Interaction of sensations - Academic discipline “General Psychology”. Cheat sheets

Sensory adaptation

The sensitivity of sensations, both absolute and relative, does not remain unchanged, and their thresholds cannot be expressed in constant numbers.
Absolute and relative sensitivity, as studies have shown, can vary widely. For example, in the dark, vision sharpens 200,000 times, and in strong light its sensitivity decreases significantly. A person's sensitivity changes dramatically depending on the environment. Such changes in sensitivity are associated with the phenomenon of sensory adaptation. This is nothing more than a change in sensitivity that occurs as a result of the adaptation of the sense organ to the stimulus.

Adaptation is expressed in the following:

• Sensitivity decreases when the sense organs are exposed to sufficiently strong stimuli;
• Sensitivity increases when exposed to a weak stimulus or its absence.

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We offer to become the author of the Directory Working Conditions There is no immediate change in sensitivity; this requires a certain time, and the time characteristics for different senses differ. Vision in a dark room acquires the required sensitivity after 30 minutes. The hearing organs adapt to the surrounding background much faster - after 15 seconds.

The phenomenon of thermal adaptation, such as getting used to changes in environmental temperature, is well known. But this phenomenon is only clearly expressed in the middle range. Accustoming to extreme cold or extreme heat is almost never seen. There are phenomena of adaptation to smells.

In the receptor itself, processes occur on which the adaptation of our sensations depends, for example, under the influence of light, visual purple, located in the rods of the retina, decomposes. While in the dark, on the contrary, visual purple is restored, and this leads to increased sensitivity.

The phenomenon of adaptation is also associated with the processes that occur in the central sections of the analyzers. Different excitability of nerve centers affects changes in sensitivity. With prolonged stimulation, the cerebral cortex responds with internal protective inhibition, as a result of which sensitivity decreases. As inhibition develops, the excitation of other foci increases, and this leads to an increase in sensitivity under new conditions.

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Thus, adaptation as an important process speaks of the great plasticity of the organism in its adaptation to environmental conditions.

Text of the book “General Psychology: Answers to Examination Papers”

All colors perceived by humans, even those that appear monochromatic, are the result of a complex interaction of light waves of different lengths. Waves of different lengths simultaneously enter the eye, and the waves mix, resulting in a person seeing one specific color. The laws of color mixing were established through the work of Newton and Helmholtz. Of these laws, two are of greatest interest. Firstly, for each chromatic color you can choose another chromatic color, which, when mixed with the first, gives an achromatic color, i.e. white or gray. These two colors are usually called complementary. Secondly, by mixing two non-complementary colors, a third color is obtained - an intermediate color between the first two. One very important point follows from the above laws: all color tones can be obtained by mixing three appropriately selected chromatic colors. This point is extremely important for understanding the nature of color vision.

In order to understand the nature of color vision, let's get acquainted with the theory of three-color vision, the idea of ​​which was put forward by Lomonosov in 1756, expressed 50 years later by T. Jung, and another 50 years later developed in more detail by Helmholtz. According to Helmholtz's theory, the eye is assumed to have the following three physiological apparatuses: red-sensing, green-sensing and violet-sensing. Isolated excitation of the first gives the sensation of red color. The isolated sensation of the second apparatus gives a sensation of green color, and the excitation of the third gives a violet color. However, as a rule, the light simultaneously affects all three devices or at least two of them. In this case, the excitation of these physiological apparatuses with different intensities and in different proportions in relation to each other produces all known chromatic colors. The sensation of white color occurs when all three apparatuses are uniformly excited.

This theory explains well many phenomena, including the disease of partial color blindness, in which a person cannot distinguish individual colors or shades of color. Most often, there is an inability to distinguish shades of red or green. This disease was named after the English chemist Dalton, who suffered from it.

The ability to see is determined by the presence of a retina in the eye, which is a branch of the optic nerve that enters the eyeball from behind. There are two types of apparatus in the retina: cones and rods (so named because of their shape). Rods and cones are the terminal devices of the nerve fibers of the optic nerve. The retina of the human eye has about 130 million rods and 7 million cones, which are unevenly distributed across the retina. Cones fill the central fovea of ​​the retina, that is, the place where the image of the object we are looking at falls. Toward the edges of the retina, the number of cones decreases. There are more rods at the edges of the retina; in the middle they are practically absent.

Cones have low sensitivity. To provoke their reaction, you need a strong enough light. Therefore, with the help of cones, a person sees in bright light. They are also called day vision devices. Rods are more sensitive and can be used to see at night, which is why they are called night vision devices. However, only with the help of cones do people distinguish colors, since they determine the ability to cause chromatic sensations. In addition, cones provide the necessary visual acuity.

There are people whose cone apparatus does not function, and they see everything around them only in gray. This disease is called complete color blindness. Conversely, there are cases when the rod apparatus does not function. Such people cannot see in the dark. Their disease is called hemeralopia

(“night blindness”).

Touch.

It should be noted that the interaction of motor and skin sensations makes it possible to study the subject in more detail.
This process - the process of combining skin and motor sensations - is called touch
. At one time, the interaction of these types of sensations was studied in detail and interesting experimental data were obtained. Thus, various figures were applied to the skin of the forearm of subjects sitting with their eyes closed: circles, triangles, rhombuses, stars, figures of people, animals, etc. However, they were all perceived as circles. The results were only slightly better when these figures were applied to a stationary palm. But as soon as the subjects were allowed to touch the figures, they immediately and accurately determined their shape.

Thanks to the sense of touch, a person can evaluate such properties of objects as hardness, softness, smoothness, roughness.

You should pay attention to the fact that almost all types of sensations are interconnected. Thanks to this interaction, a person can obtain the most complete information about the world around him. However, this information is limited only to information about the properties of objects.

Sensory adaptation and interaction of sensations

Changes in sensitivity depending on environmental conditions are associated with the phenomenon of sensory adaptation. Sensory adaptation

is a change in sensitivity that occurs as a result of the adaptation of a sensory organ to the stimuli acting on it. As a rule, adaptation is expressed in the fact that when the sense organs are exposed to sufficiently strong stimuli, sensitivity decreases, and when exposed to weak stimuli or in the absence of a stimulus, sensitivity increases.

This change in sensitivity does not occur immediately, but requires a certain amount of time. Moreover, the time characteristics of this process are not the same for different sense organs. So, in order for vision in a dark room to acquire the necessary sensitivity, about 30 minutes should pass. Only after this does a person acquire the ability to navigate well in the dark. Adaptation of the auditory organs occurs much faster. Human hearing adapts to the surrounding background within 15 s. The sensitivity of touch also changes quickly (a slight touch to the skin is no longer perceived after just a few seconds).

The phenomena of thermal adaptation (getting used to changes in ambient temperature) are quite well known. However, these phenomena are clearly expressed only in the average range and addiction to extreme cold or extreme heat, as well as to painful stimuli, almost never occurs. The phenomena of adaptation to odors are also known.

Adaptation of sensations mainly depends on the processes occurring in the receptor itself. For example, 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 increased sensitivity. However, the phenomenon of adaptation is also associated with processes occurring in the central sections of the analyzers, in particular with changes in the excitability of nerve centers. With prolonged stimulation, the cerebral cortex responds with internal protective inhibition, reducing sensitivity. The development of inhibition causes increased excitation of other foci, contributing to increased sensitivity in new conditions. In general, adaptation is an important process, indicating the greater plasticity of the organism in its adaptation to environmental conditions.

There is one more phenomenon that needs to be considered. All types of sensations are not isolated from each other, therefore 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 senses is called the interaction of sensations

.

It is necessary to distinguish two types of interaction of sensations:

1) interaction of sensations of the same type;

2) interaction of sensations of different types.

The interactions of sensations of different types can be illustrated by the research of Academician P. P. Lazarev, who found that illumination of the eyes makes audible sounds louder. Similar results were obtained by Professor S.V. Kravkov. He established that not a single sense organ can work without influencing the functioning of other organs. Thus, it turned out that sound stimulation (for example, a whistle) can sharpen the functioning of the visual sense, increasing its sensitivity to light stimuli. Some odors have a similar effect, increasing or decreasing light and auditory sensitivity. All 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 decrease in sensitivity. The general pattern is that weak stimuli increase, and strong ones decrease, the sensitivity of analyzers during their interaction.

A similar picture can be observed during the interaction of sensations of the same type. For example, a point in the dark is easier to see against a light background. An example of the interaction of visual sensations is the phenomenon of contrast, which is expressed in the fact that a color changes in the opposite direction in relation to the colors surrounding it. For example, gray against a white background will look darker, but when surrounded by black it will look lighter.

As the examples above suggest, there are ways to increase the sensitivity of the senses. Increased sensitivity as a result of the interaction of analyzers or exercise is called sensitization

. A. R. Luria distinguishes two aspects of increased sensitivity according to the type of sensitization. The first is long-term, permanent and depends mainly on lasting changes occurring in the body, so the age of the subject is clearly related to changes in sensitivity. Studies have shown that the sensitivity of the sensory organs increases with age, reaching a maximum by 20–30 years, in order to gradually decrease thereafter. The second side of increased sensitivity according to the type of sensitization is temporary and depends on both physiological and psychological emergency effects on the subject’s condition.

The interaction of sensations is also found in a phenomenon called synesthesia

, – the occurrence, under the influence of irritation of one analyzer, of a sensation characteristic of other analyzers. In psychology, the facts of “colored hearing” are well known, which occurs in many people, and especially in many musicians (for example, Scriabin). Thus, it is widely known that high-pitched sounds are most often regarded by people as “light”, and low-pitched sounds as “dark”.

In some people, synesthesia manifests itself with exceptional clarity. One of the subjects with exceptionally pronounced synesthesia, the famous mnemonist Sh., was studied in detail by A. R. Luria. This person perceived all voices as colored and often said that the voice of the person addressing him, for example, was “yellow and crumbly.” The tones he heard gave him visual sensations of various shades (from bright yellow to purple). The perceived colors were felt by him as “ringing” or “dull”, as “salty” or “crispy”. Similar phenomena in more erased forms occur quite often in the form of an immediate tendency to “color” numbers, days of the week, names of months in different colors. The phenomena of synesthesia are another evidence of the constant interconnection of the analytical systems of the human body, the integrity of the sensory reflection of the objective world.

Patterns of development of sensations in ontogenesis

The sensation begins to develop immediately after the birth of the child. Shortly after birth, the baby begins to respond to stimuli of all kinds. However, there are differences in the degree of maturity of individual feelings and in the stages of their development.

Immediately after birth, the baby's skin sensitivity is more developed. When born, the baby trembles due to the difference in the mother’s body temperature and the air temperature. A newborn baby also reacts to touch, with the lips and the entire mouth area being the most sensitive. It is likely that a newborn can feel not only warmth and touch, but also pain.

Already by the time of birth, the child’s taste sensitivity is quite highly developed. Newborn babies react differently to the introduction of a solution of quinine or sugar into their mouth. A few days after birth, the child distinguishes mother's milk from sweetened water, and the latter from plain water.

From the moment of birth, the child’s olfactory sensitivity is already quite developed. A newborn baby determines by the smell of mother's milk whether the mother is in the room or not. If a child has been fed mother's milk for the first week, he will turn away from cow's milk only when he smells it. However, olfactory sensations not related to nutrition take quite a long time to develop. They are poorly developed in most children, even at four or five years of age.

Vision and hearing go through a more complex path of development, which is explained by the complexity of the structure and organization of the functioning of these sense organs and their lower maturity at the time of birth. In the first days after birth, the baby does not respond to sounds, even very loud ones. This is explained by the fact that the newborn’s ear canal is filled with amniotic fluid, which resolves only after a few days. Usually the child begins to respond to sounds during the first week, sometimes this period lasts up to two to three weeks.

The child's first reactions to sound are of the nature of general motor excitement: the child throws up his arms, moves his legs, and emits a loud cry. Sensitivity to sound is initially low, but increases in the first weeks of life. After two to three months, the child begins to perceive the direction of sound and turns his head towards the sound source. In the third or fourth month, some children begin to respond to singing and music.

As for the development of speech hearing, the child first of all begins to respond to the intonation of speech. This is observed in the second month of life, when a gentle tone has a calming effect on the child. Then the child begins to perceive the rhythmic side of speech and the general sound pattern of words. However, the distinction of speech sounds occurs by the end of the first year of life. From this moment the development of speech hearing itself begins. First, the child develops the ability to distinguish vowels, and at a subsequent stage he begins to distinguish consonants.

A child's vision develops most slowly. Absolute sensitivity to light in newborns is low, but increases markedly in the first days of life. From the moment visual sensations appear, the child reacts to light with various motor reactions. Color discrimination increases slowly. It has been established that a child distinguishes color already in the fifth month, after which he begins to show interest in all kinds of bright objects.

The child, starting to sense light, at first cannot see objects. This is explained by the fact that the child’s eye movements are not coordinated: one eye may look in one direction, the other in the other, or may even be closed. The child begins to control eye movements only at the end of the second month of life. He begins to distinguish objects and faces only in the third month. From this moment, the long-term development of the perception of space, the shape of an object, its size and distance begins.

In relation to all types of sensitivity, it should be noted that absolute sensitivity reaches a high level of development already in the first year of life. The ability to distinguish sensations develops somewhat more slowly. In a preschool child, this ability is developed incomparably less than in an adult. Rapid development of this ability is observed during school years.

It should also be noted that the level of development of sensations varies from person to person. This is largely due to human genetic characteristics.

Perception. Physiological basis of perception

Perception is a holistic reflection of objects, situations, phenomena that arise from the direct impact of physical stimuli on the receptor surfaces of the sense organs.

The concepts of “sensation” and “perception” are interrelated, but there are fundamental differences between them. The essence of sensation processes is to reflect only individual properties of objects and phenomena of the surrounding world. However, a person does not live in a world of isolated spots of light or color, sounds or touches, he lives in a world of things, objects and forms, in a world of complex situations. Whatever a person perceives, everything invariably appears before him in the form of holistic images. Therefore, the main difference between perception and sensation is the objectivity of awareness of everything that affects a person, that is, the display of an object in the real world in the totality of all its properties, or, in other words, a holistic display of the object.

Perception includes sensation and is based on it. Moreover, any perceptual image includes a whole range of sensations, since any object or phenomenon has many and different properties, each of which is capable of causing a sensation, independently of other properties. However, it would be a mistake to believe that such a process (from relatively simple sensations to a complex image of perception) is a simple summation of individual sensations. In fact, the perception (or reflection) of entire objects or situations is much more complex. In addition to sensations, the process of perception involves previous experience, processes of understanding what is perceived, i.e. mental processes of an even higher level, such as memory and thinking, are included in the process of perception. Therefore, perception is often called the human perceptual system.

Currently, there are various theories of the pattern recognition process. These theories focus on the following question: how are external signals affecting the senses transformed into meaningful perceptual images? As a rule, a person recognizes surrounding objects and events easily and quickly; therefore, it may seem that the operations involved in recognition are simple and straightforward. However, this is not at all true. Attempts by engineers to create machines that would be able to recognize symbols and sounds common to the human environment, in most cases end in failure. The perception systems of animals, even the most primitive ones, are far ahead of such machines in their capabilities.

The physiological basis of perception is the processes taking place in the sensory organs, nerve fibers and the central nervous system. Thus, under the influence of stimuli at the endings of the nerves present in the sensory organs, nervous excitation arises, which is transmitted along pathways to the nerve centers and ultimately to the cerebral cortex. Here it enters the projection (sensory) zones of the cortex, which represent, as it were, the central projection of the nerve endings present in the sense organs. Depending on which organ the projection zone is connected to, certain sensory information is generated.

It should be noted that the mechanism described above is the mechanism by which sensations arise. And indeed, at the level of the proposed scheme, sensations are formed. Consequently, sensations can be considered as a structural element of the process of perception. Own physiological mechanisms of perception are included in the process of forming a holistic image at subsequent stages, when excitation from the projection zones is transferred to the integrative zones of the cerebral cortex, where the formation of images of real world phenomena is completed. Therefore, the integrative zones of the cerebral cortex, which complete the process of perception, are often called perceptual zones. Their function differs significantly from the functions of projection zones.

This difference is clearly revealed when the activity of one or another zone is disrupted. For example, when the functioning of the visual projection zone is disrupted, so-called central blindness occurs, i.e., when the periphery - the sensory organs - is completely in working order, the person is completely deprived of visual sensations, he sees nothing. The situation is completely different with lesions or disruption of the integrative zone. A person sees individual spots of light, some contours, but does not understand what he sees. He ceases to comprehend what affects him, and does not even recognize familiar objects. A similar picture is observed when the activity of integrative zones of other modalities is disrupted. Thus, when the auditory integrative zones are disrupted, people cease to understand human speech. Such diseases are called agnostic disorders (disorders leading to the impossibility of cognition), or agnosia.

Since perception is closely related to sensation, it can be assumed that it, like sensation, is a reflexive process. The reflex basis of perception was proved by I. P. Pavlov. He showed that perception is based on conditioned reflexes, i.e. temporary nerve connections formed in the cerebral cortex when receptors are exposed to objects or phenomena in the surrounding world. Moreover, the latter act as complex stimuli, since when processing the excitation caused by them, complex processes of analysis and synthesis occur in the nuclei of the cortical sections of the analyzers. I. P. Pavlov wrote: “In harmony with the continuously and diversely fluctuating nature, agents as conditioned stimuli were either isolated by the hemispheres for the body in the form of extremely small elements (analyzed), or merged into diverse complexes (synthesized).” Analysis and synthesis ensures the selection of the object of perception from the environment, and on this basis, all its properties are combined into a holistic image.

Temporary nerve connections that ensure the process of perception can be of two types: formed within one analyzer and interanalyzer. The first type occurs when the body is exposed to a complex stimulus of one modality. For example, such a stimulus is a melody, which is a unique combination of individual sounds that affect the auditory analyzer. This entire complex acts as one complex stimulus. In this case, nerve connections are formed not only in response to the stimuli themselves, but also to their relationship - temporal, spatial, etc. (the so-called relation reflex). As a result, a process of integration, or complex synthesis, occurs in the cerebral cortex.

The second type of neural connections formed under the influence of a complex stimulus are connections within different analyzers, the emergence of which I.M. Sechenov explained by the existence of associations (visual, kinesthetic, tactile, etc.). These associations in humans are necessarily accompanied by an auditory image of the word, thanks to which the perception acquires a holistic character. For example, if you are blindfolded and given a spherical object in your hands, after having been told that it is an edible object, and at the same time you can feel its peculiar smell, taste its taste, then you will easily understand what you are dealing with. In the process of working with this familiar, but currently invisible to you object, you will definitely mentally name it, i.e., an auditory image will be recreated, which in its essence is a kind of generalization of the properties of the object. As a result, a person can even describe what he does not observe at the moment. Consequently, thanks to the connections formed between analyzers, a person reflects in perception such properties of objects or phenomena for the perception of which there are no specially adapted analyzers (for example, the size of an object, specific gravity, etc.).

Thus, the complex process of constructing a perception image is based on systems of intra-analyzer and inter-analyzer connections that provide the best conditions for seeing stimuli and taking into account the interaction of the properties of an object as a complex whole.

Interaction of sensations

All human senses are able to adapt to changing physical conditions and this is a well-known fact. The immediate cause of sensory adaptation lies in the adaptation of the receptors themselves. Neurons can increase or decrease their excitability. One organ contains many receptors, so a person perceives a field of sensations within each modality. The sensitivity of one area in this field affects the sensitivity of another, so a gray dot on a white background appears almost black and, conversely, almost white on a black background.

In science, it has long been accepted that a change in the sensitivity of an organ occurs due to a change in the physical parameters of the signal that is received by this organ. But a change in sensitivity in one organ, as it turns out, leads to a change in another, and this phenomenon is called the interaction of sensations.

There are two types of interaction of sensations:

1. Interaction between sensations of the same type of modality;
2. Interaction between sensations of different modalities.

In the experiments of P.P. Lazarev, it was discovered that audible sounds are made louder by illumination of the eyes. Experiments carried out by S.V. Kravtsov, led to the conclusion that not a single sense organ can work without influencing the functioning of other organs. For example, whistling as a sound irritation can sharpen the visual sense and increase its sensitivity to light stimuli. Light and hearing sensitivity can be increased or decreased by certain odors.

The influence of analyzers on each other leads to an increase or decrease in sensitivity.

Thus, in a single receptor, a change in sensitivity occurs under the influence of three factors:

1. Physical. Changing the parameters of the effect on the receptor;
2. Intramodal. Neighborhood sensitivity matters;
3. Intermodal. Level of sensitivity in other organs.

Methods have been developed to increase the sensitivity of the senses, called sensitization.

Types of sensations

There are different approaches to classifying sensations. For a long time, five main types of sensations were identified (according to the number of senses): smell, taste, touch, vision and hearing.

This classification of sensations in accordance with basic conditions is correct, although not exhaustive.

B.G. Ananyev spoke about eleven types of sensations. A.R. Luria believes that the classification of sensations can be made according to at least two basic principles - systemic and genetic (i.e., on the one hand, according to the principle of modality, and on the other, according to the principle of complexity or level of their structure).

Let's consider a systematic classification of sensations. This classification was proposed by the English physiologist K. Sherrington. Considering the largest and most significant groups of sensations, he divided them into three main types:

• proprioceptive, proprioceptive and exteroceptive sensations. The first are signals that come to us from the internal environment of the body;
• the latter provide information about the position of the body in space and the location of the musculoskeletal system, regulate our movements;
• Finally, the third provides signals from the external world and creates the basis for our conscious behavior. Let us consider separately the main types of sensations.

Intercepting sensations, signaling the state of the internal processes of the body, arise from receptors located on the walls of the stomach and intestines, heart and blood circulation, as well as other internal organs. This is the oldest and most elementary group of sensations. Receptors that sense information about the state of internal organs, muscles, etc. are called internal receptors. Interceptive sensations are among the least conscious and most diffuse forms of sensations and always retain their proximity to emotional states. It should also be noted that interceptive sensations are often called organic.

Proprioceptive sensations transmit signals about the position of the body in space, form the afferent basis of human movements and play a decisive role in their regulation. This group of sensations includes equilibrium or static sensations, as well as motor or kinesthetic sensations.

Peripheral receptors of proprioceptive sensations are located in muscles and joints (tendons, ligaments) and are called the body of Pacchini. Peripheral vestibular sensory receptors are located in the arcades of the inner ear.

The third and largest group of sensations is exteroceptive sensations. They bring information to a person from the outside world and are the main group of sensations that connect a person with the environment.

The entire group of exteroceptive sensations is conventionally divided into two subgroups: Contact and remote sensations.

Contact sensations are caused by the direct impact of an object on the senses. Examples of contact sensations are taste and touch. Distant sensations reflect the properties of objects located at some distance from the sense organs; these senses include hearing and vision.

It should be noted that, according to many authors, the sense of smell occupies an intermediate position between contact and distant sensations, since formally olfactory sensations arise at a distance from the object, but at the same time, the molecules that characterize the smell of the object with which the olfactory receptor comes into contact undoubtedly belong to this object.

This is the duality of the position occupied by the sense of smell in the classification of sensations.

Since sensation is produced by the action of a specific physical stimulus on a corresponding receptor, the primary classification of sensations that we have been considering is naturally based on the nature of the receptor that gives the sensation a certain quality or “modality.” There are, however, sensations that cannot be attributed to any particular method. Such sensations are called intermodal.

These include, for example, vibration sensations that connect the tactile-motor domain with the auditory domain.

Vibration sensitivity is sensitivity to vibrations caused by a moving body. According to most researchers, the sensation of vibration is an intermediate and transitional form between tactile and auditory sensitivity. In particular, the school L.E. Komendantova suggests that tactile-educational sensitivity is one of the forms of sound perception. With normal hearing it is not particularly pronounced, but if the auditory organ is damaged, its function is clearly manifested.

The main meaning of the “auditory” theory is that tactile perception of sound vibrations is understood as diffuse auditory sensitivity. Vibration sensitivity is of particular practical importance in cases of impaired vision and hearing.

It plays an important role in the lives of deaf and deaf-blind people. Deaf and mute people detected the approach of a truck and other vehicles at a great distance due to the high development of sensitivity to vibrations. Likewise, deaf and mute people know when someone is entering their space through the sense of vibration. Consequently, sensations, which are the simplest type of mental process, are in fact very complex and not fully understood. It should be noted that there are other approaches to the classification of sensations.

Sensitization

As mentioned above, there are ways to increase the sensitivity of organs as a result of the interaction of analyzers or exercise. This method is called sensitization. According to the type of sensitization A.R. Luria identifies two aspects of increased sensitivity:

1. The first side depends on sustainable changes occurring in the body, and therefore is long-lasting and permanent. The age of the subject is associated with changes in sensitivity and reaches a maximum at 20-30 years, then gradually decreases;
2. The second side is temporary and depends on physiological and psychological emergency effects on the subject’s condition.

Sensitization, adaptation, synesthesia refer to qualitative characteristics of sensations and are directly related to changes in sensitivity. Experienced tasters are examples of sensitization, conducting sensory analysis on subtle nuances, or musicians who distinguish by ear the relative duration of notes. On the contrary, industrial workers are characterized by desensitization, where high noise levels lead to deterioration of vision. When various types of sensations are suppressed or absent, compensatory sensitization occurs. This disadvantage is compensated for by increasing the sensitivity of other analyzers, for example, improving hearing in the dark.

Sensitization, as studies show, depends on factors:

• Age;
• Type of nervous system. People with a weak nervous system, people who do not have endurance and stability are predisposed to it;
• Endocrine balance of the body.

Basic properties and characteristics of sensations

All sensations can be characterized in terms of their properties. And the properties can be not only specific, but also common to all types of sensations. The main properties of sensations include: Quality, intensity, duration and spatial localization, absolute and relative threshold of sensations.

It should be remembered that often when we talk about the quality of sensations, we mean the modality of the sensations, because it is the modality that reflects the main quality of the corresponding sensation. The intensity of the sensation is its quantitative characteristic and depends on the strength of the stimulus and the functional state of the receptor, which determines the readiness of the receptor to perform its function. For example, if you have a runny nose, the intensity of perceived odors may be distorted.

The duration of a sensation is a temporary property of the sensation that occurs. This is also determined by the functional state of the sensory organ, but mainly by the time of the stimulus and its intensity. It should be noted that sensations have a so-called latent (hidden) period.

When a stimulus acts on a sensory organ, the sensation does not arise immediately, but after some time. The latency period of different types of sensations varies. For example, for tactile sensations it is 130 ms, for pain it is 370 ms, and for taste it is only 50 ms.

The sensation does not appear simultaneously with the onset of action of the stimulant and does not disappear simultaneously with the cessation of its action. This inertia of sensations manifests itself in the so-called afterreflect. Visual sensations, for example, have a certain inertia and do not disappear immediately after the cessation of the stimulus that caused them. The stimulus traces remain as a sequential image. There are positive and negative sequence images.

The positive sequence image corresponds to the original stimulus and consists of maintaining a stimulus trace of the same quality as the actual stimulus.

The image of a negative sequence consists in the appearance of a sensation opposite to the current stimulating effect. For example, light-dark, sky-light, warm-cold, etc. The appearance of negative sequential images is explained by a decrease in the sensitivity of this receptor to this effect. Finally, sensations are characterized by the spatial localization of the stimulus. The analysis carried out by the receptors gives us information about the localization of the stimulus in space, i.e. we can tell where the light is coming from, where the heat is coming from, or what part of the body the stimulus is affecting.

All the properties described above, to one degree or another, reflect the qualitative characteristics of sensations. However, no less important are the quantitative parameters of the main signs of sensations - the degree (thresholds) of sensitivity.

It should be remembered that the same stimulus may be below the threshold of sensation for one person and above it for another. The weaker the stimuli that a person can perceive, the higher his sensitivity. In other words, the lower the absolute threshold of sensation, the higher the absolute sensitivity, and vice versa.

Thus, sensation is the simplest mental process of reflecting a single quality (property) of an object in the direct influence of stimuli on the perceiving part of the analyzer.