M. Buger at the end of the 18th century studied the ability of a person to distinguish between close levels of illumination. The equipment used by Bouguer in his experiments was quite consistent with that time: a table with a measuring ruler, on which two candles were placed, and a screen illuminated by these candles. By moving each of the candles at different distances relative to the screen, Booger tried to measure what we now call the difference (differential) threshold for the perception of illumination. Booger came to the conclusion that the magnitude of the barely noticeable difference (ESD) between two illuminations is not constant, it increases in proportion to the initial illumination: ΔL=kL. In other words, the ratio of EZR (ΔL) to the initial illumination level is a constant value; ∆L/L= const. Similar studies for stimuli of other sensory modalities were carried out in the middle of the 19th century by E. Weber. So, in one of his experiments, Websr asked the subjects to determine the difference between the weight of two loads lifted simultaneously. It was found, in particular, that if a load of 100 grams served as the initial load, then the subject perceived a barely noticeable increase in gravity when adding a load of 3 grams. If the weight of the original load increased by 2, 3, 5... times, then the value of the difference threshold ΔР = P1 - Р2 increased in the same proportion. For a weight of 200 grams, the value of the difference threshold was 6 grams, for 300 - 9 grams, etc. It is not difficult to see that in this case, too, the rule ΔР/P = const is observed.

This relationship, expressed in a generalized form:

∆S/S= const,

where S is the magnitude of the stimulus (regardless of its sensory modality), later they began to call the Weber (or Bouguer-Weber) rule. As will be shown below, this pattern played an important role in Fechner's formulation of his basic psychophysical law.

Despite the fact that the emergence of psychophysics as a science is usually dated to 1860 (the year the book by G. Fechner "Elements of Psychophysics" was published), some authors give an earlier date - October 22, 1850. It was on this day that Fechner came up with the idea of ​​the law of quantitative relationship between physical and mental quantities. As noted earlier, Fechner had no doubts about the possibility of quantitative measurement of subjective processes. In his opinion, not only elementary mental processes (in particular, sensations), but also high-order Orley processes: “... the vividness of memories, images of fantasy, the intensity of individual thoughts, etc.” can be expressed quantitatively. As for the measurement of sensations, Fechner's reasoning basically boiled down to the following.

1. Recognizing the validity of the rule of Bouguer - Weber A5 / 5 - cosh1, you can get an elementary unit of measurement of sensations. In other words, the value of the differential threshold, which is a constant value and does not depend on the absolute value of the stimulus, is nothing but an elementary "quantum" of sensation, and it can be used as a unit of measurement of subjective values. Fechner proposed the following formula:

∆S/S=∆R

where ΔR is the magnitude of the barely perceptible sensation.

It was quite bold to mathematically equate the ratio of two physical quantities to a subjective (mental) quantity. To be fair, it should be noted that the value of ΔS/S has no dimension and cannot be expressed in any physical units.

2. Assuming that the quantities ΔS and ΔR are infinitesimal (and this is the most vulnerable point of Fechner's concept), one can write the psychophysical relation in the form of a differential equation of the following form:

3. Integrating the expression dS / S = dR, we can derive the law of the relationship between the value of R (sensation) and S (strength of the stimulus):

R=klnS+C, or R=k'lgS+ C'.

As already noted, the logarithmic law derived by mathematical reasoning (the magnitude of the sensation is proportional to the logarithm of the strength of irritation) was elevated by Fechner to the rank of a basic psychophysical law. In 1877, in his afterword to The Elements of Psychophysics, Fechner wrote: “The Tower of Babel was not built at the time, because the workers could not agree on how to build it. My psychophysical structure (meaning the basic psychophysical law) will never be destroyed, since scientists will never agree on how to destroy it.

But no matter how ambitious such a statement, one must pay tribute to Fechner's foresight. Despite numerous and prolonged attacks by Fechner's opponents, the logarithmic law proved its viability not only in psychophysics, but also in neurophysiology, sensory physiology, etc. It was shown, in particular, that the physical scale of stimulus intensity at the receptor level really undergoes logarithmic transformation.

By the will of fate, Fechner's logarithmic law was included in almost all textbooks and manuals on psychology and sensory physiology. At the same time, objections to this law and alternative variants of psychophysical dependence put forward by Fechner's contemporaries and subsequent generations of psychophysicists remained little known until recently. It seems to us that this issue is quite important and deserves detailed consideration.

The appearance in 1860 of Fechner's Elements of Psychophysics truly revolutionized psychology. The major psychologists of the second half of the 19th century divided into two camps.

Some of them correctly understood and appreciated the essence of Fechner's concept of the possibility of a quantitative approach to the description of mental phenomena and processes, and accelerated their efforts in this direction. Wilhelm Wundt, the greatest scientist of that time, became the founder of the world's first laboratory of experimental psychology, in which studies of the time of motor reaction were carried out, attempts were made to divide the psyche into separate elementary mental acts, register, measure, calculate them, and only after that construct a complete picture of mental activity. Others (William James can serve as a vivid example) met with hostility the very idea of ​​the possibility of a quantitative approach in psychology.

Both among the supporters and among the opponents of Fechner there were those who tried to destroy the "Tower of Babel". At the same time, "undermining" under the psychophysical structure was made from different sides. Some argued that it was wrong to take the Bouguer-Weber rule as a basis, since it is valid only in the region of average values ​​of the stimulus strength, and is violated at low and high intensities. Others (and they were the majority) pointed out the illegality of differentiating the quantities A5 and DD, since they are not infinitesimal (we will talk about the fact that this is actually the case in the following sections). Finally, still others believed that ΔR (the subjective value of a subtle difference) was not constant. James, in particular, wrote: “A barely perceptible sensation of an increase in heaviness is perceived more strongly when adding a few pounds to a hundred-pound weight than when adding a few ounces to a one-pound weight. Fechner ignored this fact."

As an alternative to Fechner's law, F. Breptano proposed an equation of the following form:

∆R/R =k (∆S/S)

In other words, he suggested that the Bouguer - Vsbav rule is valid not only for the physical parameters of the stimulus (ΔS=kS), but also for sensations (ΔR=k'R). Differentiating this equation gives the following expression:

dR/R=k’/k (dS/S),

and integrating it leads to a double logarithmic (or power) dependence of the type:

lnR=(k'/k)lnS + C, or R = k''Sk'/k

Experimental confirmation of this form of dependence was obtained at the end of the last century by P. Breston, I. Merkel and other researchers.

In addition to the two above interpretations of the basic psychophysical law (logarithmic and power-law forms of dependence), other modifications were proposed: exponential (A. Pütter), tangential (E. Zinnsr), arctangential (G. Bsnssh), fi-gamma function (P . Houston), etc.

Based on the experimental data of Weber, another German scientist - G. Fechner - formulated the following law, usually called Fechner's law: if the intensity of stimulation increases exponentially, then the sensations will increase in arithmetic progression. In another formulation, this law sounds like this: the intensity of sensations grows in proportion to the logarithm of the intensity of the stimulus. Therefore, if the stimulus forms such a series: 10; 100; 1000; 10,000, then the intensity of the sensation will be proportional to the numbers 1; 2; 3; 4. The main meaning of this pattern is that the intensity of sensations does not increase in proportion to the change in stimuli, but much more slowly.. In mathematical form, the dependence of the intensity of sensations on the strength of the stimulus is expressed by the formula:

S=K*LgI+C,

(where S- intensity of sensation; I- the strength of the stimulus; To and With- constants). This formula reflects the situation, which is called basic psychophysical law, or Weber-Fechner law. Half a century after the discovery of the basic psychophysical law, it again attracted attention and gave rise to much controversy about its accuracy. The American scientist S. Stevens came to the conclusion that the basic psychophysical law is expressed not by a logarithmic, but by a power curve. He proceeded from the assumption that sensations, or sensory space, are characterized by the same relationship as the space of stimuli. This pattern can be represented by the following mathematical expression:

where E- initial feeling E- the minimum change in sensation that occurs when the acting stimulus changes by the minimum amount noticeable to a person. Thus, from this mathematical expression it follows that the ratio between the minimum possible change in our sensations and the primary sensation is a constant value - To. And if so, then the relationship between stimulus space and sensory space (our sensations) can be represented by the following equation:

This equation is called the Stevens law. The solution to this equation is expressed by the following formula:

S=K´ R n,

where S- the power of feeling To- a constant determined by the chosen unit of measure, n- an indicator that depends on the modality of sensations and varies from 0.3 for the sensation of loudness to 3.5 for the sensation received from an electric shock, R- the value of the stimulus.

American scientists R. and B. Tetsunyan tried to mathematically explain the meaning of the degree n. As a result, they concluded that the value of the degree n for each modality (i.e., for each sense organ) determines the relationship between the range of sensations and the range of perceived stimuli.

The dispute about which of the laws is more accurate has never been resolved. Science knows numerous attempts to answer this question. One of these attempts belongs to Yu. M. Zabrodin, who offered his own explanation of the psychophysical correlation. The world of stimuli again represents the Bouguer-Weber law, and Zabrodin proposed the structure of the sensory space in the following form:

Obviously, at z=0 the formula of the generalized law goes over into the Fechner logarithmic law, and when z=1 - into the Stevens power law.

Why Yu. M. Zabrodin introduced the constant z and what is its meaning? The fact is that the value of this constant determines the degree of awareness of the subject about the goals, objectives and course of the experiment. G. Fechner's experiments involved "naive" subjects who fell into a completely unfamiliar experimental situation and knew nothing about the upcoming experiment except for the instructions. Thus, in Fechner's law z= 0, which means complete ignorance of the subjects. Stephens solved more pragmatic problems. He was more interested in how a person perceives a sensory signal in real life, and not in the abstract problems of the sensory system. He proved the possibility of direct estimates of the magnitude of sensations, the accuracy of which increases with proper training of the subjects. In his experiments, subjects who had undergone preliminary training, trained to act in the situation of a psychophysical experiment, took part. Therefore, in Stevens' law z=1, which shows the complete awareness of the subject.

Thus, the law proposed by Yu. M. Zabrodin removes the contradiction between the laws of Stevens and Fechner. Therefore, it is no coincidence that he received the name generalized psychophysical law.

However, no matter how the contradiction between the laws of Fechner and Stevens is resolved, both options quite accurately reflect the essence of the change in sensations with a change in the magnitude of irritation. First, sensations change disproportionately to the strength of the physical stimuli acting on the sense organs. Secondly, the strength of sensation grows much more slowly than the magnitude of physical stimuli. This is the meaning of psychophysical laws.

7.4. Sensory adaptation and interaction of sensations

Speaking about the properties of sensations, we cannot but dwell on a number of phenomena associated with sensations. It would be wrong to assume that the absolute and relative sensitivity remain unchanged and their thresholds are expressed in constant numbers. Studies show that sensitivity can vary over a very wide range. For example, in the dark, our vision becomes sharper, and in strong light, its sensitivity decreases. This can be observed when you move from a dark room to light or from a brightly lit room to darkness. In both cases, the person is temporarily "blind", it takes some time for the eyes to adjust to bright light or darkness. This suggests that, depending on the environment (illumination), the visual sensitivity of a person changes dramatically. Studies have shown that this change is very large and the sensitivity of the eye in the dark is aggravated by 200,000 times.

The described changes in sensitivity, depending on environmental conditions, are associated with the phenomenon of sensory adaptation. Sensory adaptation called a change in sensitivity that occurs as a result of the adaptation of the sense organ to the stimuli acting on it. As a rule, adaptation is expressed in the fact that when sufficiently strong stimuli act on the sense organs, sensitivity decreases, and when weak stimuli or in the absence of a stimulus act, sensitivity increases.

Such a change in sensitivity does not occur immediately, but requires a certain 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 that a person acquires the ability to navigate well in the dark. The adaptation of the auditory organs is much faster. Human hearing adapts to the surrounding background after 15 seconds. Just as quickly, there is a change in the sensitivity of touch (a weak touch on the skin ceases to be perceived after a few seconds). The phenomena of thermal adaptation (getting used to changes in ambient temperature) are well known. However, these phenomena are clearly expressed only in the middle range, and addiction to extreme cold or extreme heat, as well as to pain stimuli, is almost never encountered. The phenomena of adaptation to smells are also known.

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

There is another phenomenon that we must consider. 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 sense organs is called interaction of sensations.

Two types of interaction of sensations should be distinguished: 1) interaction between sensations of the same type and 2) interaction between sensations of different types.

Interactions between sensations of different types can be illustrated by the studies of Academician P.P. Lazarev, who found that eye lighting makes audible sounds louder. Similar results were obtained by Professor S. V. Kravkov. He established that no sense organ can work without affecting the functioning of other organs. So, it turned out that sound stimulation (for example, whistling) can sharpen the work of visual sensation, increasing its sensitivity to light stimuli. Some odors also affect in a similar way, increasing or decreasing light and auditory sensitivity. 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 of increasing and decreasing sensitivity. The general pattern is that weak stimuli increase, and strong ones decrease the sensitivity of the analyzers during their interaction.

Luria Alexander Romanovich(1902-1977) - Russian psychologist who dealt with many problems in various areas of psychology. He is rightfully considered the founder of Russian neuropsychology. Active member of the Academy of Sciences of the USSR, Doctor of Psychological and Medical Sciences, professor, author of more than 500 scientific papers. He worked with L. S. Vygotsky on the creation of a cultural-historical concept of the development of higher mental functions, as a result of which, in 1930, together with Vygotsky, he wrote the work “Etudes on the History of Behavior”. Researching in the 1920s affective states of a person, created an original psychophysiological method of conjugated motor reactions intended for the analysis of affective complexes. Repeatedly organized expeditions to Central Asia and personally took part in them. Based on the material collected in these expeditions, he made a number of interesting generalizations regarding intercultural differences in the human psyche.

The main contribution of A. R. Luria to the development of psychological science is the development of the theoretical foundations of neuropsychology, which was expressed in his theory of systemic dynamic localization of higher mental functions and their disturbances in brain damage. He conducted research on the neuropsychology of speech, perception, attention, memory, thinking, voluntary movements and actions.

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

As follows from the above examples, there are ways to increase the sensitivity of the senses. An increase in sensitivity as a result of the interaction of analyzers or exercises is called sensitization. A. R. Luria distinguishes two sides of increased sensitivity according to the type of sensitization. The first is of a long-term, permanent nature and depends mainly on stable changes occurring in the body, so the age of the subject is clearly associated with a change in sensitivity. Studies have shown that the acuteness of the sensitivity of the sense organs increases with age, reaching a maximum by the age of 20-30, in order to gradually decrease in the future. The second side of the increase in 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 appearance 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, in Scriabin). So, it is widely known that we regard high sounds as “light”, and low ones 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 a person addressing him, for example, was “yellow and crumbly.” The tones he heard caused him visual sensations of various shades (from bright yellow to purple). Perceived colors were perceived by him as "sonorous" or "deaf", as "salty" or "crunchy". Similar phenomena in more obliterated forms occur quite often in the form of a direct 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 analyzer systems of the human body, the integrity of the sensory reflection of the objective world.

7.5. Development of sensations

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 child's skin sensitivity is more developed. When born, the baby trembles due to the difference in the temperature of the mother's body and air temperature. A newborn child also reacts to touch, and his lips and the entire area of ​​\u200b\u200bthe mouth are 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 has a highly developed taste sensitivity. Newborn children react differently to the introduction of a solution of quinine or sugar into their mouth. A few days after birth, the baby 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 sufficiently developed. A newborn child determines by the smell of mother's milk whether the mother is in the room or not. If the child ate mother's milk for the first week, then he will turn away from cow's milk only when he smells it. However, olfactory sensations that are not related to nutrition develop over a long period of time. They are poorly developed in most children, even at the age of four or five.

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

The child's first reactions to sound are in the nature of general motor excitation: the child throws up his arms, moves his legs, and utters a loud cry. Sensitivity to sound is initially low, but increases in the first weeks of life. After two or three months, the child begins to perceive the direction of the sound, turns his head towards the source of the sound. In the third or fourth month, some babies 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 the 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 proper begins. First, the child develops the ability to distinguish between vowels, and at a subsequent stage, he begins to distinguish between consonants.

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

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

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 child of preschool age, this ability is developed incomparably lower than in an adult. The rapid development of this ability is noted in the school years.

It should also be noted that the level of development of sensations in different people is not the same. This is largely due to the genetic characteristics of a person. Nevertheless, sensations can be developed within certain limits. The development of sensations is carried out by the method of constant training. It is thanks to the possibility of developing sensations that, for example, children are taught music or drawing.

7.6. Characteristics of the main types of sensations

Skin sensations. We will begin our acquaintance with the main types of sensations with the sensations that we receive from the impact of various stimuli on receptors located on the surface of human skin. All the sensations that a person receives from skin receptors can be combined under one name - skin sensations. However, the category of these sensations should also include those sensations that arise when irritants are exposed to the mucous membrane of the mouth and nose, the cornea of ​​​​the eyes.

Skin sensations refer to the contact type of sensations, i.e., they arise when the receptor is in direct contact with the object of the real world. In this case, sensations of four main types can arise: sensations of touch, or tactile sensations; sensations of cold; sensations of warmth; sensations of pain.

Each of the four types of skin sensations has specific receptors. Some points of the skin give only sensations of touch (tactile points), others - sensations of cold (cold points), others - sensations of heat (heat points), fourth - sensations of pain (pain points) (Fig. 7.2).

Rice. 7.2. Skin receptors and their functions

Normal stimuli for tactile receptors are touches that cause deformation of the skin, for cold - exposure to objects of lower temperature, for heat - exposure to objects of higher temperature, for pain - any of the above effects, provided that the intensity is sufficiently high. The location of the corresponding receptor points and the absolute sensitivity thresholds are determined using aesthesiometer. The simplest device is a hair esthesiometer (Fig. 7.3), consisting of a horsehair and a device that allows you to measure the pressure exerted by this hair on any point of the skin. With a weak touch of the hair to the skin, sensations arise only when directly hit the tactile point. Similarly, the location of cold and heat points is determined, only instead of a hair, a thin metal tip is used, filled with water, the temperature of which can vary.

The existence of cold spots can be verified without a device. To do this, it is enough to draw the tip of a pencil along the lowered eyelid. As a result, from time to time there will be a feeling of cold.

Rice. 7.3. Hair Esthesiometer

Repeated attempts have been made to determine the number of skin receptors. There are no exact results, but it is approximately established that there are about one million touch points, about four million pain points, about 500 thousand cold points, and about 30 thousand warm points.

Points of certain types of sensations are unevenly located on the surface of the body. For example, on the fingertips there are twice as many touch points as there are pain points, although the total number of the latter is much greater. On the cornea, on the contrary, there are no touch points at all, but only pain points, so that any touch on the cornea causes a sensation of pain and a protective reflex of closing the eyes.

The uneven distribution of skin receptors over the surface of the body causes uneven sensitivity to touch, to pain, etc. Thus, the fingertips are most sensitive to touch and the back, abdomen and outer side of the forearm are less sensitive. Sensitivity to pain is distributed quite differently. The back, cheeks are most sensitive to pain and the fingertips are the least sensitive. As for the temperature regimes, the most sensitive are those parts of the body that are usually covered by clothing: the lower back, chest.

Tactile sensations carry information not only about the stimulus, but also about localization its impact. In different parts of the body, the accuracy of determining the localization of exposure is different. It is characterized by spatial threshold of tactile sensations. If we touch the skin at two points at the same time, then we will not always feel these touches as separate - if the distance between the touch points is not large enough, both sensations will merge into one. Therefore, the minimum distance between the places of contact, which allows you to distinguish the touch of two spatially separate objects, is called spatial threshold of tactile sensations.

Usually, to determine the spatial threshold of tactile sensations, circular esthesiometer(Fig. 7.4), which is a compass with sliding legs. The smallest threshold of spatial differences in skin sensations is observed in areas of the body that are more sensitive to touch. So, on the back, the spatial threshold of tactile sensations is 67 mm, on the forearm - 45 mm, on the back of the hand - 30 mm, on the palm - 9 mm, on the fingertips 2.2 mm. The lowest spatial threshold for tactile sensations is at the tip of the tongue - 1.1 mm. It is here that touch receptors are most densely located.

Rice. 7.4. Circular esthesiometer

Rice. 7.5. Taste receptors

Taste and olfactory sensations. Taste receptors are taste buds composed of sensitive taste cells connected to nerve fibers (Fig. 7.5). In an adult, taste buds are located mainly at the tip, along the edges and on the back of the upper surface of the tongue. The middle of the upper surface and the entire lower surface of the tongue are not sensitive to taste. Taste buds are also found on the palate, tonsils, and back of the throat. In children, the distribution of taste buds is much wider than in adults. Dissolved flavoring substances serve as irritants for taste buds.

Receptors olfactory sensations are olfactory cells, immersed in the mucous membrane of the so-called olfactory region (Fig. 7.6). Irritants for the olfactory receptors are various odorous substances that penetrate the nose along with the air. In an adult, the area of ​​the olfactory region is approximately 480 mm 2 . In a newborn, it is much larger. This is due to the fact that in newborns the leading sensations are gustatory and olfactory sensations. It is thanks to them that the child receives the maximum amount of information about the world around him, they also provide the newborn with the satisfaction of his basic needs. In the process of development, olfactory and gustatory sensations give way to other, more informative sensations, and first of all to vision.

Rice. 7.6. olfactory sensory receptors

It should be noted that taste sensations in most cases mixed with olfactory ones. The variety of taste largely depends on the admixture of olfactory sensations. For example, with a runny nose, when the olfactory sensations are "off", in some cases the food seems tasteless. In addition, tactile and temperature sensations from receptors located in the area of ​​the mucous membrane in the mouth are mixed with taste sensations. Thus, the peculiarity of the "spicy" or "astringent" food is mainly associated with tactile sensations, and the characteristic taste of mint largely depends on the irritation of cold receptors.

If we exclude all these impurities of tactile, temperature and olfactory sensations, then the actual taste sensations will be reduced to four main types: sweet, sour, bitter, salty. The combination of these four components allows you to get a variety of flavor options.

Experimental studies of taste sensations were carried out in the laboratory of P. P. Lazarev. To obtain taste sensations, sugar, oxalic acid, table salt and quinine were used. It has been found that most taste sensations can be imitated with these substances. For example, the taste of a ripe peach gives a combination of sweet, sour and bitter in certain proportions.

Experimentally, it was also found that different parts of the tongue have different sensitivity to the four taste qualities. For example, sensitivity to sweet is maximum at the tip of the tongue and minimum at the back of it, while sensitivity to bitter, on the contrary, is maximum at the back and minimum at the tip of the tongue.

Unlike taste sensations, olfactory sensations cannot be reduced to combinations of basic odors. Therefore, there is no strict classification of odors. All smells are tied to a specific object that possesses them. For example, the smell of a flower, the smell of a rose, the smell of jasmine, etc. As for taste sensations, impurities of other sensations play an important role in obtaining a smell: taste (especially from irritation of the taste buds located in the back of the throat), tactile and temperature. The sharp caustic smells of mustard, horseradish, ammonia contain an admixture of tactile and painful sensations, and the refreshing smell of menthol contains an admixture of cold sensations.

You should also pay attention to the fact that the sensitivity of olfactory and taste receptors increases during the state of hunger. After several hours of fasting, the absolute sensitivity to sweet increases significantly, and sensitivity to sour increases, but to a lesser extent. This suggests that olfactory and gustatory sensations are largely related to the need to satisfy such a biological need as the need for food.

Individual differences in taste sensations among people are small, but there are exceptions. Thus, there are people who are able to a much greater extent, compared with most people, to distinguish between the components of smell or taste. Taste and smell sensations can be developed through constant training. This is taken into account when mastering the profession of a taster.

auditory sensations. The irritant for the organ of hearing is sound waves, i.e., the longitudinal vibration of air particles, propagating in all directions from the oscillating body, which serves as a source of sound.

All sounds that the human ear perceives can be divided into two groups: musical(sounds of singing, sounds of musical instruments, etc.) and noises(all kinds of squeaks, rustles, knocks, etc.). There is no strict boundary between these groups of sounds, since musical sounds contain noises, and noises can contain elements of musical sounds. Human speech, as a rule, simultaneously contains the sounds of both groups.

In sound waves, there are frequency, amplitude and mode of vibration. Accordingly, auditory sensations have the following three aspects: pitch, which is a reflection of the oscillation frequency; sound volume, which is determined by the amplitude of wave oscillations; timbre, which is a reflection of the shape of the wave oscillations.

Sound pitch is measured in hertz, i.e., in the number of vibrations of a sound wave per second. The sensitivity of the human ear has its limits. The upper limit of hearing in children is 22,000 hertz. By old age, this limit drops to 15,000 hertz and even lower. Therefore, older people often do not hear high-pitched sounds, such as the chirping of grasshoppers. The lower limit of human hearing is 16-20 hertz.

The absolute sensitivity is highest in relation to the sounds of the average oscillation frequency - 1000-3000 hertz, and the ability to distinguish the pitch of a sound varies greatly from person to person. The highest threshold of discrimination is observed among musicians and tuners of musical instruments. The experiments of B. N. Teplov testify that in people of this profession the ability to distinguish the pitch of a sound is determined by a parameter of 1/20 or even 1/30 of a semitone. This means that between two adjacent piano keys, the tuner can hear 20-30 intermediate pitch steps.

The loudness of sound is the subjective intensity of the auditory sensation. Why subjective? We cannot talk about the objective characteristics of sound, because, as follows from the basic psychophysical law, our sensations are proportional not to the intensity of the irritant, but to the logarithm of this intensity. Secondly, the human ear has different sensitivity to sounds of different pitches. Therefore, sounds that we do not hear at all can exist and with the highest intensity affect our body. Thirdly, there are individual differences between people with regard to absolute sensitivity to sound stimuli. However, practice determines the need to measure the loudness of sound. The units of measurement are decibels. One unit of measurement is the intensity of the sound coming from the ticking of a clock at a distance of 0.5 m from the human ear. So, the volume of ordinary human speech at a distance of 1 meter will be 16-22 decibels, street noise (without a tram) - up to 30 decibels, noise in a boiler room - 87 decibels, etc.

Helmholtz Hermann(1821-1894) - German physicist, physiologist and psychologist. Being a physicist by education, he sought to introduce physical methods of research into the study of a living organism. In his work "On the Conservation of Force" Helmholtz mathematically substantiated the law of conservation of energy and the position that a living organism is a physico-chemical environment in which this law is exactly fulfilled. He was the first to measure the speed of conduction of excitation along nerve fibers, which marked the beginning of the study of reaction time.

Helmholtz made a significant contribution to the theory of perception. In particular, in the psychology of perception, he developed the concept of unconscious inferences, according to which the actual perception is determined by the habitual ways already existing in a person, due to which the constancy of the visible world is maintained and in which muscle sensations and movements play a significant role. Based on this concept, he made an attempt to explain the mechanisms of perception of space. Following M. V. Lomonosov, he developed a three-component theory of color vision. Developed the resonance theory of hearing. In addition, Helmholtz made a significant contribution to the development of world psychological science. Thus, W. Wundt, I. M. Sechenov and others were his collaborators and students.

Timbre is that specific quality that distinguishes sounds of the same height and intensity from different sources from each other. Very often, timbre is spoken of as the "color" of sound.

Differences in timbre between two sounds are determined by the variety of forms of sound vibration. In the simplest case, the shape of the sound wave will correspond to a sinusoid. Such sounds are called "simple". They can only be obtained with the help of special devices. Close to a simple sound is the sound of a tuning fork - a device used to tune musical instruments. In everyday life, we do not encounter simple sounds. The sounds around us are composed of various sound elements, so the shape of their sound, as a rule, does not correspond to a sinusoid. Nevertheless, musical sounds arise with sound vibrations that have the form of a strict periodic sequence, while for noise it is the other way around. The form of sound vibration is characterized by the absence of strict periodization.

It should also be borne in mind that in everyday life we ​​perceive many simple sounds, but we do not distinguish this variety, because all these sounds merge into one. So, for example, two sounds of different pitch often, as a result of their merging, are perceived by us as one sound with a certain timbre. Therefore, the combination of simple sounds in one complex one gives originality to the form of sound vibrations and determines the timbre of the sound. The timbre of the sound depends on the degree of fusion of sounds. The simpler the shape of the sound wave, the more pleasant the sound. Therefore, it is customary to highlight a pleasant sound - consonance and unpleasant sound dissonance.

Rice. 7.7. The structure of auditory receptors

Helmholtz's resonance theory of hearing provides the best explanation for the nature of auditory sensations. As you know, the terminal apparatus of the auditory nerve is the organ of Corti, which rests on basilar membrane, running along the entire spiral bone canal, called snail(Fig. 7.7). The main membrane consists of a large number (about 24,000) of transverse fibers, the length of which gradually decreases from the top of the cochlea to its base. According to the Helmholtz resonant theory, each such fiber is tuned, like a string, to a certain frequency of oscillation. When sound vibrations of a certain frequency reach the cochlea, a certain group of fibers of the main membrane resonates and only those cells of the organ of Corti that rest on these fibers are excited. Shorter fibers lying at the base of the cochlea respond to higher sounds, longer fibers lying at its top respond to low sounds.

It should be noted that the staff of IP Pavlov's laboratory, who studied the physiology of hearing, came to the conclusion that Helmholtz's theory quite accurately reveals the nature of auditory sensations.

visual sensations. The irritant for the organ of vision is light, that is, electromagnetic waves having a length of 390 to 800 millimicrons (millimicrons - a millionth of a millimeter). Waves of a certain length cause a person to experience a certain color. So, for example, sensations of red light are caused by waves of 630-800 millimicrons, yellow - by waves from 570 to 590 millimicrons, green - by waves from 500 to 570 millimicrons, blue - by waves from 430 to 480 millimicrons.

Everything we see has color, so visual sensations are sensations of color. All colors are divided into two large groups: colors achromatic and colors chromatic. Achromatic colors include white, black and grey. All other colors (red, blue, green, etc.) are chromatic.

From the history of psychology

Theories of hearing

It should be noted that Helmholtz's resonance theory of hearing is not the only one. So, in 1886, the British physicist E. Rutherford put forward a theory with which he tried to explain the principles of encoding the pitch and intensity of sound. His theory contained two statements. First, in his opinion, a sound wave causes the entire eardrum (membrane) to vibrate, and the vibration frequency corresponds to the frequency of the sound. Secondly, the frequency of vibrations of the membrane sets the frequency of nerve impulses transmitted along the auditory nerve. Thus, a tone with a frequency of 1000 hertz causes the membrane to vibrate 1000 times per second, as a result of which the fibers of the auditory nerve are discharged at a frequency of 1000 pulses per second, and the brain interprets this as a certain height. Since this theory assumed that the pitch depends on changes in sound over time, it was called the temporal theory (in some literary sources it is also called the frequency theory).

It turned out that Rutherford's hypothesis is not able to explain all the phenomena of auditory sensations. For example, it was found that nerve fibers can transmit no more than 1000 impulses per second, and then it is not clear how a person perceives a pitch with a frequency of more than 1000 hertz.

In 1949, V. Weaver made an attempt to modify Rutherford's theory. He suggested that frequencies above 1000 hertz are encoded by different groups of nerve fibers, each of which is activated at a slightly different pace. If, for example, one group of neurons fires 1000 pulses per second, and then 1 millisecond later another group of neurons starts firing 1000 pulses per second, then the combination of the pulses of these two groups will give 2000 pulses per second.

However, some time later it was found that this hypothesis is able to explain the perception of sound vibrations, the frequency of which does not exceed 4000 hertz, and we can hear higher sounds. Since Helmholtz's theory can more accurately explain how the human ear perceives sounds of different pitches, it is now more accepted. In fairness, it should be noted that the main idea of ​​this theory was expressed by the French anatomist Joseph Guichard Duvernier, who in 1683 suggested that the frequency is encoded by the pitch mechanically, by resonance.

Exactly how the membrane vibrates was not known until 1940, when Georg von Bekeschi was able to measure its movements. He found that the membrane behaved not like a piano with separate strings, but like a sheet that was shaken at one end. When a sound wave enters the ear, the entire membrane begins to oscillate (vibrate), but at the same time, the place of the most intense movement depends on the pitch of the sound. High frequencies cause vibration at the near end of the membrane; as the frequency increases, the vibration shifts towards the oval window. For this and for a number of other studies of hearing, von Bekesy received the Nobel Prize in 1961.

At the same time, it should be noted that this theory of locality explains many, but not all, phenomena of pitch perception. In particular, the main difficulties are associated with low frequency tones. The fact is that at frequencies below 50 hertz, all parts of the basilar membrane vibrate approximately the same. This means that all receptors are activated equally, which means that we have no way to distinguish between frequencies below 50 hertz. In fact, we can distinguish a frequency of only 20 hertz.

Thus, at present, there is no complete explanation of the mechanisms of auditory sensations.

Sunlight, like the light of any artificial source, consists of waves of different wavelengths. At the same time, any object, or physical body, will be perceived in a strictly defined color (combination of colors). The color of a particular object depends on which waves and in what proportion are reflected by this object. If the object uniformly reflects all waves, i.e., it is characterized by the absence of reflection selectivity, then its color will be achromatic. If it is characterized by selectivity in the reflection of waves, i.e., it mainly reflects waves of a certain length, and absorbs the rest, then the object will be painted in a certain chromatic color.

Achromatic colors differ from each other only in lightness. Lightness depends on the reflectance of the object, that is, on how much of the incident light it reflects. The higher the reflectance, the lighter the color. So, for example, white writing paper, depending on its grade, reflects from 65 to 85% of the light falling on it. The black paper in which photographic paper is wrapped has a reflectance of 0.04, i.e., it reflects only 4% of the incident light, and good black velvet reflects only 0.3% of the light incident on it - its reflectance is 0.003.

Chromatic colors are characterized by three properties: lightness, hue and saturation. The color tone depends on which particular wavelengths prevail in the light flux reflected by a given object. saturation the degree of expression of a given color tone is called, that is, the degree of difference between a color and gray, which is the same with it in lightness. The saturation of a color depends on how much those wavelengths that determine its color tone predominate in the light flux.

It should be noted that our eye has unequal sensitivity to light waves of different lengths. As a result, the colors of the spectrum, with objective equality of intensity, seem to us to be unequal in lightness. The lightest color seems to us yellow, and the darkest - blue, because the sensitivity of the eye to waves of this wavelength is 40 times lower than the sensitivity of the eye to yellow. It should be noted that the sensitivity of the human eye is very high. For example, between black and white, a person can distinguish about 200 transitional colors. However, it is necessary to separate the concepts of "eye sensitivity" and "visual acuity".

Visual acuity is the ability to distinguish between small and distant objects. The smaller the objects that the eye is able to see in specific conditions, the higher its visual acuity. Visual acuity is characterized by the minimum gap between two points, which from a given distance are perceived separately from each other, and do not merge into one. This value can be called the spatial threshold of vision.

In practice, all the colors we perceive, even those that appear to be monochromatic, are the result of a complex interaction of light waves of different wavelengths. Waves of different lengths enter our eye at the same time, and the waves mix, as a result of which we see one specific color. The works of Newton and Helmholtz established the laws of mixing colors. Of these laws, two are of greatest interest to us. First, 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 called complementary. And 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 suitably chosen chromatic colors. This provision is extremely important for understanding the nature of color vision.

In order to comprehend the nature of color vision, let's take a closer look at the theory of tricolor vision, the idea of ​​which was put forward by Lomonosov in 1756, expressed by T. Jung 50 years later, and 50 years later was developed in more detail by Helmholtz. According to Helmholtz's theory, the eye is supposed to have the following three physiological apparatuses: red-sensing, green-sensing, and violet-sensing. Isolated excitation of the first gives a sensation of red color. The isolated sensation of the second apparatus gives the sensation of green color, and the excitation of the third apparatus gives the violet color. However, as a rule, light acts simultaneously on all three apparatuses, or at least on two of them. At the same time, the excitation of these physiological apparatuses with different intensity and in different proportions in relation to each other gives all known chromatic colors. The sensation of white color occurs with uniform excitation of all three apparatuses.

This theory explains many phenomena well, including the disease of partial color blindness, in which a person does not distinguish between individual colors or color shades. 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 the retina in the eye, which is a branching of the optic nerve that enters the back of the eyeball. There are two types of apparatus in the retina: cones and rods (so named because of their shape). Rods and cones are the terminal apparatus of the nerve fibers of the optic nerve. There are about 130 million rods and 7 million cones in the retina of the human eye, which are unevenly distributed throughout the retina. The cones fill the fovea of ​​the retina, that is, the place where the image of the object we are looking at falls. The number of cones decreases towards the edges of the retina. There are more rods at the edges of the retina, in the middle they are practically absent (Fig. 7.8).

Rice. 7.8. visual sensory receptors

Cones are less sensitive. To cause their reaction, you need a strong enough light. Therefore, with the help of cones, we see in bright light. They are also called day vision devices. Rods are more sensitive, and with their help we see at night, so they are called night vision apparatus. However, it is only with the help of cones that we distinguish colors, since it is they that determine the ability to evoke chromatic sensations. In addition, cones provide the necessary visual acuity.

There are people in whom the cone apparatus does not function, and they see everything around them only in gray. This disease is called total 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(or "night blindness").

Concluding the consideration of the nature of visual sensations, we need to dwell on several more phenomena of vision. Thus, the visual sensation does not stop at the same moment as the action of the stimulus ceases. It continues for some time. This is because visual arousal has a certain inertia. This continuation of sensation for some time is called in a positive consistent way.

To observe this phenomenon in practice, sit near the lamp in the evening and close your eyes for two or three minutes. Then open your eyes and look at the lamp for two or three seconds, then close your eyes again and cover them with your hand (so that the light does not penetrate through the eyelids). You will see a light image of the lamp on a dark background. It should be noted that it is due to this phenomenon that we watch a movie when we do not notice the movement of the film due to the positive sequential image that occurs after the exposure of the frame.

Another phenomenon of vision is connected with the negative sequential image. The essence of this phenomenon lies in the fact that after exposure to light for some time, the sensation of the opposite irritant in terms of lightness remains. For example, put two blank white sheets of paper in front of you. Place a square of red paper in the middle of one of them. In the middle of the red square, draw a small cross and look at it for 20-30 seconds without taking your eyes off. Then look at a blank white sheet of paper. After a while, you will see an image of a red square on it. Only its color will be different - bluish-green. After a few seconds, it will begin to turn pale and soon disappear. The image of the square is the negative sequential image. Why is the image of the square greenish-blue? The fact is that this color is complementary to red, that is, their merging gives an achromatic color.

The question may arise: why, under normal conditions, do we not notice the emergence of negative sequential images? Only because our eyes are constantly moving and certain parts of the retina do not have time to get tired.

Theories of color vision

Considering the problem of color vision, it should be noted that in world science the three-color theory of vision is not the only one. There are other points of view on the nature of color vision. Thus, in 1878, Ewald Hering noticed that all colors can be described as consisting of one or two of the following sensations: red, green, yellow and blue. Hering also noted that a person never perceives anything as reddish-green or yellowish-blue; a mixture of red and green is more likely to look yellow, and a mixture of yellow and blue is more likely to look white. From these observations, it follows that red and green form an opponent pair - just like yellow and blue - and that the colors included in the opponent pair cannot be perceived simultaneously. The concept of "opposing pairs" was further developed in studies in which the subject first looked at colored light and then at a neutral surface. As a result, when examining a neutral surface, the subject saw a color on it that was complementary to the original one. These phenomenological observations prompted Hering to propose another theory of color vision called the opponent color theory.

Hering believed that there are two types of color-sensitive elements in the visual system. One type reacts to red or green, the other to blue or yellow. Each element reacts oppositely to its two opponent colors: for a red-green element, for example, the strength of the reaction increases when red is presented and decreases when green is presented. Since the element cannot react in two directions at once, when two opponent colors are presented, yellow is perceived simultaneously.

The theory of opponent colors with a certain degree of objectivity can explain a number of facts. In particular, according to a number of authors, it explains why we see exactly the colors that we see. For example, we perceive only one tone - red or green, yellow or blue - when the balance is shifted for only one type of opponent pair, and we perceive combinations of tones when the balance is shifted for both types of opponent pairs. Objects are never perceived as red-green or yellow-blue because the element cannot react in two directions at once. In addition, this theory explains why subjects who first looked at colored light and then at a neutral surface say they see complementary colors; if, for example, the subject first looks at red, then the red component of the pair gets tired, as a result of which the green component comes into play.

Thus, in the scientific literature you can find two theories of color vision - tricolor (trichromatic) and the theory of opponent colors - and each of them can explain some facts, but some can not. For many years, these two theories in the works of many authors were considered as alternative or competitive, until the researchers proposed a compromise theory - a two-stage one.

According to the two-stage theory, the three types of receptors that are considered in the trichromatic theory supply information to opponent pairs located at a higher level of the visual system. This hypothesis was put forward when color-opponent neurons were found in the thalamus, one of the intermediate links between the retina and visual cortex. Studies have shown that these nerve cells have a spontaneous activity that increases in response to one range of wavelengths and decreases in response to another. For example, some cells located at a higher level of the visual system fire faster when the retina is stimulated with blue light than when it is stimulated with yellow light; such cells form the biological basis of the blue-yellow opponent pair. Therefore, targeted studies have established the presence of three types of receptors, as well as color-opposing neurons, located in the thalamus.

This example clearly shows how complex a person is. It is likely that many judgments about psychic phenomena that seem true to us after some time may be questioned, and these phenomena will have a completely different explanation.

Rice. 7.9. Sense of balance receptors

proprioceptive sensations. As you remember, proprioceptive sensations include sensations of movement and balance. Receptors for sensations of balance are located in the inner ear (Fig. 7.9). The latter consists of three parts: the vestibule, the semicircular canals and the cochlea. Balance receptors are located in the vestibule.

The movement of fluid irritates the nerve endings located on the inner walls of the semicircular tubes of the inner ear, which is the source of a sense of balance. It should be noted that under normal conditions we get a sense of balance not only from these receptors. For example, when our eyes are open, the position of the body in space is also determined with the help of visual information, as well as motor and skin sensations, through the information they transmit about movement or information about vibration. But in some special conditions, for example, when diving into water, we can receive information about the position of the body only with the help of a sense of balance.

It should be noted that the signals coming from the balance receptors do not always reach our consciousness. In most cases, our body reacts automatically to changes in body position, that is, at the level of unconscious regulation.

Receptors for kinesthetic (motor) sensations are found in muscles, tendons, and articular surfaces. These sensations give us ideas about the magnitude and speed of our movement, as well as the position in which this or that part of our body is located. Motor sensations play a very important role in the coordination of our movements. Performing this or that movement, we, or rather our brain, constantly receive signals from receptors located in the muscles and on the surface of the joints. If a person's processes of forming sensations of movement are disturbed, then, having closed his eyes, he cannot walk, because he cannot maintain balance in movement. This disease is called ataxia, or movement disorder.

Touch. It should also 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. In a detailed study of the interaction of these types of sensations, interesting experimental data were obtained. Thus, various figures were applied to the skin of the forearm of the 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 unmistakably determined their shape.

To touch, that is, to the combination of skin and motor sensations, we owe the ability to evaluate such properties of objects as hardness, softness, smoothness, and roughness. For example, the feeling of hardness mainly depends on how much resistance the body offers when pressure is applied to it, and we judge this by the degree of muscle tension. Therefore, it is impossible to determine the hardness or softness of an object without the participation of sensations of movement. In conclusion, you should pay attention to the fact that almost all types of sensations are interconnected with each other. Thanks to this interaction, we receive the most complete information about the world around us. However, this information is limited only to information about the properties of objects. A holistic image of the object as a whole we get through perception.

test questions

1. What is "feeling"? What are the main characteristics of this mental process?

2. What is the physiological mechanism of sensations? What is an "analyzer"?

3. What is the reflex nature of sensations?

4. What concepts and theories of sensations do you know?

5. What classifications of sensations do you know?

6. What is the "modality of sensations"?

7. Describe the main types of sensations.

8. Tell us about the main properties of sensations.

9. What do you know about the absolute and relative thresholds of sensations?

10. Tell us about the basic psychophysical law. What do you know about the Weber constant?

11. Talk about sensory adaptation.

12. What is sensitization?

13. What do you know about skin sensations?

14. Tell us about the physiological mechanisms of visual sensations. What theories of color vision do you know?

15. Tell us about hearing sensations. What do you know about the resonance theory of hearing?

1. Ananiev B. G. On the problems of modern human knowledge / USSR Academy of Sciences, Institute of Psychology. - M.: Nauka, 1977.

2. WeckerL. M. Mental processes: In 3 vols. T. 1. - L .: Publishing House of Leningrad State University, 1974.

3. Vygotsky L. S.. Collected Works: In 6 vols. Vol. 2: Problems of General Psychology / Ch. ed. A. V. Zaporozhets. - M.: Pedagogy, 1982.

4. Gelfand S. A. Hearing. Introduction to psychological and physiological acoustics. - M., 1984.

5. Zabrodin Yu. M., Lebedev A. N. Psychophysiology and psychophysics. - M.: Nauka, 1977.

6. Zaporozhets A. V. Selected psychological works: In 2 vols. Vol. 1: Mental development of the child / Ed. V. V. Davydova, V. P. Zinchenko. - M.: Pedagogy, 1986.

7. w. Functional organization of the auditory system: Textbook. - M.: Publishing House of Moscow State University, 1985.

8. Lindsay P., NormanD. Information processing in humans: Introduction to psychology / Per. from English. ed. A. R. Luria. - M.: Mir, 1974.

9. Luria A. R. Feelings and perception. - M.: Publishing House of Moscow State University, 1975.

10. Leontiev A. N. Activity. Consciousness. Personality. - 2nd ed. - M.: Politizdat, 1977.

11. Neisser U. Cognition and reality: Meaning and principles of cognitive psychology / Per. from English. under total ed. B. M. Velichkovsky. - M.: Progress, 1981.

12. Nemov R. S. Psychology: Textbook for students. higher ped. textbook institutions: In 3 books. Book. 1: General foundations of psychology. - 2nd ed. - M.: Vlados 1998.

13. General psychology: a course of lectures / Comp. E. I. Rogov. - M.: Vlados, 1995.

14. Rubinstein S. L. Fundamentals of General Psychology. - St. Petersburg: Peter, 1999.

15. Fresse P., Piaget J. Experimental psychology / Sat. articles. Per. from French: Issue. 6. - M.: Progress, 1978.

Chapter 8

Summary

General characteristics of perception. The concept of perception. The relationship between sensation and perception. Perception as a holistic reflection of objects. Theories of pattern recognition. Perception is a complex perceptual process.

Physiological basis of perception. Physiological mechanisms of perception. Reflex basis of perception according to IP Pavlov.

Basic properties and types of perception. The main properties of perception: objectivity, integrity, constancy, structure, meaningfulness, apperception, activity. apperception phenomenon. The concept of the illusion of perception. Meaningfulness of perception. Basic classifications of perception. Classification by modality. Classification according to the form of existence of matter: space, time, motion.

Individual differences in perception and its development in children. Individual types of perception. Synthetic and analytical types of perception. Descriptive and explanatory types of perception. Objective and subjective types of perception. Observation. Stages of development of perception in children. Works by B. M. Teplov, A. N. Zaporozhets.

Object and background in perception. The ratio of object and background. Conditions for selecting an object from the background. Ease of selecting a subject from the background.

The relationship between the whole and the part in perception. Peculiarities of perception of the whole and the part. Identification features of an object. Individual differences and stages of perception.

Perception of space. Spatial properties of objects: size, shape of objects, position in space. Factors influencing the features of the perception of the size of the object. Constancy and contrast of objects. The transfer of the property of the whole to its separate parts. Features of the perception of the shape of the object. Mechanisms of binocular vision. Perception of three-dimensional space and its physiological mechanisms. The concept of convergence and divergence of the eyes. Mechanisms of orientation in space.

Perception of movement and time. Movement perception mechanisms. E. Mach's experiments. Basic theories of motion perception. Theory of W. Wundt. Phyphenomenon M. Wertheimer. Perception theory in Gestalt psychology. Mechanisms of perception of time. The concept of time periods. Factors that determine the characteristics of the perception of time.

8.1. General characteristics of perception

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

Similar information.

Another concept related to the problem of thresholds is differential threshold , or distinction threshold. The measurement of the differential threshold (an estimate of the subtle difference between two sensations) is related to the already mentioned empirical fact - our limited ability to distinguish between stimuli.

The most important principle of origin barely noticeable difference (EZR) between two sensations was discovered by Ernst Weber (1795–1878), who, by the way, was a member of the Russian Academy of Sciences. Weber established that our ability to distinguish stimuli does not depend on the intensity of the stimulus as such, but on the ratio of the stimulus increment to its initial value. In other words, how much the intensity of the stimulus needs to be changed in order for ESR to appear depends not on the absolute, but on the relative magnitude of the change. Weber experimented with the ability to distinguish between weights. It turned out that the same increase in weights of different sizes may or may not cause a change in sensation. For example, weights of 40 and 41 g seemed different to the subjects, while weights of 80 and 81 g were evaluated as equal. Thus, Weber found that the EZP value for the weight is 2.5% of the original and is constant, i.e. constant. For example, if the initial weight is 1 kg, then 1000 x 0.025 (25 g) must be added to detect the difference. If the initial weight is 10 kg, then 10,000 x 0.025 (250 g) must be added to detect the difference. In other words, in order for EZR to be discovered, the stimulus must be increased by a constant percentage of the original intensity. Weber constants were calculated for each modality.

Simultaneously with Weber, another scientist, P. Buger, was also conducting research, so the dependence they discovered was called the Weber-Bouguer law. This law is expressed by the formula

where I is the intensity of the stimulus; Δ I - increase in stimulus.

True, subsequent studies have shown that the Weber-Bouguer law is valid only for the middle part of the sensitivity range of the sensory system. When approaching the threshold values, the law should be amended to reflect the magnitude of the sensation from the activity of the system itself (for example, the heartbeat in the auditory modality or the intrinsic retinal glow in the visual modality). Thus, in its final form, this law has the following form:

where R – correction for "noise" from the operation of the sensor system.

Data on the value of EZR for sensations of various modalities are presented in Table. 7.4.

Table 7.4

The meaning of the Weber-Bouguer constant for sensations of various modalities

Basic psychophysical law

Mathematical transformations of the Weber-Bouguer relation allowed G. Fechner to formulate basic psychophysical law , the essence of which is as follows: the ratio of the change in the strength of the stimulus and the subjective experience of sensation is described logarithmic function. It is important to note that when deriving this law, Fechner proceeded from the impossibility of a direct assessment by the subject of the intensity of the sensation that arises in him, therefore, in his formula, physical (rather than psychological) quantities act as units of measurement. In addition, Fechner relied on some assumptions: a) all EZRs are psychologically equal, i.e. our sensations grow in equal "steps"; b) the higher the intensity of the initial stimulus, the greater the "gain" is needed in order to feel the ESR.

Wording basic psychophysical law is: the change in the strength of sensation is proportional to the logarithm of the change in the strength of the acting stimulus. In other words, when the stimulus grows exponentially (increases in N times), the sensation grows only in an arithmetic progression (increases by N ). Fechner's basic psychophysical law is expressed by the formula

where R- sensation intensity: I is the intensity of the current stimulus; I 0 is the stimulus intensity corresponding to the lower absolute threshold; WITH - Weber-Bouguer constant specific to each modality.

Graphs that visually express the relationship between the intensity of the action of a physical stimulus and the strength of the sensation that occurs in response are called psychophysical curves. As an example, let's give the shape of the psychophysical curve for the sensation of sound volume (Fig. 7.5).

Rice. 7.5.

In 1941, psychologist and psychophysiologist S. Stevens of Harvard University questioned Fechner's assumptions and suggested that EHRs were not always constant. He also put forward the idea of ​​the possibility of a direct assessment and numerical comparison by a person of his sensations. In his experiments, Stevens used the method of direct evaluation of stimulus intensity. The subject was offered some "reference" stimulus, the intensity of which was assumed to be unity. Then the subject evaluated a number of other stimuli, bringing them into line with the standard. For example, he could say that one stimulus is 0.5 and the other 0.7 of the reference. As a result of his research, Stevens modified the Weber-Bouguer ratio, replacing in it the ratio of the physical magnitude of a barely noticeable change in stimulus to the physical intensity of the initial stimulus by the ratio subjective experience subtle change in stimulus subjective experience of intensity original stimulus. It turned out that in this case the relation is constant for each modality. Stevens brought his version basic psychophysical law, which is not logarithmic, as in Fechner, but power character, i.e. the magnitude of the experienced sensation is equal to the magnitude of the physical intensity of the stimulus raised to a constant power for a given sensory system:

where R- the strength of the feeling M - correction for units of measurement, I - physical intensity, a - exponent specific to each modality.

Indicator a the Stevens power function, as well as the Weber constant, is different for different modalities of sensations (Table 7.5).

Table 7.5

Exponent values ​​for the basic psychophysical law of S. Stevens

How do the psychophysical laws proposed by G. Fechner and S. Stevens relate to each other? At present, Fechner's and Stevens' versions of the psychophysical law are regarded as somewhat complementary to each other. It is easy to see that if a< 1, то функция принимает форму, аналогичную закону Фехнера (большое приращение интенсивности стимула дает небольшое приращение ощущения). Однако если а >1, then the result is the opposite of Fechner's law. For example, in an electric shock, a small increase in stimulus intensity produces a large change in sensation. Such work of the sensory system is evolutionarily justified, since it allows you to quickly respond to potentially dangerous types of stimulation.

In 1760, the French scientist P. Bouguer, the creator of photometry, investigated his ability to distinguish the shadow cast by a candle if the screen on which the shadow falls is simultaneously illuminated by another candle. His measurements established quite accurately that the ratio l R / R (where l R is the minimum perceived increase in illumination, R is the initial illumination) is a relatively constant value.

In 1834, the German psychophysicist E. Weber repeated and confirmed the experiments of P. Buger. E. Weber, studying the difference in weight, showed that the minimum perceived difference in weight is a constant value equal to approximately 1/30. A load of 31 g differs from a load of 30, a load of 62 g from a load of 60 g; 124 g from 120 g.

This ratio entered the history of research in the psychophysics of sensations under the name of the Bouguer-Weber law: the differential threshold of sensations for different sense organs is different, but for the same analyzer it is a constant value, i.e. l R/R = const.

This ratio indicates how much of the original stimulus value must be added to this stimulus in order to get a barely perceptible change in sensation.

Further studies showed that Weber's law is valid only for medium-sized stimuli: when approaching absolute thresholds, the magnitude of the increase ceases to be constant. Weber's law applies not only to barely noticeable, but to any differences in sensations. The difference between pairs of sensations seems equal to us if the geometric ratios of the corresponding stimuli are equal. Thus, an increase in lighting strength from 25 to 50 candles gives subjectively the same effect as an increase from 50 to 100.

Based on the Bouguer-Weber law, Fechner made the assumption that subtle differences (s.d.r.) in sensations can be considered equal, since they are all infinitely small quantities. If the increment of sensation corresponding to a barely perceptible difference between stimuli is denoted as le, then Fechner's postulate can be written as le = const.

Fechner accepted e.s.r. (lE) as a unit of measure, with the help of which one can numerically express the intensity of sensations as the sum (or integral) of barely noticeable (infinitely small) increases, counting from the threshold of absolute sensitivity. As a result, he obtained two series of variable quantities—the magnitudes of stimuli and the magnitudes of sensations corresponding to them. Feelings grow exponentially when stimuli grow exponentially.

What does it mean? We take, for example, such irritants as 10 candles, increase their number: 10 - 100 - 1000 - 10000, etc. This is a geometric progression. When there were 10 candles, we had a corresponding feeling. With an increase in stimuli to 100 candles, the sensation doubled; the appearance of 1000 candles caused the sensation to triple, and so on. The increase in sensations goes in an arithmetic progression, i.e. much slower than the increase in the stimuli themselves. The ratio of these two variables can be expressed in a logarithmic formula: E \u003d K lg R + C, where E is the strength of sensation, R is the magnitude of the acting stimulus, K is the proportionality coefficient, C is a constant that is different for sensations of different modalities.

This formula is called the basic psychophysical law, which in fact is the Weber-Fechner law.

According to this law, the change in the strength of sensation is proportional to the decimal logarithm of the change in the strength of the acting stimulus (Fig. 8).

A number of phenomena revealed by sensitivity studies do not fit into the framework of the Weber-Fechner law. For example, sensations in the area of ​​protopathic sensitivity do not show a gradual increase as the stimulation intensifies, but upon reaching a certain threshold they immediately appear to the maximum extent. They approach in nature the type of reactions "all or nothing".

stimulus illustrating the Weber-Fechner law

Approximately half a century after the discovery of the basic psychophysical law, he again attracted attention and, on the basis of new experimental data, gave rise to a discussion about the true, precisely expressed by a mathematical formula, the nature of the relationship between the strength of sensation and the magnitude of the stimulus. The American scientist S. Stevens argued as follows: what happens when the illumination of a spot of light and, on the other hand, the strength of the current (frequency 60 Hz) passed through the finger doubles? Doubling the illuminance of a spot against a dark background has surprisingly little effect on its apparent brightness. The typical observer estimates that the apparent increase is only 25%. When the current strength is doubled, the sensation of impact increases tenfold. S. Stevens rejects Fechner's postulate (le = const.) and declares that another quantity is constant, namely the ratio l E / E. Extending the Bouguer-Weber law to sensory values ​​(l E / E = const.), S. Stevens, through a series of mathematical transformations, obtains a power-law relationship between sensation and stimulation: E \u003d HR ^, where k is a constant determined by the chosen unit of measurement, E - the strength of sensation, R is the value of the acting stimulus, n is an indicator that depends on the modality of sensation. The exponent n takes the value 0.33 for brightness and 3.5 for electric shock. This pattern is called the Stevens law.

According to S. Stevens, the exponential function has the advantage that when using a logarithmic scale on both axes, it is expressed as a straight line, the slope of which corresponds to the value of the exponent (n). This is seen in fig. 9: Slow increase in brightness contrast and fast increase in electric shock feeling.

stimulus illustrating Stevens' law. 1. Electric shock. 2. Brightness.

For more than a hundred years, disputes between supporters of the logarithmic dependence of the strength of sensation on the magnitude of the stimulus (Fechner's law) and the power law (Stevens' law) have not stopped. If we neglect the purely psychophysical subtleties of this dispute, then both laws in their psychological meaning will turn out to be very close: both assert, firstly, that sensations change disproportionately to the strength of physical stimuli acting on the sense organs, and, secondly, that the strength of sensation grows much more slowly than the magnitude of physical stimuli.

Bouguer-Weber law

(sometimes - Weber's law) - one of the basic laws of psychophysics - established for the case of distinguishing one-dimensional sensory stimuli is directly proportional to the dependence of the differential threshold on the magnitude of the stimulus I, to which it is adapted ( cm.) this system is sensory: 1L=K (const). The coefficient K, called the Weber ratio, is different for different sensory stimuli: 0.003 - for pitch; 0.02 - for visible brightness; 0.09 - for the volume of sounds, etc. It fixes the amount by which you need to increase or decrease the stimulus in order to get a barely noticeable change in sensation. This dependence was established in the 18th century. the French scientist P. Buger and later - independently - studied in detail the German physiologist E. G. Weber, who conducted experiments to distinguish between weights, line lengths and sound pitch, in which he also showed the constancy of the ratio of a barely noticeable change in the stimulus to its initial value. Later it was shown that the revealed law is not universal, but is valid only for the middle part of the range of perception of the sensory system, where the differential sensitivity has a maximum value. Outside this part of the range, the differential threshold increases, especially in the ranges of the absolute lower and upper thresholds. A further development and partly an interpretation of the Bouguer-Weber law was the Weber-Fechner law.

Dictionary of practical psychologist. - M.: AST, Harvest. S. Yu. Golovin. 1998 .

First discovered by the French scientist P. Buger.

Category.

One of the basic psychophysical laws.

Specificity.

According to this law, a barely noticeable change in sensation with a change in the intensity of the stimulus occurs when the initial stimulus is increased by some constant fraction. Thus, while investigating the ability of a person to recognize a shadow on a screen that was simultaneously illuminated by another light source, Bouguer showed that the minimum increase in object illumination (delta I) necessary to evoke a sensation of a barely noticeable difference between the shadow and the illuminated screen depends on the level of illumination of the screen. I, but the ratio (delta I/I) is a constant value. E. Weber came to the identification of the same regularity somewhat later, but independently of Bouguer. He conducted experiments to distinguish between weights, line lengths, and pitches of a sound tone, in which he also showed the constancy of the ratio of a barely perceptible change in the stimulus to its initial value. This ratio (delta I/I), which characterizes the magnitude of the differential threshold, depends on the modality of sensation: for vision it is 1/100, for hearing it is 1/10, for touch it is 1/30.

Criticism.

Later it was shown that the revealed law does not have a universal distribution, but is valid only for the middle part of the range of the sensory system, in which the differential sensitivity has a maximum value. Outside this part of the range, the differential threshold increases, especially in the ranges of the absolute lower and upper thresholds.

Psychological Dictionary. THEM. Kondakov. 2000 .

See what the "Bouguer-Weber law" is in other dictionaries:

Bouguer–Weber law- Weber's Bouguer's law is one of the basic laws of psychophysics, discovered by the French scientist P. Bouguer, according to which a barely noticeable change in sensation with a change in the intensity of the stimulus occurs with an increase in the initial stimulus ... Psychological Dictionary

- (sometimes Weber's law) established for the case of distinguishing one-dimensional sensory stimuli, a directly proportional dependence of the difference threshold (see sensation threshold) dI on the magnitude of the stimulus I, to which it is adapted (see adaptation ... ...

Bouguer-Weber law- (R. Bouguer, 1698 1758, French mathematician and astronomer; E. N. Weber, 1795 1878, German anatomist and physiologist) the ratio of the threshold of sensation of an increase in the stimulus to the initial value of the latter is a constant value ... Big Medical Dictionary

- (or Weber's Bouguer's law; English Weber's law) one of the laws of classical psychophysics, which asserts the constancy of the relative differential threshold (in the entire sensory range of the variable property of the stimulus). In 1729, Fr. physicist, "father" ... ... Great Psychological Encyclopedia- logarithmic dependence of the strength of sensation E on the physical intensity of the stimulus P: E = k log P + c, where k and c are some constants determined by this sensory system. The dependence was derived by the German psychologist and physiologist G. T. Fechner ... Great Psychological Encyclopedia

Feeling- This article is about the reflection of sensory signals. On the reflection of emotional processes, see Experience (psychology). Sensation, sensory experience is the simplest mental process, which is a mental reflection ... ... Wikipedia