What adaptation is observed with a decrease in brightness. Dark Adaptation Disorders

The structure of the organ of vision. The organ of vision consists of eyeball and ancillary apparatus. The eyeball contains peripheral department visual analyzer. The human eye consists of an inner shell (retina), vascular and outer protein coat.

The outer shell consists of two parts - the sclera and the cornea.

The opaque sclera occupies 5/6 of the surface of the outer shell, the transparent cornea - 1/6. The choroid consists of three parts: the iris, the ciliary body, and the choroid proper. In the center of the iris is a hole - the pupil, through which rays of light penetrate into the eye. It contains pigments that determine the color of the eyes. The iris passes into the body, and then, in turn, into the choroid proper. The retina is the inner lining of the eye. It has a complex layered structure nerve cells and their fibers.

There are ten layers of the retina. Rods and cones, which are modified processes of light-sensitive visual cells, approach the outer pigment layer of the retina. From the nerve cells of the retina comes the optic nerve - the beginning of the leading part of the visual analyzer.

Scheme of the anatomical structure of the eye: 1 - retina, 2 ~ lens, 3 iris, 4 cornea, 5 - tank shell (sclera), 6 - choroid, 7 - optic nerve.

The sclerous body is a completely transparent substance that is contained in a very delicate capsule and fills most eyeball. It acts as a cluttering medium and is part of optical system eyes. Its anterior, slightly concave surface is adjacent to the posterior surface of the lens. His loss is not replenished.

The upper lateral corner of the orbit contains lacrimal gland, which secretes tear fluid (tear), moisturizing the surface of the eyeball, prevents it from drying out and hypothermia. The tear, moistening the surface of the eye, flows down the exit channel in the nasal cavity. The eyelids and eyelashes protect the eyeball from foreign particles getting inside the eye, the eyebrows divert away the sweat flowing from the forehead, and this also has a protective value.

Eye adaptation

The development of the ability of the eye to see in different light conditions is called adaptation. If in the evening the light in the room is turned off, then at first the person does not distinguish the surrounding objects at all. However
already after 1-2 minutes she begins to grasp the contours of objects, and after a few minutes she sees objects quite clearly. This is due to a change in the sensitivity of the retina in the dark. Staying in the dark for one hour increases the sensitivity of the eye by about 200 times. And the sensitivity increases especially quickly in the first minutes.

This phenomenon is explained by the fact that in bright light the visual purple of the rod-shaped visual cells is completely destroyed. In the dark, it quickly recovers, and rod-shaped cells, which are very sensitive to light, begin to perform their functions, while cone-like cells, which are insensitive to light, are not able to perceive visual stimuli. That is why a person in the dark does not distinguish colors.
However, when the light is turned on in a dark room, it seems to blind a person. She almost does not distinguish surrounding objects, and after 1-2 minutes her eyes begin to see well. This is explained by the fact that the visual purple in the rod-shaped cells has collapsed, the sensitivity to light has sharply decreased, and visual stimuli are now perceived only by cone-shaped visual cells.

Eye accommodation

The ability of the eye to see objects at different distances is called accommodation. An object is clearly visible when the rays reflected from it are collected on the retina. This is achieved by changing the convexity of the lens. The change occurs reflexively - when considering objects located at different distances from the eye. When we look at nearby objects, the bulge of the lens increases. The refraction of the rays in the eye becomes greater, as a result of which an image appears on the retina. When we look into the distance, the lens is flattened.

In the state of accommodation rest (gaze into the distance), the radius of curvature of the anterior surface of the lens is 10 mm, and at maximum accommodation, when the object is closest to the eye, the radius of curvature of the anterior surface of the lens is 5.3 mm.

The loss of elasticity of the lens bag with age leads to a decrease in its cluttering ability with the greatest accommodation. This increases the ability of older people to view objects at a distance. The nearest point of clear vision is removed with age. So, at the age of 10, it is located at a distance of less than 7 cm from the eye, at 20 years old - 8.3 cm, at 30 - 11 cm, at 35 - 17 cm, and at 60-70 years old it approaches 80-100 cm .

As we age, the lens becomes less elastic. The ability to accommodate begins to decline from the age of ten, but this affects vision only in old age (senile farsightedness).

Visual acuity - this is the ability of the eye to separately perceive two points located at a certain distance from each other. The vision of two points depends on the size of the image on the retina. If they are small, then both images merge and it is impossible to distinguish between them. The size of the image on the retina depends on the angle of view: the smaller it is when perceiving two images, the greater the visual acuity.

To determine visual acuity great importance has lighting, coloration, pupil size, angle of view, distance between objects, retinal locations on which the image falls, and adaptation state. Visual acuity is a simple indicator characterizing the state of the visual analyzer in children and adolescents. Knowing the visual acuity in children, it is possible to carry out an individual approach to students, place them in the classroom, recommend the appropriate mode academic work, corresponds to an adequate load on the visual analyzer.

Pathways of the visual analyzer(Fig. 146). The light that enters the retina first passes through the transparent refractive apparatus of the eye: the cornea, aqueous humor of the anterior and rear cameras, lens and vitreous body. The beam of light on its way is regulated by the pupil. The refractive apparatus directs a beam of light to a more sensitive part of the retina - the place of the best vision - a spot with its central fovea. Passing through all the layers of the retina, light causes complex photochemical transformations of visual pigments there. As a result, in light-sensitive cells (rods and cones) nerve impulse, which is then transmitted to the next neurons of the retina - bipolar cells (neurocytes), and after them - neurocytes of the ganglionic layer, ganglionic neurocytes. The processes of the latter go towards the disc and form the optic nerve. Entering the skull through the optic nerve canal bottom surface brain, the optic nerve forms an incomplete optic chiasm. From the optic chiasm begins the optic tract, which consists of nerve fibers ganglion cells of the retina of the eyeball. Then the fibers along the optic tract go to the subcortical visual centers: lateral geniculate body and superior hillocks of the roof of the midbrain. In the lateral geniculate body, the fibers of the third neuron (ganglionic neurocytes) visual pathway end and come into contact with the cells of the next neuron. The axons of these neurocytes pass through the internal capsule and reach the cells of the occipital lobe near the spur groove, where they end (the cortical end of the visual analyzer). Some axons of ganglion cells pass through geniculate body and as part of the handle enters the upper mound. Further, from the gray layer of the superior colliculus, impulses go to the nucleus oculomotor nerve and into the accessory nucleus, from where the innervation of the oculomotor muscles, the muscles that constrict the pupils, and the ciliary muscle occurs. These fibers carry an impulse in response to light stimulation and the pupils constrict (pupillary reflex), and a turn in the necessary direction of the eyeballs also occurs.

The adaptation of the eye to see clearly at a distance is called accommodation. The accommodation mechanism of the eye is associated with contraction ciliary muscles which change the curvature of the lens.

When considering objects at close range, simultaneously with accommodation, there is also convergence, i.e., the axes of both eyes converge. The lines of sight converge the more, the closer the object under consideration is.

The refractive power of the optical system of the eye is expressed in diopters ("D" - diopters). For 1 D, the power of a lens is taken, the focal length of which is 1 m. The refractive power of the human eye is 59 diopters when considering distant objects and 70.5 diopters when considering close ones.

There are three main anomalies in the refraction of rays in the eye (refraction): myopia, or myopia; farsightedness, or hypermetropia; senile farsightedness, or presbyopia (Fig. 147). The main cause of all eye defects is that the refractive power and the length of the eyeball do not agree with each other, as in a normal eye. With myopia (myopia), the rays converge in front of the retina in the vitreous body, and instead of a point, a circle of light scattering appears on the retina, while the eyeball has great length than normal. Concave lenses with negative diopters are used to correct vision.

With farsightedness (hypermetropia), the eyeball is short, and therefore parallel rays coming from distant objects are collected behind the retina, and an obscure, blurry image of the object is obtained on it. This disadvantage can be compensated by using the refractive power of convex lenses with positive diopters.

Senile farsightedness (presbyopia) is associated with a weak elasticity of the lens and a weakening of the tension of the zinn ligaments with normal length eyeball.

This refractive error can be corrected with biconvex lenses. Vision with one eye gives us an idea of ​​the object in only one plane. Only when seeing simultaneously with two eyes is it possible to perceive depth and a correct idea of ​​the relative position of objects. The ability to merge individual images received by each eye into a single whole provides binocular vision.

Visual acuity characterizes the spatial resolution of the eye and is determined by the smallest angle at which a person is able to distinguish two points separately. The smaller the angle, the better eyesight. Normally, this angle is 1 min, or 1 unit.

To determine visual acuity, special tables are used, which show letters or figures of various sizes.

32. The structure of the organ of hearing and balance.

The organ of hearing and balance, the vestibulocochlear organ (organum vestibulocochleare) in humans has complex structure, perceives vibrations of sound waves and determines the orientation of the position of the body in space.

The vestibulocochlear organ (Fig. 148) is divided into three parts: the outer, middle and inner ear. These parts are closely related anatomically and functionally. The outer and middle ear conducts sound vibrations to the inner ear, and thus is a sound-conducting apparatus. inner ear, in which the bone and membranous labyrinths are distinguished, forms the organ of hearing and balance.

Rice. 148. Vestibulocochlear organ (organ of hearing and balance):

1- superior semicircular canal; 2 - vestibule; 3 - snail; 4- auditory nerve; 5 - carotid artery; 6 - auditory tube; 7- tympanic cavity; 8- eardrum; 9- external auditory canal; 10- external auditory opening; 11 - Auricle; 12- hammer

There are two types of transmission of sound vibrations - air and bone conduction of sound. With air conduction of sound sound waves caught auricle and are transmitted through the external auditory canal to the eardrum, and then through the system auditory ossicles perilymph and endolymph. A person with air conduction is able to perceive sounds from 16 to 20,000 Hz. Bone conduction sound is carried through the bones of the skull, which also have sound conductivity. Air conduction of sound is better than bone conduction.

Receptors of the vestibular apparatus are irritated by the tilt or movement of the head. In this case, reflex muscle contractions occur, which contribute to straightening the body and maintaining an appropriate posture. With the help of receptors of the vestibular apparatus, the position of the head is perceived in the space of movement of the body. known; that sensory cells are immersed in a jelly-like mass that contains otoliths, consisting of small crystals of calcium carbonate. In the normal position of the body, gravity causes the otoliths to exert pressure on certain hair cells. If the head is tilted with the crown down, the otolith sags on the hairs; with a lateral tilt of the head, one otolith presses on the hairs, and the other sags. A change in otolith pressure causes excitation of hair sensory cells, which signal the position of the head in space. sensitive cells scallops in the ampullae of the semicircular canals are excited during movement and acceleration. Since the three semicircular canals are located in three planes, the movement of the head in any direction causes the movement of the endolymph. Irritations of hair sensory cells are transmitted to the sensitive endings of the vestibular part of the vestibulocochlear nerve. The bodies of the neurons of this nerve are located in the vestibular node, which lies at the bottom of the internal auditory canal, and the central processes as part of the vestibulocochlear nerve go into the cranial cavity, and then into the brain to the vestibular nuclei. The processes of the cells of the vestibular nuclei (another neuron) are sent to the nuclei of the cerebellum and to spinal cord, further form the pre-door-spinal path. They also enter the posterior longitudinal bundle of the brainstem. Part of the fibers of the vestibular part of the vestibulocochlear nerve, bypassing the vestibular nuclei, go directly to the cerebellum.

With the excitability of the vestibular apparatus, numerous reflex reactions of a motor nature occur, which change the activity internal organs and various sensory responses. An example of such reactions may be the appearance of rapidly repetitive movements of the eyeballs (nystagmus) after a rotational test: a person makes rhythmic eye movements in the direction opposite to the rotation, and then very quickly in the direction that coincides with the direction of rotation. There may also be changes in the activity of the heart, in the narrowing or expansion of blood vessels, a decrease blood pressure, increased peristalsis of the intestines and stomach, etc. With the excitability of the vestibular apparatus, a feeling of dizziness appears, orientation in environment, there is a feeling of nausea. vestibular apparatus participates in the regulation and redistribution of muscle tone

Factors that reduce the degree of visibility (fog, snow, rain, haze, etc.) make observation extremely difficult. sea, At night, the observation conditions also worsen, and they have their own characteristics.

The duties of an officer in charge of the watch on the move of the vessel consist of two main equally important functions. Firstly, it performs various computational operations, solves navigational and other tasks, monitors the position of the vessel and keeps a dead reckoning of its path on the navigation chart. Secondly, along with the sailor on duty, he provides visual and auditory observation of the environment using appropriate technical means. In other words, the navigator has to alternate these two types of activity: either work in the wheelhouse on manuals and a map, or go out and stay on the open part of the bridge. This mode of action of the navigator is associated with dark time days with a known phenomenon of eye adaptation. Vision adaptation is called a change in the sensitivity of the eye, depending on its stay in the light or in the dark. A decrease in the sensitivity of vision during light stimulation is called adaptation, or adaptation of the eye to light, and an increase in sensitivity as you stay in the dark is called adaptation of the eye to darkness, or dark adaptation of the eye.

Light adaptation occurs much faster than dark adaptation and it takes 1-3 min(dark adaptation not less than 5-7 min).

It can be seen from what has been said that the phenomenon of adaptation of vision is of the greatest importance for nighttime observations. In order for the sensitivity of the eye in the dark to be at the same high level during the watch, the observer's vision should not be exposed to light. However, according to the conditions of activity, the watch navigator cannot avoid periodic, albeit short-lived, flashes of the eye while working in the wheelhouse on the map or with instruments. task in this case, obviously, will consist in eliminating or at least weakening the influence of light as much as possible.

It is known that the increase in the sensitivity of vision in the dark occurs much faster after it has been in low light conditions. According to scientific research, red light stimulus has little effect on the retina of the eye - several tens of times weaker than white.

From the foregoing, it can be seen that the nature of the illumination of the chart house, where the watch officer has to work periodically, as well as all the wheelhouse instruments, is exclusively importance. We must strive to ensure that this illumination lies within the optimum from all points of view.

As you know, lighting is divided into two types: general

local. General is designed to simultaneously illuminate both the work surface and the rest of the room, " "stnoe-only for a relatively small space

my workplace, as, for example, for part of the navigation

table occupied by the card.

It is not recommended to use the general lighting of the chart house at night while the vessel is moving. Local lighting above the chart table is arranged in the form of a special sconce, | reflecting a beam of light down onto a table. The lamp receives power through a rheostat, which allows you to reduce or increase the light intensity. A folding red or orange light filter is mounted on the reflector.

Watch officer for short visits:

chart house for calculations and drawing a point on the map, it is recommended to constantly keep the sconce under the filter. In extreme cases, in the absence of a filter, the luminous intensity of the sconce must be reduced by a rheostat so that, on the one hand, it is possible to work freely on the map, and on the other hand, so that the reduction in vision sensitivity is minimized. This is necessary so that the eye is always adapted to the dark.

The illumination of compass cards, engine telegraphs, dials and displays of various instruments and installations, both in the wheelhouse and in the chart house, should be reduced to the minimum limit, allowing only to distinguish readings or indications, in order to exclude negative impact of this illumination on the dark adaptation of the navigator's eye. During direction finding of any objects, the light on compasses or repeaters also needs to be weakened. The radar screen during surveys at night should not have strong illumination. When setting up the device, you need to skillfully use the “Brightness” knob, setting it each time to the optimal position. The illumination of the scales is turned on only for a short time when it is necessary to read the reading of the bearing or heading angle, and usually only for one step.

Dark adaptation of vision plays important role in ensuring safe navigation, and this issue should be given the most serious attention. Adaptation of the eye to darkness is a slow process, lasting tens of minutes, hence it is clear what danger bright light poses during night observations on a ship. It is worth staying in a lit room for a short time or looking at a bright light source, such as a searchlight beam, as dark adaptation will be immediately lost, and it will take a long time to restore the sensitivity of the eye.

In the charter of service on courts navy it is said that "but when the watch officer is called, the captain is obliged to immediately go to the bridge and in case adverse conditions sailing stay there as long as it is necessary, regardless of the time of day. Typically, such calls come in difficult situations, at a divergence from oncoming or overtaken vessels. If in daytime the captain, having climbed onto the bridge, is able to immediately assess the situation, take appropriate

decisions and issue commands, then at night he finds himself in a difficult position, since the first 5-7 min his vision is almost completely devoid of light sensitivity. The watch navigator must take this important circumstance into account. During the dark period of the day, when ships or other dangers are detected, he is obliged to immediately report this to the captain, so that the latter can go to the bridge in advance and allow the eye to adapt to the darkness to some extent.

Captain while in indoor areas it is recommended to avoid bright light of your vision in every possible way. At night, he should not turn on the lighting in the cabin, all the more bright; the corridors along which the captain passes to the bridge should be darkened or equipped with lamps with red shades.

Visual acuity, i.e., the ability to see distant objects and distinguish between their thin and small details, but in angular dimensions, different people different Their ability to adapt their vision is not the same. It is known, for example, that dark adaptation changes significantly with hypertension. This change manifests itself in the form of a slowdown in the process of increasing light sensitivity and a decrease in its final values. Speed ​​and degree dark adaptation also decreases with age.

Taking into account all these factors, it should be recommended that the captain has his own separate multiple-use binoculars, pre-set to his eyes. Such binoculars should be stored in a special and convenient place on the bridge so that the captain, upon arrival on a call, can immediately, without prior adjustment, use it for observation.

The darkening of the vessel is of no small importance for night vision. No light should be allowed to penetrate the deck, even from weak sources or reflected. The duties of the watch service include ensuring complete darkness both on the navigation bridge itself and ahead of it. Foredeck lookouts and other observers, wherever stationed, must refrain from smoking and lighting matches. The use of hand torches for any purpose is permitted only in extreme cases with the permission of the watch officer.

The most sensitive areas of the retina do not lie in the center of the visual field, but somewhat to the side, on the periphery of the eye. This circumstance ^ determines the so-called " peripheral vision". Its essence lies in the fact that at night a weak fire is not detected by a direct look at the point of its source, but as soon as the observer looks away a little to the side, this light will be clearly perceived by the lateral part of the retina. Well-trained observers successfully use this property of vision, detecting danger in time. They are in ta-

In some cases, they direct their gaze not to the point on the horizon where fire is expected, but somewhat to the side of it.

A night observer has to look first at a bright light, then into the darkness, as, for example, a navigator when working with a locator, so one should alternately use one eye, then the other. So, you can look at the screen only with the left eye, closing the right one, which will retain dark adaptation and allow you to see well in the dark, although the left eye will be blinded to some extent by the light. This method gives good results, but without prior training, it quickly tires the observer's eyesight.

Light perception- this is the ability of the visual analyzer to perceive light and distinguish between the degrees of its brightness. In the study of light perception, the ability to distinguish between minimal light irritation - the threshold of irritation - and to capture the smallest difference in the intensity of illumination - the threshold of discrimination.

The process of adapting the eye to different conditions lighting is called adaptation. There are two types of adaptation: adaptation to darkness when the light level decreases and adaptation to light when the light level increases.

Everyone knows how helpless you feel when you get from a brightly lit room into a dark one. Distinguishing poorly lit objects begins only after 8-10 minutes, and in order to orientate freely enough, it takes at least another 20 minutes until visual sensitivity in the dark reaches the degree necessary for this. With dark adaptation, sensitivity to light increases, the maximum adaptation is observed after an hour.

The reverse process of adaptation to high light levels is much faster than adaptation to darkness. When adapting to light, the sensitivity of the eye to a light stimulus decreases, it lasts about 1 minute. Upon leaving a dark room, visual discomfort disappears after 3-5 minutes. In the first case, scotopic vision is manifested in the process of dark adaptation, in the second case, photopic vision is manifested during light adaptation.

The visual system responds adequately to both fast and slow changes in radiant energy. Moreover, it is characterized by an almost instantaneous reaction to a rapidly changing environment. The light sensitivity of the visual analyzer is as variable as the characteristics of the light stimuli of the world around us. The need to adequately perceive the energy of both very weak and very strong light sources, without being subjected to structural damage, is ensured by the ability to rearrange the mode of operation of the receptors. In bright light, the light sensitivity of the eye decreases, but at the same time, the reaction to the spatial and temporal differentiation of objects becomes more acute. In the dark, the whole process is reversed. This complex of changes in both light sensitivity and resolving power of the eye depending on the external (background) illumination is called visual adaptation.

The scotopically adapted retina is maximally sensitive to the light energy of the low level, but at the same time its spatial resolution sharply decreases and color perception disappears. The photopic-adapted retina, being low-sensitive to distinguish between weak light sources, at the same time has a high spatial and temporal resolution, as well as color perception. For these reasons, even on a cloudless day, the moon fades and the stars go out, and at night, without highlighting, we lose the ability to read text even in large print.

The range of illumination within which visual adaptation is carried out is enormous; in quantitative terms, it is measured from a billion to several units.

Retinal receptors are very high sensitivity- they can be annoyed by one quantum visible light. This is due to the action of the biological law of amplification, when, after the activation of one molecule of rhodopsin, hundreds of its molecules are activated. In addition, retinal rods are organized into large functional units in low light. Impulse from a large number rods converges into bipolar and then into ganglion cells, causing an amplifying effect.

As the illumination of the retina increases, vision, determined mainly by the rod apparatus, is replaced by cone vision, and the maximum sensitivity shifts in the direction from the short-wavelength to the long-wavelength part of the spectrum. This phenomenon, described by Purkinje as early as the 19th century, is well illustrated by everyday observations. In a bouquet of wild flowers on a sunny day, yellow and red poppies stand out, at dusk - blue cornflowers (shift of the maximum sensitivity from 555 to 519 nm).

Visual acuity

The ability of different people to see larger or smaller details of an object from the same distance with the same shape of the eyeball and the same refractive power of the diopter of the eye system is due to the difference in the distance between the sensitive elements of the retina and is called visual acuity.

Visual acuity is the ability of the eye to perceive separately two points located at some distance from each other. The measure of visual acuity is the angle of view, that is, the angle formed by the rays emanating from the edges of the object in question (or from two points A and B) to the nodal point (K) of the eye.

Visual acuity is inversely proportional to the visual angle, that is, the smaller it is, the higher the visual acuity. Normally, the human eye is able to separately perceive objects, the angular distance between which is not less than 1 ′ (1 minute).

Visual acuity is one of essential functions vision. It depends on the size of the cones located in the area yellow spot, retina, as well as from a number of factors: refraction of the eye, pupil width, transparency of the cornea, lens (and its elasticity), vitreous body(which make up the refractive apparatus), the state of the retina and optic nerve, age.

Vision adaptation

The above properties of vision are closely related to the ability of the eye to adapt. Adaptation of the eye - the adaptation of vision to different lighting conditions. Adaptation occurs to changes in illumination (distinguish between adaptation to light and darkness), the color characteristics of lighting (the ability to

perceive white objects as white even with a significant change in the spectrum of the incident light).

Adaptation to light occurs quickly and ends within 5 minutes, adaptation of the eye to darkness is a slower process. The minimum brightness that causes the sensation of light determines the light sensitivity of the eye. The latter increases rapidly in the first 30 minutes. stay in the dark, its increase practically ends in 50-60 minutes. Adaptation of the eye to darkness is studied using special devices - adaptometers.

A decrease in the adaptation of the eye to darkness is observed in some eye (retinitis pigmentosa, glaucoma) and general (A-avitaminosis) diseases.

Adaptation is also manifested in the ability of vision to partially compensate for defects in the visual apparatus itself (optical defects of the lens, retinal defects, scotomas, etc.)

Perception, its types and properties

External phenomena, acting on our senses, cause a subjective effect in the form of sensations without any counter activity of the subject in relation to the perceived impact. The ability to feel is given to us and to all living beings with nervous system, since birth. Only man and higher animals are endowed with the ability to perceive the world in the form of images; it develops and improves in their life experience.

Unlike sensations, which are not perceived as properties of objects, specific phenomena or processes occurring outside and independently of us, perception always acts as subjectively correlated with the reality existing outside of us, designed in the form of objects, and even in the case when we have dealing with illusions or when the perceived property is relatively elementary, causes a simple sensation (in this case, this sensation necessarily refers to some phenomenon or object, is associated with it).

Sensations are in ourselves, while the perceived properties of objects, their images are localized in space. This process, characteristic of perception as opposed to sensation, is called objectification.

Another difference between perception in its developed forms and sensations is that the result of the occurrence of a sensation is a certain feeling (for example, sensations of brightness, loudness, salty, pitch, balance, etc.), while as a result of perception, an image that includes a complex of various interrelated sensations attributed by human consciousness to an object, phenomenon, process. In order for a certain object to be perceived, it is necessary to perform some kind of counter activity in relation to it, aimed at its research, construction and clarification of the image. For the appearance of sensation, this, as a rule, is not required.

Separate sensations are, as it were, “tied” to specific analyzers, and it is enough for the stimulus to act on their peripheral organs - receptors, for the sensation to arise. The image formed as a result of the process of perception implies interaction, coordinated work of several analyzers at once. Depending on which of them works more actively, processes more information, receives the most significant features, testifying to the properties of the perceived object, distinguish types of perception. Accordingly, visual, auditory, tactile perception is distinguished. Four analyzers - visual, auditory, skin and muscle - most often act as leaders in the process of perception.

Perception, thus, acts as a meaningful (including decision-making) and signified (associated with speech) synthesis of various sensations received from integral objects or complex phenomena perceived as a whole. This synthesis appears in the form of an image of a given object or phenomenon, which is formed in the course of their active reflection.

Objectivity, integrity, constancy and categoriality (meaningfulness and significance) are the main properties of the image that develop in the process and result of perception. Objectivity is the ability of a person to perceive the world not in the form of a set of sensations that are not connected with each other, but in the form of objects separated from each other that have properties that cause these sensations. The integrity of perception is expressed in the fact that the image of perceived objects is not given in a fully finished form with all necessary elements, but, as it were, is mentally completed to some integral form based on a small set of elements. This also happens if some details of an object are directly in the this moment time is not accepted. Constancy is defined as the ability to perceive objects relatively constant in shape, color and size, a number of other parameters, regardless of changing physical conditions perception. The categorical nature of human perception is manifested in the fact that it is of a generalized nature, and we designate each perceived object with a word-concept, refer to a certain class. In accordance with this class, we look for and see signs in the perceived object that are characteristic of all objects of this class and expressed in the volume and content of this concept.

The described properties of objectivity, integrity, constancy and categorization of perception from birth are not inherent in a person; they gradually take shape in life experience, partly being a natural consequence of the work of analyzers, the synthetic activity of the brain.

Most often and most of all, the properties of perception were studied using the example of vision, the leading sense organ in humans. A significant contribution to understanding how the individual visually perceived details of objects form their complete picture - the image, was made by representatives of Gestalpsypsychology - the direction of scientific research that developed at the beginning of the 20th century. in Germany. One of the first classification of factors influencing the organization of visual sensations into images in line with Gestalt psychology was proposed by M. Wertheimer. The factors he identified are:

Proximity of elements to each other visual field that evoked the corresponding sensations. The closer to each other spatially in the visual field are the corresponding elements, the more likely they combine with each other and create a single image.

Similarity of elements to each other. This property is manifested in the fact that similar elements tend to combine.

The "natural continuation" factor. It manifests itself in the fact that elements that act as parts of figures, contours and forms familiar to us are more likely to be combined in our minds precisely in these figures, shapes and contours than in others.

Closure. This property visual perception acts as the desire of the elements of the visual field to create complete, closed images.

The principles of the perceptual organization of visual perception are illustrated in fig. 36. Closer to each other lines in row A are more likely to unite with each other in our perception than far apart. The addition of horizontal, multidirectional line segments to separate, far apart vertical lines in row B encourages us, on the contrary, to see whole figures in them, and not in closely spaced lines. In this case, they are squares. The corresponding impression is intensified even more (row B), it becomes irreversible if the contours are closed.

It turned out that the perception of more complex, meaningful images by a person occurs differently. Here, first of all, the mechanism of the influence of past experience and thinking is triggered, highlighting the most informative places in the perceived image, on the basis of which, by correlating the information received with memory, one can form a holistic view of it. Analysis of eye movement recordings by AL. Yarbus 1, showed that the elements of planar images that attract the attention of a person contain areas that carry the most interesting and useful information for the perceiver. A close examination of such elements, on which the eye stops most of all in the process of viewing pictures, reveals that the movements of the eyes actually reflect the process of human thinking. It has been established that when looking at a human face, the observer pays the most attention to the eyes, lips and nose. The eyes and lips of a person are indeed the most expressive and mobile elements of the face, by the nature and movements of which we judge the psychology of a person and his condition. They can tell the observer a lot about the mood of a person, about his character, attitude towards people around him, and much more.

When moving from bright light to complete darkness (so-called dark adaptation) and when moving from darkness to light (light adaptation). If the eye, which was previously in bright light, is placed in darkness, then its sensitivity increases rapidly at first, and then more slowly.

The process of dark adaptation takes several hours, and by the end of the first hour the sensitivity of the eye increases several times, so that the visual analyzer is able to distinguish changes in the brightness of a very weak light source caused by statistical fluctuations in the number of emitted photons.

Light adaptation is much faster and takes 1-3 minutes at medium brightness. Such large changes in sensitivity are observed only in the eyes of humans and those animals whose retina, like that of humans, contains rods. Dark adaptation is also characteristic of cones: it ends faster and the sensitivity of cones increases only 10-100 times.

Dark and light adaptation of the eyes of animals have been studied by studying the electrical potentials that arise in the retina (electroretinogram) and in the optic nerve under the action of light. The results obtained are generally consistent with the data obtained for humans by the adaptometry method, based on the study of the appearance of a subjective sensation of light in time after a sharp transition from bright light to complete darkness.

see also

Links

• Lavrus V. S. Chapter 1. Light. Light, vision and color // Light and heat. - International social organization"Science and Technology", October 1997. - S. 8.

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See what "Eye adaptation" is in other dictionaries:

- (from late Latin adaptatio adjustment, adaptation), adaptation of the sensitivity of the eye to changing lighting conditions. When moving from bright light to darkness, the sensitivity of the eye increases, the so-called. dark A., in the transition from darkness ... ... Physical Encyclopedia

Adaptation of the eye to changing light conditions. When moving from bright light to dark, the sensitivity of the eye increases, when moving from darkness to light, it decreases. The spectrum also changes. sensitivity of the eye: the perception of the observed ... ... Natural science. encyclopedic Dictionary

- [lat. adaptatio adjustment, adaptation] 1) adaptation of the organism to environmental conditions; 2) processing of the text in order to simplify it (for example, an artistic prose work in foreign language for those who are not good enough… … Dictionary of foreign words of the Russian language

Not to be confused with Adoption. Adaptation (Latin adapto I adapt) is the process of adaptation to changing environmental conditions. Adaptive system Adaptation (biology) Adaptation (control theory) Adaptation in processing ... ... Wikipedia

Adaptation- making changes to the IR YEGKO in Moscow, carried out solely for the purpose of their functioning on specific technical means user or under the control of specific user programs, without coordinating these changes with ... ... Dictionary-reference book of terms of normative and technical documentation

sensory adaptation- (from Latin sensus feeling, sensation) an adaptive change in sensitivity to the intensity of the stimulus acting on the sense organ; can also manifest itself in a variety of subjective effects (see sequential about ... Great Psychological Encyclopedia

DARK ADAPT, slow sensitivity change human eye at the moment when a person from a brightly lit space enters an unlit one. The change occurs due to the fact that in the RETINA of the eye, with a decrease in the total ... ...

ADAPTATION- (from lat. adaptare to adapt), the adaptation of living beings to environmental conditions. A. the process is passive and comes down to the body's reaction to changes in physical. or physical. chem. environmental conditions. Examples A. In freshwater protozoans, osmotic concentration... ... Big medical encyclopedia

- (Adaptation) the ability of the retina of the eye to adapt to a given strength of illumination (brightness). Samoilov K.I. Marine Dictionary. M. L .: State Naval Publishing House of the NKVMF of the USSR, 1941 Adaptation adaptability of the body ... Marine Dictionary

ADAPTATION TO LIGHT, a shift in functional dominance from rods to cones (visual cells of different types) in the RETINA of the EYE with increasing illumination brightness. Unlike DARK ADAPTATION, light adaptation is fast but creates… … Scientific and technical encyclopedic dictionary

Books

• The Painted Veil: Intermediate A Book to Read, Maugham William Somerset. Written in 1925 by British classicist William Somerset Maugham, the title of the novel The Patterned Veil reflects the lines of Percy Bysshe Shelley's sonnet Lift not thepainted veil which...