7. Sensation-Mental processes

The general concept of sensation. The general place and role of cognitive mental processes in human life. Feeling as a sensual display of individual properties of objects. Physiological mechanisms of sensation. The concept of analyzers. The reflex nature of the analyzer. Teachings about sensation. The law of "specific" energy I. Muller. The concept of "signs" Helmholtz. Theory of Solipsism. Feeling as a product of historical human development.

Types of sensations. General idea of ​​the classification of sensations. Systematic Classification of Sensations A. R. Luri ". Interocentery, iprioceptive and exterocensive sensations. Contact and distant sensations. Genetic classification of sensations:

irotonatic and sensations. Classification of sensations B. M. Teplova. The concept of the modality of sensations. Classification of sensations by modality.

The basic properties and characteristics of sensations. Properties of sensations: quality, intensity, duration, spatial localization. Absolute sensitivity and sensitivity to difference. Absolute and relative thresholds of sensations. "Subsensory region" G. V. Gershuni. The law of the Booger-Vsber. The essence of the Weber constant. The basic psychophysical law of Weber-Fehnsra. Stevens Act. The generalized psychophysical law of Yu. M. Zabrodin.

Sensory adaptation and interaction of sensations. The concept of sensory adaptation. The interaction of sensations: the interaction between sensations of the same type, the interaction between the sensations of different types. The concept of sensitization. The phenomenon of synesthesia.

The development of sensations. Feelings newborn. Features of the development of vision and hearing. The development of speech hearing. The development of absolute sensitivity. Genetic Predisposition and the possibility of developing sensations.

Characteristics of the main types of sensations *. Skin sensations. Taste and olfactory sensations. Auditory sensations. Visual sensations. Proprioceptive sensations. The concept of touch.

7.1. General concept of sensation

We begin the study of cognitive mental processes, the simplest of which is sensation. The process of sensation arises due to the impact on the senses of various material factors, which are called stimuli, and the process of this influence - irritation. In turn, irritation causes another process — excitement, which, along centripetal, or a4> fermentic, nerves passes into the cerebral cortex, where sensations arise. Thus, sensation is a sensual representation of objective reality.

The essence of the feeling is to reflect the individual properties of the object. What does "individual properties" mean? Each stimulus has its own characteristics, depending on which it can be perceived by certain organs.

Sensations arise on the basis of irritability. Sensation is a product of development in phylogenesis of irritability. Irritability - the common property of all living bodies to come into a state of activity under the influence of external influences (the pre-psychic level) (for example, the ciliate-slipper) there is no need to distinguish between specific objects for their vital activity - irritability is sufficient. Sensitivity is the ability to respond to neutral, indirect effects that do not affect the life of the organism (for example, with a frog reacting to rustling). The totality of feelings creates elementary mental processes, processes of mental reflection .

Sensation is the simplest mental process of reflecting a separate quality (property) of an object with the direct influence of stimuli on the perceptive part of the analyzer.

The main feature of the sensation is that only one quality of the object is reflected separately .

* The chapter is based on chapters from the book: Psychology. / Ed. prof. K. I. Kornilov, prof. A. A. Smirnova., Prof. B.M. Teplova. - Ed. 3rd, pererabot. and add. - M .: Uchpedgiz, 1948.

feelings For example, we can hear the sound of a flight of a mosquito or feel its bite. In this example, sound and bite are irritants that affect our senses. In this case, one should pay attention to the fact that the sensation process reflects only sound and only a bite in consciousness, without connecting these sensations with each other, and therefore with the mosquito. This is the process of reflection of individual properties of the object.

The physiological basis of sensations is the activity of complex complexes of anatomical structures, called by I. P. Pavlov analyzers. Each analyzer consists of three parts: 1) the peripheral section, called the receptor (the receptor is the sensory part of the analyzer, its main function is the transformation of external energy into a nervous process); 2) conductive nerve pathways; 3) the cortical parts of the analyzer (they are also differently called the central parts of the analyzers), in which the processing of nerve impulses coming from the peripheral parts takes place. The cortical part of each analyzer includes an area that is a projection of the periphery (i.e., a projection of the sense organ) in the cerebral cortex, since certain receptors correspond to certain areas of the cortex. For the emergence of sensation it is necessary to use all the components of the analyzer. If you destroy any part of the analyzer, the emergence of the corresponding sensations becomes impossible. Thus, visual sensations cease when the eyes are damaged, and when the integrity of the optic nerves is disturbed, and when the occipital lobes of both hemispheres are destroyed.

The analyzer is an active organ that is reflexively rearranged under the influence of stimuli; therefore, sensation is not a passive process, it always includes motor components. Thus, an American psychologist D. Neff, observing a skin area with a microscope, made sure that when stimulated with a needle, the moment of sensation is accompanied by reflex motor responses of this skin area. Subsequently, numerous studies have established that sensation is closely associated with movement, which sometimes manifests itself in the form of a vegetative reaction (vasoconstriction, galvanic skin reflex), sometimes in the form of muscle reactions (eye rotation, neck muscle tension, hand motor responses, and d.) Thus, sensations are not at all passive processes - they are active, or reflex, in nature.

It should be noted that sensations are not only the source of our knowledge about the world, but also our feelings and emotions. The simplest form of emotional experience is the so-called sensual, or emotional, tone of sensation, that is, a feeling directly connected with sensation. For example, it is well known that some colors, sounds, smells can by themselves, regardless of their meaning, from the memories and thoughts associated with them, cause us a pleasant or unpleasant feeling. The sound of a beautiful voice, the taste of an orange, the smell of a rose are pleasant, have a positive emotional tone. The creak of the knife on the glass, the smell of hydrogen sulfide, the taste of quinine are unpleasant, have a negative emotional tone. This kind of simplest emotional experiences play a relatively minor role in the life of an adult, but in terms of the origin and development of emotions, their significance is very great.

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How does the transfer of information from the receptor to the brain!

A person is able to perceive and perceive the objective world due to special brain activity. It is with the brain that all the senses are connected. Each of these organs responds to a certain kind of stimulus; organs of vision - on light, organs of hearing and touch - on mechanical effects, organs of taste and smell - on chemicals. However, the brain itself is unable to perceive these types of effects. He "understands" only the electrical signals associated with nerve impulses. In order for the brain to respond to the stimulus, in each sensory modality, first, the corresponding physical energy must be converted into electrical signals, which then follow their own paths to the brain. This process of translation is carried out by special cells in the sense organs, called receptors. Visual receptors, for example, are located in a thin layer on the inner side of the eye; in each visual receptor there is a chemical substance that reacts to light, and this reaction triggers a series of events that result in a nerve impulse. Auditory receptors are thin hair cells located deep in the ear; air vibration, which is a sound stimulus, bends these hair cells, as a result of which a nerve impulse arises. Similar processes occur in other sensory modalities. A receptor is a specialized nerve cell, or neuron; being energized, it sends an electrical signal to intermediate neurons. This signal moves until it reaches its receptive zone in the cerebral cortex, and each sensory modality has its own receptive zone. Somewhere in the brain — perhaps in the receptive zone of the cortex, or perhaps in some other part of the cortex — an electrical signal causes a conscious experience of sensation. So, when we feel a touch, this sensation “happens” in our brain, not on the skin. At the same time, the electrical impulses that directly mediate the sensation of touch were themselves caused by the electrical impulses generated in the receptors of touch, which are located in the skin. In a similar way, the feeling of bitter taste is born not in the tongue, but in the brain; but the brain impulses mediating the sensation of taste were themselves caused by the electrical impulses of the taste buds of the tongue. The brain perceives not only the effect of the stimulus, it also perceives a number of characteristics of the stimulus, for example, the intensity of the effect. Consequently, the receptors must have the ability to encode the intensity and quality parameters of the stimulus. How do they do it? In order to answer this question, scientists needed to conduct a series of experiments on recording the activity of single receptor cells and pathways during the presentation of various input signals or stimuli to the subject. So you can accurately determine what properties of the stimulus reacts one or another neuron. How is this experiment practically carried out? Before the beginning of the experiment, the animal (monkey) is subjected to a surgical operation, during which thin wires are implanted into certain areas of the visual cortex. Of course, such an operation is performed under sterile conditions and with appropriate anesthesia. Thin wires - microelectrodes - are covered with insulation everywhere, except for the very tip, which records the electrical activity of the neuron in contact with it. After implantation, these microelectrodes do not cause pain, and the monkey can live and move quite normally. During the actual experiment, the monkey is placed in the device for testing, and the microelectrodes are connected to amplifying and recording devices. Then monkeys impose various visual stimuli. Observing from which electrode a steady signal comes in, it is possible to determine which neuron reacts to each of the stimuli. Since these signals are very weak, they need to be amplified and displayed on the screen of the oscilloscope, which transforms them into curves of changes in electrical voltage. Most neurons produce a range of nerve

It is interesting

pulses reflected on the oscilloscope in the form of vertical bursts (spikes). Even in the absence of stimuli, many cells produce rare impulses (spontaneous activity). When a stimulus is presented to which a given neuron is sensitive, a rapid sequence of spikes can be seen. By registering the activity of a single cell, scientists have learned a great deal about how the senses encode the intensity and quality of the stimulus. The main method of coding the intensity of a stimulus is the number of nerve impulses per unit of time, that is, the frequency of nerve impulses. Let's show it on the example of touch. If someone touches your hand lightly, a series of electrical impulses will appear in the nerve fibers. If the pressure increases, the magnitude of the pulses remains the same, but their number per unit of time increases. Same with other modalities. In general, the greater the intensity, the higher the frequency of nerve impulses and the greater the perceived intensity of the stimulus. The intensity of the stimulus can be encoded in other ways. One of them is to encode the intensity in the form of a temporary pulse-following pattern. At low intensity, nerve impulses follow relatively rarely and the interval between adjacent impulses is variable. At high intensity, this interval becomes fairly constant. Another possibility is to code the intensity in the form of the absolute number of activated neurons: the greater the intensity of the stimulus, the greater the number of neurons involved. Encoding the quality of the stimulus is more complicated. Trying to explain this process, I. Muller in 1825. He suggested that the brain is able to distinguish information from different sensory modalities due to the fact that it travels along various sensory nerves (some nerves transmit visual sensations, others auditory, etc.). Therefore, if one does not take into account a number of Muller's statements about the unknowability of the real world, then one can agree that the nerve pathways starting at different receptors end in different zones of the cerebral cortex. Consequently, the brain receives information about the qualitative parameters of the stimulus due to those nerve channels that connect the brain and the receptor. However, the brain is able to distinguish the effects of one modality. For example, we distinguish red from green or sweet from sour. Apparently, coding here is also associated with specific neurons. For example, there is evidence that a person distinguishes sweet from sour simply because each type of taste has its own nerve fibers. So, the information from the sweet receptors is transmitted through the "sweet" fibers, through the "acidic" fibers - from the acidic receptors, and the same with the "salty" fibers and the "bitter" fibers, However, specificity is not the only possible coding principle. It is also possible that in the sensory system a specific pattern of nerve impulses is used to encode quality information. A separate nerve fiber, reacting as much as possible, say, to a sweet, can react, but to varying degrees, to other types of taste stimuli. One fiber reacts most to the sweet, weaker to the bitter, and even weaker to the salty; so a “sweet” stimulus would activate a large amount of fibers with varying degrees of excitability, and then this particular pattern of nervous activity would be a code for sweets in the system. As a bitter code, another pattern would be transmitted through the fibers. However, in the scientific literature, we can meet another opinion. For example, there is every reason to assert that the qualitative parameters of the stimulus can be encoded through the form of an electrical signal entering the brain. We encounter a similar phenomenon when we perceive the timbre of a voice or the timbre of a musical instrument. If the waveform is close to a sine wave, then the timbre is pleasant to us, but if the shape is significantly different from a sine wave, then we have a feeling of dissonance. Thus, the reflection in sensations of the qualitative parameters of the stimulus is a very complex process, the nature of which is not fully understood. By: Atkinson, R.L., Agkinson, R.S., Smith, E.E., et al. Introduction to Psychology: A Textbook for Universities / Trans. from English under. ed. V.P. Zinchenko. - M .: Trivola, 1999.

Sensations connect a person with the outside world and are both the main source of information about him and the main condition for mental development. However, despite the obviousness of these provisions, they were repeatedly questioned. Representatives of the idealistic trend in philosophy and psychology often expressed the idea that the real source of our conscious activity is not sensations, but the inner state of consciousness, the ability of rational thinking, built from nature and not dependent on the flow of information coming from the outside world. These views formed the basis of the philosophy of rationalism. Its essence consisted in the statement that consciousness and mind are the primary, further unexplainable property of the human spirit.

Idealist philosophers and many psychologists who advocate an idealistic concept often attempted to reject the notion that a person’s feelings connect him to the outside world and prove the opposite, paradoxical situation, which means that an insurmountable wall separates a person from the outside world. A similar provision was put forward by representatives of subjective idealism (D. Berkeley, D. Hume, E. Mach).

I. Muller, one of the representatives of the dualistic trend in psychology, on the basis of the aforementioned position of subjective idealism, formulated the theory of the “specific energy of the sense organs”. According to this theory, each of the senses (eye, ear, skin, tongue) does not reflect the effects of the outside world, does not provide information about real processes in the environment, but only receives impulses from external influences that excite their own processes. According to this theory, each sense organ has its own “specific energy”, excited by any influence coming from the outside world. So, it is enough to press on the eye or act on it with an electric current to get the feeling of light; enough mechanical or electrical stimulation of the ear to create a sensation of sound. From these provisions it was concluded that the senses do not reflect external influences, but are only excited from them, and the person perceives not the objective influences of the external world, but only his own subjective states, reflecting the activity of his senses.

The point of view of G. Helmholtz, who did not reject the fact that sensations arise as a result of the effects of objects on the senses, was considered to be close, but he believed that the mental images arising as a result of this impact had nothing to do with real objects. On this basis, he called sensations "symbols", or "signs", of external phenomena, refusing to recognize them as images, or displays, of these phenomena. He believed that the impact of a particular object on the sense organ causes in consciousness a “sign” or “symbol” acting on an object, but not its image. “For the image requires a certain resemblance to the imaged object ... From the sign, however, no similarity is required with what it is sign of.”

It is easy to see that both of these approaches lead to the following statement: a person cannot perceive the objective world, and the only reality is the subjective processes reflecting the activity of his senses, which create the subjectively perceived “elements of the world”.

Such conclusions were the basis of the theory of solipsism (from the Latin. Solus - one, ipse - myself) which boiled down to the fact that a person can know only himself and has no evidence of the existence of anything other than himself.

On opposite positions are the representatives of the materialistic direction, who consider it possible an objective reflection of the external world. The study of the evolution of the senses convincingly shows that in the process of a long historical development, special perceiving organs (sense organs, or receptors) have been formed, which specialized in reflecting specific types of objectively existing forms of motion of matter (or energy): auditory receptors, reflecting sound coils ** * of; visual receptors reflecting certain ranges of electromagnetic collars *** ,. etc. The study of the evolution of organisms shows that in reality we have not “the specific energies of the senses themselves”, but specific organs objectively reflecting different types of energy. Moreover, the high specialization of various sense organs is based not only on the structural features of the peripheral part of the analyzer - receptors, but also on the highest specialization of the neurons that make up the central nervous apparatus, which are received by signals perceived by peripheral sense organs.

It should be noted that human sensations are a product of historical development, and therefore they are qualitatively different from animal sensations. In animals, the development of sensations is entirely limited by their biological, instinctive needs. In many animals, certain types of sensations are striking in their subtlety, but the manifestation of this subtly developed ability of sensation cannot go beyond the range of objects and their properties that are of direct vital importance to animals of a given species. For example, bees are capable of much thinner than the average person, to distinguish the concentration of sugar in the solution, but this also limits the subtlety of their taste sensations. Another example: a lizard that is able to hear the light rustle of a crawling insect will not react to a very loud knock of a stone on a stone.

In humans, the ability to feel is not limited to biological needs. Labor created an incomparably wider range of needs than animals, than animals, and in the activities aimed at meeting these needs, human abilities constantly developed, including the ability to feel. Therefore, a person can feel a much larger number of properties of the objects around him than an animal.

7.2. Types of sensations

There are various approaches to the classification of sensations. It has long been customary to distinguish five (by the number of sense organs) of the main types of sensations: smell, taste, touch, sight and hearing. This classification of sensation according to basic modalities is correct, although not exhaustive. B. G. Ananiev spoke about eleven kinds of sensations. A.R. Luria considers classification

Names

Sherrington Charles Scott (1857-1952) - English physiologist and psychophysiologist. In 1885 He graduated from the University of Cambridge, and then worked in such famous universities as London, Liverpupsky, Oxford and Edinburgh. From 1914 to 1917 He is a research professor in physiology at the Royal Institute of the United Kingdom. He won the Nobel Prize. He gained wide popularity due to his experimental research, which he conducted on the basis of his idea of ​​the nervous system as an integral system. He was one of the first to attempt experimental verification of the theory of James-Lange and showed that the separation of the visceral nervous system from The central nervous system does not alter the animal’s general behavior in response to an emotional effect.

Ch. Sherrington belongs to the classification of receptors for exteroceptors, propriocep torors and interoceptors. He also experimentally showed the possibility of the origin of the distant receptors from the contact receptors.

sensations can be carried out at least according to two basic principles - systematic and genetic (in other words, according to the principle of modality, on the one hand, and according to the principle of complexity or the level of their construction, on the other).

Consider the systematic classification of sensations (Fig. 7.1). This classification was proposed by the English physiologist C. Sherrington. Considering the largest and most significant groups of sensations, he divided them into three main types: interoceptive, proprioceptive and exteroceptive sensations. The first combine the signals that reach us from the internal environment of the body; the second transmit information about the position of the body in space and the position of the musculoskeletal system, provide the regulation of our movements; Finally, others provide signals from the outside world and form the basis for our conscious behavior. Consider the main types of sensations separately.

Interoceptive sensations that signal the state of the internal processes of the body arise due to receptors located on the walls of the stomach and intestines, the heart and circulatory system and other internal organs. This is the most ancient and most elementary group of sensations. Receptors that perceive information about the state of internal organs, muscles, etc., are called internal receptors. Interoceptive sensations are among the least recognized and most diffuse forms of sensations and always maintain their proximity to emotional states. It should also be noted that interoceptive sensations are very often called organic.

Proprioceptive sensations transmit signals about the position of the body in space and constitute the afferent basis of human movements, playing a crucial role in their regulation. The described group of sensations includes a sense of balance, or static sensation, as well as motor, or kinesthetic sensation.

Peripheral receptors for proprioceptive sensitivity are found in muscles and joints (tendons, ligaments) and are called Paccini bodies.

In modern physiology and psychophysiology, the role of proprioception as an afferent basis of movement in animals was studied in detail by A. A. Orbeli, P. K. Anokhin, and in man by N. A. Bernshtein.

The peripheral receptors of the sense of balance are located in the semicircular canals of the inner ear.

The third and largest group of sensations are exteroceptive sensations. They bring information to the person from the outside world and are the main group of sensations connecting the person with the external environment. Всю группу экстероцептивных ощущений принято условно разделять на две подгруппы:

контактные и дистантные ощущения.

Fig. 7.1. Систематическая классификация основных видов ощущений

Контактные ощущения вызываются непосредственным воздействием объекта на органы чувств. Примерами контактного ощущения являются вкус и осязание. Дистантные ощущения отражают качества объектов, находящихся на некотором расстоянии от органов чувств, К таким ощущениям относятся слух и зрение. Следует отметить, что обоняние, по мнению многих авторов, занимает промежуточное положение между контактными и дистантными ощущениями, поскольку формально обонятельные ощущения возникают на расстоянии от предмета, но ' в то же время молекулы, характеризующие запах предмета, с которыми происходит контакт обонятельного рецептора, несомненно принадлежат данному предмету. В этом и заключается двойственность положения, занимаемого обонянием в классификации ощущений.

Поскольку ощущение возникает в результате воздействия определенного физического раздражителя на соответствующий рецептор, то первичная классификация ощущений, рассмотренная нами, исходит, естественно, из типа рецептора, который дает ощущение данного качества, или «модальности». Однако существуют ощущения, которые не могут быть связаны с какой-либо определенной модальностью. Такие ощущения называют интермодальными. К ним относится, например, вибрационная чувствительность, которая связывает тактильно-моторную сферу со слуховой.

Ощущение вибрации — это чувствительность к коле***ниям, вызываемым движущимся телом. По мнению большинства исследователей, вибрационное чувство является промежуточной, переходной формой между тактильной и слуховой чувствительностью. В частности, школа Л. Е. Комендантова считает, что тактильно-вибрационная чувствительность есть одна из форм восприятия звука. При нормальном слухе она особенно не выступает, по при поражении слухового органа эта ее функция ясно проявляется. Основное положение «слуховой» теории заключается в том, что тактильное восприятие звуковой вибрации понимается как диффузная звуковая чувствительность.

Of particular practical importance vibration sensitivity acquires with the defeat of vision and hearing. In the life of the deaf and deaf and dumb she plays a big role. Deaf-blind, due to the high development of vibration sensitivity, learned about the approach of the truck and other modes of transport at a great distance. In the same way, through the vibrational feeling, the blind and deaf-and-dumb learn when someone enters their room. Consequently, sensations, being the simplest type of mental processes, are in fact very complex and not fully understood.

It should be noted that there are other approaches to the classification of sensations. For example, the genetic approach proposed by the English neurologist X. Head. Genetic classification allows to distinguish two types of sensitivity: 1) protopathic (more primitive, affective, less differentiated and localized), which include organic feelings (hunger, thirst, etc.); 2) epicritical (more subtly differentiating, objectified and rational), which includes the main types of human sensations. The epicritical sensitivity is younger genetically, and it controls protopathic sensitivity.

The well-known domestic psychologist B. M. Teplov, considering the types of sensations, divided all receptors into two large groups: exteroceptors (external

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receptors) located on or near the body surface and exposed to external stimuli, and interoceptors (internal receptors) located deep in tissues, such as muscles, or on the surface of internal organs. The group of sensations, which we called “proprioceptive sensations,” B. M. Teplov considered as internal sensations.

7.3. Basic properties and characteristics of sensations

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

Quality is a property that characterizes the basic information displayed by a given sensation, distinguishing it from other types of sensations and varying within the limits of this type of sensations. For example, tastes provide information about some of the chemical characteristics of an item:

sweet or sour, bitter or salty. The sense of smell also provides us with information about the chemical characteristics of the object, but of a different kind: a floral smell, the smell of almonds, the smell of hydrogen sulfide, etc.

It should be borne in mind that quite often, when they talk about the quality of sensations, they mean the modality of sensations, since it is the modality that reflects the basic quality of the corresponding sensation.

The intensity of sensation is its quantitative characteristic and depends on the strength of the acting stimulus and the functional state of the receptor, which determines the degree of readiness of the receptor to perform its functions. For example, if you have a runny nose, then the intensity of perceived odors may be distorted.

The duration of the sensation is a temporary characteristic of the sensation that has arisen. It is also determined by the functional state of the sense organ, but mainly by the duration of the stimulus and its intensity. It should be noted that sensations have a so-called. Patent (hidden) period. When a stimulus is applied to the sense organ, the sensation does not appear immediately, but after a while. The latent period of different types of sensations is not the same. For example, for tactile sensations, it is 130 ms, for pain - 370 ms, and for gustatory sensations - only 50 ms.

The sensation does not occur simultaneously with the onset of the action of the stimulus and does not disappear simultaneously with the cessation of its action. This inertia of sensations manifests itself in the so-called after-effect. A visual sensation, for example, has some inertia and does not disappear immediately after the cessation of the stimulus that caused it. The trace of the stimulus remains as a sequential image. There are positive and negative consecutive

Names

Fechner Gustav Theodore (1801-1887) - German physicist, philosopher and psychologist, founder of psychophysics. Fechner is the author of the program work Elements of Psychophysics (1860). In this work, he put forward the idea of ​​creating a special science - psychophysics. In his opinion, the natural relationship of two types of phenomena, mental and physical, functionally interconnected should be the subject of this science. The idea put forward by him had a significant impact on the development of experimental psychology, and the research that he conducted in the field of sensations allowed him to substantiate several laws, including the basic psychophysical law. Fechner developed a number of methods for the indirect measurement of sensations, in particular, the three classical methods for measuring thresholds. However, after researching successive images caused by the observation of the sun, he partially lost his sight, which made him leave psychophysics and take up philosophy. Fechner was a comprehensively developed man. So, he published several satirical works under the pseudonym "Dr. Mises."

images. The positive sequential image corresponds to the initial irritation, consists in maintaining a trace of irritation of the same quality as the active stimulus.

A negative sequential image is the emergence of the quality of sensation, the opposite of the quality of the stimulus. For example, light-darkness, severity-lightness, heat-cold, etc. The occurrence of negative sequential images is explained by a decrease in the sensitivity of this receptor to a specific effect.

Finally, sensation is characterized by spatial localization of the stimulus. The analysis carried out by the receptors gives us information about the localization of the stimulus in space, that is, we can tell where the light is coming from, where the heat goes, or on which part of the body the stimulus acts.

All the above properties in varying degrees reflect the qualitative characteristics of sensations. However, not less important are the quantitative parameters of the main characteristics of sensations, in other words, the degree of sensitivity. The human senses are surprisingly subtle devices. Thus, academician S.I. Vavilov experimentally established that the human eye can distinguish a light signal of 0.001 candles at a distance of a kilometer. The energy of this stimulus is so small that it would take 60,000 years to heat 1 cm 3 of water through 1 °. Perhaps no physical device has such sensitivity.

There are two types of sensitivity: absolute sensitivity and sensitivity to difference. By absolute sensitivity is meant the ability to sense weak stimuli, and by sensitivity to difference, the ability to sense weak differences between stimuli. However, not all irritation causes sensation. We do not hear ticking clocks in another room. We do not see stars of the sixth magnitude. In order for a sensation to arise, the strength of the irritation must have a certain amount.

The minimum magnitude of the stimulus at which sensation first appears is called the absolute sensation threshold. Irritants, the strength of which lies below the absolute threshold of sensation, do not give sensations, but this does not mean that they have no effect on the body. Thus, studies of the Russian physiologist G. V. Gershuni and his staff have shown that sound stimuli that lie below the sensation threshold can cause a change in the electrical activity of the brain and the expansion of the pupil. The zone of influence of stimuli that do not cause sensations was named by GV Gershuni as a “subsensory region”.

The beginning of the study of thresholds of sensations was laid by the German physicist, psychologist and philosopher G. T. Fechner, who believed that the material and the ideal are two sides of a single whole. Therefore, he set out to find out where the boundary between the material and the ideal lies. Fechner approached this problem as a naturalist. In his opinion, the process of creating a mental image can be represented by the following scheme:

Irritation -> Excitement -> Sensation -> Judgment (physics) (physiology) (psychology) (logic)

The most important thing in Fechner's idea was that for the first time he included elementary sensations in the interests of psychology. Before Fechner, it was believed that physiologists, doctors, even physicists, but not psychologists, should study sensations, if it is interesting to anyone. For psychologists, this is too primitive.

According to Fechner, the desired border passes where the sensation begins, that is, the first mental process arises. The magnitude of the stimulus at which the sensation begins, Fechner called the absolute lower threshold. To determine this threshold, Fechner has developed methods that are actively used in our time. The basis of the methodology of his research Fehner put the levers of the statement, called the first and second paradigm of classical psychophysics.

1. The human sensory system is a measuring device that responds appropriately to the physical stimuli that are acting.

2. Psychophysical characteristics of people are distributed according to the normal law, i.e., they randomly differ from some average value, similarly to anthropometric characteristics.

Today there is no doubt that both of these paradigms are already outdated and to some extent contradict modern principles of the study of the psyche. In particular, one can note the contradiction to the principle of activity and integrity of the psyche, because today we understand that it is impossible to isolate and investigate in the experiment one, even the most primitive, mental system from the integral structure of the human psyche. In turn, the activation in the experiment of all mental systems from the lowest to the highest leads to a very large variety of reactions of the subjects, which requires an individual approach to each subject.

Nevertheless, Fechner's research was inherently innovative. He believed that a person can not directly assess their feelings quantitatively, so he developed "indirect" methods with which you can

176 • Part II. Mental processes

quantify the relationship between the magnitude of the stimulus (stimulus) and the intensity of the sensation caused by it. Suppose we are interested in what the minimum value of the sound signal the subject can hear this signal, that is, we must determine the lower absolute volume threshold . Measurement by the method of minimal changes is carried out as follows. The subject is instructed to say “yes” if he hears the signal, and “no” - if he does not. First, the subject is presented with a stimulus, which he clearly can hear. Then, with each presentation, the magnitude of the stimulus decreases. This procedure is carried out until the responses of the subject change. For example, instead of “yes”, he may say “no” or “seemingly no”, etc.

The magnitude of the stimulus at which the responses of the subject change, corresponds to the threshold for the disappearance of sensation (P 1). At the second stage of measurement, in the first presentation, the subject is offered a stimulus that he cannot hear at all. Then, at each step, the magnitude of the stimulus increases until the subject's answers go from “no” to “yes” or “maybe yes”. This value of the stimulus corresponds to the threshold of sensation (P 2). But the threshold for the disappearance of sensation is rarely equal to the threshold of appearance. And two cases are possible:

P 1> P 2 or P 1

Accordingly, the absolute threshold (Stp) will be equal to the arithmetic mean of the appearance and disappearance thresholds:

Stp = (P 1 + P 2) / 2

In a similar way, the upper absolute threshold is determined - the value of the stimulus at which it ceases to be perceived adequately. The upper absolute threshold is sometimes called the pain threshold, because with the corresponding values ​​of the stimuli we experience pain in the eyes with a too bright light, pain in the ears with a too loud sound.

Absolute thresholds - upper and lower - define the boundaries accessible to our perception of the world. By analogy with a measuring device, absolute thresholds determine the range in which a sensor system can measure stimuli, but in addition to this range, the operation of the device is characterized by its accuracy, or sensitivity. The magnitude of the absolute threshold characterizes the absolute sensitivity. For example, the sensitivity of two people will be higher for someone who has sensations when exposed to a weak stimulus, when another person does not have sensations (that is, who has less than the absolute threshold). Consequently, the weaker the stimulus that causes the sensation, the higher the sensitivity.

Thus, absolute sensitivity is numerically equal to the value inversely proportional to the absolute threshold of sensations. If the absolute sensitivity is denoted by the letter E, and the magnitude of the absolute threshold P, then the relationship of absolute sensitivity and absolute threshold can be expressed by the formula:

E = 1 / P

Different analyzers have different sensitivity. On the sensitivity of the eyes, we have already spoken. Very sensitive and our sense of smell. The threshold of one human olfactory cell for the corresponding odorous substances does not exceed eight molecules. It takes at least 25,000 times more molecules to produce a taste sensation than the appearance of an olfactory sensation.

The absolute sensitivity of the analyzer equally depends on both the lower and the upper threshold of sensation. The magnitude of the absolute thresholds, both lower and upper, varies depending on different conditions: the nature of the activity and the age of the person, the functional state of the receptor, the strength and duration of the action of the stimulation, etc.

Another characteristic of sensitivity is sensitivity to difference. It is also called relative, or differential, as it is sensitive to changes in the stimulus. If we put a weight of 100 grams on our hands and then add another gram to this weight, then no one can feel this increase. In order to feel the increase in weight, you must add three to five grams. Thus, in order to feel the minimal difference in the characteristics of the acting stimulus, it is necessary to change the strength of its effect by a certain amount, and the minimal difference between the stimuli, which gives a barely noticeable difference in sensations, is called the threshold of discrimination.

Back in 1760 The French physicist P. Buger established a very important fact on the material of light sensations regarding the magnitude of the thresholds of discrimination: in order to feel the change in illumination, it is necessary to change the flow of light by a certain amount. Changes in the characteristics of the luminous flux to a smaller value, we can not notice with the help of our senses. Later, in the first half of the nineteenth century. German scientist M. Weber, studying the feeling of gravity, came to the conclusion that, comparing objects and observing the differences between them, we perceive not the differences between the objects, but the ratio of the difference to the size of the compared objects. So, if you need to add three grams to a load of 100 grams to feel the difference, then you need to add six grams to a load of 200 grams. In other words: in order to notice the increase in weight, it is necessary to add approximately ^ g of its mass to the initial load. Further studies have shown that a similar pattern exists in other types of sensations. For example, if the initial illumination of a room is 100 lux, then the increase in illumination, which we observe for the first time, should be at least one lux. If the illumination is 1000 lux, then the increment should be at least 10 lux. The same applies to the auditory, and motor, and to other sensations. So, the threshold of differences of sensations is determined by the ratio

D I / I

where D I is the value by which the initial stimulus, which has already generated a feeling, must be changed, so that the person will notice that he has really changed; I - the value of the current stimulus. Moreover, studies have shown that the relative

the value characterizing the threshold of distinction is constant for a particular analyzer. For the visual analyzer, this ratio is approximately 1/1000, for the auditory - 1/10, for the tactile - 1/30. Thus, the distinction threshold has a constant relative value, i.e. it is always expressed as a relation indicating what part of the original stimulus value must be added to this stimulation in order to get a subtle difference in sensations. This provision was called the law of the Booger-Weber. In mathematical form, this law can be written as follows:

D I / I = const,

где const (константа) — постоянная величина, характеризующая порог различия ощущения, названная константой Вебера. Параметры константы Вебера приведены в табл. 7.1.

Таблица 7.1 Значение константы Вебера для различных органов чувств

Sensations	Значение константы
Ощущение изменения высоты звука Ощущение изменения яркости света Ощущение изменения веса предметов Ощущение изменения громкости звука Ощущение изменения давления на поверхность кожи Ощущение изменения вкуса соляного раствора	0,003 0,017 0,020 0,100 0,140 0,200

Основываясь на экспериментальных данных Вебера, другой немецкий ученый — Г. Фехнер — сформулировал следующий закон, называемый обычно законом Фехнера: если интенсивность раздражений увеличивается в геометрической прогрессии, то ощущения будут расти в арифметической прогрессии. В другой формулировке этот закон звучит так: интенсивность ощущений растет пропорционально логарифму интенсивности раздражителя. Следовательно, если раздражитель образует такой ряд: 10; 100; 1000; 10 000, то интенсивность ощущения будет пропорциональна числам 1; 2; 3; 4. Главный смысл данной закономерности заключается в том, что интенсивность ощущений возрастает не пропорционально изменению раздражителей, а гораздо медленнее. В математическом виде зависимость интенсивности ощущений от силы раздражителя выражается формулой:

S = K * LgI +C,

(где S — интенсивность ощущения; I — сила раздражителя; K и C — константы). Данная формула отражает положение, которое носит название основного психофизического закона, или закона Вебера—Фехнера.

Спустя полстолетия после открытия основного психофизического закона он вновь привлек к себе внимание и породил много споров по поводу своей точности. Американский ученый С. Стивене пришел к выводу о том, что основной психофи-

зический закон выражается не логарифмической, а степенной кривой. Он исходил из предположения о том, что для ощущений, или сенсорного пространства, характерно то же отношение, что и для пространства стимулов. Данная закономерность может быть представлена следующим математическим выражением:

D Е / Е = К

где Е — первичное ощущения, D Е — минимальное изменение ощущения, которое возникает при изменении воздействующего стимула на минимальную величину, заметную для человека. Таким образом, из данного математического выражения следует, что соотношение между минимально возможном изменение наших ощущений и первичным ощущением есть величина постоянная — К. А если это так, то соотношение между пространством стимулов и сенсорным пространством (нашими ощущениями) может быть представлено следующим уравнением:

D Е / Е = К х D I / I

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

S = K x R n,

where S is the power of sensations, K is a constant determined by the selected unit of measurement, n is an indicator depending 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 is the value affecting stimulus.

American scientists R. and B. Tetsunyan attempted to explain mathematically the meaning of the degree of n. As a result, they came to the conclusion that the value of the degree n for each modality (that is, for each sense organ) determines the ratio between the range of sensations and the range of perceived stimuli.

The debate about which of the laws is more accurate has not been resolved. Science is known for numerous attempts to answer this question. One of such attempts belongs to Yu. M. Zabrodin, who offered his explanation of the psychophysical relationship. The world of stimuli again represents the Booger – Weber law, and Zabrodin proposed the structure of the sensory space in the following form:

D E / E z

i.e., added a constant - g. As a result, the relationship between the world of stimuli and the world of our sensations is reflected in the following equation:

D E / E z = K x D I / I

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

Why did Yu. M. Zabrodin introduce the constant 2 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 the course of the experiment. In the experiments G. Fechner took

the participation of "naive" subjects who got into a completely unfamiliar experimental situation and did not know anything about the upcoming experiment except the instructions. Thus, in the Fechner law, z = 0, which means that the subjects are completely ignorant. Stevens solved more pragmatic tasks. He was more interested in how a person perceives the sensory signal in real life, rather than the abstract problems of the sensory system. He argued the possibility of direct estimates of the magnitude of sensations, the accuracy of