From introduction: "Turning pale or red in the face, besides expressive movements (mimic and pantomimic) belonged to the earliest observed symptoms of emotions, which sometimes were even directly treated as symptoms of the lie (Trovillio 1938/1939, Eysenck 1971). Th anks to experimental psychology and physiology, since the end of the 19th and early 20th centuries they have been known to result from changes in the blood supply to the face related to the functioning of the circulatory system, movement of muscles, and chemical changes in the blood and its energetic value (dependent on the amount of oxygen, catecholamines, etc.), a knowledge embracing also the fact that physiological changes accompanying emotions encompass the entire organism and are clearly correlated. Th us, theoretically, it suffi ces to observe any fragment of the organism to detect emotions, and the number of physiological correlates of emotions, if not unlimited, is certainly very large. Some of them are clearly visible for an external observer (for example, the expressive movements, blanching, blushing, tremors, etc.). Others can be observed only with specialist devices, with polygraph being the best known among them. "(...)