On Options: My Thoughts Explained

On Options: My Thoughts Explained

What Data Are Measured in Polygraph Tests? For centuries, humans have searched for accurate means of detecting lies. In early Hindu and Chinese cultures, authorities “detected” lies by instructing the subject to chew a grain of rice and spew it out. A dry grain of rice would be considered a sign of the dry mouth of a liar. In India, if rice stuck to the mouth, it would be a sign of guilt. While these methods were primeval and non-scientific, they nonetheless emphasized the elemental conjecture humans make in lie detection: lying can be detected using physiological indications. Whenever a person lies or is asked a critical question, his heart may begin to race, increasing his blood pressure. Also, the test subject may also hold his breath, inhale a large one, or perspire. Such physiological irregularities are recognized by the polygraph to be interpreted by the polygraph examiner. It is the decision of the examiner to take the sudden data changes as dishonesty. Cardiovascular Activity
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An encircling, air-filled cuff placed around the upper arm records blood pressure and heart rate. When blood pressure changes, so does the air pressure in the cuff. The polygraph machine takes note of such changes, displaying them on a computer monitor simultaneously with respiratory and perspiratory data.
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Respiration The subject’s respiration pattern is recorded by two pneumograph devices which capture thoracic movement or volume change when a person is breathing. One pneumograph tube is placed around the chest and the other around the abdomen. Like the arm cuffs that detect cardiovascular changes in a subject, the pneumograph tubes are also air-filled and connected to the machine. As the subject inhales and exhales, the air pressure inside the tubing changes, and every change will be recorded by the polygraph machine. Perspiration Sweat measurement, scientifically referred to as the measurement of galvanic skin resistance, is conducted by attaching a two-piece galvanometer to two fingertips of the subject. Through the galvanometer, a small electric current is sent into the skin from one fingerplate, and the amount of current that got through on the other fingerplate will be recorded. Dry skin conducts electricity poorly. However, during perspiration, water and salt from the sweat drives down skin resistance, allowing a bigger amount of electric current to flow on the surface of the skin. In other words, whatever amount of electric current is recorded by the galvanometer, indicates the amount of sweat that fingertips of the subject produced. While not a hundred percent accurate, polygraph tests are commonly used as an instructive tool by law enforcement agencies and many government authorities. Through rapid technological advancements, humans will soon to strengthen the correlation between the psychological state of lying and its physiological indications.