In psychology, there are several concepts of the threshold of sensitivity.

The lower absolute threshold of sensitivity is defined as the smallest strength of the stimulus that can cause sensation.

Human receptors are distinguished by a very high sensitivity to an adequate stimulus. So, for example, the lower visual threshold is only 2-4 quantums of light, and the olfactory one is equal to 6 molecules of an odorous substance.

Stimuli that have a strength less than the threshold do not cause sensations. They are called subthreshold and are not realized, however, they can penetrate into the subconscious, determining a person's behavior, and also forming the basis of his dreams, intuition, unconscious drives. Psychological research shows that the human subconscious can respond to very weak or very short stimuli that are not perceived by consciousness.

The upper absolute threshold of sensitivity changes the very nature of sensations (most often - to pain). For example, with a gradual increase in water temperature, a person begins to perceive not heat, but already pain. The same thing happens with a strong sound or pressure on the skin.

The relative threshold (discrimination threshold) is the minimum change in the intensity of the stimulus that causes changes in sensations. According to the Bouguer - Weber law, the relative threshold of sensations is constant, if measured as a percentage of the initial value of irritation.

In a newborn child, all analyzer systems are morphologically ready for display. However, they must go through a significant path of functional development.

The most organ of knowledge of the child is the mouth, so taste sensations arise before the rest. At 3-4 weeks of a child's life, auditory and visual concentration appears, which indicates her readiness for visual and auditory sensations. In the third month of life, she begins to master the motor skills of the eyes. The fixation of an object that acts on the analyzer is associated with the coordination of eye movements.

The child quickly develops a visual analyzer. Especially sensitivity to colors, visual acuity, general sensitivity to light stimuli.

The development of auditory sensations is of great importance. Already in the third month, the child localizes sounds, turns his head to the source of the sound, reacts to music and singing. The development of auditory sensations is closely related to language acquisition. At the third month of life, the child can already distinguish the affectionate and angry tone of the tongue stretching towards her, and at the sixth month of life, she distinguishes the voices of people close to her.

I. M. Sechenov emphasized the great importance of kinesthetic sensations in the development of cognitive activity. The perfection of the motor sphere of the child, the differentiation of its movements, necessary for the performance of various types of activity, largely depends on them.

M. M. Koltsova put forward the idea of ​​the unity and interconnection of all manifestations of the motor analyzer, starting from simple motor components and ending with the kinesthesia of the language. During the formation of the language, restriction of movements leads to the cessation of babble and pronunciation of the first syllables. The rhythm of speech correlates with the rhythm of bodily movements that the child makes. The arguments of M. M. Koltsova coincide with those experimental data that show the relationship of rhythm, tempo and loudness of speech with temperament.

Organic sensations in interaction with kinesthesia and distant sensations form another vital complex of sensitivity. The basis here is organic feelings and sensations of the body scheme (correspondence of its parts). The feeling of health, strength gives a person cheerfulness, self-confidence, stimulates vigorous activity.

Consequently, sensations arise and develop throughout a person's life and constitute its sensory organization.

B. G. Ananiev writes that there are no significant differences in the level of sensitivity of the same analyzers in children, although they are obvious in an adult. Hypersensitivity is noted in steelmakers, artists, textile workers. So, textile workers distinguish 30-40 shades of black fabric, while non-specialists - only 2-3 shades. Therapists are very good at distinguishing noises. Consequently, activity affects the development of types of sensitivity that are significant for a given profession. It has been experimentally confirmed that it is possible to increase the sensitivity to human recognition tenfold.

The formation of a socially significant personality can take place on an extremely limited sensory basis, even if the two leading sensitivities - sight and hearing - are lost. Then tactile, vibrational, olfactory sensitivity becomes the leading one in the development of personality. The example of the deaf-blind A. Skorokhodov, an outstanding psychologist, convincingly shows what heights of creative activity a person can achieve, relying in his development on "non-wire" sensations.

Psychology studies various mental phenomena, processes and states. Sensation, perception, representation, imagination, thinking, speech, memorization, preservation, reproduction - this is.

Feel- this is a reflection of the individual properties of objects and phenomena that currently affect the senses. The peculiarity of sensations lies in their immediacy and momentaryness. When a person touches an object, puts it on the tongue, brings it to the nose, this effect is called contact. The impact of the object irritates special sensitive cells of the receptor. Irritation is a physiological process, under the influence of which excitation arises in nerve cells, which is transmitted through afferent nerve fibers to the corresponding part of the brain. Only in the brain does the physiological process turn into a mental one, and the individual feels one or another property of an object or phenomenon.

Feeling properties. Our sense organs are able to change their characteristics, adapting to changing environmental conditions. An increase in sensitivity as a result of the interaction of sensations or the appearance of other stimuli is called sensitization.

Often, under the influence of one stimulus, sensations characteristic of another stimulus may occur. This phenomenon is associated with synesthesia (from the Greek synaisthesin - a one-time sensation, a joint feeling) - a mental state in which the action of an irritant on the corresponding sense organ, in addition to the will of the subject, causes not only a sensation specific to this sense organ, but at the same time also an additional a sensation or representation characteristic of another sense organ. For example, it is well known that color combinations affect temperature sensitivity: blue-green color causes a feeling of cold, and yellow-orange - warm. This feature is taken into account by designers.

The phenomenon of sensory hunger, or a great deficit of sensations, is called sensory deprivation. In the case of sensory deprivation, a variety of abnormal phenomena occur in the human psyche - from hallucinations and falling into oblivion to complete brain shutdown.

Types of sensations. When classifying sensations, the following criteria are put forward:
a) at the location of the receptors;
b) by the presence or absence of direct contacts of the receptor with the stimulus that causes sensation;
c) according to the time of occurrence in the course of evolution;
d) according to the modality (kind) of the stimulus.

There are three main classes of sensations: interoreceptive (organic), exteroceptive and proprioceptive. Interoreceptive ones signal what is happening in the body (sensations of pain, thirst, hunger, etc.). Exteroceptive arise when exposed to external stimuli on receptors located on the surface of the body. Proprioreceptors are located in the muscles and tendons, with their help the brain receives information about the movement and position of body parts.

In addition, sensations can be distant and contact. The former include visual, which transmit 85% of information about the outside world, and auditory. To the second - tactile, gustatory and olfactory.

Each type of human sensation provides specific information. However, there are general patterns that are characteristic of all types of sensations. These include levels of sensitivity, or "sensation thresholds". Sensitivity is the ability to recognize the magnitude and quality of a stimulus. "The threshold of sensations" is called the psychological relationship between the intensity of sensation and the strength of the causing stimulus.

The minimum value of the stimulus that causes a barely noticeable sensation is called the lower absolute threshold of sensitivity. The highest value of the stimulus at which this sensation is still preserved is called the upper threshold of sensitivity (for example, light is already blinding beyond this threshold).

Thanks to the threshold of sensitivity, a person can constantly capture minor changes in the parameters of the external and internal environment: the strength of vibration, a decrease or increase in the strength of sound, the level of illumination, the level of gravity, etc. Sensitivity thresholds for each individual. Their value depends on many factors. The nature of the activity, profession, motives, interests, degree of training have a special influence on the increase in sensitivity.

Changes in the strength and nature of the active stimulus noticed by a person are called the differential threshold, or "threshold of discrimination." The amount of difference between the signal, at which the accuracy and speed of discrimination reach a maximum, is called the operational threshold. The operational threshold of sensations is 10-15 times higher than the differential one.

There is also a time threshold - this is a measure of the duration and impact of the stimulus necessary for the sensation to occur.

Latent threshold - the period of reaction, the length of time from the moment the signal is given to the moment the sensation occurs.

Sensation refers to a more complex psychological process - perception. Perception is a holistic reflection of objects and phenomena of the objective world with their direct impact at a given moment on the senses.

There are auditory, visual, tactile, olfactory, gustatory and kinesthetic (motor) perceptions.

Apparent motion perception determined by data on the spatial position of objects, i.e. associated with the visual perception of the degree of remoteness of the object and the assessment of the direction in which this or that object is located.

Perception of space is based on the perception of the shape and size of objects through the synthesis of visual, tactile, muscle sensations, as well as on the perception of the distance and volume of objects, which is provided by human binocular vision.

Perception of the passage of time is that the perception of time does not change the apparent physical stimulus. Of course, time itself is calculated in seconds, minutes, that is, it can be measured, but there is no specific object whose energy would affect a certain time receptor (as smell, light, etc. do). To date, scientists have not been able to discover a mechanism that converts physical time intervals into the corresponding sensory signals. However, it has been reliably established that everyone has a “biological clock”: heart rate and metabolic processes help us navigate in time. If a person wakes up at the same time on an alarm clock for several months, then soon the body is tuned to wake up at a certain hour without additional stimulus.

The perception of time is changed by some medications that affect the rhythm of the body. Caffeine speeds up time, quinine and alcohol slow it down. Drugs (hashish, marijuana, etc.) can either speed up or slow down subjective time. Time, saturated in the past with experiences, emotions, activities, is remembered as longer, and a long period of life, filled with uninteresting events and everyday life, is remembered as quickly past.

With a sharp emotional or physical overwork, there is often an increase in susceptibility to ordinary external stimuli. Sounds are deafening, light is blinding, odors "eat in", causing acute irritation. Such changes in perception are called hyperesthesia.

Hypothesia is the opposite state, expressed in a decrease in susceptibility to external stimuli. Hypothesia is associated with mobile or immobile stimuli, unchanging content (stable hallucinations) and constantly changing: in the form of various events played out like in a theater or cinema (stage-like hallucinations).

It is worth distinguishing from hallucinations illusions (from Latin Illusio - “deception”) - erroneous perceptions of real-life phenomena or things. Illusions are divided into affective, pareidolic and verbal (verbal).

Perceptual Properties. Researchers distinguish five main properties (qualities) of perception: constancy, integrity, meaningfulness, selectivity and apperception.

Constancy - stability, constancy of images of perception. This is largely a manifestation of the influence of our past experience. The skydiver knows that the forest is green, so even from a great height he perceives it as such. The law of constancy: a person considers familiar objects around him as unchanged.

Integrity - every object and situation is perceived as a stable systemic whole, even when parts of this whole cannot be observed (for example, the opposite part of a building). This becomes possible because the image that is formed in the process of reflecting reality has a high redundancy, i.e. some set of the image contains information not only about itself, but also about other components, as well as about the image as a whole. If we see only the head and shoulders of the interlocutor, then we can complete the position of his arms and torso.

Meaningfulness - as a rule, a person perceives only what he understands. It has been experimentally proven that meaningful words are remembered much faster and more accurately than a meaningless set of letters or syllables.

Selectivity is manifested in the preferential selection of some objects in comparison with others.

Apperception is the dependence of perception on past experience, on the general mental state of a person, on his individual abilities. When there is a dependence of perception on stable personality traits (beliefs, worldview, etc.), such apperception is called stable. There is also a temporary apperception, in which situationally arising mental states of a person (strong emotions, the action of an attitude, etc.) turn out to be.

Crib

Psychology and esotericism

Any change in the environment that is accessible to the sight of hearing and other modalities is psychologically presented as a sensation. If we cannot determine the taste of the product sugar honey, then we are talking only about sensations. Pain signals are almost always presented as sensations, since only a person with a very rich imagination can 'construct' an image of pain. Otherwise, we can learn nothing about any forms of matter and about any forms of movement through sensations.

1. The concept of sensation. The role of sensations in human life

2. Physiological basis of sensations. The concept of the analyzer

3. Classification of sensations

4. Basic properties of sensations

5. Sensitivity and its measurement

6. Adaptation of the sense organs

7. Interaction of sensations: sensitization and synesthesia

8. Sensitivity and exercise

1. THE CONCEPT OF SENSATION. THE ROLE OF SENSATIONS IN THE LIFE OF PEOPLE

Feeling - this is the simplest mental process, consisting in the reflection of individual properties of objects and phenomena of the material world, as well as the internal states of the body with the direct impact of material stimuli on the corresponding receptors.

Reflection - a universal property of matter, which consists in the ability of objects to reproduce with varying degrees of adequacy the features, structural characteristics and relationships of other objects.

Receptor - a specialized organic device located on the surface of the body or inside it and designed to perceive stimuli of various nature: physical, chemical, mechanical, etc., and convert them into nerve electrical impulses.

Sensation constitutes that initial region of the sphere of mental cognitive processes, which is located at the boundary that sharply separates mental and prepsychic phenomena.Mental cognitive processes- dynamically changing mental phenomena, in their totality providing knowledge as a process and as a result.

Psychologists have traditionally used the term “sensation” to denote an elementary perceptual image and the mechanism for its construction. In psychology, they speak of sensation in those cases when a person is aware that some kind of signal has arrived at his sense organs. Any change in the environment that is accessible to sight, hearing and other modalities is psychologically presented as a sensation. Sensation is the primary conscious representation of a formless and non-objective fragment of reality of a certain modality:color, light, sound, indefinite touch.

In the realm of taste and smell, the difference between sensation and perception is much smaller, and sometimes there is actually none. If we cannot determine the product (sugar, honey) by taste, then we are talking only about sensations. If odors are not identified with their objective sources, then they are presented only as sensations. Pain signals are almost always presented as sensations, since only a person with a very rich imagination can “build” an image of pain.

The role of sensations in human life is extremely great, since they are the source of our knowledge about the world and about ourselves. We learn about the richness of the world around us, about sounds and colors, smells and temperature, sizes and much more through the senses. With the help of the sense organs, the human body in the form of sensations receives a variety of information about the state of the external and internal environment.

The sense organs receive, select, accumulate information and transmit it to the brain, which processes its huge and inexhaustible flow every second. As a result, there is an adequate reflection of the surrounding world and the state of the organism itself. On this basis, nerve impulses are formed that arrive at the executive organs responsible for regulating body temperature, the functioning of the digestive organs, organs of movement, endocrine glands, for tuning the sense organs themselves, etc.

All this extremely complex work, consisting of many thousands of operations per second, is performed, according to T.P. Zinchenko, continuously.

The sense organs are the only channels through which the outside world "penetrates" into human consciousness. “Otherwise, as through sensations, we cannot learn anything about any forms of matter and any forms of movement ...” Sense organs give a person the opportunity to navigate in the world around him. If a person lost all his senses, he would not know what was happening around, could not communicate with people around him, get food, and avoid danger.

The famous Russian doctor S.P. Botkin (1832-1889) described a rare case in the history of medicine when a patient lost all types of sensitivity (only one eye could see and the sense of touch was preserved in a small part of the arm). When the patient closed her seeing eye and no one touched her hand, she fell asleep.

A person needs to receive information about the world around him all the time. Adaptation of an organism to the environment, understood in the broadest sense of the word, implies some permanent informational balance between the environment and the organism. The information balance is opposed by information overload and information underload (sensory isolation), which lead to serious functional disorders of the body.Sensory Isolation- prolonged, more or less complete deprivation of a person's sensory impressions.

In this regard, the results of research on the limitation of sensory information that have been developing in recent years are indicative. These studies are related to the problems of space biology and medicine. In cases where the subjects were placed in special chambers that provide almost complete sensory isolation (constant monotonous sound, frosted glasses that let only weak light through, cylinders on their arms and legs that remove tactile sensitivity, etc.), after a few hours the subjects became anxious and insistently asked to stop the experiment.

The literature describes an experiment conducted in 1956 at McGill University by a group of psychologists. The researchers asked volunteers to stay as long as possible in a special chamber, where they were protected from all external stimuli as much as possible. All that was required of the subjects was to lie on the bed. The subject's hands were placed in long cardboard tubes (so that there were as few tactile stimuli as possible). Thanks to the use of special glasses, their eyes perceived only diffused light. The auditory stimuli were "masked" by the noise of the continuously running air conditioner and fan.

The subjects were fed, watered, if necessary, they could take care of their toilet, but the rest of the time they had to remain as motionless as possible.

Scientists were struck by the fact that most of the subjects were unable to withstand such conditions for more than 2-3 days. What happened to them during this time? At first, most of the subjects tried to focus on personal problems, but soon the subjects began to notice that their minds were “walking away” from this. Very soon they lost the idea of ​​time, then a period came when they lost the ability to think at all. To get rid of the monotony, the subjects gladly agreed to listen to children's stories and even began to demand that they be given the opportunity to listen to them again and again.

More than 80% of the subjects claimed that they were victims of visual hallucinations: the walls shook, the floor rotated, corners rounded, objects became so bright that it was impossible to look at them. Many subjects after this experiment for a long time could not make simple conclusions and solve easy mathematical problems, and many had memory disorders.

Experiments on partial sensory isolation, for example, isolation from external influences of certain areas of the body surface, showed that in the latter case, violations of tactile, pain and temperature sensitivity are observed in these places. Subjects exposed to monochromatic light for a long time also developed visual hallucinations.

These and many other facts testify to how strong a person's need is to receive impressions about the world around him in the form of sensations.

1.1. The evolution of psychological ideas about sensation

Let us consider the issue of determining the essence and characteristics of sensation in the retrospective of the historical development of psychological knowledge. The methodology for solving this problem basically boiled down to answering a few questions:

1. By what mechanisms are the physical movements of the external world transformed into internal physical movements in the sense organs, nerves and brain?

2. How does physical movement in the sense organs, nerves, and brain produce sensation in what Galileo called the “living and sentient body”?

3. What information does a person receive with the help of vision, hearing and other senses, what sensory signals does he need to receive these sensations?

Thus, ancient thought developed two principles that underlie modern ideas about the nature of a sensory image - the principle of the causal effect of an external stimulus on the perceiving organ and the principle of the dependence of the sensory effect on the structure of this organ.

Democritus, for example, proceeded from the hypothesis of "outflows", of the emergence of sensations as a result of the penetration into the sense organs of material particles emitted by external bodies. Atoms - indivisible smallest particles, sweeping along the eternal and unchanging laws, are completely alien to such qualities as color and heat, taste and smell. Sensual qualities were considered inherent not in the sphere of real objects, but in the sphere of interaction of these objects with the sense organs.

Among the sensual products themselves, Democritus distinguished two categories:

1) colors, sounds, smells, which, arising under the influence of certain properties of the world of atoms, do not copy anything in it;

2) holistic images of things (“eidol”), unlike colors, reproducing the structure of the objects from which they are separated. The doctrine of Democritus about sensations as the effects of atomic impacts was the first causal concept of the emergence of individual sensory qualities.

If the concept of Democritus proceeded from the principle “like is known by like”, then the founders of the theories believed that sweet, bitter and other sensual properties of things cannot be known with their own help. Every sensation is associated with suffering, Anaxagoras taught. The mere contact of an external object with an organ is not enough for a sensory impression to arise. It is necessary to counteract the organ, the presence of contrasting elements in it.

Aristotle resolved the antinomy of like and opposite from new general biological positions. In his opinion, already at the origins of life, where the flow of inorganic processes begins to obey the laws of the living, at first the opposite acts on the opposite (for example, until the food is digested), but then (when the food is digested) “like feeds on like”. Perceived ability is interpreted by him as likening a sense organ to an external object. The sensing faculty perceives the form of an object "without its matter, just as wax takes the impression of a seal without iron and without gold." The object is primary, its sensation is secondary, compared with an imprint, an imprint. But this imprint appears only due to the activity of the “sensory” (“animal”) soul. The activity of which the organism is the agent transforms the physical effect into a sensory image.

Thus, Aristotle, in addition to the penetration into the body of outflows from the object, also recognized the process emanating from the body itself as necessary for the occurrence of a sensory effect.

The doctrine of sensations was raised to a higher level in Arabic science by Ibn al-Khaytham. So, in his opinion, the basis of visual perception should be the construction in the eye according to the laws of optics of the image of an external object. What later became known as the projection of this image, i.e. its relation to an external object, Ibn al-Khaytham considered the result of additional mental activity of a higher order.

In each visual act, he distinguished, on the one hand, the direct effect of imprinting an external influence, on the other hand, the work of the mind that joins this effect, due to which the similarity and difference of visible objects are established. Moreover, such work occurs unconsciously. He was thus the forerunner of the doctrine of the participation of "unconscious inferences" (Helmholtz) in the process of direct visual perception. Thus, the direct effect of the action of light rays on the eye and additional mental processes, due to which there is a visual perception of the shape of an object, its volume, etc., were divided.

Until the 19th century, the study of sensory phenomena, among which the leading place was occupied by visual perception, was carried out mainly by mathematicians and physicists, who, based on the laws of optics, established a number of physical indicators in the activity of the eye, and discovered some phenomena important for the future physiology of visual sensations and perceptions (accommodation, color mixing, etc.). For a long time, nervous activity was conceived on the model of mechanical movement (R. Descartes). The smallest bodies, designated by the terms “animal spirits”, “nervous fluids”, etc., were considered to be its carrier. Cognitive activity was also represented according to a mechanical model.

With the development of natural science, new ideas about the properties of the nervous system were born. The notion that the process of sensory cognition consists in the transmission of non-corporeal copies of an object along the nerves was finally crushed.

In the first decades of the nineteenth century, there was an intensive study of the functions of the eye as a physiological system. A significant place is given to subjective visual phenomena, many of which have long been known under the names of “optical illusions”, “random colors”, etc. Thus, Müller achieves a physiological explanation of illusions at the cost of denying the differences between sensations that correctly reflect the external world and purely subjective sensory products. He interprets both those and others as the result of the actualization of the “specific energy” inherent in the sense organ. Thus, reality turned into a mirage created by the neuropsychic organization. According to Müller, the sensory quality is immanently inherent in the organ, and sensations are determined solely by the properties of the nervous tissue.The principle of specific energy of the sense organs- the idea that the quality of sensation depends on which sense organ is excited.

Another scientist - C. Bell, studying the patterns of building an image on the retina of the eye, puts forward the assumption that the activity of consciousness, interfering with optical laws, reverses the image, returning it to a position corresponding to real spatial relationships. Thus, he insisted on the contribution of muscle work to the construction of sensory imagery. According to C. Bell, muscle sensitivity (and hence motor activity) is an indispensable participant in the acquisition of sensory information.

Further studies of the sense organs prompted us to consider sensory patterns (sensation, perception) as a derivative not only of receptors, but also of effectors. The psychic image and psychic action are united into an integral product. This conclusion was firmly substantiated experimentally in the experiments of Helmholtz and Sechenov.

Helmholtz proposed a hypothesis according to which the work of the visual system in the construction of a spatial image occurs according to the analogue of a logical scheme. He called this scheme "unconscious inference." A glance running over objects, comparing them, analyzing them, etc. performs operations, in principle, similar to what the thought does, following the formula: “If ... then ...”. From this it followed that the construction of a mental image occurs according to the type of actions that the body initially learns in the “school” of direct contacts with surrounding objects (according to A.V. Petrovsky and M.G. Yaroshevsky). In other words, the subject is able to realize the external world in the form of images only because he is not aware of his intellectual work, hidden behind the visible picture of the world.

I. Sechenov proved the reflex nature of this work.Sechenov Ivan Mikhailovich (1829-1905)- Russian physiologist and psychologist, author of the natural science theory of mental regulation of behavior, who anticipated in his works the concept of feedback as an indispensable regulator of behavior. He presented the sensory-motor activity of the eye as a model of “coordination of movement with feeling” in the behavior of an integral organism. In the motor apparatus, instead of the usual muscle contraction, he saw a special mental action, which is directed by feeling, that is, by the mental image of the environment to which it (and the organism as a whole) adapts.

At the end of the 19th century, research on sensations was determined by the desire of researchers to split the “matter” of consciousness into “atoms” in the form of the simplest mental images from which it is built (W. Wundt). Sensations in Wundt's laboratory, studied using the method of introspection, were presented as special elements of consciousness, accessible in their true form only to the subject observing them.

Modern views on the physiological foundations of sensations integrate everything useful that has been accumulated by various scientists in previous centuries and decades.

2. PHYSIOLOGICAL BASES OF SENSATIONS. THE CONCEPT OF THE ANALYZER

All living beings that have a nervous system have the ability to sense. As for conscious sensations (about the source and quality of which an account is given), only a person has them. In the evolution of living beings, sensations arose on the basis of primary irritability , which is a property of living matter to respond to biologically significant environmental influences by changing its internal state and external behavior.

In their origin, from the very beginning, sensations were associated with the activity of the organism, with the need to satisfy its biological needs. The vital role of sensations is to timely bring to the central nervous system (as the main organ for managing human activity and behavior) information about the state of the external and internal environment, the presence of biologically significant factors in it. Sensation, in contrast to irritability, carries information about certain qualities of external influence.

A person's sensations in their quality and diversity reflect the diversity of the properties of the environment that are significant for him. The sense organs, or human analyzers, from the moment of birth are adapted for the perception and processing of various types of energy in the form of stimuli-stimuli (physical, mechanical, chemical, and others). Stimulus - any factor that affects the body and can cause any reaction in it.

It is necessary to distinguish between stimuli that are adequate for a given sense organ and those that are not adequate for it. This fact testifies to the subtle specialization of the sense organs to reflect one or another type of energy, certain properties of objects and phenomena of reality. The specialization of the sense organs is a product of a long evolution, and the sense organs themselves are products of adaptation to the influences of the external environment, therefore, in their structure and properties, they are adequate to these influences.

In humans, subtle differentiation in the field of sensations is associated with the historical development of human society and with social and labor practices. “Serving” the processes of adaptation of the organism to the environment, the sense organs can successfully perform their function only if they correctly reflect its objective properties. Thus, the non-specificity of the sense organs gives rise to the specificity of sensations, and the specific qualities of the external world gave rise to the specificity of the sense organs. Sensations are not symbols, hieroglyphs, but reflect the actual properties of objects and phenomena of the material world that act on the senses of the subject, but exist independently of him.

Sensation arises as a reaction of the nervous system to a particular stimulus and, like any mental phenomenon, has a reflex character. Reaction The body's response to a specific stimulus.

The physiological basis of sensation is a nervous process that occurs when a stimulus acts on an analyzer adequate to it. Analyzer - a concept (according to Pavlov), denoting a set of afferent and efferent nervous structures involved in the perception, processing and response to stimuli.

efferent is a process directed from the inside out, from the central nervous system to the periphery of the body.

Afferent - a concept that characterizes the course of the process of nervous excitation through the nervous system in the direction from the periphery of the body to the brain.

The analyzer consists of three parts:

1. Peripheral department ( or receptor ), which is a special transformer of external energy into the nervous process. There are two types of receptors:contact receptors- receptors that transmit irritation by direct contact with objects that act on them, anddistant receptors- receptors that respond to stimuli emanating from a distant object.

2. Afferent (centripetal) and efferent (centrifugal) nerves, conducting paths connecting the peripheral section of the analyzer with the central one.

3. Subcortical and cortical sections (brain end) of the analyzer, where the processing of nerve impulses coming from the peripheral sections takes place.

In the cortical region of each analyzer isanalyzer core, i.e. the central part, where the main mass of receptor cells is concentrated, and the periphery, consisting of scattered cellular elements, which are located in one quantity or another in various areas of the cortex.

The nuclear part of the analyzer consists of a large mass of cells that are located in the area of ​​the cerebral cortex where the centripetal nerves from the receptor enter. Scattered (peripheral) elements of this analyzer enter the regions adjacent to the nuclei of other analyzers. This ensures participation in a separate act of sensation of a large part of the entire cerebral cortex. The analyzer core performs the function of fine analysis and synthesis, for example, it differentiates sounds by pitch. Scattered elements are associated with rough analysis functions, such as distinguishing between musical sounds and noises.

Certain cells of the peripheral parts of the analyzer correspond to certain parts of the cortical cells. So, spatially different points in the cortex are, for example, different points of the retina; spatially different arrangement of cells is presented in the cortex and the organ of hearing. The same applies to other sense organs.

Numerous experiments carried out by methods of artificial stimulation now make it possible to quite definitely establish the localization in the cortex of certain types of sensitivity. Thus, the representation of visual sensitivity is concentrated mainly in the occipital lobes of the cerebral cortex. Auditory sensitivity is localized in the middle part of the superior temporal gyrus. Tactile-motor sensitivity is represented in the posterior central gyrus, etc.

For the sensation to arise, the work of the entire analyzer as a whole is necessary. The impact of the stimulus on the receptor causes the appearance of irritation. The beginning of this irritation lies in the transformation of external energy into a nervous process, which is produced by the receptor. From the receptor, this process along the centripetal nerve reaches the nuclear part of the analyzer located in the spinal cord or brain. When the excitation reaches the cortical cells of the analyzer, we feel the qualities of the stimuli, and after this, the body's response to the irritation occurs.

If the signal is due to a stimulus that threatens to cause damage to the body, or is addressed to the autonomic nervous system, then it is very likely that it will immediately cause a reflex reaction emanating from the spinal cord or other lower center, and this will happen before we are aware of this effect ( reflex - an automatic response of the body to the action of any internal or external stimulus).

Our hand recoils when we get burned by a cigarette, our pupil constricts in bright light, our salivary glands start to salivate when we put a lollipop in our mouth, and all this happens before our brain can decipher the signal and give the appropriate order. The survival of an organism often depends on the short neural circuits that make up the reflex arc.

If the signal continues down the spinal cord, then it takes two different paths: one leads to the cerebral cortex via thalamus , and the other, more diffuse, passes throughreticular formation filter, which keeps the cortex awake and decides whether the signal transmitted directly is important enough for the cortex to “engage” in deciphering it. If the signal is considered important, a complex process will begin, which will lead to a sensation in the truest sense of the word. This process involves changing the activity of many thousands of cortical neurons, which will have to structure and organize the sensory signal in order to give it meaning. ( Sensory - associated with the work of the senses).

First of all, the attention of the cerebral cortex to the stimulus will now entail a series of movements of the eyes, head or torso. This will allow you to get acquainted with the information coming from the sensory organ, the primary source of this signal, and, possibly, connect other senses. As new information becomes available, it will be associated with traces of similar events stored in memory.

Between the receptor and the brain there is not only a direct (centripetal), but also a reverse (centrifugal) connection. The feedback principle discovered by I.M. Sechenov, requires the recognition that the sense organ is alternately both a receptor and an effector.

Thus, sensation is not only the result of a centripetal process; it is based on a complete and complex reflex act, which in its formation and course obeys the general laws of reflex activity. In this case, the analyzer constitutes the initial and most important part of the entire path of nervous processes, or the reflex arc.

reflex arc- a concept denoting a set of nervous structures that conduct nerve impulses from stimuli located on the periphery of the body to the center, processing them in the central nervous system and causing a reaction to the corresponding stimuli.

The reflex arc consists of a receptor, pathways, a central part, and an effector. The relationship of the elements of the reflex arc provides the basis for the orientation of a complex organism in the surrounding world, the activity of the organism, depending on the conditions of its existence.

The dynamics of the processes occurring in the reflex arc is a kind of likening to the properties of an external influence. For example, touch is just such a process in which hand movements repeat the outlines of a given object, as if becoming like its structure. The eye operates on the same principle due to the combination of the activity of its optical “device” with oculomotor reactions. The movements of the vocal cords also reproduce the objective pitch nature. When the vocal-motor link was turned off in the experiments, the phenomenon of a kind of pitch deafness inevitably arose. Thus, due to the combination of sensory and motor components, the sensory (analyzing) apparatus reproduces the objective properties of the stimuli acting on the receptor and is likened to their nature.

Numerous and versatile studies on the participation of effector processes in the occurrence of sensation have led to the conclusion that sensation as a mental phenomenon is impossible in the absence of an organism's response or its inadequacy. In this sense, the fixed eye is as blind as the fixed hand ceases to be an instrument of knowledge. The sense organs are closely connected with the organs of movement, which perform not only adaptive, executive functions, but also directly participate in the processes of obtaining information.

Thus, the connection between touch and movement is obvious. Both functions are merged in one organ - the hand. At the same time, the difference between the executive and groping movements of the hand is also obvious (Russian physiologist, author of the doctrine of higher nervous activity) I.P. Pavlov called the latter orienting-exploratory reactions related to a special type of behavior - perceptual rather than executive behavior. Such perceptual regulation is aimed at enhancing the input of information, optimizing the process of sensation. All this suggests that for the emergence of a sensation it is not enough that the organism is subjected to the corresponding action of a material stimulus, but some work of the organism itself is also necessary. This work can be expressed both in internal processes and in external movements.

In addition to the fact that the sense organs are a kind of “window” for a person into the world around them, they are, in fact, energy filters through which the corresponding changes in the environment pass. By what principle is the selection of useful information in sensations carried out? In part, we have already touched on this issue. To date, several hypotheses have been formulated.

According to the first hypothesis, there are mechanisms for detecting and passing restricted signal classes, with messages not matching those classes being rejected. The task of such selection is performed by comparison mechanisms. For example, in insects, these mechanisms are involved in solving the difficult task of finding a partner of their own species. "Winks" of fireflies, "ritual dances" of butterflies, etc. - all these are genetically fixed chains of reflexes that follow one after another. Each stage of such a chain is sequentially solved by insects in a binary system: “yes” - “no”. Not the movement of the female, not the spot of color, not the pattern on the wings, not the way she “answered” in the dance - it means that the female is alien, of a different species. The stages form a hierarchical sequence: the beginning of a new stage is possible only after the previous question is answered “yes”.

Second hypothesis suggests that the acceptance or non-acceptance of messages can be regulated on the basis of special criteria, which, in particular, represent the needs of a living being. All animals are usually surrounded by a "sea" of stimuli to which they are sensitive. However, most living organisms respond only to those stimuli that are directly related to the needs of the organism. Hunger, thirst, readiness for mating, or some other internal attraction can be the regulators, the criteria by which the selection of stimulus energy is carried out.

According to the third hypothesis, the selection of information in sensations occurs on the basis of the criterion of novelty. Under the action of a constant stimulus, the sensitivity seems to be dulled and the signals from the receptors cease to flow to the central nervous apparatus (sensitivity- the ability of the body to respond to environmental influences that do not have direct biological significance, but cause a psychological reaction in the form of sensations). Thus, the sensation of touch tends to fade away. It can completely disappear if the irritant suddenly stops moving across the skin. Sensitive nerve endings signal the brain that irritation is present only when the strength of the stimulation changes, even if the time during which it presses harder or weaker on the skin is very short.

The same is true with hearing. It has been found that the singer needs vibrato, a slight fluctuation in pitch, to control his own voice and to keep it at the right pitch. Without stimulation of these deliberate variations, the singer's brain does not notice the gradual changes in pitch.

The visual analyzer is also characterized by the extinction of the orienting reaction to a constant stimulus. The visual sensory field, it would seem, is free from the obligatory connection with the reflection of movement. Meanwhile, the data of the genetic psychophysiology of vision show that the initial stage of visual sensations was precisely the display of the movement of objects. The compound eyes of insects work effectively only when exposed to moving stimuli.

This is the case not only in invertebrates, but also in vertebrates. It is known, for example, that the retina of a frog, described as a “detector of insects,” reacts precisely to the movement of the latter. If there is no moving object in the frog's field of vision, its eyes do not send essential information to the brain. Therefore, even being surrounded by many motionless insects, the frog can die of hunger.

The facts testifying to the extinction of the orienting reaction to a constant stimulus were obtained in the experiments of E.N. Sokolov. The nervous system finely models the properties of external objects acting on the sense organs, creating their neural models. These models perform the function of a selectively acting filter. If the stimulus acting on the receptor at the moment does not coincide with the previously established nervous model, impulses of mismatch appear, causing an orienting reaction. Conversely, the orienting reaction fades to the stimulus that was previously used in the experiments.

Thus, the process of sensation is carried out as a system of sensory actions aimed at the selection and transformation of the specific energy of external influence and providing an adequate reflection of the surrounding world.

3. CLASSIFICATION OF SENSATIONS

All kinds of sensations arise as a result of the impact of appropriate stimuli-irritants on the sense organs. sense organs - bodily organs specially designed for the perception, processing and storage of information. They include receptors, nerve pathways that conduct excitations to the brain and back, as well as the central parts of the human nervous system that process these excitations.

The classification of sensations proceeds from the properties of the stimuli that cause them, and the receptors that are affected by these stimuli. So, according to the nature of the reflection and the location of the receptors, sensations are usually divided into three groups:

1. interoceptive sensations,having receptors located in the internal organs and tissues of the body and reflecting the state of the internal organs. The signals coming from the internal organs are in most cases less noticeable, with the exception of painful symptoms. The information of interoreceptors informs the brain about the states of the internal environment of the body, such as the presence of biologically useful or harmful substances in it, body temperature, the chemical composition of the fluids present in it, pressure, and much more.

2. proprioceptive sensations, whose receptors are located in ligaments and muscles - they give information about the movement and position of our body. Proprioceptive sensations mark the degree of contraction or relaxation of muscles, signal the position of the body relative to the direction of gravity forces (a sense of balance). The subclass of proprioception that is sensitive to movement is called kinesthesia , and the corresponding receptorskinesthetic or kinesthetic.

3. exteroceptive sensations,reflecting the properties of objects and phenomena of the external environment and having receptors on the surface of the body. Exteroceptors can be divided into two groups: contact and remote . Contact receptors transmit irritation upon direct contact with objects that act on them; these aretouch, taste buds. Distant receptors respond to stimuli emanating from a distant object; distant receptors arevisual, auditory, olfactory.

From the point of view of the data of modern science, the accepted division of sensations into external (exteroceptors) and internal (interoceptors) is not enough. Some types of sensations can be consideredexternal-internal. These include, for example, temperature and pain, taste and vibration, muscular-articular and static-dynamic. An intermediate position between tactile and auditory sensations is occupied by vibrational sensations.

Sensations play an important role in the general process of human orientation in the environment. balance and acceleration . The complex systemic mechanism of these sensations covers the vestibular apparatus, vestibular nerves and various parts of the cortex, subcortex and cerebellum. Common for different analyzers and pain sensations, signaling the destructive power of the stimulus.

Touch (or skin sensitivity) is the most widely represented type of sensitivity. The composition of touch, along with tactile sensations (sensations of touch: pressure, pain) includes an independent type of sensations - temperature sensations (heat and cold). They are a function of a special temperature analyzer. Temperature sensations are not only part of the sense of touch, but also have an independent, more general significance for the entire process of thermoregulation and heat exchange between the body and the environment.

Unlike other exteroreceptors localized in narrowly limited areas of the surface of the predominantly head end of the body, the receptors of the skin-mechanical analyzer, like other skin receptors, are located over the entire surface of the body, in areas bordering on the external environment. However, the specialization of skin receptors has not yet been accurately established. It is not clear whether there are receptors exclusively intended for the perception of one impact, generating differentiated sensations of pressure, pain, cold or heat, or the quality of the resulting sensation may vary depending on the specifics of the property affecting it.

The function of tactile receptors, like all others, is to receive the process of irritation and transform its energy into the corresponding nervous process. Irritation of nerve receptors is the process of mechanical contact of the stimulus with the area of ​​the skin surface in which this receptor is located. With a significant intensity of the action of the stimulus, contact turns into pressure. With the relative movement of the stimulus and the area of ​​the skin surface, contact and pressure are carried out under changing conditions of mechanical friction. Here irritation is carried out not by stationary, but by fluid, changing contact.

Research shows that sensations of touch or pressure only occur if a mechanical stimulus causes deformation of the skin surface. When pressure is applied to a very small area of ​​skin, the greatest deformation occurs precisely at the site of direct application of the stimulus. If pressure is exerted on a sufficiently large surface, then it is distributed unevenly - its least intensity is felt in the depressed parts of the surface, and the greatest is felt along the edges of the depressed area. G. Meissner's experiment shows that when a hand is immersed in water or mercury, the temperature of which is approximately equal to the temperature of the hand, pressure is felt only at the boundary of the part of the surface immersed in the liquid, i.e. precisely where the curvature of this surface and its deformation are most significant.

The intensity of the sensation of pressure depends on the speed at which the skin surface is deformed: the stronger the sensation, the faster the deformation occurs.

Smell is a type of sensitivity that generates specific sensations of smell. This is one of the most ancient and vital sensations. Anatomically, the olfactory organ is located in most living beings in the most advantageous place - in front, in a prominent part of the body. The path from the olfactory receptors to those brain structures where the impulses received from them are received and processed is the shortest. Nerve fibers extending from the olfactory receptors directly enter the brain without intermediate switching.

Part of the brain called olfactory is also the most ancient; the lower rung of the evolutionary ladder a living being is, the more space it occupies in the mass of the brain. In fish, for example, the olfactory brain covers almost the entire surface of the hemispheres, in dogs - about one-third of it, in humans, its relative share in the volume of all brain structures is about one-twentieth. These differences correspond to the development of other sense organs and the significance that this type of sensation has for living beings. For some species of animals, the meaning of smell goes beyond the perception of smells. In insects and higher apes, the sense of smell also serves as a means of intraspecific communication.

In many ways, the sense of smell is the most mysterious. Many have noticed that although the smell helps to recall an event, it is almost impossible to remember the smell itself, just as we mentally restore an image or sound. Smell serves memory so well because the mechanism of smell is intimately connected to the part of the brain that controls memory and emotion, although we don't know exactly how that connection works.

Flavoring sensations have four main modalities: sweet, salty, sour and bitter. All other taste sensations are various combinations of these four basic sensations. Modality - a qualitative characteristic of sensations that arise under the influence of certain stimuli and reflect the properties of objective reality in a specifically encoded form.

Smell and taste are called chemical senses because their receptors respond to molecular signals. When molecules dissolved in a liquid, such as saliva, excite the taste buds on the tongue, we experience taste. When molecules in the air hit the olfactory receptors in the nose, we smell. Although in man and in most animals taste and smell, having developed from a common chemical sense, have become independent, they remain interconnected. In some cases, for example, when inhaling the smell of chloroform, we think that we smell it, but in fact it is a taste.

On the other hand, what we call the taste of a substance is often its smell. If you close your eyes and pinch your nose, you may not be able to tell a potato from an apple or wine from coffee. If you pinch your nose, you will lose 80 percent of the ability to smell the flavors of most foods. That is why people who do not breathe through the nose (runny nose) do not feel the taste of food well.

Although our olfactory apparatus is remarkably sensitive, humans and other primates sense smells much worse than most other animal species. Some scientists suggest that our distant ancestors lost their sense of smell when they climbed trees. Since visual acuity was more important at that time, the balance between different types of feelings was disturbed. During this process, the shape of the nose changed and the size of the olfactory organ decreased. It became less subtle and did not recover even when the ancestors of man descended from the trees.

However, in many animal species, the sense of smell is still one of the main means of communication. Possibly and for the person smells are more important, than it was supposed so far.

Usually people distinguish each other, relying on visual perception. But sometimes the sense of smell plays a role here. M. Russell, a psychologist at the University of California, proved that babies can recognize their mother by smell. Six out of ten six-week-old babies smiled when they smelled their mother and did not respond or started crying when they smelled another woman. Another experience proved that parents can recognize their children by smell.

Substances have an odor only if they are volatile, that is, they easily pass from a solid or liquid to a gaseous state. However, the strength of the smell is not determined by volatility alone: ​​some less volatile substances, such as those contained in pepper, smell stronger than more volatile ones, such as alcohol. Salt and sugar are almost odorless, since their molecules are so tightly linked to each other by electrostatic forces that they hardly evaporate.

Although we are very good at detecting odors, we are not good at recognizing them in the absence of visual cues. For example, the smells of pineapple or chocolate would seem to be pronounced, and yet, if a person does not see the source of the smell, then as a rule he cannot accurately determine it. He can say that the smell is familiar to him, that it is the smell of something edible, but most people in this situation cannot name its origin. This is the property of our perception mechanism.

Diseases of the upper respiratory tract, allergy attacks can block the nasal passages or dull the sharpness of the olfactory receptors. But there is also a chronic loss of smell, the so-called anosmia.

Even people who do not complain about their sense of smell may not be able to smell some odors. So, J. Emur from the University of California found that 47% of the population do not smell the hormone androsterone, 36% do not smell malt, 12% - musk. Such perceptual features are inherited, and the study of the sense of smell in twins confirms this.

Despite all the shortcomings of our olfactory system, the human nose is generally better at detecting the presence of an odor than any instrument. Nevertheless, devices are necessary to accurately determine the composition of the smell. Gas chromatographs and mass spectrographs are commonly used to analyze odor components. The chromatograph separates the odor components, which then enter the mass spectrograph, where their chemical structure is determined.

Sometimes a person's sense of smell is used in combination with a device. For example, manufacturers of perfumes and fragrant food additives, in order to reproduce, for example, the aroma of fresh strawberries, use a chromatograph to split it into more than a hundred components. An experienced odor taster inhales an inert gas with these components emerging from the chromatograph in turn, and determines the three or four main components that are most noticeable to a person. These substances can then be synthesized and mixed in the appropriate proportion to obtain a natural aroma.

Ancient Oriental medicine used smells for diagnosis. Often doctors, lacking sophisticated instruments and chemical tests, relied on their own sense of smell to make a diagnosis. In the old medical literature there is information that, for example, the smell emitted by a sick typhus is similar to the aroma of freshly baked black bread, and the smell of sour beer comes from patients with scrofula (a form of tuberculosis).

Today, doctors are rediscovering the value of odor diagnostics. So it was found that the specific smell of saliva indicates gum disease. Some doctors are experimenting with smell catalogs - pieces of paper soaked in various compounds, the smell of which is characteristic of a particular disease. The smell of the leaves is compared with the smell emanating from the patient.

Some medical centers have special facilities for studying the smells of diseases. The patient is placed in a cylindrical chamber through which a stream of air is passed. At the outlet, the air is analyzed by gas chromatographs and mass spectrographs. The possibilities of using such a device as a tool for diagnosing a number of diseases, especially diseases associated with metabolic disorders, are being studied.

Smell and the sense of smell are much more complex phenomena and affect our lives to a greater extent than we thought until recently, and it seems that scientists dealing with this range of problems are on the verge of many amazing discoveries.

visual sensations- a type of sensation caused by exposure to the visual system of electromagnetic waves in the range from 380 to 780 billionths of a meter. This range occupies only a part of the electromagnetic spectrum. Waves that are within this range and differ in length give rise to sensations of different colors. The table below provides data that reflects the dependence of color perception on the length of electromagnetic waves. (The table shows the data developed by R.S. Nemov)

The apparatus of vision is the eye. Light waves reflected by an object are refracted, passing through the lens of the eye, and formed on the retina in the form of an image - an image. The expression: “It is better to see once than hear a hundred times,” speaks of the greatest objectivity of the visual sensation. Visual sensations are divided into:

Achromatic, reflecting the transition from darkness to light (from black to white) through a mass of shades of gray;

Chromatic, reflecting the color gamut with numerous shades and color transitions - red, orange, yellow, green, blue, indigo, violet.

The emotional impact of color is associated with its physiological, psychological and social meaning.

auditory sensationsare the result of mechanical action on the receptors of sound waves with an oscillation frequency of 16 to 20,000 Hz. Hertz is a physical unit by which the frequency of air oscillations per second is estimated, numerically equal to one oscillation per second. Fluctuations in air pressure, following with a certain frequency and characterized by the periodic appearance of areas of high and low pressure, are perceived by us as sounds of a certain height and loudness. The higher the frequency of air pressure fluctuations, the higher the sound we perceive.

There are three types of sound sensations:

Noises and other sounds (arising in nature and in the artificial environment);

Speech, (associated with communication and mass media);

Musical (artificially created by man for artificial experiences).

In these types of sensations, the auditory analyzer distinguishes four qualities of sound:

Strength (loudness, measured in decibels);

Height (high and low oscillation frequency per unit time);

Timbre (originality of coloring of sound - speech and music);

Duration (sounding time plus tempo-rhythmic pattern).

It is known that a newborn is able to recognize distinct sounds of different intensity from the very first hours. He can even distinguish his mother's voice from other voices saying his name. The development of this ability begins even in the period of intrauterine life (hearing, as well as vision, already functions in a seven-month-old fetus).

In the process of human development, the sense organs have also developed, as well as the functional place of various sensations in the life of people from the point of view of their ability to “deliver” biologically significant information. Thus, for example, optical images formed on the retina of the eye (retinal images) are light patterns that are important only in so far as they can be used to recognize the non-optical properties of things. The image cannot be eaten, just as it cannot eat itself; biologically the images are inconsequential.

The same cannot be said for all sensory information in general. After all, the senses of taste and touch directly convey biologically important information: whether the object is solid or hot, edible or inedible. These senses give the brain the information it needs to keep alive; moreover, the significance of such information does not depend on what the given object is as a whole.

This information is also important in addition to the identification of objects. Whether there is a burning sensation in the hand from the flame of a match, from a red-hot iron, or from a stream of boiling water, the difference is small - the hand is in all cases withdrawn. The main thing is that there is a sensation of a burn; it is this sensation that is transmitted directly, the nature of the object can be established later. Reactions of this kind are primitive, subperceptual; they are reactions to physical conditions, not to the object itself. Recognition of an object and response to its hidden properties appear much later.

In the process of biological evolution, it seems that the first senses arose that provide a reaction to precisely such physical conditions that are directly necessary for the preservation of life. Touch, taste, and the perception of temperature changes must have arisen before sight, because in order to perceive visual images, they must be interpreted - only in this way can they be connected with the world of objects.

The need for interpretation requires a complex nervous system (a kind of "thinker"), since behavior is guided more by a guess about what objects are than by direct sensory information about them. The question arises: did the appearance of the eye precede the development of the brain, or vice versa? Indeed, why do we need an eye if there is no brain capable of interpreting visual information? But, on the other hand, why do we need a brain that can do this, if there are no eyes capable of “feeding” the brain with relevant information?

It is possible that development followed the path of transformation of the primitive nervous system, which responds to touch, into the visual system that serves primitive eyes, since the skin was sensitive not only to touch, but also to light. Vision developed, probably, from a reaction to shadows moving on the surface of the skin - a signal of imminent danger. Only later, with the emergence of an optical system capable of forming an image in the eye, did the recognition of objects appear.

Apparently, the development of vision went through several stages: first, light-sensitive cells, previously scattered over the surface of the skin, were concentrated, then “eye cups” were formed, the bottom of which was covered with light-sensitive cells. The “glasses” gradually deepened, as a result of which the contrast of the shadows falling on the bottom of the “glass” increased, the walls of which more and more protected the light-sensitive bottom from oblique rays of light.

The lens, apparently, at first was just a transparent window that protected the "eye cup" from clogging with particles floating in sea water - then it was a permanent habitat for living beings. These protective windows gradually thickened in the center, as this gave a quantitative positive effect - it increased the intensity of illumination of light-sensitive cells, and then there was a qualitative leap - the central thickening of the window led to the appearance of the image; this is how the real “image-creating” eye appeared. The ancient nervous system - the touch analyzer - received an ordered pattern of light spots at its disposal.

The sense of touch can communicate the shape of an object in two very different ways. When an object is in contact with a large surface of the skin, signals about the shape of the object enter the central nervous system through many skin receptors simultaneously along many parallel nerve fibers. But the signals that characterize the form can also be transmitted with one finger (or other probe), which explores the forms, moving along them for some time. A moving probe can transmit signals not only about two-dimensional forms with which it is in direct contact, but also about three-dimensional bodies.

The perception of tactile sensations is not mediated - this is a direct method of research, and the radius of its application is limited by the need for close contact. But this means that if the touch "recognizes the enemy" - there is no time to choose the tactics of behavior. Immediate action is needed, which, precisely for this reason, cannot be either subtle or planned.

The eyes, on the other hand, penetrate into the future, because they signal distant objects. It is very likely that the brain - as we know it - could not have evolved without an influx of information about distant objects, information supplied by other senses, especially vision. It can be said without exaggeration that the eyes “liberated” the nervous system from the “tyranny” of reflexes, allowing the transition from reactive behavior to planned behavior, and ultimately to abstract thinking.

4. BASIC PROPERTIES OF SENSATIONS

Feel is a form of reflection of adequate stimuli. So, an adequate stimulus of visual sensation is electromagnetic radiation, characterized by wavelengths in the range from 380 to 780 millimicrons, which are transformed in the visual analyzer into a nervous process that generates a visual sensation. Excitability - the property of living matter to come into a state of excitation under the influence of stimuli and retain its traces for some time.

Auditory sensations are the result of reflection sound waves, acting on receptors. Tactile sensations are caused by the action of mechanical stimuli on the surface of the skin. Vibratory, which acquire special significance for the deaf, are caused by the vibration of objects. Other sensations (temperature, olfactory, taste) also have their own specific stimuli. However, different types of sensations are characterized not only by specificity, but also by properties common to them. These properties include:spatial localization- displaying the location of the stimulus in space. So, for example, contact sensations (tactile, pain, taste) are correlated with that part of the body that is affected by the stimulus. At the same time, the localization of pain sensations is more “spilled” and less accurate than tactile ones.Spatial Threshold- the minimum size of a barely perceptible stimulus, as well as the minimum distance between stimuli, when this distance is still felt.

Feeling intensity- a quantitative characteristic that reflects the subjective magnitude of the sensation and is determined by the strength of the stimulus and the functional state of the analyzer.

Emotional tone of sensations- the quality of sensation, manifested in its ability to cause certain positive or negative emotions.

Feeling speed(or time threshold) - the minimum time required to reflect external influences.

Differentiation, subtlety of sensations- an indicator of distinctive sensitivity, the ability to distinguish between two or more stimuli.

Adequacy, accuracy of feeling- the correspondence of the sensation to the characteristics of the stimulus.

Quality (feelings of a given modality)- this is the main feature of this sensation, which distinguishes it from other types of sensation and varies within a given type of sensation (a given modality). So, auditory sensations differ in pitch, timbre, loudness; visual - by saturation, color tone, etc. The qualitative variety of sensations reflects the infinite variety of forms of motion of matter.

Sensitivity Stability– the duration of maintaining the required intensity of sensations.

Duration of sensationis its temporal characteristic. It is also determined by the functional state of the sense organ, but mainly by the duration of the stimulus and its intensity. The latent period for different types of sensations is not the same: for tactile sensations, for example, it is 130 milliseconds, for pain - 370 milliseconds. A taste sensation occurs 50 milliseconds after a chemical irritant is applied to the surface of the tongue.

Just as a sensation does not arise simultaneously with the beginning of the action of the stimulus, it does not disappear simultaneously with the termination of the latter. This inertia of sensations is manifested in the so-called aftereffect.

The visual sensation has some inertia and does not disappear immediately after the stimulus that caused it ceases to act. The trace from the stimulus remains in the formserial image. Distinguish between positive and negative sequential images. A positive consistent image in terms of lightness and color corresponds to the initial irritation. The principle of cinematography is based on the inertia of vision, on the preservation of a visual impression for a certain period of time in the form of a positive consistent image. The sequential image changes in time, while the positive image is replaced by a negative one. With colored light sources, there is a transition of a sequential image into a complementary color.

I. Goethe wrote in his “Essay on the Doctrine of Color”: “When one evening I went into a hotel and a tall girl with a dazzlingly white face, black hair and a bright red corsage came into my room, I gazed at her, standing in the semi-darkness at some distance from me. After she left there, I saw on the light wall opposite me a black face, surrounded by a light radiance, while the clothes of a completely clear figure seemed to me the beautiful green color of the sea wave.

The appearance of successive images can be explained scientifically. As is known, the presence of color-sensing elements of three types is assumed in the retina of the eye. In the process of irritation, they get tired and become less sensitive. When we look at red, the corresponding receivers get more fatigued than the others, so when white light then falls on the same area of ​​the retina, the other two types of receivers remain more sensitive and we see blue-green.

Auditory sensations, like visual sensations, can also be accompanied by successive images. The most comparable phenomenon in this case is “ringing in the ears”, i.e. an unpleasant sensation that often accompanies exposure to deafening sounds. After a series of short sound impulses acts on the auditory analyzer for several seconds, they begin to be perceived in a single or muffled way. This phenomenon is observed after the cessation of the sound pulse and continues for several seconds, depending on the intensity and duration of the pulse.

A similar phenomenon occurs in other analyzers. For example, temperature, pain and taste sensations also continue for some time after the action of the stimulus.

5. SENSITIVITY AND ITS MEASUREMENT

Various sense organs that give us information about the state of the external world around us can be more or less sensitive to the phenomena they display, that is, they can display these phenomena with greater or lesser accuracy. In order for a sensation to arise as a result of the action of a stimulus on the sense organs, it is necessary that the stimulus causing it reach a certain value. This value is called the lower absolute threshold of sensitivity.Lower absolute threshold of sensitivity- the minimum strength of the stimulus, causing a barely noticeable sensation. This is the threshold of conscious recognition of the stimulus.

However, there is another, "lower" threshold -physiological. This threshold reflects the sensitivity limit of each receptor, beyond which excitation can no longer occur (see Figure 3).

So, for example, one photon may be enough to excite the receptor in the retina, but 5-8 such portions of energy are needed for our brain to perceive a luminous dot. It is quite clear that the physiological threshold of sensations is genetically determined and can only change depending on age or other physiological factors. The threshold of perception (conscious recognition), on the contrary, is much less stable. In addition to the above factors, it also depends on the level of wakefulness of the brain, on the attention of the brain to a signal that has overcome the physiological threshold.

Between these two thresholds there is a zone of sensitivity in which the excitation of the receptors entails the transmission of a message, but it does not reach consciousness. Despite the fact that the environment at any moment sends us thousands of various signals, we can only catch a small part of them.

At the same time, being unconscious, being below the lower threshold of sensitivity, these stimuli (subsensory) are capable of influencing conscious sensations. With the help of such sensitivity, for example, our mood can change, in some cases they affect the desires and interest of a person in certain objects of reality.

Currently, there is a hypothesis that in the area below the level of consciousness - in the subthreshold zone - the signals perceived by the senses may be processed by the lower centers of our brain. If so, then every second there must be hundreds of signals that pass by our consciousness, but are nevertheless registered at lower levels.

This hypothesis allows us to find an explanation for many controversial phenomena. Especially when it comes to perceptual defense, subthreshold and extrasensory perception, awareness of inner reality in conditions such as sensory isolation or in a state of meditation.

The fact that stimuli of lesser strength (subthreshold) do not cause sensations is biologically expedient. The cortex at every single moment of an infinite number of impulses perceives only the vital ones, delaying all the rest, including impulses from the internal organs. It is impossible to imagine the life of an organism in which the cerebral cortex would equally perceive all impulses and provide reactions to them. This would lead the body to inevitable death. It is the cerebral cortex that “guards” the vital interests of the body and, by raising the threshold of its excitability, turns irrelevant impulses into subthreshold ones, thereby relieving the body of unnecessary reactions.

However, subthreshold impulses are not indifferent to the organism. This is confirmed by numerous facts obtained in the clinic of nervous diseases, when it is precisely weak, subcortical stimuli from the external environment that create a dominant focus in the cerebral cortex and contribute to the occurrence of hallucinations and "deception of the senses." Subthreshold sounds can be perceived by the patient as a host of intrusive voices with simultaneous complete indifference to real human speech; a weak, barely noticeable beam of light can cause hallucinatory visual sensations of various contents; barely noticeable tactile sensations - from skin contact with clothing - a number of all kinds of acute skin sensations.

The transition from imperceptible stimuli that do not cause sensations to perceived stimuli does not occur gradually, but abruptly. If the impact has already almost reached the threshold value, then it may be enough to slightly change the magnitude of the current stimulus so that it turns from completely imperceptible to fully perceptible.

At the same time, even very significant changes in the magnitude of stimuli within the subthreshold range do not give rise to any sensations, with the exception of the subsensory stimuli considered above and, accordingly, subsensory sensations. In the same way, significant changes in the meaning of already sufficiently strong, transthreshold stimuli may also not cause any changes in already existing sensations.

So, the lower threshold of sensations determines the level of absolute sensitivity of this analyzer, associated with the conscious recognition of the stimulus. There is an inverse relationship between absolute sensitivity and the threshold value: the lower the threshold value, the higher the sensitivity of this analyzer. This relationship can be expressed by the formula:

E - 1 / P,

where: E - sensitivity, and P - threshold value of the stimulus.

Our analyzers have different sensitivities. Thus, the threshold of one human olfactory cell for the corresponding odorous substances does not exceed 8 molecules. However, it takes at least 25,000 times more molecules to produce a taste sensation than it does to produce an olfactory sensation.

The sensitivity of the visual and auditory analyzer is very high. The human eye, as the experiments of S.I. Vavilov (1891-1951) showed, is able to see light when only 2-8 quanta of radiant energy hit the retina. This means that we would be able to see a burning candle in complete darkness at a distance of up to 27 kilometers. At the same time, in order for us to feel touch, we need 100–10,000,000 times more energy than with visual or auditory sensations.

Each type of sensation has its own thresholds. Some of them are presented in table 2.

The average values ​​of the absolute thresholds for the occurrence of sensations for different human senses

The absolute sensitivity of the analyzer is characterized not only by the lower, but also by the upper threshold of sensation.Upper absolute threshold of sensitivitycalled the maximum strength of the stimulus, at which there is still an adequate sensation to the acting stimulus. A further increase in the strength of stimuli acting on our receptors causes only a painful sensation in them (for example, an ultra-loud sound, a blinding light).

The value of absolute thresholds, both lower and upper, varies depending on various conditions: the nature of the activity and the age of the person, the functional state of the receptor, the strength and duration of stimulation, etc.

The sensation does not arise immediately, as soon as the desired stimulus begins to act. Between the onset of the action of the stimulus and the appearance of sensation, a certain time passes. It is called the latency period.Latent (temporary) period of sensation- the time from the onset of the stimulus to the onset of sensation. During the latent period, the energy of the acting stimuli is converted into nerve impulses, they pass through specific and non-specific structures of the nervous system, and they switch from one level of the nervous system to another. By the duration of the latent period, one can judge the afferent structures of the central nervous system through which nerve impulses pass before reaching the cerebral cortex.

With the help of the sense organs, we can not only ascertain the presence or absence of a particular stimulus, but also distinguish stimuli by their strength and quality. The smallest difference between two stimuli that causes a barely perceptible difference in sensations is calledthreshold of discrimination, or difference threshold.

The German physiologist E. Weber (1795-1878), testing a person's ability to determine the heavier of the two objects in the right and left hand, found that the difference sensitivity is relative, not absolute. This means that the ratio of the additional stimulus to the main stimulus must be a constant value. So, if there is a load of 100 grams on the arm, then for a barely noticeable feeling of weight gain, you need to add about 3.4 grams. If the weight of the load is 1000 grams, then for a sensation of a barely noticeable difference, you need to add about 33.3 grams. Thus, the greater the value of the initial stimulus, the greater should be the increase to it.

The difference threshold is related to andoperational discrimination threshold- the value of the difference between the signals, at which the accuracy and speed of discrimination reach a maximum.

The threshold of discrimination for different sense organs is different, but for the same analyzer it is a constant value. For the visual analyzer, this value is a ratio of approximately 1/100, for the auditory - 1/10, for the tactile - 1/30. Experimental verification of this provision showed that it is valid only for stimuli of medium strength.

The constant value itself, expressing the ratio of that increment of the stimulus to its initial level, which causes the sensation of a minimal change in the stimulus, was calledWeber constants. Its values ​​for some human senses are shown in Table 3.

The value of the Weber constant for different senses

This law of constancy of the magnitude of the increment of the stimulus was established, independently of each other, by the French scientist P. Bouguer and the German scientist E. Weber and was called the Bouguer-Weber law.Bouguer-Weber law- a psychophysical law expressing the constancy of the ratio of the increment in the magnitude of the stimulus, which gave rise to a barely noticeable change in the strength of sensation to its original value:

I / I \u003d K,

where: I - the initial value of the stimulus,  I - its increment, K is a constant.

Another identified pattern of sensations is associated with the name of the German physicist G. Fechner (1801-1887). Due to the partial blindness caused by observing the sun, he took up the study of sensations. At the center of his attention is the long-known fact of differences between sensations depending on what was the initial magnitude of the stimuli that caused them. G. Fechner drew attention to the fact that similar experiments were carried out a quarter of a century earlier by E. Weber, who introduced the concept of “barely noticeable difference between sensations”. It is not always the same for all views. This is how the idea of ​​the thresholds of sensations appeared, that is, the magnitude of the stimulus that causes or changes the sensation.

Investigating the relationship that exists between changes in the strength of stimuli affecting the human senses and the corresponding changes in the magnitude of sensations, and taking into account the experimental data of Weber, G. Fechner expressed the dependence of the intensity of sensations on the strength of the stimulus by the following formula:

S = K lg J + C,

where: S is the intensity of sensation, J is the strength of the stimulus, K and C are constants.

According to this provision, which is calledbasic psychophysical law,the intensity of sensation is proportional to the logarithm of the strength of the stimulus. In other words, with an increase in the strength of the stimulus in a geometric progression, the intensity of the sensation increases in an arithmetic progression. This ratio was called the Weber-Fechner law, and G. Fechner's book Fundamentals of Psychophysics was of key importance for the development of psychology as an independent experimental science.

There is also stevens law - one of the variants of the basic psychophysical law, assuming the presence of not a logarithmic, but a power-law functional relationship between the magnitude of the stimulus and the strength of sensation:

S = K * In,

where: S is the power of sensation, I - the magnitude of the current stimulus, K and n are constants.

The dispute about which of the laws better reflects the dependence of the stimulus and sensation did not end with the success of any of the parties leading the discussion. However, these laws have one thing in common: both of them state that sensations change disproportionately to the strength of physical stimuli acting on the sense organs, and the strength of these sensations grows much more slowly than the magnitude of physical stimuli.

According to this law, in order for the strength of sensation, which has a conditional initial value of 0, to become equal to 1, it is necessary that the value of the stimulus that initially caused it increase by 10 times. Further, in order for the sensation having a value of 1 to increase three times, it is necessary that the initial stimulus, which is 10 units, become equal to 1000 units, etc., i.e. each subsequent increase in the strength of sensation by one unit requires an increase in the stimulus ten times.

Difference sensitivity, or sensitivity to discrimination, is also inversely related to the value of the discrimination threshold: the higher the discrimination threshold, the lower the difference sensitivity. The concept of differential sensitivity is used not only to characterize the discrimination of stimuli by intensity, but also in relation to other features of certain types of sensitivity. For example, they talk about sensitivity to distinguishing shapes, sizes and colors of visually perceived objects or about sound-altitude sensitivity.

Subsequently, when the electron microscope was invented and the electrical activity of individual neurons was studied, it turned out that the generation of electrical impulses obeys the Weber-Fechner law. This indicates that this law owes its origin mainly to electrochemical processes occurring in receptors and converting the acting energy into nerve impulses.

6. ADAPTATION OF SENSORS

Although our sense organs are limited in their ability to perceive signals, nevertheless, they are under the constant influence of stimuli. The brain, which must process the received signals, is often threatened by information overload, and it would not have time to “sort and arrange” it if there were no regulatory mechanisms that maintain the number of perceived stimuli at a more or less constant acceptable level.

This mechanism, called sensory adaptation, operates in the receptors themselves.Sensory adaptation, or adaptation is a change in the sensitivity of the sense organs under the influence of the action of a stimulus. It reduces their sensitivity to repetitive or long-term (weak, strong) stimuli. There are three types of this phenomenon.

1. Adaptation as the complete disappearance of sensation in the process of prolonged action of the stimulus.

In the case of constant stimuli, the sensation tends to fade. For example, a light load lying on the skin soon ceases to be felt. The distinct disappearance of olfactory sensations shortly after we enter an atmosphere with an unpleasant odor is also a common fact. The intensity of the taste sensation is weakened if the corresponding substance is kept in the mouth for some time, and finally the sensation may die out altogether.

Full adaptation of the visual analyzer under the action of a constant and immobile stimulus does not occur. This is due to compensation for the immobility of the stimulus due to the movements of the receptor apparatus itself. Constant voluntary and involuntary eye movements ensure the continuity of the visual sensation. Experiments in which the conditions for image stabilization relative to the retina were artificially created showed that in this case, the visual sensation disappears 2–3 seconds after its occurrence, i.e. complete adaptation occurs (stabilization in the experiment was achieved using a special suction cup, on which an image was placed that moved along with the eye).

2. Adaptation is also called another phenomenon, close to the one described, which is expressed in the dulling of sensation under the influence of a strong stimulus. For example, when a hand is immersed in cold water, the intensity of the sensation caused by a cold stimulus decreases. When we get from a semi-dark room into a brightly lit space (for example, leaving the cinema to the street), we are first blinded and unable to distinguish any details around. After some time, the sensitivity of the visual analyzer decreases sharply, and we begin to see normally. This decrease in the sensitivity of the eye to intense light stimulation is called light adaptation.

The described two types of adaptation can be called negative adaptation, since as a result of them the sensitivity of the analyzers decreases.Negative adaptation- a type of sensory adaptation, expressed in the complete disappearance of sensation in the process of prolonged action of the stimulus, as well as in the dulling of sensation under the influence of the action of a strong stimulus.

3. Finally, adaptation is called an increase in sensitivity under the influence of a weak stimulus. This kind of adaptation, which is characteristic of certain types of sensations, can be defined as positive adaptation.Positive adaptation- a type of increased sensitivity under the influence of the action of a weak stimulus.

In the visual analyzer, this is adaptation to darkness, when the sensitivity of the eye increases under the influence of being in the dark. A similar form of auditory adaptation is silence adaptation. In temperature sensations, positive adaptation is found when a pre-cooled hand feels warm, and a pre-heated hand feels cold when immersed in water of the same temperature. The question of the existence of negative pain adaptation has long been controversial. It is known that repeated use of a painful stimulus does not reveal negative adaptation, but on the contrary, it acts more and more strongly over time. However, new facts indicate the presence of a complete negative adaptation to needle pricks and intense hot irradiation.

Studies have shown that some analyzers detect fast adaptation, others slow. For example, touch receptors adapt very quickly. On their sensory nerve, when exposed to any prolonged stimulus, only a small “volley” of impulses runs at the beginning of the stimulus. The visual receptor adapts relatively slowly (the time of tempo adaptation reaches several tens of minutes), the olfactory and gustatory receptors.

Adaptive regulation of the level of sensitivity, depending on which stimuli (weak or strong) affect the receptors, is of great biological importance. Adaptation helps (through the sense organs) to catch weak stimuli and protects the sense organs from excessive irritation in case of unusually strong influences.

The phenomenon of adaptation can be explained by those peripheral changes that occur in the functioning of the receptor during prolonged exposure to a stimulus. So, it is known that under the influence of light, visual purple, located in the rods of the retina, decomposes (fades). In the dark, on the contrary, visual purple is restored, which leads to an increase in sensitivity.

In order for the human eye to be able to fully adapt to darkness after daylight, i.e. it takes 40 minutes for its sensitivity to approach the absolute threshold. During this time, vision changes according to its physiological mechanism: from cone vision, characteristic of daylight, within 10 minutes, the eye passes to rod vision, typical of the night. At the same time, the sensations of color disappear, they are replaced by black and white tones, characteristic of achromatic vision.

With regard to other sense organs, it has not yet been proven that their receptor apparatuses contain any substances that chemically decompose when exposed to a stimulus and are restored in the absence of such exposure.

The phenomenon of adaptation is also explained by the processes taking place in the central sections of the analyzers. With prolonged stimulation, the cerebral cortex responds with internal protective inhibition, which reduces sensitivity. The development of inhibition causes increased excitation of other foci, which contributes to an increase in sensitivity in new conditions (the phenomenon of successive mutual induction).

Another regulatory mechanism is located at the base of the brain, in the reticular formation. It enters into action in the case of more complex stimulation, which, although captured by receptors, is not so important for the survival of the organism or for the activity in which it is currently engaged. We are talking about addiction, when certain stimuli become so habitual that they cease to affect the activity of the higher parts of the brain: the reticular formation blocks the transmission of the corresponding impulses so that they do not “clutter up” our consciousness. For example, the greenery of meadows and foliage after a long winter seems very bright to us at first, and after a few days we get used to it so much that we simply stop noticing it. A similar phenomenon is observed in people living near an airfield or highway. They no longer “hear” the noise of planes taking off or passing trucks. The same thing happens with a city dweller who ceases to feel the chemical taste of drinking water, and on the street does not smell the exhaust gases of cars or does not hear car signals.

Thanks to this useful mechanism (the mechanism of habituation), it is easier for a person to notice any change or a new element in the environment, it is easier to concentrate his attention on it, and, if necessary, to resist it. This kind of mechanism allows us to focus all our attention on some important task, ignoring the usual noise and bustle around us.

7. INTERACTION OF SENSATIONS: SENSITIZATION AND SYNESTHESIA

The intensity of sensations depends not only on the strength of the stimulus and the level of adaptation of the receptor, but also on the stimuli currently affecting other sense organs. A change in the sensitivity of the analyzer under the influence of irritation of other sense organs is calledinteraction of sensations.

The literature describes numerous facts of sensitivity changes caused by the interaction of sensations. Thus, the sensitivity of the visual analyzer changes under the influence of auditory stimulation. S.V. Kravkov (1893-1951) showed that this change depends on the loudness of auditory stimuli. Weak auditory stimuli increase the color sensitivity of the visual analyzer. At the same time, a sharp deterioration in the distinguishing sensitivity of the eye is observed when, for example, the noise of an aircraft engine is used as an auditory stimulus.

Visual sensitivity also increases under the influence of certain olfactory stimuli. However, with a pronounced negative emotional coloring of the smell, a decrease in visual sensitivity is observed. Similarly, with weak light stimuli, auditory sensations increase, with intense light stimuli, auditory sensitivity worsens. There are known facts of increasing visual, auditory, tactile and olfactory sensitivity under the influence of weak pain stimuli.

A change in the sensitivity of any analyzer can also occur with subthreshold stimulation of other analyzers. So, P.P. Lazarev (1878-1942) obtained evidence of a decrease in visual sensitivity under the influence of skin irradiation with ultraviolet rays.

Thus, all our analyzer systems are capable of influencing each other to a greater or lesser extent. At the same time, the interaction of sensations, like adaptation, manifests itself in two opposite processes: an increase and a decrease in sensitivity. The general pattern here is that weak stimuli increase, and strong ones decrease the sensitivity of the analyzers during their interaction. The increase in sensitivity as a result of the interaction of analyzers and exercises is calledsensitization.

The physiological mechanism for the interaction of sensations is the processes of irradiation and concentration of excitation in the cerebral cortex, where the central sections of the analyzers are represented. According to IP Pavlov, a weak stimulus causes an excitation process in the cerebral cortex, which easily irradiates (spreads). As a result of the irradiation of the excitation process, the sensitivity of another analyzer increases.

Under the action of a strong stimulus, a process of excitation occurs, which, on the contrary, has a tendency to concentration. According to the law of mutual induction, this leads to inhibition in the central sections of other analyzers and a decrease in the sensitivity of the latter. Changes in the sensitivity of the analyzers can be caused by exposure to secondary signal stimuli. Thus, the facts of changes in the electrical sensitivity of the eyes and tongue in response to the presentation of the words "sour as a lemon" to the subjects were obtained. These changes were similar to those observed when the tongue was actually irritated with lemon juice.

Knowing the patterns of changes in the sensitivity of the sense organs, it is possible, by using specially selected side stimuli, to sensitize one or another receptor, i.e. increase its sensitivity. Sensitization can also be achieved through exercise. It is known, for example, how pitch hearing develops in children who study music.

The interaction of sensations is manifested in another kind of phenomena called synesthesia. Synesthesia - this is the appearance under the influence of irritation of one analyzer of a sensation characteristic of another analyzer. Synesthesia is seen in a wide variety of sensations. The most common visual-auditory synesthesia, when, under the influence of sound stimuli, the subject has visual images. There is no overlap in these synesthesias between people, however, they are fairly constant for each individual. It is known that some composers (N. A. Rimsky-Korsakov, A. I. Skryabin, and others) possessed the ability of color hearing.

The phenomenon of synesthesia is the basis for the creation in recent years of color-music devices that turn sound images into color, and an intensive study of color music. Less common are cases of auditory sensations when exposed to visual stimuli, taste sensations in response to auditory stimuli, etc. Not all people have synesthesia, although it is quite widespread. No one doubts the possibility of using such expressions as “sharp taste”, “screaming color”, “sweet sounds”, etc. The phenomena of synesthesia are another evidence of the constant interconnection of the analyzer systems of the human body, the integrity of the sensory reflection of the objective world ( according to T.P. Zinchenko).

8. SENSITIVITY AND EXERCISE

Sensitization of the sense organs is possible not only through the use of side stimuli, but also through exercise. The possibilities for training the sense organs and their improvement are endless. There are two areas that determine the increase in the sensitivity of the senses:

1) sensitization, which spontaneously leads to the need to compensate for sensory defects (blindness, deafness);

2) sensitization caused by activity, specific requirements of the subject's profession.

Loss of sight or hearing is compensated to a certain extent by the development of other types of sensitivity. There are cases when people deprived of sight are engaged in sculpture, their sense of touch is well developed. The development of vibrational sensations in the deaf belongs to the same group of phenomena.

Some deaf people develop vibration sensitivity to such an extent that they can even listen to music. To do this, they put their hand on the instrument or turn their backs to the orchestra. Some deaf-blind-mutes, holding their hand to the throat of a speaking interlocutor, can thus recognize him by his voice and understand what he is talking about. Due to their highly developed olfactory sensitivity, they can associate many close people and acquaintances with the smells emanating from them.

Of particular interest is the emergence in humans of sensitivity to stimuli for which there is no adequate receptor. Such, for example, is the remote sensitivity to obstacles in the blind. The phenomena of sensitization of the sense organs are observed in persons with certain special professions. The extraordinary visual acuity of grinders is known. They see gaps from 0.0005 millimeters, while untrained people - only up to 0.1 millimeters. Fabric dyeers distinguish between 40 and 60 shades of black. To the untrained eye, they appear exactly the same. Experienced steelmakers are able to quite accurately determine its temperature and the amount of impurities in it from the faint color shades of molten steel.

A high degree of perfection is achieved by olfactory and gustatory sensations in tasters of tea, cheese, wine, and tobacco. Tasters can tell exactly not only which grape variety the wine is made from, but also name the place where this grape was grown.

Painting makes special demands on the perception of shapes, proportions and color relationships when depicting objects. Experiments show that the artist's eye is extremely sensitive to the assessment of proportions. He distinguishes between changes equal to 1/60-1/150 of the size of the subject. The subtlety of color sensations can be judged by the mosaic workshop in Rome - it contains more than 20,000 shades of primary colors created by man.

Opportunities for the development of auditory sensitivity are also quite large. Thus, playing the violin requires a special development of pitch hearing, and it is more developed among violinists than among pianists. In people who have difficulty distinguishing the pitch, it is possible, through special exercises, to improve pitch hearing. Experienced pilots can easily determine the number of engine revolutions by ear. They freely distinguish between 1300 and 1340 rpm. Untrained people catch the difference only between 1300 and 1400 rpm.

All this is proof that our sensations develop under the influence of the conditions of life and the requirements of practical labor activity.

Despite the large number of such facts, the problem of exercising the sense organs has not yet been studied enough. What underlies the exercise of the sense organs? It is not yet possible to give an exhaustive answer to this question. An attempt has been made to explain the increased tactile sensitivity in the blind. It was possible to isolate tactile receptors - Pacinian corpuscles, present in the skin of the fingers of blind people. For comparison, the same study was conducted on the skin of sighted people of various professions. It turned out that the number of tactile receptors is increased in the blind. So, if in the skin of the nail phalanx of the thumb in the sighted the number of bodies on average reached 186, then in the blind born it was 270.

Thus, the structure of receptors is not constant, it is plastic, mobile, constantly changing, adapting to the best performance of a given receptor function. Together with the receptors and inseparably from them, in accordance with the new conditions and requirements of practical activity, the structure of the analyzer as a whole is also being reconstructed.

Progress entails a colossal information overload of the main channels of communication between a person and the external environment - visual and auditory. Under these conditions, the need to “unload” the visual and auditory analyzers inevitably leads to an appeal to other communication systems, in particular, to skin systems. Animals have been developing vibrational sensitivity for millions of years, while the idea of ​​transmitting signals through the skin is still new for humans. And there are great opportunities in this regard: after all, the area of ​​​​the human body capable of receiving information is quite large.

For a number of years, attempts have been made to develop a “skin language” based on the use of stimulus properties adequate for vibrational sensitivity, such as the location of the stimulus, its intensity, duration, and frequency of vibrations. The use of the first three of the listed qualities of stimuli made it possible to create and successfully apply a system of coded vibrational signals. A subject who learned the alphabet of the “vibrational language” after some training could perceive sentences dictated at a speed of 38 words per minute, and this result was not the limit. Obviously, the possibilities of using vibrational and other types of sensitivity to transmit information to a person are far from being exhausted, and the importance of developing research in this area can hardly be overestimated.

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Feeling- this is an elementary mental process of reflecting the individual properties of the surrounding reality and the internal states of the body with the direct impact of stimuli on the senses.

Difference between sensation and perception: Sensations reflect individual properties, and not phenomena and objects, as in perception . Sensation is a reflection of not only properties from the external environment, but also states from the internal environment, and perception reflects the properties of only the external world surrounding us. Thus, external phenomena, acting on our senses, cause a subjective effect in the form of sensations without any counter activity of the subject in relation to the perceived impact.

Feeling functions:Cognitive- those. sensations act as channels through which we are connected with the outside world . Energy - It consists in the fact that due to the sensations the necessary level of wakefulness is maintained. Educational - is closely associated with the cognitive function and lies in the fact that the influx of sensations is necessarily necessary for normal mental development, it is especially dangerous if sensations do not arrive during sensitive periods of life (periods favorable for the development of a particular mental function - at 1 year, 3 years, 13 -14 years old). The range of human sensations is strongly related to the way of life and the state of the body.

Classification of sensations: Exteroceptive- sensations from outside, contact and distant. Interoceptive- irritants from the internal environment, which we are sometimes not even aware of. proprioceptive- sensations from our musculoskeletal system.

Kinds: visual auditory, gustatory, tactile, organic.

Patterns of feeling: 1) there is a min. (lower threshold) and max. (upper threshold of sensations); 2) The presence of a difference threshold; 3) Adaptation (this is a change in the sensory analyzer under the influence of prolonged exposure to an irritant); 4) Sensitization (the mutual influence of the stimulus of one receptor on the work of another). Sensations do not occur immediately after the onset of the stimulus: there is a very short period of time when the stimulus is active, but there are no sensations.

Perception - this is a holistic reflection in the mind of a person of objects and phenomena that directly affect his senses as a whole, and not their individual properties, as happens during sensation. Perception is a reflection of a complex stimulus. There are four levels of perceptual action: detection, discrimination, identification and recognition. The first two relate to perceptual, the last - to identification actions.

Detection- the initial phase of development of any sensory process. At this stage, the subject can only answer the simple question of whether there is a stimulus. The next perception operation is distinction, or perception itself. Its end result is the formation of a perceptual image of the standard.

Identification is the identification of a directly perceived object with an image stored in memory, or the identification of two simultaneously perceived objects.

Identification also includes categorization (assignment of an object to a certain class of objects perceived earlier) and extraction of the corresponding standard from memory. Perception is divided into unintentional (involuntary) and intentional (arbitrary).

Unintended Perception can be caused both by the features of the surrounding objects (their brightness, unusualness), and by the correspondence of these objects to the interests of the individual. There is no predetermined goal in unintentional perception. There is also no volitional activity in it, which is why it is called involuntary. Walking, for example, along the street, we hear the noise of cars, people talking, we see shop windows, we perceive various smells.

Intentional Perception from the very beginning it is regulated by the task - to perceive this or that object or phenomenon. Intentional perception will be looking at the electrical circuit of the machine being studied, listening to a report, viewing a thematic exhibition. It can be included in any activity (in a labor operation, in the performance of an educational task), it can act as an independent activity - observation- this is an arbitrary systematic perception, which is carried out with a specific, conscious goal with the help of voluntary attention. People perceive the same information differently, subjectively, depending on their interests, needs, abilities. The dependence of perception on the content of a person's mental life, on the characteristics of his personality is apperception name.

Perceptual Properties: Integrity, i.e. perception is always a holistic image of an object. perception is formed in the process of practice.

constancy perception - thanks to it, we perceive the surrounding objects as relatively constant in shape, color, size

Structurality perceptions – perception is not a simple sum of sensations. listening to music, we perceive not individual sounds, but a melody, and recognize it Meaningfulness of perception- perception is closely connected with thinking, with understanding the essence of objects.

Selectivity perception - is manifested in the preferential selection of some objects in comparison with others.

Types of perception. There are: the perception of objects, time, the perception of relationships, movements, space, the perception of a person.

Disorder of perception. The pathology of perception occurs when, for various reasons, the identification of the subjective image of perception with the perceived image is violated, and proceeds against the background of a violation of the automation of various mental processes.

Sensation is the process of reflecting individual properties of objects of the objective world, both the external environment and one's own organism, arising from their direct impact on receptors (sense organs). This is the process of primary information processing, characteristic of both animals and humans. The vital role of sensations is to timely and quickly bring to the central nervous system, as the main organ for controlling activity, information about the state of the external and internal environment, the presence of biologically significant factors in it.

The reflex nature of sensations

Sensations are the initial source of our knowledge about the world. Objects and phenomena of reality that affect our sense organs are called stimuli, and the effect of stimuli on the sense organs is called irritation. Irritation, in turn, causes excitation in the nervous tissue. Sensation arises as a reaction of the nervous system to a stimulus and, like any mental phenomenon, has a reflex character. The physiological mechanism of sensations is the activity of special nervous apparatuses called analyzers. There are various approaches to the classification of sensations. It has long been customary to distinguish five (according to the number of sense organs) basic types of sensations: smell, taste, touch, sight and hearing.

Systematic classification of sensations

There are various approaches to the classification of sensations. Singling out the largest and most significant groups of sensations, they can be divided into three main types: interoceptive, proprioceptive and exterocentric sensations. The former combine signals that reach us from the internal environment of the body; the latter provide information about the position of the body in space and the position of the musculoskeletal system, provide regulation of our movements; finally, others provide signals from the outside world and provide the basis for our conscious behavior.

Individual characteristics

Individual differences in sensations is a little studied area of ​​psychology. It is known that the sensitivity of different sense organs depends on many factors. Influence features of the central nervous system (in individuals with a strong nervous system, sensitivity is lower); emotionality (the emotional ones have a more developed sense of smell); age (hearing acuity is greatest at 13 years old, vision - at 20-30 years old, old people hear low-frequency sounds quite well, and high ones are worse); gender (women are more sensitive to high sounds, and men to low ones); the nature of the activity (steelworkers distinguish the subtlest shades of a hot metal flow, etc.). The main organ of the child's cognition is the mouth, therefore taste sensations appear before the others. At 3-4 weeks of a child's life, auditory and visual concentration appears, which indicates her readiness for visual and auditory sensations. In the third month of life, he begins to master the motor skills of the eyes. The fixation of an object that acts on the analyzer is associated with the coordination of eye movements. The child quickly develops a visual analyzer. Already in the third month, the child localizes sounds, turns his head to the source of the sound, reacts to music and singing. The development of auditory sensations is closely related to language acquisition. I. M. Sechenova emphasized the great importance of kinesthetic sensations in the development of cognitive activity. The perfection of the motor sphere of the child largely depends on them. M. M. Koltsova spoke about the idea of ​​unity and interconnection of all manifestations of the motor analyzer. B. G. Ananiev writes that there are no significant differences in the level of sensitivity of the same analyzers in children, although they are obvious in an adult. In general, the absolute sensitivity of all species reaches a high level of development in the first year of life. Relative sensitivity develops more slowly (rapid development occurs at school age).