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

Chapter 9 Your emotional cognition will betray you (1)
Polygraph detection is the activity of identifying lies. After a lot of practical experience, the FBI has concluded that when a person lies, his various physiological indicators (such as pulse, blood pressure, respiration, skin resistance, etc.) will change, and this change can be detected by sensitive instruments.Polygraph technology is to use an effective instrument to stimulate the subject in a controlled manner by asking questions to stimulate the subject's physiological response, and then analyze and compare the physiological indicators collected by the instrument to determine whether the subject is lying. technology.

The basic process of polygraph detection is to use verbal stimulation to trigger physiological responses, determine whether the suspect is lying or not according to the physiological responses detected by the instrument, and then judge the relationship between the suspect and the incident.

§§§Section [-] Emotional Response and Lie Detector

The multi-channel psychological and physiological testers (lie detectors) that are generally used at present mainly collect changes in physiological parameters such as pulse, blood pressure, respiration, and skin resistance.A large number of studies have shown that changes in these physiological parameters are caused by the arousal of the sympathetic nervous system in the autonomic nervous system.

The autonomic nervous system regulates the visceral and vascular systems, including the two main parts of the sympathetic nervous system and the parasympathetic nervous system. Its main physiological function is to regulate the activities of cardiac muscle, smooth muscle and glands.The autonomic nervous system is highly automatic, usually at the level of subconscious regulation.When the sympathetic nervous system is excited, it will affect the neurons of many organs, causing general nervous excitement and wide-ranging effects, such as pupil dilation, increased heart rate, increased blood pressure, respiratory ratio imbalance, sweating of the skin, thirst, etc. These reactions Prepare for an emergency called organism.The role of the parasympathetic nervous system lies in the preservation of energy, manifested as miosis, heart rate reduction, vasodilation, gastrointestinal peristalsis, secretion of insulin to lower blood sugar, and restore organ balance. It usually dominates.When external stimuli threaten the organism, the sympathetic nervous system is automatically awakened.Threatening the parasympathetic nerves to regain dominance in the past, restore the internal balance of the body.The functions of the sympathetic nervous system and the parasympathetic nervous system complement each other and unite opposites to ensure the balance of the internal and external environment of the body.

The sympathetic nervous system, on the other hand, is strongly influenced by emotional states and is the emergency system that responds to threats.Experiments have shown that emotions such as excitement, anger, surprise, fear, and tension can awaken the sympathetic nervous system, causing abnormal responses to physiological indicators such as blood pressure, heart rate, respiration, and skin resistance.These physiological responses can be instrumented to determine the level of emotional response. In 1895, Lumber Rosso of Italy was the first to identify lies by measuring pulse and blood pressure changes; in 1914, Benussi used a breath recorder to measure the breathing rate of criminals; Marston used a sphygmomanometer to measure the deception. Landis and Hunter used a skin resistance tester to record the number of ohms reflected by the skin resistance when the subject’s emotions changed, and later developed an electroencephalograph, which recorded the potential difference of different parts when emotions occurred. Variety.Applying the above various instruments to comprehensively measure the change of the suspect's mood has just had the invention of the lie detector. In 1921, Larsen developed a lie detector with three parameters of blood pressure, pulse, and respiration; in 1931, Keeler added skin resistance to the Larsen instrument, and invented the Larsen-Keeler lie detector.This instrument is called a Polygraph, that is, a multi-graph or multi-electric graph recorder.

So why does telling a lie arouse the sympathetic nervous system and cause abnormal physiological responses?Chapter 18 "Symptoms of Deception" in the book "Criminal Interrogation" in the United States wrote: "Interrogation will cause anxiety, nervous tension, increased mental burden, and even mental breakdown to the interrogated. If the interrogated wants to escape guilt, he will have to Don't lie to the sky, try to deceive or try to deceive the interrogators. These attempts to deceive are always accompanied by various symptoms or phenomena of guilt in the mind of the interrogated. Such spiritual symptoms or phenomena generally have one or more physiological and emotional symptoms. , or mental and psychological symptoms and signs, or a mixture of all these phenomena." American scholar Davis further proposed the hypothesis of "fear of consequences" for the principle of lie detection.He believes that when a subject's lies are exposed, facing imprisonment, or property loss, because of fear of such things happening, his emotions will activate the sympathetic nervous system and change the records on the psychological tester.That is to say, worry, fear, and nervousness about being detected by the lie are the root causes of the physiological response.This hypothesis has always been the dominant theory in the field of panic measurement.

A technique commonly used in the United States called CQT (abbreviation of English Control Question Technique, translated as Control Question Test Method or Principle Question Test Method) test method is based on the "fear of consequences" hypothesis of American scholar Davis.Invented by Reed in Chicago, USA in 1947.In the question model of CQT, there are mainly three types: related questions or subject questions, criterion questions, irrelevant questions or neutral questions.Relevant questions clearly relate to the facts of the case, and are the core and key questions in the test; standard questions refer to those questions that are generally illegal or in violation of moral standards, and the subjects know that the answer is a lie or may be a lie; neutral questions are non-irritating question.Related questions and criterion questions are some stimulating questions, and these questions can arouse strong emotional responses of the subjects, including fear, tension, worry, contradiction, anxiety, etc.The difference was that the guilty evoked a stronger emotional response to the subject matter, while the innocent evoked a greater response to the yardstick matter.The polygraph tester judges whether the subject is lying by comparing the subject's emotional response level to the subject question and the criterion question.

It can be seen that the basis of CQT technology is mainly emotional response.The key to the implementation of CQT technology is how the polygrapher can effectively stimulate the emotional responses of the subjects and clearly separate the level of emotional antipathy between the subject question and the criterion question.

§§§Second Section Cognitive Response and Lie Detector

Human emotion is an attitude and experience towards things.It develops in the cognition process of feeling, perception, memory, thinking, etc., and is caused by the stimuli in the surrounding environment having certain meanings to people.Therefore, lie detection is not only related to emotions, but also closely related to people's cognitive and psychological processes.The high accuracy of a large number of laboratory simulated crime tests and digital and playing card tests makes it difficult to explain the "fear emotion" theory.With the invention and widespread use of another test technology called GKT, people began to understand the psychological basis of lie detection from the perspective of cognitive psychology.

GKT is the abbreviation of Guilty Knowledge Technique in English, translated as crime scenario test method, which was proposed by Laiken, a professor of Minnesota Medical College in the United States in 1958.The test pattern [-] of this test technique consists of multiple sets of questions, each with a target question and four or five foil questions.The target question is a certain detail in the case under investigation, and the foil question is similar to the target question but its content has nothing to do with the case.

GKT technology is mainly to test whether there are memory traces of criminal behavior that criminal suspects should leave in their brains.In the GKT topic, no matter what kind of question is, it will form a stimulus for the subject and arouse a certain response.But for the guilty subjects, the responses elicited by the target question and the foil question stimulus were different.The information of the target question is the imprint left in the brain of the criminal during the criminal activities, which has special significance for the criminal suspect. When the polygraph tester stimulates the subject to ask questions, it will cause him to be interested in what he saw, when he committed the crime. Mental activities such as the memory of what you hear, do, and feel, and cognition (recognition).This kind of mental activity causes the resurrection of old stimulation traces, makes the nerve cells in the corresponding area of ​​the brain in an excited state, and becomes the dominant excitation center of the brain's nerve center, which in turn causes certain physiological changes.The information that sets off the problem is left in daily life, and it has no special significance to the criminal suspect, so it is in the position of the non-dominant excitation center in the cerebral cortex.This makes the two types of questions elicit different intensities of psychological responses to the stimuli of the guilty subjects.The difference in the intensity of this psychological reaction is the external manifestation of the difference between criminal psychological traces and general psychological traces.For the innocent subjects, there are only general information left in their daily life in their brains, but no memory traces of criminal plots.Therefore, there is no special difference in the response to the stimulus of the target question and the foil question, and the size of the response is random.In this way, the GKT problem can distinguish the guilty suspect from the innocent suspect. GKT technology believes that the important psychological difference between criminals and innocents lies in their different "cognition" of "crime scenarios", but not in whether the subjects are afraid or fearful of the test questions.From this point of view, the psychological basis of GKT technology is mainly based on cognitive psychology.

(End of this chapter)