is quite mature, and the use of polygraphs is also quite common.

It was the famous Italian jurist Lumber Rosso in the 19th century who was the first to apply the theories of neurophysiology and experimental psychology to the field of lie detection with the help of physiological and psychological instruments.At that time, the polygraph instruments used by Lumber Rosso were called blood vessel plethysmography and water column pulse recorder.

In 1902, Long Bo Rosso personally conducted a polygraph test on a murder suspect. This test is considered to be the first time in history that an instrument was used to detect polygraphs in criminal cases.Following Lumber Rosso, those who have made great contributions to the development of polygraph technology are Stick, Flegus, Marston, Benassi, Larsen, Kira, Luria, etc.Among the greatest contributions were Larsen and his student Kira, the inventors and earliest users of the multispectral physiological recorder, and they were also authorities in the field of lie detection in the 20s.Larsen and Kira's "multispectral physiological recorder" is very close in principle to modern polygraphs.Since then, after decades of hard work by scientists, the polygraph instrument has developed from a single-channel test to a multi-channel psychological test, and the accuracy and operation level of the polygraph instrument have been perfected day by day.

Although polygraph detection can help and solve various problems, since polygraph detection involves human rights issues, and the polygraph detection of criminal suspects is more related to the objective and fair issues of conviction, sentencing and law enforcement, the accuracy of polygraph detection has changed. It is very important.When the scientific polygraph technology first appeared, due to the single method, insufficient precision of the instrument, and the poor operation skills of the staff, the accuracy of the polygraph was not high, and the interpretation of the polygraph results was inconsistent, which led to suspicion in the legal profession. Reliability of polygraph technology.To this end, the U.S. Congress banned the use of polygraph results as evidence in court in 1923.

With the development and improvement of polygraph technology, the utilization rate of polygraph in the United States is increasing year by year.In the United States, which attaches great importance to "human rights", it is conceivable that it will inevitably lead to some protests. For example, in the early 20s, according to an order of the Reagan administration, the US federal government wanted to widely use polygraphs to carry out tests related to the protection of national security. investigation.But if so, about 80 employees of the Ministry of Defense will be tested by this instrument.As a result, the order caused an uproar, and even then-Secretary of State Schultz strongly opposed it.Alan Dershowitz, a professor at Harvard Law School, criticized this, saying that in a country that claims to be a democracy, millions of people are forced to be tied up in front of the machine. Anyway, this is a ridiculous thing.As a result, under strong pressure from Congress, the Reagan administration's order was postponed indefinitely.

At present, 30 states in the United States allow polygraph results to be used as evidence in court.According to statistics from the American Polygraph Association, in the 3030 cases concerned, the accuracy rate of polygraph detection was 98%.Today, polygraphs are widely used in the United States, playing an important role in the headaches of terrorism and the removal of moles.

In 1987, the United States established the Polygraph Research Institute affiliated to the Department of Defense. Its main function is to train the US Army, Navy, Air Force, and anti-drug and anti-smuggling personnel to provide the accuracy of polygraph detection for the entire United States.The latest CPS computer tester developed in the United States can analyze physiological changes and report the probability of honesty or falsehood of the subject under trial, making the lie detector develop from an instrument that simply records the trajectory of mental activities to a collection of records, analysis, An intelligent instrument that integrates judgment into a veritable "polygraph".

Polygraph technology and the application of polygraphs started relatively late in my country, and it was not until 1989 that the uI type psychological tester was developed. In the early 20s, the Ministry of Public Security and Beijing Normal University jointly developed the improved IZ-II psychological tester of the uI type. In 90, the Ministry of Public Security officially approved the project. With the assistance of the Science and Technology Information Institute of the Ministry of Public Security, it was developed by the Institute of Automation of the Chinese Academy of Sciences and supervised by the Ministry of Public Security. In May of that year, a model of the PG-I psychological testing system was developed. With the assistance of teachers and students, an in-depth simulation experiment was carried out, and in June 1991, it passed the examination and approval hosted by the Science and Technology Intelligence Bureau of the Ministry of Public Security. The PG-I psychological test system has been used in many major criminal cases across the country and has achieved good results.Engineer Zhang Zufeng, a polygraph expert at the Chinese Academy of Sciences, said his test was 5% accurate.At present, in our country, polygraph detection can only be carried out with the consent of the person being tested, and the test results can only be attached to the investigation file. Polygraph detection cannot replace investigation and interrogation, but can only be used as an auxiliary method.

At present, polygraphs have been used in Beijing, Shandong, Liaoning, Shanghai, Zhejiang and other places in my country, and are gradually being valued by decision makers in public security departments and judicial departments because of their unique effectiveness in criminal investigation and pre-trial work, and they are playing an increasingly important role. more important role.According to incomplete statistics, in the past 10 years, public security departments in various parts of my country have cracked many difficult criminal cases by using polygraph technology.

§§§ Section [-] Aspects of the Lie Detector Test
According to the FBI, the actual polygraph process is very complicated. A polygraph test for investigating crimes may take 3 to 4 hours, of which only about 15 minutes are used for physiological measurements, and most of the rest of the time is spent on reviewing questions, Interrogation before the test, explaining the procedure and judging, discussing the measurement results, etc.

Generally speaking, before the formal measurement, the polygraph examiner will have a long conversation with the person being tested.This conversation has two purposes: one is to understand the personality and honesty of the person being tested through conversation and interrogation, so as to finally determine the interrogation questions and interrogation methods during the formal measurement; the other is to introduce the polygraph to the person being tested The "consistent correctness" of the test makes it convinced that the polygraph has a reliable function of accurately distinguishing truth from lies, thereby deterring it and eliminating the fluke mentality of the tested person.At the same time, in order to convince the person being tested that the polygraph is undeceivable, the polygraph tester also asks the person being tested to participate in a demonstration verification.For example, let the person to be tested randomly select one card from a deck and mix it with other cards.When the tester holds these cards and asks the person under test "Is this one?", the person under test will always answer "no", but the lie detector can always correctly point out which card the person under test draws. One, and tell the subject that this is based on the measurement of physiological changes when the polygraph responds to it (in fact, these cards are usually marked in advance).

In the process of implementing a formal measurement, the way of asking or interrogating a polygrapher has an important impact on the results of the polygraph, so the questioning skills play a very important role.The most commonly used questioning technique when investigating crimes is frame-of-reference questioning, which involves asking not only the "key" questions about the crime itself (such as "did you steal that 5000 yuan?" or "did you steal that 19 yuan?" ever take something that doesn't belong to you"), and ask "irrelevant" questions that serve as a frame of reference (such as "Is it Friday today" or "Did you graduate from X x school in [-]X X"), So that the polygrapher can compare the chart recorded by the polygraph to find out whether the response of the autonomic nervous system is consistent when the tested person answers the "key" question and the "irrelevant" question.

(End of this chapter)