Closely related to each other. Both are so-called sensory reflections of objective reality that exists independently of consciousness and as a result of its influence on the sense organs: this is their unity. But perception- awareness of a sensual given object or phenomenon; in perception, we usually have a world of people, things, phenomena that are filled with a certain meaning for us and are involved in diverse relationships. These relationships create meaningful situations, witnesses and participants of which we are. Feeling on the other hand, it is a reflection of a separate sensory quality or undifferentiated and unobjectified impressions from the environment. In this last case sensations and perceptions are distinguished as two different forms or two different relations of consciousness to objective reality. Sensations and perceptions are thus one and different. They make up: sensory-perceptual level of mental reflection. At the sensory-perceptual level, we are talking about those images that arise from the direct impact of objects and phenomena on the senses.
The concept of sensations
The main source of our knowledge about the external world and about our own body is sensations. They constitute the main channels through which information about the phenomena of the external world and about the states of the body reaches the brain, giving a person the opportunity to navigate in the environment and in his body. If these channels were closed and the sense organs did not bring the necessary information, no conscious life would be possible. There are known facts that a person deprived of a constant source of information falls into a sleepy state. Such cases: take place when a person suddenly loses sight, hearing, smell, and when his conscious sensations are limited by some pathological process. A result close to this is achieved when a person is placed for some time in a light and soundproof chamber that isolates him from external influences. This state first induces sleep and then becomes intolerable for the subjects.
Numerous observations have shown that impaired information flow in early childhood, associated with deafness and blindness, causes severe delays in mental development. If children born deaf-deaf or deprived of hearing and sight at an early age are not taught special techniques that compensate for these defects due to touch, their mental development will become impossible and they will not develop independently.
As will be described below, 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 neurons that are part of the central nervous apparatus, which reach the signals perceived by the peripheral sense organs.
The reflex nature of sensations
So, sensations are the initial source of all our knowledge about the world. Objects and phenomena of reality that act on our senses are called stimuli, and the effect of stimuli on the senses is called irritation. Irritation, in turn, causes excitation in the nervous tissue. Sensation arises as a reaction of the nervous system to a particular stimulus and, like any mental phenomenon, has a reflex character.
The physiological mechanism of sensations is the activity of special nervous apparatuses called.
Each analyzer consists of three parts:- the peripheral section, called the receptor (the receptor is the perceiving part of the analyzer, its main function is the transformation of external energy into a nervous process);
- afferent or sensory nerves (centripetal), conducting excitation to the nerve centers (the central section of the analyzer);
- cortical sections of the analyzer, in which the processing of nerve impulses coming from the peripheral sections takes place.
The cortical part of each analyzer includes an area that is a projection of the periphery in the cerebral cortex, since certain cells of the periphery (receptors) correspond to certain areas of the cortical cells. For a sensation to arise, the work of the entire analyzer as a whole is necessary. The analyzer is not a passive energy receiver. This is an organ that reflexively rebuilds under the influence of stimuli.
Physiological studies show that sensation is not at all a passive process, it always includes motor components in its composition. So, observations with a microscope of a skin area, carried out by the American psychologist D. Neff, made it possible to make sure that when it is irritated with a needle, the moment the sensation occurs is accompanied by reflex motor reactions of this skin area. Subsequently, numerous studies found that each sensation includes movement, sometimes in the form of a vegetative reaction (vasoconstriction, galvanic skin reflex), sometimes in the form of muscle reactions (eye rotation, neck muscle tension, motor reactions of the hand, etc. .). Thus, sensations are not passive processes at all - they are active. In pointing out the active character of all these processes, the reflex theory of sensations consists.
Classification of sensations
It has long been customary to distinguish five main types (modalities) of sensations: smell, taste, touch, sight and hearing. This classification of sensations according to the main modalities is correct, although not exhaustive. A.R. Luria believes that the classification of sensations can be carried out according to at least two main 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).
Systematic classification of sensations
Singling out the largest and most significant groups of sensations, they can be divided into three main types; interoceptive, proprioceptive and exterocentric sensations. The former combine signals that reach us from the internal environment of the body; the latter provide information about the position of the body in space and the position of the musculoskeletal system, provide regulation of our movements; finally, others provide signals from the outside world and provide the basis for our conscious behavior. Consider the main types of sensations separately.
Interoceptive sensationsInteroceptive sensations, signaling the state of the internal processes of the body, bring irritation from the walls of the stomach and intestines, the heart and circulatory system and other internal organs to the brain. This is the oldest and most elementary group of sensations. Interoceptive sensations are among the least conscious and most diffuse forms of sensation and always retain their proximity to emotional states.
proprioceptive sensationsProprioceptive sensations provide signals about the position of the body in space and form the afferent basis of human movements, playing a decisive role in their regulation. Peripheral receptors for proprioceptive sensitivity are found in muscles and joints (tendons, ligaments) and have the form of special nerve bodies (Paccini bodies). The excitations that arise in these bodies reflect the sensations that occur when muscles are stretched and the position of the joints changes. In modern physiology and psychophysiology, the role of proprioception as the afferent basis of movements in animals was studied in detail by A. A. Orbeli, P. K. Anokhin, and in humans, by N. A. Bernshtein. The described group of sensations includes a specific type of sensitivity, called a sense of balance, or a static sensation. Their peripheral receptors are located in the semicircular canals of the inner ear.
exteroreceptive sensationsThe third and largest group of sensations are exteroreceptive sensations. They bring information from the outside world to a person and are the main group of sensations that connects a person with the external environment. The whole group of exteroceptive sensations is conventionally divided into two subgroups: contact and distant sensations.
Contact sensations are caused by an impact directly applied to the surface of the body and the corresponding perceived organ. Taste and touch are examples of contact sensation.
Distant sensations are caused by stimuli acting on the sense organs at some distance. These senses include the sense of smell and, especially, hearing and sight.
Genetic classification of sensations
Genetic classification allows us to distinguish two types of sensitivity:- protopathic(more primitive, affective, less differentiated and localized), which includes organic feelings (hunger; thirst, etc.);
- epicritical(more subtly differentiating, objectified and rational), which includes the main human senses.
Epicritical sensitivity is genetically younger and controls protopathic sensitivity.
General properties of sensations
Different types of sensations are characterized not only by specificity, but also by properties common to them. These properties include: quality, intensity, duration and spatial localization.
Quality- this is the main feature of this sensation, which distinguishes it from other types of sensations and varies within the limits of this type of sensations. The qualitative variety of sensations reflects the infinite variety of forms of motion of matter.
Intensity sensation is its quantitative characteristic and is determined by the strength of the acting stimulus and the functional state of the receptor.
Duration sensation is its temporal characteristic. It is also determined by the functional state of the sense organ, but mainly by the duration of the stimulus and its intensity.
When a stimulus is exposed to a sensory organ, sensation does not occur immediately, but after some time - the so-called latent (hidden) period of sensation. The latent period of various types of sensations is not the same: for example, for tactile sensations it is 130 ms; for pain - 370, and for taste - only 50 ms.
Just as a sensation does not arise simultaneously with the beginning of the action of the stimulus, it does not disappear simultaneously with the termination of its action. The presence of positive successive images explains why we do not notice the breaks between successive frames of the film: they are filled with traces of previous frames - successive images from them. The sequential image changes in time, the positive image is replaced by a negative one. With colored light sources, the sequential image turns into a complementary color.
Characteristics of the main types of sensations
Each type of sensation has its own specific characteristics.Skin sensations
Skin sensations are obtained from the direct action of various stimuli on receptors located on the surface of human skin. All such sensations have the general name of skin sensations, although, strictly speaking, these sensations 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. This is due to the fact that they occur during direct contact of the receptor with the object of the real world. There are four main types of sensations:
Feelings of touch (tactile),
Feelings of cold
Feelings of warmth
Feelings of pain.
Although it is said that skin sensations occur only through direct contact with a real-world object, there are exceptions. If you hold your hand in some proximity to a hot object, you can feel the heat emanating from it. This warm air is transferred from a hot object to your hand. In this case, we can say that we feel an intermediary object (warm air). However, if you put a glass partition that completely separates the hot object, you can still feel the feeling of warmth. The fact is that hot objects emit infrared rays that heat our skin.
Interesting and something else. People familiar with electronics might assume that one type of receptor is enough to perceive heat and cold. The vast majority of temperature sensors (like conventional thermometers) measure temperature in a fairly wide range: from cold to hot. However, nature has equipped us with two types of receptors: for the sensation of cold and for the sensation of heat. At normal temperature, the receptors of both types are "silent". Touching warm objects makes heat receptors "talk". Touching the cold - cold receptors.
Each of the four types of skin sensations mentioned above has specific receptors. In experiments, it was shown that some points of the skin give only sensations of touch (tactile points), others - sensations of cold (cold points), third - sensations of heat (heat points), fourth - sensations of pain (pain points). Tactile receptors are arranged in such a way that they react to touch that causes deformation of the skin. Thermal are arranged so that they react to cold or heat. And painful ones react to deformation, and to heat, and to cold, but only at a high intensity of exposure.
To determine the location of receptor points and sensitivity thresholds, a special device, an esthesiometer, is used. The simplest esthesiometer consists of a horsehair and a transducer to measure the pressure exerted by that hair. 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 in this case, instead of a hair, a thin metal tip is used, filled with water, the temperature of which can vary.
The total number of skin receptors in humans is not yet known. It has been approximately established that there are about one million touch points, about four million pain points, about 500 thousand cold points, and about 30 thousand hot points.
On the surface of the body, the density of receptors is not a constant value. The proportions of receptors of different species also change. So on the fingertips, the number of touch receptors is twice as large as pain points, although the total number of the latter is much larger (see above). 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 density of certain receptors in one place or another is determined by the value of the corresponding signals. If for manual operations it is very important to have an accurate idea of the object that is held in the hands, then the density of tactile receptors will be higher here. The back, abdomen, and outer side of the forearm contain significantly fewer touch receptors. The back, cheeks are most sensitive to pain and the fingertips are the least sensitive. Interestingly, in relation to temperature, those parts of the body that are usually covered by clothing are most sensitive: lower back, chest.
The greater the density of receptors in a particular part of the body, the more accurately we can determine the coordinates of the source of a new sensation. Experiments often explore the spatial threshold between the places of contact, which makes it possible to distinguish between the touch of two (or more) spatially separated objects.
To determine the spatial threshold of tactile sensations, a circular esthesiometer is used, 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. 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. Obviously, this is due to the peculiarity of chewing food.
Taste and olfactory sensations
Taste receptors are the so-called taste buds, consisting of sensitive taste cells connected to nerve fibers. 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. In children, the distribution of taste buds is much wider than in adults. Taste buds are present on the palate, tonsils and posterior pharyngeal wall (more so in children).The middle of the upper surface and the entire lower surface of the tongue are not sensitive to taste.
Irritants for taste buds are chemicals dissolved in water. In the course of evolution, nature endowed us with the ability to distinguish between the most significant classes of chemicals (acids, salts, sugars, etc.)
The receptors for olfactory sensations are olfactory cells immersed in the mucous membrane of the so-called olfactory region. Irritants for the olfactory receptors are various odorous chemicals that enter the nose along with the air. In an adult, the area of the olfactory region is approximately equal to five hundred square millimeters.
In newborns, the olfactory area is much larger, which 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 further ontogenetic development, olfactory taste sensations give way to other, more informative sensations, and first of all to vision.
Taste sensations are closely related to olfactory ones. Therefore, in most cases they are mixed with each other. Many people, for example, notice that during a severe runny nose, when olfactory sensations are turned off for obvious reasons, food becomes less tasty, one dish begins to taste like another.
Also, tactile and temperature sensations from receptors located in the area of the oral mucosa are mixed with taste sensations. The perception of "spicy" or "astringent" food is mainly associated with tactile sensations. The characteristic taste of mint "with a chill" largely depends on the stimulation of cold receptors.
If we exclude admixtures of tactile, temperature and olfactory sensations from taste sensations, then the actual taste sensations will be reduced to a combination of four main types:
Sweet,
bitter,
Salty.
In 1997, Japanese scientists showed that there are also receptors responsible for the perception of lipids, that is, recognizing a fatty taste. Thus, it turns out that any taste is a combination of five separate tastes.
It was also found in experiments that different parts of the tongue have different sensitivity to individual 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.
Although taste and smell are very similar, there is a huge difference between them. If taste sensations can be reduced to a combination of four or five basic tastes, olfactory sensations are not a combination of some "basic smells". Therefore, a strict classification of odors does not exist. And it is even difficult to imagine in what form such a classification could exist.
Each scent is tied to a specific item or classes of items that possess it. Examples:
floral scent,
The scent of a rose
The smell of an animal
The smell of a rat
gasoline smell,
The smell of a new car
The smell of rotten eggs
The smell of fried pies.
In most cases, a unique smell is made up of many chemicals. In some cases, the smell consists predominantly of one substance (dominant). For example, the smell of rotten eggs consists mainly of hydrogen sulfide. Throughout life, we learn new smells, learn to distinguish them from others, sometimes we give these smells verbal names ("the smell of my favorite perfume") or adopt common names ("the smell of sweat").
In receiving and recognizing a smell, impurities of other sensations also matter:
Taste (especially from irritation of the taste buds located in the back of the throat - next to the air movement channel),
Tactile,
pain,
temperature.
The smell of fresh buns seems tasty to us not only because it is associated with delicious buns - its source. But also because it directly irritates the taste buds (chemicals dissolve in the moisture of the mouth and irritate the taste buds). Some pungent odors, such as mustard, contain both tactile and painful sensations. The smell of menthol includes a "chill" due to the fact that it irritates the cold receptors.
Interestingly, 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. Nature has endowed us with taste sensations (to a greater extent) and olfactory sensations (to a lesser extent) mainly so that we can detect potential food and try it out by checking for edibility. It is logical to assume that hunger activates this ability.
Also, taste and smell sensations include a mechanism for obtaining pleasure from eating food (especially in a state of hunger). Thus, nature has taken care that we enjoy not the long-term result of eating food (when it is all swallowed and digested), but "in real time." It is necessary to reinforce your strength daily, and therefore nature has come up with such a powerful incentive.
auditory sensations
For the organ of hearing, the irritant is sound waves, that is, longitudinal wave-like vibrations of air particles. The source of such a wave-like movement of air is an oscillating body (and usually a solid one). Sound propagates from this body in all directions. It is worth noting that sound can propagate not only through the air, but also through any matter: liquid, gaseous, solid. In a vacuum where there is no matter, sound does not propagate.All sounds can be divided into two categories:
Noises (chaotic alternation of sound waves),
Ordered sounds.
With some convention, ordered sounds can be divided into four types:
Sounds of inanimate nature (howling wind, dripping water, crunching snow),
Signal sounds of living beings (meow, chirp, human speech),
Man-made sounds (squeak of a speaker, buzz of a servo, clang of a caterpillar),
The more ordered the sounds, the less random elements they contain. The least chaotic sounds are the sounds of music, in a typical piece of music every note, every overtone, every sequence is not a random element at all.
Sound waves are:
in the form of a wave,
frequency,
Amplitude
Timbre (coloring with additional elements).
Sound waves are not always sinusoidal. The sound of a bell, for example, does not have the form of a sinusoid. However, by default, when talking about a sound wave, they mean a sinusoid.
The pitch of a sound is measured in hertz, that is, in the number of vibrations per second. If the membrane of the source or receiver swung back and forth 100 times, then the pitch would be 100 Hz. We are not able to perceive the sound of any frequency. The highest sound that an adult perceives is 20,000 Hz. In children - 22000 Hz, in the elderly - 15000 Hz. The lower limit of hearing is 16-20 hertz. We can also perceive lower-frequency sounds, but not with the ear, but with the skin.
The human ear is most sensitive to sounds with a frequency of 1000-3000 Hz. Pitch accuracy develops with experience.
The loudness of the sound determines the subjective intensity of the auditory sensation. It might be assumed that for our perception the loudness of the auditory sensation would be proportional to the pressure exerted on the eardrum. It turned out, however, that the auditory sensation is only proportional to the logarithm of the pressure intensity.
The units of measure for hearing 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 meters from the human ear. So, the volume of ordinary human speech at a distance of 1 meter will be 16-22 dB, the noise on the street (without a tram) - up to 30 dB, the noise in the boiler room - 87 dB, the noise of an airplane taking off - 130 dB (pain threshold).
Timbre is a specific quality that distinguishes sounds of the same height and intensity from different sources from each other. And vice versa - a quality that can combine sounds of different heights and intensities. Timbre can be called the color of sound.
In music, the form of sound vibration, especially for stringed instruments, corresponds to a sinusoid. Such sounds are called "harmonious". By themselves, they already cause pleasant sensations.
But the fact is that in a sound wave there can be an overlay of several sinusoids. Even a simple string, in addition to the main sinusoid, also gives out accompanying (overtones). If the fundamental oscillation frequency is 100 Hz, then the overtone frequency will be: 200 Hz, 300 Hz, 400 Hz, 500 Hz, etc.
With the help of a tuning fork or special electronic devices, a computer can get a simple sound - it consists of one sinusoid, has a constant sound frequency. But in everyday life we do not meet 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.
The combination of simple sounds in one complex one gives originality to the form of sound vibrations and determines the timbre of the sound. This timbre also 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 single out a pleasant sound - consonance and an unpleasant sound - dissonance.
In modern science, Helmholtz's resonance theory is used to explain auditory sensations. The terminal apparatus of the auditory nerve is the organ of Corti, resting on the main membrane, which runs along the entire spiral bone canal, called the cochlea. The basilar membrane consists of about 24,000 transverse fibers. The length of these fibers gradually decreases from the top of the cochlea to its base.
Each such fiber is tuned, like a string, to a certain frequency of oscillation. When sound vibrations reach the cochlea, consisting as a rule of a combination of different frequencies, certain groups of fibers of the main membrane resonate. After that, 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.
In the future, the sound goes through complex processing in specialized think tanks. In the process of this processing: separate independent sequences in sounds are singled out (for example, a person's voice is separated from the noise of the city), repeating elements are sought out, identified.
visual sensations
For the organ of vision, the irritant is light, or rather, electromagnetic waves having a length of 390 to 800 nanometers (one billionth of a meter). If the electromagnetic wave is "energetic", that is, it has a large oscillation amplitude, we perceive bright light, otherwise - weak light.Nature endowed us with the ability to distinguish light not only in intensity, but also in quality. More specifically, the wavelength. We perceive light with a length of 500 nm differently than 700 nm. Unfortunately (or joyfully), our consciousness does not perceive light in this order: "I see a light spot with a wavelength of 539 nm." Instead, we perceive light according to a scale of names, that is, according to color.
The sensations of red light are caused by waves of 630-800 nm, yellow - 570-590 nm, green - 500-570 nm, blue - 430-480 nm.
Visual sensations are sensations of color. Everything we see, we perceive in color. But at the same time, colors are divided into:
Achromatic ("colorless" colors - white, gray and black),
Chromatic (everything else).
Gray color includes waves of different lengths. Bright gray is white. Dark gray color - black. But that's kind of in theory. In fact, any chromatic color (such as blue or red) when very dark is perceived as black (low intensity), and when very light (high intensity) is perceived as white.
Chromatic color tone depends on which particular wavelengths prevail in the light flux reflected by a given object.
The eye has unequal sensitivity to light waves of different wavelengths. 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.
Human color vision is excellently developed. For example, between black and white, a person can distinguish about 200 transitional colors. You can distinguish dozens of shades of red or blue, many of which even have their own names ("blood red", "ruby", "scarlet", etc.).
Visual acuity is the ability to distinguish 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 everyday life, the colors we perceive, even those that appear to be monochromatic, are the result of the addition of many 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. And this is a very characteristic feature of our vision. For comparison - our hearing analyzes sound waves, puts them "on the shelves". If hearing worked like vision, then we would perceive any sound as simple - no matter if the metronome is ticking or the stadium is wailing, in both cases we would hear the same thing, only slightly different in intensity.
Newton and Helmholtz established the laws of mixing colors. First, for each chromatic color, you can pick up another chromatic color, which, when mixed with the first, gives an achromatic color (gray). These two colors are called complementary. Secondly, mixing two non-complementary colors results in a third color - 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.
If we again compare vision and hearing, it may seem like an amusing absurdity that green is not only a certain and rather narrow part of the spectrum, but also (in another version) a mixture of blue and yellow parts of the spectrum. And completely different parts of the spectrum: not perceiving the "green waves", we nevertheless still see the green color. It's like listening to the balalaika and the roar of an elephant at the same time, and in the end perceive the murmur of a stream. However, it is quite obvious that nature simply did not come up with a way to make a spectrometer as effective as in the case of hearing. Basically, the problem is that for each perceived point in space, one would have to have not three receptors, but tens or hundreds.
The retina is the most important and characteristic element of our vision. It is a branching of the optic nerve that enters the back of the eyeball. There are two types of receptors in the retina:
cones,
Sticks.
These receptors got their name 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, i.e. the place where the image of the object to which our attention is drawn falls. The number of cones decreases towards the edges of the retina.
There are more rods just at the edges of the retina, in the middle they are practically absent.
Cones have low light sensitivity. To cause their reaction, you need a strong enough light. Therefore, with the help of cones, we see only in bright light or artificial lighting. This is why cones are sometimes referred to as day vision apparatus.
Rods are more sensitive, and with their help we see at night, so they are called night vision apparatus.
The most important difference between rods and cones is that we use cones to distinguish colors. Cones are of three types. Each species is responsible for its part of the spectrum.
There is a disease in which the cone apparatus does not work completely. Patients see everything only in shades of gray. They can't see right in front of them. With another disease - "night blindness" - on the contrary, the rod apparatus does not work, and then the patient perceives almost nothing in the dark.
Visual arousal has a certain inertia. This continuation of sensation for some time is called a positive sequential image. It can be observed simply by closing your eyes.
proprioceptive sensations
Proprioceptive sensations are sensations of movement and balance. Balance receptors are located in the inner ear. 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.The fact is that motor sensations play a very important role in coordinating our movements. Nature could not be satisfied with the rest of the senses. If there were no proprioceptive sensations, we would have to constantly look at our hands and feet in order to achieve something with them. In the process of performing a particular movement, our brain constantly receives signals from receptors located in the muscles and on the surface of the joints. This helps correct movement. Without proprioceptive sensations, it would be difficult to both move and maintain balance in movement. The human body consists of a huge number of moving elements and muscles, proprioceptive sensitivity allows you to control all this huge "orchestra".
The main properties of sensations include:
quality,
intensity,
duration,
spatial localization,
absolute and relative thresholds of sensations.
All sensations can be characterized in terms of their properties. Moreover, properties can be not only specific, but also common to all types of sensations. The main properties of sensations include: quality, intensity, duration and spatial localization, absolute and relative thresholds of sensations.
Quality- this is a property that characterizes the basic information displayed by this sensation, distinguishing it from other types of sensations and varying within this type of sensation. For example, taste sensations provide information about certain chemical characteristics of an object: 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: the smell of flowers, the smell of almonds, the smell of hydrogen sulfide, etc.
Feeling intensity- a 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, the intensity of perceived odors may be distorted.
Duration of sensation- This is a temporal characteristic of the sensation that has arisen. It is also determined by the functional state of the sense organ, but mainly by the time of action of the stimulus and its intensity. It should be noted that sensations have a so-called latent (hidden) period. When a stimulus is applied to the sense organ, the sensation does not occur immediately, but after some time. 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 taste - only 50 ms. The sensation does not arise simultaneously with the beginning of the action of the stimulus and does not disappear simultaneously with the termination of its action. The visual sensation has some inertia and does not disappear immediately after the cessation of the action of the stimulus that caused it. The trace from the stimulus remains in the form of a consistent image. Distinguish between positive and negative sequential images.
positive serial image corresponds to the initial irritation, consists in maintaining a trace of irritation of the same quality as the current stimulus.
Negative serial image consists in the appearance of a quality of sensation that is opposite to the quality of the irritant. For example, light-darkness, heaviness-lightness, heat-cold, etc. The appearance of negative sequential images is explained by a decrease in the sensitivity of this receptor to a certain effect.
Spatial localization of the stimulus. The analysis carried out by the receptors gives us information about the localization of the stimulus in space, i.e. we can tell where the light is coming from, where the heat is coming from, or what part of the body is affected by the stimulus.
Quantitative parameters the main characteristics of sensations, in other words, the degree of sensitivity. The human sense organs are surprisingly fine working apparatuses.
There are two types of sensitivity:
absolute sensitivity - the ability to feel weak stimuli;
difference sensitivity - the ability to sense subtle differences between stimuli.
However, not every irritation causes a sensation. In order for a sensation to arise, the force of irritation must have a certain value.
Absolute threshold of sensation - the minimum value of the stimulus at which a sensation first occurs. Stimuli, the strength of which lies below the absolute threshold of sensation, do not give sensations, but this does not mean that they do not have any effect on the body. Thus, studies by the Russian physiologist G.V. Gershuni and his collaborators showed that sound stimuli below the threshold of sensation can cause a change in the electrical activity of the brain and dilation of the pupil. The zone of influence of irritants that do not cause sensations was called by G.V. Gershuni "subsensory area".
The beginning of the study of the 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:
Fechner Gustav Theodor (1801 -1887)- German physicist, philosopher and psychologist, founder of psychophysics. Fechner is the author of the programmatic work "Elements of Psychophysics" (I860). In this work, he put forward the idea of creating a special science - psychophysics. In his opinion, the subject of this science should be the regular correlations of two types of phenomena - mental and physical - functionally interconnected. 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 indirect measurement of sensations, in particular three classical methods for measuring thresholds. However, after studying the successive images caused by the observation of the sun, he partially lost his sight, which forced him to leave psychophysics and take up philosophy.
Irritation - "Excitation -" 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 circle of interests of psychology. Before Fechner, it was believed that the study of sensations, if anyone was interested, should be dealt with by physiologists, doctors, even physicists, but not psychologists. For psychologists, this is too primitive.
According to Fechner, the desired boundary passes where sensation begins, i.e., the first mental process occurs. The magnitude of the stimulus at which sensation begins, Fechner called lower absolute threshold . To determine this threshold, Fechner developed methods that are actively used in our time. Fechner based his research methodology on two statements, called the first and second paradigms of classical psychophysics.
Human sensory system is a measuring device that responds appropriately to physical stimuli.
Psychophysical characteristics in humans, they are distributed according to the normal law, that is, they randomly differ from some average value, similar to anthropometric characteristics.
The paradigms are already outdated and, to a certain extent, contradict modern principles of the study of the psyche, but Fechner's research was inherently innovative.
Today, researchers understand that it is impossible to isolate and study in an 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.
Different analyzers have different sensitivities. We have already talked about the sensitivity of the eye. The sensitivity of our sense of smell is also very high. 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 it does to produce an olfactory sensation.
The absolute sensitivity of the analyzer equally depends on both the lower and the upper threshold of sensation.
The value of absolute thresholds , both lower and upper, varies depending on different conditions:
the nature of the activity,
person's age,
functional state of the receptor,
the strength and duration of the action of irritation, etc.
sensitivity to difference. Relative, or differential sensitivity - to a change in the stimulus. If we put a weight of 100 grams on our hand, and then add another gram to this weight, then no person will be able to feel this increase. In order to feel an increase in weight, you need to add three to five grams.
To feel the minimum difference in the characteristics of the acting stimulus, it is necessary to change the strength of its impact by a certain amount.
Discrimination Threshold - the minimum difference between stimuli, which gives a barely noticeable difference in sensations.
The values of constants were calculated for the perception of changes in various stimuli.
In 1760, the French physicist P. Bouguer, using the material of light sensations, established a very important fact regarding the magnitude of the thresholds of discrimination: in order to feel a change in illumination, it is necessary to change the light flux by a certain amount.
Later, in the first half of the XIX century. German scientist M. Weber, exploring the sensation of heaviness, came to the conclusion that when 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.
MeaningconstantsWeberforvariousbodiesfeelings
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Feel |
Constant value |
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1. Feeling the change in pitch | |
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2.Sensation of light brightness change | |
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3. Feeling the change in the weight of objects | |
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4. Feeling the change in sound volume | |
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5.Sensation of pressure change on the surface of the skin | |
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6. Sensation of a change in the taste of saline solution |
So, sensation is a mental reflection of the isolated properties of objects of the objective world, arising from their direct impact on the senses.
The emergence of sensations is associated with special physiological processes involved in the reception and primary transformation of the effects of certain stimuli from the external and internal environment of the body. These devices are called analyzers(I.P. Pavlov). Each analyzer consists of three parts: first, the peripheral section (receptor), where the recoding of physical effects into nerve impulses takes place; secondly, afferent (from lat. afferentis - bringing) nerve pathways, along which information encoded in the form of nerve impulses is transmitted to the central nervous system (at the exit
7.1. Feeling
our animals and humans - to the brain), and, thirdly, the analyzer center - a special section of the cerebral cortex. As a result of the processing of the information received in the cortical section of the analyzer, sensations arise. The reverse signal, which implements the body's response to a stimulus, passes through the efferent (from Latin efterentis - outgoing) nerve pathways.
Living beings differ in the stimuli to which they respond, and, accordingly, in the sensations that they experience. There is evidence that birds navigate during long-distance flights along the Earth's magnetic field and therefore must have some kind of “magnetic” sensation that is inexplicable to humans. Sharks are sensitive to electrical discharges coming from the scales of fish. Bats have a special ultrasonic analyzer with which they recognize obstacles encountered in their path. Insects see in the part of the color spectrum inaccessible to us. Human hearing fixes a range of 15-20,000 Hz, while a dog can distinguish sounds of a higher frequency. This effect is based on the well-known circus act of "transmitting orders at a distance" from the trainer to the animal. The dog is trained to respond in a certain way to a whistle at about 35,000 Hz. The spectators cannot hear the conditioned signal (producing such sounds is quite simple with a slightly modified whistle), and it seems to them that the dog is performing tricks by magic, reading the owner's mind. Probably, under certain conditions, a person can also develop sensitivity to stimuli that are usually beyond the ability of sensory systems to work. An example is the experiment on the formation of "skin vision", conducted by A.N. Leontiev (see 7.1.4).
Various analyzers have an unequal projection in the cerebral cortex. Experimentally, maps were obtained that schematically show the location and size of the area of the cortex, which provides an analysis of sensations coming from different areas of the body. One such map is shown in Fig. 40. Note that different types of animals have significantly different "maps".
Thus, in humans, the maximum area of the cerebral cortex of the brain is occupied by the projection zones of the mouth, eyes and hands, which is determined by the leading role of vision, speech activity (it requires developed sensory sensitivity of the lips and tongue) and fine hand movements for social life. In an animal for which another type of sen-
The presence of highly specific analyzers, each of which is susceptible to only one particular type of stimulation, raises the problem of the relationship between the properties of sensations and the properties of objects in the external world. In other words, it is necessary to understand how accurately we can judge the real properties of stimuli from our feelings?
I. Müller (1801-1858) put forward the hypothesis of "specific energies of the sense organs". The essence of this hypothesis is that sensations do not reflect the real properties of the stimulus, but only signal the state of our analyzers. “What our sensations give us reflects, expresses the nature and state of our sense organs, nerves, and not the nature of what causes these sensations,” Muller wrote. He illustrated his idea with simple examples: if you hit the eyeball, a person will feel how “sparks fell from the eyes”, i.e. will receive a subjective visual sensation. Similarly, if you lick a strip of metal through which a weak electric current is passed, you get a sensation of a sour taste. One gets the impression that sensations are pure subjectivity, only incidentally connected with the objective world. The position of I. Müller at one time had a great influence on the interpretation of the phenomena of sensation. However, evolutionary reasoning leads us to the conclusion that we are dealing with a pseudo-problem.
7.1. Feeling
Even if in some cases we feel the world is not the way it is, in fact, our sensations as a whole are adequate to the world, since they allow us to effectively navigate in the environment. A deeper comprehension of the world is provided by another mental function - thinking, which consists in a generalized and mediated cognition of reality (see Chapter 9).
The second question that arises when discussing the topic of sensation is the question of the "immediacy" of the action of the stimulus. Indeed, we not only get sensations from stimuli that are in direct contact with the surface of our body (we touch, taste and smell), but we also see and hear what is at a considerable distance from us. Ancient thinkers solved this problem by assuming that objects "emit" the thinnest ethereal copies from themselves, which freely penetrate the eyes, ears, etc. At a new round of development, science, in essence, has returned to a similar understanding, having found physical carriers of "distant" stimuli that make them "close". For vision, such a stimulus will be light, for hearing - air vibrations, for smell - the smallest particles of matter suspended in a neutral medium. According to Ch. Sherrington, sensations are usually divided into contact(the stimulus itself acts on the perceiving organ, and an intermediary delivering information is not required) and distant(i.e., a special “agent” is needed to bring information to the touch surface). Contact sensations are gustatory, olfactory, skin, kinesthetic (sensations of the position of individual parts of the body) and organic (hunger, thirst, etc.), distant - auditory and visual sensations.
However, there are other prerequisites for dividing sensations into distant and contact ones. They lie in the anatomical features of the structure of the corresponding sense organs. Obviously, contact sensations are phylogenetically older than distant sensations. The receptors of contact analyzers do not generally constitute integral sense organs. For example, tactile sensitivity is provided by isolated cells - skin receptors (the so-called Paccini's body, Meissner's body). The former respond to pressure, the latter to vibration. Distant analyzers, on the other hand, are complex ensembles that include both the receptors themselves, concentrated in a certain area of the body, and additional “devices” that ensure maximum sensing efficiency. As A.N. Leontiev, at a certain stage of evolution, these ensembles acquire their own engine -
Chapter 7. Cognitive processes. Feeling and Perception
nym apparatus, they acquire motor capabilities that are quite autonomous from the rest of the body (propriomotor apparatus). The eye, for example, has oculomotor muscles, ciliary muscles, and so on. Thus, the impact on the distant sense organs implies a higher counter activity of the subject. No wonder A. Schopenhauer compared vision with feeling: “Vision can be regarded as an imperfect, but far-reaching touch that uses rays of light as long tentacles,” he wrote in his work “The World as Will and Representation.” Such an emancipation of distant senses can no doubt be regarded as an evolutionary breakthrough in the formation of sensory systems. Unlike contacts, they do not react to an already existing situation, but actively forestall it (P.K. Anokhin).
In addition to the division into contact and distant, C. Sherrington also proposed to classify sensations according to the location of their corresponding receptors (according to receptive fields). In this case, they differ interoreceptive sensations (from receptors located in the internal organs), proprioceptive(from receptors located in muscles, ligaments and tendons) and exteroceptive(from receptors located on the outer surface of the body). In general, the classification of sensations is presented in Table. thirteen.
Basic properties and characteristics of sensations.
All sensations can be characterized in terms of their properties. Moreover, properties can be not only specific, but also common to all types of sensations.
The main properties of sensations include:
1. Quality of sensations- this is a property that characterizes the basic information displayed by this sensation, distinguishing it from other types of sensations and varying within this type of sensation.
It should be borne in mind that very often, when talking about the quality of sensations, they mean the modality of sensations, since it is the modality that reflects the main quality of the corresponding sensation.
2. Intensity of sensations- a quantitative characteristic 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.
3. Duration of sensation- This is a temporal 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 latent (hidden) period. When a stimulus is applied to the sense organ, the sensation does not occur immediately, but after some time. The latent period of different types of sensations is not the same. For tactile sensations, it is 130 ms, for pain - 370 ms, and for taste - 50 ms.
The sensation does not arise simultaneously with the beginning of the action of the stimulus and does not disappear simultaneously with the termination of its action. This inertia of sensations manifests itself in the so-called aftereffect.
The trace from the stimulus remains in the form of a consistent image. Distinguish positive and negative serial images.
positive serial image corresponds to the initial irritation, consists in maintaining a trace of irritation of the same quality as the current stimulus.
Negative serial image consists in the appearance of a quality of sensation that is opposite to the quality of the irritant. The occurrence of negative sequential images is explained by a decrease in the sensitivity of this receptor to a certain effect.
4. Spatial localization of the stimulus. The analysis carried out by the receptors gives us information about the localization of the stimulus in space.
All properties to some extent reflect the qualitative characteristics of sensations. The quantitative parameters of the main characteristics of sensations are important, in other words, degree of sensitivity. There are two types of sensitivity:
1. Absolute sensitivity- the ability to feel weak stimuli.
2. Sensitivity to difference- the ability to sense subtle differences between stimuli.
In order for a sensation to arise, the force of irritation must have a certain value.
Absolute threshold of sensation- the minimum value of the stimulus at which a sensation first occurs.
Stimuli, the strength of which lies below the absolute threshold of sensation, do not give sensations, but this does not mean that they do not have any effect on the body.
Subsensory area (according to G.AT.Gershuni)- the zone of influence of irritants on the body that do not cause sensations.
The beginning of the study of the thresholds of sensations was laid German physicist, psychologist and philosopher.T.Fechner who believed that the material and the ideal are two sides of a single whole.
According to G.T. Fechner, the process of creating a mental image can be represented by the following scheme:
Irritation -> Excitation -> Feeling -> 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 circle of interests of psychology.
According to Fechner, the desired boundary passes where sensation begins, i.e., the first mental process occurs.
Lower absolute threshold (according to Fechner)- the magnitude of the stimulus at which the sensation begins.
To determine this threshold, Fechner developed methods that are actively used in our time. Fechner based his research methodology on two statements, called the first and second paradigms of classical psychophysics:
1. Human sensory system is a measuring device that responds appropriately to physical stimuli.
2. The psychophysical characteristics of people are distributed according to the normal law, that is, they randomly differ from some average value, similar to anthropometric characteristics.
The magnitude of the stimulus at which the responses of the subject change corresponds to threshold of disappearance of sensation (P 1).At the second stage of the measurement, in the first presentation, the subject is offered a stimulus that he cannot hear in any way. Then, at each step, the magnitude of the stimulus increases until the subject's responses go from "no" to "yes" or "maybe yes". This stimulus value corresponds to threshold of sensation (P 2). Two cases are possible:
R 1 > R 2 or R 1< Р 2 .
Absolute Threshold ( stp) is equal to the arithmetic mean of the appearance and disappearance thresholds:
Stp = (P 1 + P 2)/ 2
Upper absolute threshold - the value of the stimulus at which it ceases to be perceived adequately. The upper absolute threshold is sometimes called pain threshold, because with the corresponding values of stimuli, a person experiences pain.
Absolute Thresholds- upper and lower - define the boundaries of the world around us accessible to our perception. By analogy with a measuring instrument, absolute thresholds determine the range in which the sensory system can measure stimuli, but beyond this range, the operation of the instrument is characterized by its accuracy, or sensitivity. The value of the absolute threshold characterizes the absolute sensitivity.
The weaker the stimulus that causes the sensation, the higher the sensitivity.
The 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 value of the absolute threshold R, then the relationship between the absolute sensitivity and the absolute threshold can be expressed by the formula:
Different analyzers have different sensitivities.
The absolute sensitivity of the analyzer equally depends on both the lower and the upper threshold of sensation. The value of absolute thresholds, both lower and upper, varies depending on different conditions: the nature of the activity and the age of the person, functional state of the receptor, the strength and duration of the stimulus etc.
Another characteristic of sensitivity is sensitivity to difference. She is also called relative,or difference, since it is sensitivity to a change in the stimulus. In order to feel an increase in weight, you need to add three to five grams. Thus, in order to feel the minimum difference in the characteristics of the acting stimulus, it is necessary to change the strength of its impact by a certain amount.
Discrimination Threshold- the minimum difference between stimuli, which gives a barely noticeable difference in sensations.
More in 1760 French physicist P. Bouguer based on the material of light sensations, he established a very important fact regarding the magnitude of the thresholds of distinction: in order to feel a change in illumination, it is necessary to change the light flux by a certain amount.
In the first half of the XIX century. German scientist M. Weber, exploring the sensation of heaviness, came to the conclusion that, comparing objects and observing the differences between them, a person perceives not the differences between the objects, but the ratio of the difference to the size of the compared objects. To notice an increase in weight, it is necessary to add approximately 3% of its mass to the original load. Further studies have shown that a similar pattern exists in other types of sensations.
The threshold for differences in sensations is determined by the ratio:
DI- the amount by which the original stimulus that has already generated sensation must be changed in order for a person to notice that he has really changed.
I- the magnitude of the current stimulus.
Thus, the discrimination threshold has a constant relative value, that is, it is always expressed as a ratio showing what part of the initial stimulus value must be added to this stimulus in order to obtain a barely noticeable difference in sensations . This position was called Bouguer's law-Weber. In mathematical form, this law can be written as follows:
DI / I = const
Const (constant)- a constant value characterizing the threshold of sensation difference, called Weber's constant. The parameters of the Weber constant are given in the table.
Table. The value of the Weber constant for various sense organs.
Based on Weber's experimental data, another German scientist - G. Fechner- formulated the following law, usually called Fechner's law: if the intensity of stimuli increases exponentially, then sensations will grow in arithmetic progression. In another wording, this law reads as follows: the intensity of sensations increases in proportion to the logarithm of the intensity of the stimulus.
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
S - intensity of sensation.
I - stimulus strength.
K and C- constants.
This formula reflects the situation, which is called basic psychophysical law, or Weber-Fechner law.
American scientist C. Stevens 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:
DE / E = K
E - initial feeling.
DE - the minimum change in sensation that occurs when the impacting 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:
DE / E \u003d K x DI / I
This equation is called stevens law. The solution to this equation is expressed by the following formula:
S = KxRn
S- the power of sensation.
To- a constant defined 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.
The world of stimuli again represents the Bouguer-Weber law, and Zabrodin proposed the structure of the sensory space in the following form:
DE / E z \u003d K x DI / I
Obviously, at z=0 the formula of the generalized law goes over into the Fechner logarithmic law, and when z = 1 - to the Stevens power law.
Thus, the proposed law 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.
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.
