Physiological Illusions

Physiological illusions can arise in perfectly healthy people mentally under the influence of affective states – tension, fatigue or due to a decrease in the level of attention. Illusions of physical and physiological character are considered episodic, short-term, and they can be instantly critically evaluated.

At the same time, a person’s ability to come to a critical evaluation is considered to be the most important and basic criterion for distinguishing between simple illusions and violations of the pathological mental state studied by psychiatrists.

Approximate human reflexes are the result of the action of various external specific stimuli, manifested as contractions of muscles belonging to a specific organ, which leads him to a position most suited to external action.

Physiological Illusions

Human perception of reality, when it believes that “sees” or “hears”, is a report of consciousness due to the irritation of certain receptors of specific perceiving elements (retina, Corti’s organ, etc.). At first glance, these processes must be in full correspondence with each other (harmonious correspondence of objective manifestation and subjective perception), but this is not so.

It is the discrepancies between the objective real indicators and the erroneous or false perception of a subjective character that create physiological illusions. The most striking example of a natural physiological illusion is the violation of the eye – the inability to accurately determine “on the eye” the real dimensions of distances, objects – the discrepancies in the readings of the perception consciousness and their objective parameters.

Also, a physiological illusion is the erroneous perception of a diminished visual size of a large object, if it is in a group of small elements, and vice versa. A well-known physiological effect is often demonstrated by psychologists and ophthalmologists – when pressing a finger on the side of the eyeball, all objects in the perception of a person, forked.

That is, you can call all the physiological illusions special effects of exaggerated stimulation of the organs of vision and the brain (color, brightness, movement, position, dimensions, slopes). Any physiological illusion can arise under the influence of an inadequate in quality or strength stimulus on any sense organ.

To specialists physiological illusion is a frequently occurring phenomenon – the “illusion of counter-rotation” that appears in a person when he affects the semicircular canals of the vestibular apparatus in the process of changing the speed of rotation in a specific plane (for example, in astronauts, pilots, in the case of a long ride on the carousel). The direction of perception of the illusion of counter-rotation is directly opposite to the real process of rotation.

Any illusion of anti-rotation is accompanied by disorders of a vegetative nature, sensations (false, imaginary) of the rotation of one’s own body and objects, often a person experiences unpleasant changes in consciousness, a feeling of fear and confusion arises, attention is dispersed.

To suppress these feelings it is necessary to show strong-willed effort to avoid – prolonged training of the vestibular-vegetative apparatus, reflexes (this, of course, concerns pilots and cosmonauts, so that they have the opportunity in the process of “blind” flight not to react to the illusion, but To be guided by devices).

Physiological illusions, being phenomena, more or less all known, are easily corrected by healthy people mentally, and only in rare cases lead to false and imaginary perceptions. In themselves, such single physiological illusions do not cause a delusional state, they are not sources of its manifestation or further development. And as an additional sign they can only strengthen already developed as a result of mental illness nonsense, as a perverted external painful perception.

According to DNUznadze is one of the forms of physiological illusion that is the illusion of installation, the wrong perception of the mass, the volume of objects, of any size. This illusion is created by repeatedly comparing several pairs of objects, a series of experiments are performed to obtain the desired result, creating the prerequisites for the appearance of the physiological illusion of the installation, that is, the conditions of the installation itself.

So, for example, when lifting with each hand a pair of objects that differ in weight, followed by another pair, with the same weight, there is the illusion of setting that the object in the hand in which it was earlier an easier object is more severe (contrast physiological illusion of the installation).

DN Uznadze explains the mechanisms of the emergence of the illusion of installing the theory of persistent education in a person’s inner subconscious perceptions (attitudes), preparing him for the subsequent, already imaginary perception of further events.

Some physiological illusions of perception differ in the complex nature of the manifestation, for example, the situation of weightlessness, with the unfamiliar and unfamiliar to the human consciousness stimulating the vestibular sensations, disturbs the visual and acoustic assessment of the position of objects (such phenomena include the physiological illusions of time, touch, temperature, color, ).

There is no general theory explaining the mechanisms of the origin of physiological illusion. Illusory effects according to the theory of the German scientist G. Helmholtz, are the result of functioning under unusual conditions of the same permanent perception mechanisms, which in the usual conditions provide a stable reality.

Scientists explain the manifestations of illusions of a physiological nature by the specifics of coding processes in the consciousness of information, the peculiarities of the structure of the eye, light effects, the emergence of irradiation, contrasts.

Changing the perception of physiological illusions can be interpreted as a definition of global characteristics and personal qualities of a person – his emotional state in critical situations of perception (at the time of fatigue or activity), his character, and even determine the type of personality, pathological changes, his self-esteem, propensity to suggestion.

There are many examples of physiological illusions. There is an illusion of perception of color known to many psychologists, in which a dark figure on a light background will always appear smaller in size than a light figure on a dark background, although in reality they are the same. This effect was used by duelists in ancient times, they preferred to come to a duel, dressed in black suits, rightly believing that in a smaller visual figure, it would be more difficult to get out of the gun.

Physiological Illusions

This effect is explained by irradiation – the image formed on the retina of the eye, consisting of light and dark zones, is distorted by the fact that the light from the brightly lit areas conditionally “moves” to dark areas. Due to this phenomenon, a light object on a dark background is perceived as larger than it is in reality, as it “captures” a section of a dark background.

Scientists and specialists in various fields know the most diverse and interesting physiological illusions. Weber’s illusion is that a cold object is always perceived to be heavier than a warm object, which in reality has the same weight.

The illusion of the physiological nature of the sound contrast is expressed in the perception of sounds of equal strength against the background of quiet sounds more loud than against the background of louder ones.

Müller-Schumann’s illusion is the erroneous perception of a lighter cargo after a multiple lifting of a heavy load, even easier than it is in reality and, conversely, if several times to lift an easy load, the heavier cargo lifted after this seems heavier.

Illusion Charpentier deceives our consciousness visually-physiological way – lifting two identical in weight and appearance of the object, having thus different volume, the person will perceive smaller of them on dimensions – more heavy.

The Bezold-Brücke effect is an illusion, expressed in changes in the shade of light in cases of changes in its intensity. Especially yellow-red and yellow-green tones with increasing light intensity are perceived as more yellow, and bluish-red and bluish-green are perceived more bluish. In pure red, yellow, green and blue colors this effect does not take place.

The Purkinje effect was discovered by him in 1825, when he drew attention to the variation in the brightness of blue and red road signs at different times of the day. In the daytime, the colors were equally bright, and at sunset the blue paint seemed brighter than the red. And at dusk colors fade completely, and are perceived by a man in gray tones. The red color seems black, and the blue color is white. This effect is caused by a transition in the low illumination of the cone to the rod.

The illusion of the Moon is that the apparent (or apparent) size of this celestial body (or Sun) is perceived by a person about 1.5 times larger when the body is located low above the horizon than when it is high in the zenith. This is an example of a real physiological illusion. Prove that this “game” of perception can be, by trying to close the distance of the outstretched hands of the Moon with his thumb. It will close equally as the rising moon disc, and the heavenly body, located at the zenith.

The interesting effect is the McGurk effect, which practically proves that the auditory and visual information that speech conveys to a person’s consciousness not only interacts in consciousness with each other, but also influences what a person hears. The scientists McGurk and McDonald conducted an amazing experiment, creating conditions under which the auditory impulses of the spoken syllable did not correspond to the corresponding movements of the lips.

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For this, the participants of the experiment were shown a video of a person who only sang “ga-ga” several times with his lips, and the phonogram was sounded by other syllables – “ba-ba”. Listening to the phonogram with closed eyes, the participants learned the correct syllables. With a visual perception of only the movements of the lips of the person speaking, with the sound turned off, they just as accurately perceived the spoken sounds as “ga-ga”.

But, with simultaneous presentation of contradictory auditory and visual stimuli, they heard such sounds, which in reality were not really in any case, and what turned out to be even more interesting for scientists is that most of the participants in the experiment did not realize discrepancies between auditory and visual perception of stimulation. The effect of McGurk, many experts call a classic example of physiological illusion, because it involves two senses.

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