Tactile perception. Tactile (tactile) perception. Ways of perception of information

Tactile perception first opens the door to the knowledge of the world around children. Babies have so much to learn and learn. And they literally get the initial amount of knowledge by touch. All channels of perception help preschoolers in mastering reality: tactile, visual, auditory, gustatory, olfactory. They work in close conjunction, "reading" relevant information in their own way. Find out how tactile perception is used in children.

Tactile perception as a cognitive process

Tactile perception is the knowledge (examination, recognition) of objects by direct touch. This type of perception is also called tactile. Its essence lies in the reflection of the characteristics, features of the surface and structure of what is touched.

The mechanism of tactile perception is based on the action of skin receptors. Receptors are complex devices that receive sensory signals and read information. These devices are located on the surface of the entire body, providing skin sensitivity.

The receptors most sensitive to a variety of information are concentrated on the fingers. Feeling objects, a person can get as much information as if he were looking at them. Therefore, touch is considered, first of all, the cognitive function of the human hand.

Gives the child the opportunity to form images, to make inferences related to them. Sensory reflection and tactile sensations provide the same rich material for mental processing, as well as visual ones.

Development of tactile perception in children

Perception of a preschooler - which opens the door to understanding how the world works, what features objects and phenomena have, how they are interconnected.

In the first years of a child's life, objective activity is the main activity. Children touch different objects and feel their features, pay attention to the differences. The hard surface of the table is not at all like a terry towel, and a plastic cube is different from a soft toy. Thanks to tactile sensations, the baby perceives such signs as hardness-softness, heat-cold, pricklyness-fluffiness, etc.

All sensory information is gradually accumulated by the child's brain. The preschooler is increasingly distinguishing tactile signals. After three years, he is already well aware that the springiness of an inflatable ball is very different from a similar characteristic of a rubber ball, and the viscosity of semolina is not at all similar to the same property of plasticine.

Tactile perception of objects will allow the child to involuntarily accumulate a database of object characteristics, which is later used by him to understand the properties and characteristics of everything around him.

If in early childhood perception is characterized by involuntary and randomness, then at preschool age it becomes a meaningful intellectual process.

These qualitative characteristics can be traced even in such an elementary example as touch. A kid up to 2-3 years old is enough, clapping his hand on everything that he can reach. The younger preschooler already understands that you can’t touch everything in a row. He is careful, and in situations that alarm him, he will only touch with his finger, quickly pulling his hand back. True, there is still a problem that not all really dangerous situations are recognized by the child.

The role of tactile sensations in the perception of form

Many images in preschool age are formed and remembered thanks to information coming through tactile channels. Received as a gift a huge soft toy, the child enjoys its softness, silkiness, not yet understanding what kind of creature this giant personifies.

Then the adults will explain that a Mishka or a Camel came to the baby. But the main sign of the image for a preschooler for a long time will remain delicate artificial wool.

The isolation of a separate feature also contributes to the perception of the shape and contours of geometric bodies, of which there are plenty among children's toys. The preschooler firmly learns that the cubes have clear corners, and everything that is round in shape can be called a ball.

Visual and tactile perception helps the child to recognize these forms in the future. In most cases, the baby, of course, will see angular or spherical shapes. But, if you offer a preschooler a game with his eyes closed and give him objects of appropriate geometric shapes (a cube, a ball, a ring, a pyramid), he will successfully identify them.

Exercises for the development of sensations and touch

The tactile perception of information is so important that in psychological science it is often called tactile vision. Moreover, we have the case when it is not too early to start the active development of tactile abilities.

Currently, there are developing soft constructors with cut out shapes and a set of various shapes that the child needs to put into the appropriate cells.

In addition to ready-made models, it is useful to use improvised means. Increase the sensitivity of skin receptors to manipulation with sand, semolina or other small grains. Children touch with their palms, squeeze, pour, immerse their hands in such loose material, which gives them different sensations.

Toddlers with interest feel from all sides those objects that their mother or other significant adult gives them. Moreover, they try them by mouth, which is not necessary to advance in the development of tactile skills.

It is enough just to give the opportunity to touch the object in every possible way, to pay attention to the features of the surface or shape. Then name the properties and the object so that the child gradually remembers the necessary connections. For example, “this is an acorn - it itself is smooth, but has a rough “cap”.

Children of middle and older preschool age like exercises that have some mystery. And the recognition of objects or material by touch contains precisely the element of mystery. The game is interesting when the objects are behind a screen or in a bag, and children need to recognize them only on the basis of a tactile examination. It is better if 2-3 people participate in such a game.

Exercise 1. Prepare a set of small items familiar to the preschooler. Such a set may include a button, a shell, an acorn, a ring, a pebble, a cap from ballpoint pen and similar attributes. Put them in an opaque bag. Invite the children to take turns putting their hand into the bag, choose one object, describe it verbally without pulling it out of the bag, and name it.

Exercise 2. Introduce children in advance to various cereals and natural materials: grain, buckwheat, peas, beans, pumpkin and sunflower seeds, some types of special-shaped nuts. As in the previous exercise, participants need to determine by touch what was in their hand.

Exercise 3 Prepare small scraps of fabric of various textures. It can be scraps of satin, coarse linen, velvet, cambric, organza ... First, study with the children the tactile features of each fabric and its name, and then start the game.

Such games are undoubtedly useful for children's hands. In addition to honing skin sensitivity and tactile perception, they contribute to the development. The question of whether special attention should be paid to perception based on tactile sensations is removed by the obvious truth that the process of perception is the basis for the development of thinking and consciousness of the child.

Every person is unique. Everyone has a different character, temperament, and even One can be kinesthetic, the other - auditory, the third - visual. Nevertheless, without adequate orientation in the surrounding reality, it is difficult to imagine the life of any person. The possibility of such orientation provides tactile perception, which will be discussed in today's article.

Ways of perception of information

Perception is mental process which reflects what is happening in reality. This process helps a person to navigate in space, make decisions about their next actions and not repeat mistakes.

We suggest you familiarize yourself with the types and main properties of perception:

• Auditory. This type implies the ability to determine the various phenomena of the surrounding world with the help of sounds.
• includes tactile, skin contact and touch system. In this case, the main body is the hands of a person - it is thanks to them that he receives the necessary information. With the help of tactile perception, a person communicates with people and with the outside world through touch.
• visual. It consists in combining the processes of creating and constructing visual images of the surrounding world of people.
• Taste. When we eat food, our brain receives a signal from the receptors, with which we can distinguish a sour product from a sweet one, a bitter one from a salty one.
• Olfactory. It consists in knowing the world with the help of various smells.

What is tactile perception?

Touch is one of the types of perception of objects and phenomena, which is based on multimodal and tactile information.

Thus, tactile perception is sensations through touch, pressure, temperature or pain, due to which a person perceives the surrounding reality. With the help of this perception, a person develops the first impressions of an object or phenomenon. When the outer integuments of the body come into contact with something, we have the opportunity to know the shape, elasticity, size, roughness or density, cold or heat that are characteristic of the object.

Thus, tactile perception is information received through skin receptors. We feel when we touch an animate or inanimate object, and we also notice when we are touched. However, sensitivity is not limited to these sensations. When touching an object, it is common for a person to feel not only the main signs, but also its properties, such as smoothness, hardness, moisture, malleability, as well as feel itching, tickling and vibration.

Thanks to the tactile way of perceiving information, our skin is able to respond to the physical properties of the objects around us, and therefore it is through it that we receive certain information.

Major perceptual impairment

For detection, it is necessary to clearly know the manifestations of diseases. A separate branch of clinical medicine - psychiatry - can help with this. With the help of clinical tests, history taking, laboratory tests, a specialist in this field will be able to make an adequate diagnosis.

In psychiatry, there are several main categories of impaired tactile perception:

• illusions;
• autotopognosy;
• tactile agnosia;
• hallucinations.

The above diseases can cause a violation of various sensory organs. Within the framework of this article, we will consider such disorders that are directly related to tactile sensations and tactile perception.

World of illusion

Tactile illusions are associated with tactile sensations. Perception is imperfect, and sometimes a person can hear a sound, see an image, or feel an inexplicable touch on himself. In psychology, it is considered quite normal when, against the background of distorted perception, the human brain builds images that do not correspond to reality. Sometimes people tend not to notice obvious things or, on the contrary, create the appearance of something that is not really there. Therefore, sometimes you can see the distortion of an object in the air, a mirage and much more.

With this violation, it seems to the patient that he has tactile contact with unreal objects and fictitious objects. In addition, a person may have a sensation of a foreign object inside himself.

Letting go of illusions

The first step towards a cure is to identify the underlying disease, as illusions can be a side effect of a more severe disease. To do this, first of all, you need to contact a therapist. With the help of medical tests and examination, the doctor will be able to make a diagnosis and, if necessary, redirect to a specialized specialist. For example, if the symptoms of syphilis became the cause of illusions, then the patient will be referred to a venereologist. In this case, it is worth paying attention to the underlying disease and starting treatment from it. After she recedes, the tactile illusions will also pass.

But it happens that this disorder also has a mental character. In this case, you should contact a psychotherapist or psychiatrist. They will help to make or refute the diagnosis of "schizophrenia", "bipolar disorder". In the event that a specialist identifies a specific diagnosis, with the help of drug treatment and some therapy he can help. In this area, the approach to each patient is purely individual, so self-medication is strictly prohibited. Medicines and prescriptions read on various forums on the Internet or suggested by acquaintances can only aggravate the situation.

In case of illusions in children, before going to bed or after it, it is worth seeing a specialist and, if necessary, undergoing treatment. A psychiatrist or psychotherapist, having worked with the child and his parents, will be able to identify the root cause of this disorder, after which several sessions of psychotherapy will follow, which should subsequently help the baby cope with false perception real world.

Hallucination

This disorder can cause impairment of visual, auditory, and tactile perception. With regard to tactile hallucinations (they are also called tactile), they can manifest themselves in the form of squeezing, sensations of touch and pricks. Sometimes this can be expressed in unpleasant sensations under the skin, as if insects or other tiny creatures are digging in muscle tissue.

Hallucinations can affect both the human body and the outside world that surrounds it. If visions occur quite often and are accompanied by delirium, then in this case we are talking about hallucinosis. This disorder tends to move into a chronic state in which the patient can maintain efficiency, a critical attitude to his feelings and orderliness of behavior.

Hallucinations that accompany drug and alcohol intoxication are treated by specialists in psychiatric clinics or drug dispensaries. But this treatment is carried out only in the absence of dependence on alcohol and drugs. It is in this case that specialists will be able to help get rid of terrible sensations and visions.

Causes of hallucinations

Scientists have not yet identified specific factors that can affect the occurrence of hallucinations. The reasons are still completely unexplored, but there are still assumptions:

• alcohol and drug intoxication can cause significant damage not only to physical, but also to mental health;
• disruption of the brain;
• tactile hallucinations can be caused by schizophrenia or encephalitis;
• side effects of drug treatment;
• violation of the senses;
• experts have identified another factor called "mass psychosis" - this happens when an absolutely healthy person lends itself to mass suggestion.

Tactile agnosia

This violation is associated with damage to the parietal parts of the human brain hemisphere, which inhibits the tactile perception of information. Tactile agnosia includes the inability to identify various objects in general, while maintaining the perception of its individual features. For example, when feeling any object inserted into the patient's left or right hand, one can notice obvious difficulties.

With tactile agnosia, it is difficult to determine its weight, size, shape and material from which it is made when feeling an object. To date, a common variant of tactile agnosia is dermoalexia. It is associated with damage to the left parietal region, which is characterized by the impossibility of perceiving various symbols (these can be letters, numbers or signs) that are “drawn” by a specialist on the patient’s hand.

The essence of tactile agnosia is a violation of the recognition of various objects and touching them. There are several types of this disorder:

• finger - with this violation, the patient does not feel his fingers;
• somatognosia - impaired recognition of body parts and their location;
• object - with this type of tactile agnosia, a person fails to determine the properties of an object by touch, such as its shape, size, material, despite the fact that the visually ill person can describe this object.

Autopagnosia

The next violation is associated with the inability to perceive the location of various parts of the body, their location and relationship. Simply put, it is difficult for a person with this disorder to understand where their ears or eyes and other parts of the body are.

As a rule, this disorder extends to the trunk, face and upper limbs. There are two types of autotopagnosia:

• The patient tends to ignore one half of the body - while moving, a person simply does not notice and does not use that half of the body. There are also cases when a person has a feeling that it is simply missing part of the body.
• The second type is an incorrect assessment of the location of various parts of the body. For example, when the patient is asked to show where his nose is, he may point to a completely different part of the body or mention its absence. People with this disorder cannot find their body parts or believe they are missing altogether.

Diagnostics

With the development of the above deviations, it is necessary to consult a doctor, who, in turn, will try to identify the full picture of the disease and study the anamnesis. For example, if a patient has recently suffered a brain tumor, stroke or other various injuries, this can become an essential basis for the formation of these disorders. Therefore, the attending physician must take into account all the nuances in the process of diagnosing disorders, and then refer them to narrow specialists to check the condition of vision and hearing. Also, in the process of checking violations of tactile-motor perception, various laboratory tests are performed.

Prevention

The above violations of tactile perception do not have certain methods of prevention, but you can protect yourself from this with the help of the right lifestyle.

In order to avoid such violations that negatively affect tactile-motor perception, experts advise the following:

• first of all, give up bad and harmful habits;
• observe the daily routine;
• find a hobby and do what you love as often as possible;
• get enough sleep;
• communicate more with family and friends;
• dream and make plans.

Such simple, at first glance, advice will help to live full life where there will be no room for a world of illusions.

Treatment

After the cause of the violation of tactile perception is determined and all efforts are directed to the treatment and elimination of the underlying pathology, psychotherapeutic therapies, consultations with a speech therapist and a neuropsychologist should be carried out in parallel. Treatment can last for many years or give a good result in the first two weeks, this is a purely individual aspect. As a rule, the treatment of these disorders begins after adequate measures have been taken to eliminate the underlying disease of the patient. There are cases when, after a complete cure for the underlying disease, impaired functions were restored without the use of additional correction measures.

Forecast

If the above violations are detected, correction of tactile perception is necessary. It is not advisable to neglect treatment in this case. different kind hallucinations, agnosia, autotopagnosia are progressive diseases that will only worsen a person's condition. In this case, the prognosis will be disappointing, since the patient is unable to distinguish the real from the imaginary.

In the absence of appropriate treatment, these disorders will only progress, and the person himself will become even more distant from reality, plunging into his own world. In such situations, you should not self-medicate and look for answers to your questions on your own.

How to develop tactile perception in children

We learn about the world around us and ourselves through various kinds perceptions such as smell, touch, taste, hearing and sight. You don't have to be a psychologist or a physiologist not to notice what a huge influence the tactile perception of objects has on the child. Touching the mother, exploring toys and any other details with the help of pens, lips and even legs. It is with the help of fingers and palms Small child learns Big world which has a positive effect on mental activity. And to help the baby in the study of the environment, it is worth contributing to the development of tactile perception.

The ability to recognize objects is important not only for children, but also for adults. This is especially important when there is a visual impairment and a person has no options how to learn to explore the world with the help of the sense of touch.

We offer to consider exercises that contribute to the development of tactile perception:

1. Gather as many different objects as you can that are different to the touch: sandpaper, velvet, fur, ribbons, erasers, paper, rock fragments, shells, pieces of metal, etc. Touching these objects, discuss with your child what each of them is on touch and what it reminds us of our lives.
2. Put different things in a bag or pouch and ask your child to pull out something fluffy, smooth or rough. Or, instead of the qualities of this little thing, you can guess the name of the object itself. For example, put your keys, a toy car, a notebook, a walnut, or a pencil in the bag. Then invite the baby to get a certain item.
3. Lay various objects on the floor and try to touch them with bare feet with your child. It can be anything: fur, newspaper, rug, cardboard, velvet, sandpaper, beans, rice, buckwheat, cotton fabric and much more. If possible, go outside and walk around barefoot. Feel the contact of the feet with sand, leaves, grass, wood, bricks, asphalt, gravel and earth. Compare and discuss your experiences.
4. The following exercise is carried out in the presence of two children. The bottom line is this: invite the children to talk to each other without words, using only touch and gestures.

Bags of grain

This exercise is suitable for children over 6 months old. Pre-sew small linen bags, fill them halfway with various grains and sew them all over. Usually four pairs of identical bags are made: two each with buckwheat, rice, wheat or beans, etc. You can sew bags different colors. The task of the child is to be able to pick up bags with the same grain by touch.

Tactile track

This activity is for children over one year old. The meaning of the exercise is as follows:

1. Any object must be placed on the floor. It can be pebbles or pebbles, straw, lumps of paper, clean sand, pieces of cloth, wooden planks.
2. After the children have washed and wiped their feet dry, they are offered to walk along a rough path. The main thing is to do it slowly and try not to go to the side.

This exercise will not only be a pleasant entertainment for kids, but also a training in coordination of movement, concentration of attention. Of course, this path can be built in the yard and on the street. In fact, you don't even have to do it on purpose. Instead, just let your child run barefoot on sand, grass, pebbles, wet clay as often as possible. According to research, the centers of tactile perception in the brain are located near the centers speech development. In this regard, training the feet contributes to the speedy development of speech no worse than training the fingers. That is, tactile perception contributes to the development of speech.

It is worth noting that touch is the first sense that begins to develop in the embryo. The development of the perception of the senses in man and their relation to the development of other senses, such as hearing or sight, has become the subject of a large number research. According to scientists, newborns had great problems with survival if they did not develop a sense of touch, even if they were able to see and hear.

Do not underestimate tactile perception, because touch plays a huge role in the lives of not only children, but also adults. They can trigger the release of happiness hormones in the body and contribute to well-being. Tactile perception simultaneously affects the mind and the physical component.

Lectures on General Psychology Luria Alexander Romanovich

tactile perception

tactile perception

Simple forms of tactile perception

As already mentioned above, touch is a complex form of sensitivity, which includes both elementary(protopathic), as well as complex(epicritic) Components.

The former include the sensation of cold and heat and the sensation of pain, the latter include the actual tactile sensations (touch and pressure) and those types of deep, or kinesthetic, sensitivity that are part of proprioceptive sensations.

Peripheral apparatuses for the sensation of heat and cold are small "bulbs" scattered in the thickness of the skin.

Apparatus pain are the free endings of thin nerve fibers that perceive pain signals, the peripheral apparatus for sensations of touch and pressure - peculiar nerve formations known as Meissner's bodies, Vater-Pacchini's bodies, also located in the thickness of the skin.

Receptors of deep (proprioceptive) sensitivity are the same devices located on the surface of the joints, ligaments and deep in the muscles.

The receptor apparatus just listed is unevenly distributed over the surface of the skin. Moreover, the density of their location has a biological basis: the more subtle sensitivity is required from the work of a particular organ, the more densely the corresponding receptor components are located on its surface and the lower the thresholds for distinguishing those signals that reach them, in other words, the higher their sensitivity.

In table. 2.2 gives a summary of the average frequency, with which per 1 square. mm skin of a given area of ​​the body meet the corresponding receptors. We see that there is a maximum frequency and a relatively large number of pain receptors at the fingertips. At the same time, there are no devices that perceive cold and heat at all. A different picture is observed in the skin of the forearm, which, as you know, does not take part in active palpation: here the number of tactile elements per 1 sq. mm decreases, and the number of receptors for pain, heat and cold increases. The same can be said about the back skin.

Table 2.2 - The number of different skin sensitivity receptors per 1 sq. mm of different skin areas (according to B. G. Ananiev)

It is characteristic that if the number of peripheral devices per 1 sq. mm of the skin of the fingertips is 120, then per 1 sq. There are only 14 mm of the skin of the back of the hand, 15 of the skin of the palm, 29 of the chest, 50 of the forehead, and 100 of the tip of the nose. It is easy to see the biological significance of such a distribution of tactile elements in various parts of the skin.

The fineness of sensitivity of various body surfaces is provided not only by the density of distribution of peripheral receptors in the corresponding areas of the skin, but also by the relative area of ​​those areas of the post-central sections of the cerebral cortex, where fibers come from the corresponding areas of the periphery. We have already said above that the more subtle the function of a particular area of ​​the skin, the greater the area occupied by its projection in the cerebral cortex.

The facts just described show that skin sensitivity is a special system adapted for tactile and kinesthetic analysis of signals coming from the outside world and from one's own body. Recall that while the tactile impulses coming from the skin receptors enter the posterior horns of the spinal cord, go as part of its lateral columns and, switching in the subcortical nodes, end in the cortex of the posterior central gyrus, the impulses that conduct signals of the deep (proprioceptive) sensitivity, acting first in the posterior horns of the spinal cord, go further along the posterior columns and, interrupted in the nuclei of Gaulle and Burdach, come to the cortex of the posterior central gyrus and its secondary areas.

It should be noted that the divergence of the conducting pathways of superficial sensitivity, on the one hand, and deep (kinesthetic) sensitivity, on the other hand, explains the fact that when the posterior columns, or nuclei of Gaulle and Burdach, are affected, superficial sensitivity is preserved, while deep is disturbed. It is this case that occurs with dorsal tabes (Tabes dorsalis), in which the lesion captures the systems of deep sensitivity, without affecting the system of superficial sensitivity. A second significant discrepancy should also be noted, the consideration of which is of great clinical importance.

This leads to the possibility of dissociation between tactile and pain sensitivity, which occurs in cases of damage to the gray matter located around the spinal canal (syringomyelia). In these cases, the fibers carrying impulses of tactile sensitivity can reach the cortex, while the fibers carrying impulses of pain sensitivity and passing to the other side are interrupted.

As a result, the patient's superficial (tactile) sensitivity is preserved, while pain sensitivity disappears and the patient does not perceive the burns that occur when he touches hot objects, although he continues to feel touching them.

Finally, it should be noted that tactile sensitivity impulses conducted through thick sensory fibers are perceived faster than pain signals conducted through thinner fibers. Careful observation of the sequence of tactile and painful sensations that we receive when touching a hot stove illustrates this point well.

As mentioned above, tactile sensitivity has a heterogeneous structure; it includes:

Most simple shapes superficial sensitivity (sensation of touch and pressure);

The most complex forms of tactile sensitivity are the sensation of touch localization, distinctive sensitivity (sensation of the distance between two touches to close areas of the skin);

Feeling the direction of skin tension (if the skin of the forearm leads to or away from the hand);

Sensation of a shape, which is applied by touching a point that makes a circle, a triangle, or an image of a number or letter on the skin (the latter is often called Foerster's feeling in neurology).

Complex forms also include deep (kinesthetic) sensitivity, which allows you to recognize the position of the passively bent arm, or to give the hand the position that is passively given to the left hand (or vice versa). It is easy to see that the latter types of sensitivity are of a particularly complex nature, and complex secondary zones of the postcentral cortical regions take part in their implementation. Therefore, if the loss of elementary forms of tactile sensitivity can occur when any parts of the tactile pathway of the opposite side of the brain are affected, a violation of higher forms of tactile sensitivity, while maintaining its elementary forms, can serve as a sign of damage to more complex secondary sections of the postcentral cerebral cortex. That is why a separate study of the various forms of tactile sensitivity has great importance for topical diagnosis of brain damage.

To study various types of tactile, or proprioceptive, sensitivity, simple tricks which have firmly entered the neurological examination of patients.

For research simple tactile sensitivity to a certain area of ​​\u200b\u200bthe skin is touched with the sharp or blunt end of a pin or pencil and the subject is asked to answer whether he feels the touch, what character it is, where the injection is felt by the patient. With an accurate study, an esthesiometer or a set of hairs of various lengths is used.

For research localizations of a different feeling touch the tip to different places of the forearm and invite the subject to indicate the place that the examiner touched.

For research distinctive sensitivity use an aesthesiometer E. Weber, the legs of which are moved apart to different distances. An indicator of the subtlety of discriminative sensitivity is the minimum distance at which the subject distinguishes not a single touch, but two separate touches.

A very important approach is Taber's experience in which the examiner simultaneously touches two symmetrical points of the chest or face. The defeat of one of the hemispheres is revealed in the fact that the patient, who is well catching each individual touch, ignores one of the touches to symmetrical points, if both touches are given simultaneously. In this case, the sensation of touching a point opposite to the affected hemisphere usually falls out. Finally, research is of great importance skin-kinesthetic sense(for the analysis of which the skin of the forearm is moved towards or away from the hand, and the subject must determine the direction of passive movement of the skin and the study deep (kinesthetic) sensitivity, in this case, the subject either passively flexes (or unbends) the arm (fingers) of the subject, inviting him to determine in which direction the bend was made, or puts one hand in a certain position, inviting the subject to give the same position to the other hand. Violation of deep sensitivity in one or the other hand indicates the defeat of the complex kinesthetic sections of the cortex of the opposite hemisphere.

Finally, research "two-dimensional - spatial sense"(or Foerster's feelings) is produced as follows: the researcher draws a certain figure (or number) on the skin of the forearm with the tip of a needle or a match and proposes to determine which figure (number) was drawn. The inability to complete this task in the presence of active attempts by the subject indicates damage to the secondary parts of the parietal cortex of the opposite hemisphere.

Complex forms of tactile perception

Until now, we have considered relatively simple forms of skin and kinesthetic sensitivity, reflecting only relatively elementary signs (pressure, touch, position of limbs in space).

However, there are also more complex forms of tactile perception, in which a person can determine the shape of an object by touch, and sometimes recognize the object itself. This form of tactile perception is of great interest to psychology.

We have already indicated above that a resting hand can detect only individual signs of an immovable object acting on it (its temperature, size, less often the features of its surface), but can not catch either its shape or the sum of signs that distinguishes it. Naturally, under these conditions, there can be no question of any complex perception of the subject. In order to move from the evaluation of individual features to the tactile perception of the whole object, it is necessary, to keep the hand moving i.e. passive tactile perception was replaced active palpation of the object.

That is why the study of how the process of palpation of an object proceeds and how, in the process of palpation, a person gradually passes from the evaluation of individual signs to the recognition of the object being felt, is one of the most essential questions in the psychology of tactile perception.

The most interesting thing in the tactile perception of an object is the fact gradual transformation of sequentially (successively) incoming information about individual features of an object into its integral (simultaneous) image.

Imagine that we feel with our eyes closed some object, such as a key. At first we get the impression that we are dealing with something cold, smooth and long. In this phase, we may assume that we are feeling a metal rod, or a tube, or a metal pencil. Then our hand moves and begins to feel the ring of the key; the first group of assumptions is immediately discarded, but a new hypothesis has not yet arisen. The palpation continues, and the palpating finger moves to the key beard with its characteristic indentation. Here the most informational points are selected, all consistently perceived signs are combined, and the last hypothesis arises: “This is the key!”, Which is confirmed by subsequent verification.

It is easy to see that the process of recognizing the image of an object that occurs in vision straightaway, in touch wears extended character and occurs through a sequential (successive) chain of trials with the selection of individual features, the creation and formation of a number of alternatives and the formation of a final hypothesis.

Therefore, the process of tactile (active) perception, arising in the process of palpation, can serve us model of any perception, individual links of which are deployed here and are especially accessible for analysis.

The process of tactile perception was studied in detail by Soviet psychologists. B. G. Ananiev, B. F. Lomov, L. M. Vekker. The studies of these authors have shown a number of significant facts.

First of all, they confirmed that the perception of the form of an object without its active sequential palpation remains completely inaccessible.

The study further showed that the subject's hand should actively feel the object, trying to highlight its most informative points and combine them into one image. Passive holding of the object on the hand or the hand on the object, excluding active search movements, does not lead to the desired result, allowing only a partial and therefore incorrect reflection of the object.

Thus, active palpation is really necessary in order to navigate the features of an object and combine them into a single image. Further research also showed that the active palpation of an object is a complex process.

As a rule, it is carried out with the participation both hands moreover, each hand participates in the process of feeling in its roles. In a right-handed person, the left hand usually plays a more passive role, supporting the object and giving the most coarse information, while the right hand is active, and the groping movements of its fingers highlight the details of the object.

The subtle structure of the palpation movements made it possible to become more familiar with their course. It turned out that groping movements are carried out with the leading role of the thumb, which in the process of evolution only in humans begins to oppose other fingers, and the index finger, which acquires special mobility in humans. Further, groping movements are interspersed with stops, and the time spent on movement is one and a half times longer than the time spent on delays or stops. These facts make us think that during these stops, the smallest components, or "quanta", of tactile information stand out (B. G. Ananiev).

It is characteristic that groping movements during tactile perception of an object turn out to be heterogeneous, and in them one can distinguish small movements of the fingers(from 2 to 100 mm), usually stopping at "critical" (most informative) points, during which the subject, apparently, receives fractional information about the features of the subject, and big movements, which, obviously, combine individual features and have the function of verifying the assumptions that have arisen.

It is essential that this character of movements is preserved even in those cases when the subject palpates not with a finger, but with the help of a rod (for example, with a pencil) or in those cases when, as a result of amputation of the arm, palpation is performed by other parts of the hand, for example, a split forearm ( the so-called "Krukenberg claw").

As the exercise progresses, the process of feeling described, which is necessary for tactile recognition of an object, can gradually decrease, and if at its first stages it was necessary to compare many selected features for recognition, then with repeated feeling, the number of signs necessary for identifying an object decreases more and more, so that at the end of the one most informative feature is sufficient for the object to be identified. Interestingly, this process successive reduction in the number of samples, in which the necessary informative features are highlighted, occurs relatively slowly in young children and begins to become more pronounced in children at the age of 6–7 years. In an adult, such a reduction, or "folding", of the search movements necessary for the tactile identification of an object proceeds especially quickly. In table. 2.3 we present data on the gradual reduction of indicative samples during tactile perception of an object, obtained by Soviet psychologists V. P. Zinchenko and B. F. Lomov in the study of children of different ages.

Table 2.3 - The number of samples required for tactile identification of an object in children of different ages

Tactile (tactile) perception, begun in experiments with the feeling of objects, was continued in a special series of experiments and studies proposed by the Soviet psychologist E. N. Sokolov. This study set itself the task of studying the probabilistic structure of the perception process and consisted of the following. The subject was asked to feel with his finger a letter laid out from separate isolated elements, for example, buttons. As a rule, these were letters, the outlines of which differed only in the position of one or two elements.

The subject was asked to consistently feel the structure given to him with his finger and say which of the two letters it refers to. Experience showed that at first the palpation was of an expanded nature, then the process gradually curtailed, and, finally, the subject immediately directed his attention to the most informative points, touching which immediately gave him either positive information (the presence of an element that distinguishes one letter from another) , or negative information (absence of the desired element), which allows you to come to the desired solution.

The described technique made it possible to approach the process of perception in a new way and introduce a quantitative, probabilistic approach into its study. At the same time, it showed that young children are not able to single out the points that carry the maximum information, and to focus the process of tactile analysis precisely on these points.

Characteristically, damage to certain parts of the brain led to peculiar disturbances in the described process of tactile recognition. Patients with damage to the lower parietal parts of the brain and a violation of the ability to synthesize elements into a single whole were unable to use the information they received and mentally create a whole image of a figure from the individual elements perceived by them. Patients with damage to the frontal lobes of the brain showed failure in the very process of collecting the necessary information: the planned orienting phase of the action either fell out or was significantly disturbed in them, and they often began to give impulsive conclusions about which letter they were feeling, without bringing their search to end and without highlighting the necessary supporting features (O.K. Tikhomirov).

The complex psychophysiological structure of the process of tactile (tactile) recognition of an object leads to a phenomenon widely known in the clinic astereognosis, which some authors call the phenomenon amorphosynthesis(violation of the three-dimensional tactile perception of the object by touch or violation of the process of synthesis of the whole image of the object from individual elements). This phenomenon consists in the fact that the patient, who retains elementary tactile sensitivity, is unable to recognize the object that he feels and synthesize individual features into one single whole.

The classic picture of astereognosis occurs when the secondary and tertiary sections of the parietal cortex are affected and is associated with a violation of the ability to combine individual tactile signals into a single structure. It manifests itself, as a rule, in one hand, opposite to the side of the hearth. In all cases of classical astereognosis, the patient actively feels the object given to him, tries to synthesize its features, but is unable to do this and identify the object. Difficulties in identifying a given object by touch, arising from lesions of the frontal lobes of the brain, differ significantly from the classical picture of astereognosis. In these cases, leading, as a rule, to a sharp decrease in the patient's activity and to the inability to compare the effect of one's action with the original intention, the nature of the difficulty in tactile perception of the object is of a different nature. In such a situation, the patient either does not make any attempts to actively feel the object, or does not make enough systematic attempts to do so, interrupting the process of orientation at an early stage and prematurely expressing a hypothesis based on only one fragmented feature. Careful observations make it possible to see in which particular link the process of tactile recognition of an object is disturbed, and to draw diagnostic conclusions from this observation.