Synastrisias are rarely seen in psychopathic individuals. In some poisons such as mescaline poisoning, rich synesthesias can be observed in which individual sensory modalities are strangely united; - illusions are perverted perceptions of real-world objects. Illusions can be observed not only as a pathological phenomenon, but also in the normal person.All healthy people have the so-called physiological illusions. For example, a rod half immersed in water appears to be broken; the sun and moon look bigger on the horizon than the zenith; parallel lines crossed with hair seem to lose their parallelism, and so on. The reasons for these illusions, though insufficiently explored, are clearly varied.
Some of them are due to physical factors (for example, unequal rays of water and air), others to physiological moments or psychological attitudes. In addition to these physiological illusions, which are observed with a regular constancy, sometimes the ill person can experience illusory perceptions in the course of subjective preconditions. Thus, in the mid-twilight, the coat hanging on the coat and the hat can get the finished form of human image. These illusions clearly show the role of emotions, expectation and attitude (affective illusions of expectation). Their perception is related to the mechanism of normal perception. Normally, one does not perceive objects with all their details. It perceives only individual elements and complements the rest of it based on its previous experience.
Unlike the child who learns to read, for example, the adult in reading reads only a few of the letters, and the rest adds, so the possibilities for illusory perceptions of reading are very large. Rarely, in normal people, luscious illusions that bear the name paradjoli can be richer. They meet with representatives of the artistic type. In the normal pajamas, the "flight" of living fantasy complements the real objects by giving them fantastic outlines and details at a high brightness of the images, but with a reserved critical attitude. Often, in children, the passion of the imagination is the reason for the game in which fictional figures are hiding in the outline of the clouds. According to some authors, the pairedoids are just a normal phenomenon. According to others, this term has a place in psychology to denote rich illusions, to which a naturally critical attitude should not be expected at first.