5.2. The development of the psyche of animals in the early postnatal period

The postnatal period of development of an organism begins after its birth (hatching from an egg). Birth is a turning point in the development of the animal. However, there is continuity between the prenatal and postnatal periods, although after birth new factors and patterns appear in the development of the organism. The body faces a completely new environment for it. In such acute conditions, the acquisition of individual experience takes place, and the development of congenital forms of behavior continues.

In the early postnatal period , the foundations of the behavior of an adult animal are laid, the body acquires the skills of communication with other individuals, as well as with a changing environment. According to L.A. Orbeli, the early postnatal period is the most sensitive phase of the individual's ontogenesis, when the body actively responds to all environmental influences.

The postnatal period is very specific. This is especially true for those animal species in which newborn individuals differ in structure and lifestyle from adult animals. Such differences are observed in most invertebrates, as well as in a number of lower vertebrates, which possess larval forms (for example, cyclostomes - lamprey, myxines). In this case, the postnatal development of behavior is especially difficult: on the basis of larval behavior, maturation of the qualitatively different behavior of an adult individual takes place. For example, in marine gastropod mollusks, young individuals lead a plankton life, but after metamorphosis in adult animals, forms of bottom movement and feeding appear. Somewhat later, these animals in a fully formed form also manifest a defensive reaction in the form of avoiding enemies. Experiments were conducted in which the mollusks were given the opportunity to gain preliminary experience. To do this, they were kept in the water in which the predator used to swim. The results of the experiments showed that in this case there is no accelerated maturation of the protective reaction. Thus, all the reactions of the mollusk ripen and manifest themselves depending on the development of the corresponding nervous structures.

Of great importance for the postnatal period is the degree of animal maturity. A.N. Promptov in connection with this introduced the concept of "early biostart". By biostart, he understood the moment when biological factors began to influence the animal. The biostart will be early in an immature calf, which cannot independently provide for its livelihoods and depends in this on the parent individuals. On the contrary, the mature breed has the ability to independently perform all functions immediately after birth. However, such a “complete” full-term birth is rare, it is more often expressed to one degree or another. For example, turukhtan chicks need to be heated by their parents within ten days after hatching, and their movements become coordinated only on the fourth day. But at the same time, from the very first moments, they can feed on their own and show a reaction of concealment.

L.A. In his studies, Orbeli drew attention to differences in the development of behavior in mature and non-breeding animals. Older calves are little affected by the environment, because they are born in an already formed state. Conditioned-reflex activity in them is already developed and subject to only separate additional superstructures and complications. In immaturely born animals, by the time of birth, not only conditioned-reflex forms of behavior are not formed, but even some inborn forms are not developed. Such cubs are more vulnerable to the action of the environment, however, according to Orbeli, the development of their behavior is more beneficial. They can adapt the development of behavior to changing environmental factors, so the formation of their behavior is often more adequate to the environment. Orbeli wrote: "These animals will be born with a still poorly formed nervous system, that all further postnatal development is a complete processing of hereditary forms and newly emerging conditional forms of behavior." ^[nineteen]

It is noticed that animals with the most highly developed psyche are, as a rule, immature. They face the external environment in a state where their behavior is not yet formed. Inborn bases of behavioral reactions in such animals may undergo changes, therefore their behavior is more labile. However, the ability of animals of a given species to accumulate individual experience is still decisive in this matter. According to these indicators, mature and immature animals differ only in terms of the acquisition of this experience.

Instinctive behavior. In ontogenesis, instinctive movements go through stages of formation and improvement. Experimentally, this fact can be demonstrated with isolated breeding of babies from the moment of birth. Experiments on birds and rodents have shown that separate motor elements are developed in such animals, however the behavioral acts themselves deviate from the norm: the duration, frequency of execution and coordination of behavioral reactions are violated. Vital movements are performed, but their consistency with each other is disturbed. Thus, instinctive movements in the behavior of animals in the early postnatal period are certainly present, but they require further development. For example, an American scientist E. Hess conducted experiments with chickens, who immediately after hatching wore glasses, which shifted the field of view by 7 degrees. After a short period of time, these chicks, like the chicks in glasses with ordinary glasses, pecked at the target more accurately than when they were first presented, but the chicks in the distorting glasses continued to peck 7 degrees away from the target. It follows that the motor reaction associated with attractive movements is inborn in birds, but the accuracy of the specks is increased by acquiring individual experience. Similar data were obtained for mammals, such as monkeys and guinea pigs.

So, the idea that in the early postnatal period the innate behavior plays the most important role is true only for elementary motor responses. Instinctive acts in general require the acquisition of individual experience for their normal formation.

Congenital recognition. The importance of congenital forms of behavior in the early postnatal period of animal development is primarily manifested in the phenomenon of congenital recognition. An example is the nipple retrieval reaction in newborn baby mammals. They are able to orient their movements along tactile stimuli, moving towards the touch. For example, newborn puppies, when touched to their head, begin to creep forward, and when touched to the side, turn towards the stimulus.

The significance of this phenomenon for the life of the animal is very large. For the success of its vital activity, an animal must be able to orient its behavior towards environmental factors immediately after birth. This is especially true of such environmental factors as food, maternal or other parental individuals, other individuals of their own species, enemies, etc. K. Fabri wrote: “Congenital recognition is manifested in the inborn species-specific selective attitude of animals to certain components of the environment, featured objects, situations, the ability of animals to biologically respond adequately to certain signs of objects or situations that are still unfamiliar to them ... we are dealing here with a congenital form of orientation, appearing to be useful for an individual (and species) reactions to signs of essential components of the environment without prior learning, with “species memory” manifestations. ” ^[20]

The animal should recognize the biologically significant element of the environment when it first encounters it and adequately respond to it. The basis of congenital recognition is taxis (see 2.3). The orientation of behavior is carried out according to key stimuli (individual signs of biologically significant objects), and the direction of behavior is based on innate trigger mechanisms. All this together provides a high selectivity of innate recognition.

Along with processes that have an innate basis, early individual experience is of great importance for the behavior of the animal. The acquisition of experience during this period is closely related to the processes of postnatal learning. For example, if the stimulus, to which innate recognition exists, often repeats, but does not have biological significance for an animal, it gradually “gets used” to this stimulus and stops responding to it. Thus, brood birds nestlings have an innate hiding response to the approach of a predator. Initially, such a reaction should occur when any moving object appears in the sky, but gradually the chicks begin to respond to objects selectively and when they see a safe stimulus, for example a leaf, a falling tree, they are not hidden. In other words, innate recognition is refined by acquiring early individual experience.

In the course of early postnatal learning, the signal value of key stimuli may also change. Thus, in the first days of life, the young of sturgeon show a negative phototaxis, i.e., it swims away from the lighted areas of the reservoir, trying to stay in the shade. However, during the transition to active feeding in fish, conditioned reflexes to light are formed. As a result, the fry show positive phototaxis.

Obligatory learning. Sometimes innate recognition can change under the influence of the inclusion of new senses in the work. For example, thrush chicks after hatching react to shaking the nest by pulling the neck up and opening the beak. It does not matter what the source of irritation. After the organs of vision begin to function in the chicks, the same reaction begins to manifest itself in the appearance of the parent individual in sight. And only a few days after that, the chicks learn to determine the exact location of the approaching bird and stretch their necks in this direction.

Thus, in addition to congenital recognition, obligatory learning is of great importance for the behavior of animals in the early postnatal period , that is, all forms of learning that are vital for an animal in natural conditions. Obligatory learning is close to innate recognition, since it is also specific to a particular species, it forms an integral complex with innate recognition. For obligate learning is characterized by attachment to certain periods of ontogenesis. Such periods are called sensitive or sensible. These periods are usually very short. Especially a lot of sensitive periods in the early postnatal period, although some of them fall on the later periods of behavior development.

One of the most important areas of behavior in which obligate learning is of great importance is the formation of eating behavior. First of all, through obligatory learning, animals learn to recognize the distinguishing features of food objects. If preliminary contact of the newborn animal with the edible object is absent, then further recognition of suitable feed consumption will be difficult. In addition, methods of food extraction are formed through obligatory learning. These include motor reactions that are associated with the capture, capture, dismemberment and eating prey. These movements are innate, but without learning, they appear in a primitive, imperfect form and must be completed on the basis of individual experience. For example, mongooses have a specific movement that allows them to crack eggs with hard shells when they are thrown under their own body. This innate movement, any mongoose almost immediately after birth is able to do it. However, in order for such movements to become synchronous and effective, some time for training and training must pass. Improvement of congenital instinctive reactions in lower animals that do not have a game period in ontogenesis, is entirely due to obligatory learning. Higher animals have a special period for such development of behavioral reactions - late postnatal (learning in the process of games).

Obligatory learning as the only way to improve innate behavior is characteristic of invertebrates. Evidence can serve as observations of the ethologist V.G. Thorpe and his staff. They found that if an insect at the larval stage is exposed to any odor, then the adult insect will use this smell as a guide when searching for a place, for example, for laying eggs. However, the insects preserve the taxis to normal smells. Thus, a combination of chemotaxis based on congenital recognition (normal odors) and chemotaxis based on obligate learning (smell in experimental conditions) is observed.

Optional learning. In the early postnatal period, optional learning is assigned a relatively small role, it only serves as an addition to obligatory learning.

Experiments were carried out to clarify the timing of the formation of the components of optional learning in young species of different species. In the course of the experiments, an artificial stimulus was presented to the animal, which is not biologically significant for this species, or it was taught actions that are not typical for this type. For example, in rats at the age of 20 days, it is possible to develop a reaction of pressing the lever to obtain food reinforcement. At about the same time, the faculties of optional learning in the young of predatory mammals appear. It has been established that these abilities depend on the development of their short-term memory.

In other non-breeding animals, optional learning begins earlier. For example, in calves of lower monkeys, it is possible to develop a conditioned response to sound already at the age of three to four days. It is important to remember that the first conditioned reflexes to thermal (temperature) and tactile stimuli begin to form in animals in the first days after birth, especially in mature animals.

Manipulation. According to K. Fabri, manipulation is “the active handling of various objects with the predominant participation of the fore, less often the hind limbs, as well as other effectors: the jaw apparatus, trunk (in the elephant), prehensile tail (in the broad-bearing monkeys), tentacles (in the cephalopods clams), claws (in crayfish), etc. ” ^[21]

First of all, the manipulative activity of the animal is manifested in food-procuring and nest-building activity. In these processes, the animal actively interacts with various components of the environment, receives information about the external environment; there is an improvement in the motor reactions of the animal.

Manipulation is the highest form of animal orientation research. It is fully manifested in the animal in the late postnatal period of ontogenesis, however, the timing of the onset of manipulation and its form depend on the type of animal. The degree of maturity of the animal is of great importance.

In the early postnatal period, manipulation develops only in the simplest form, especially if the animal belongs to the immature. For example, puppies before the work of the organs of sight and hearing all the time spend in a dream or in search of the nipple and sucking. Their first movements are manipulative in nature: they crawl, touch parents and their brethren, make insufficiently precise movements of nipple grip, etc. According to the observations of the Soviet zoologist N.N. Meshkovaya, the fox cub develops manipulative activity of the jaws earlier, and later the motor activity of the forelimbs is formed. Thus, the relationship between various organs that can "replace" each other is clearly manifested.

The main direction of the manipulative activity of an immature calf in the early postnatal period is the mother's body. Brothers and sisters are perceived by the calf passively, being biologically neutral for him during this period.

Thus, the cognitive significance of manipulation in the early postnatal period in immature calves is small. In mature animals, organs of sight and hearing function from the first hours of life. This allows them to actively interact with the environment.

Imprinting Imprinting (imprinting) is an important point in the early postnatal period of ontogenesis. It refers to the forms of obligatory learning, but includes elements of optional learning.

The first imprinting studies were carried out by Spalding. He observed the behavior of chickens in the first days after hatching. The scientist noted that at the age of two or three days chickens begin to pursue any moving object, that is, for the first time described the phenomenon of imprinting. Однако термин «импринтинг» и первые подробные описания этого явления принадлежат другому этологу, О. Хейнроту (1871–1945, «Птицы средней Европы», 1912).

Хейнрот проводил исследования поведения новорожденных гусят и утят, заложив тем самым основу сравнительного метода в этологии. Он заметил, что если инкубаторных гусят во взрослом состоянии помещали к другим птицам, а до этого за ними ухаживал человек, такие птенцы игнорировали других гусей и всюду следовали за людьми. Из этих наблюдений Хейнрот сделал вывод о том, что для нормальной адаптации гусенка к жизни среди сородичей его необходимо сразу после рождения оградить от контакта с людьми. Для этого гусенка после инкубатора надо поместить в мешок, а затем выпустить к птицам. В этом случае у птенца не произойдет запечатления облика человека, и его поведение не будет нарушено.

Представления Хейнрота были расширены и дополнены наблюдениями К. Лоренца, который отметил такое важное качество импринтинга, как необратимость. Лоренц проводил исследования поведения птенцов кряквы, голубя, галки и других видов птиц. Он подтвердил мнение Хейнрота о том, что птицы, у которых произошло запечатление облика человека, в дальнейшем будут направлять на него свое половое поведение. В качестве доказательства Лоренц приводит пример из жизни египетской горлицы.

Птица была импринтирована на человека, т. е. у нее осуществили запечатление на человека. После этого горлица стала проявлять поведение, связанное с ухаживанием, на человеческую руку. Если рука была расположена определенным образом, горлица делала попытки спаривания с ней. Лоренц отметил, что узнавание объекта запечатления не имеет врожденной основы, хотя само поведение по отношению к объекту наследственно закреплено. Так, в приведенном примере врожденным является ритуал ухаживания как элемент полового поведения, а объект ухаживания зависит от импринтинга. По мнению Лоренца, запечатление привязано к определенному периоду жизни животного – чувствительному, а впоследствии направляет его половое, «сыновнее» и социальное поведение.

Parents of young and other young litters, future sexual partners may act as imprinting objects. This captures the typical signs of individuals of the same species or, on the contrary, the external signs of enemies. In the latter case, the defense response is formed as a result of a combination of these signs and warning cries or other elements of the behavior of the parents. Some scientists note that imprinting may contribute to the formation of a reaction to food objects and habitats characteristic of a species.

Лоренц считал, что запечатлен может быть практически любой предмет, даже в том случае, если он сильно отличается по внешнему облику от самого животного. Например, ученый приводит случай с попугаем, который запечатлел шарик для игры в пинг-понг. Взрослый попугай проявлял по отношению к шарику все те элементы поведения, что и к самке своего вида. Однако в действительности круг предметов, которые могут быть потенциально запечатлены, ограничен. Например, птенцы ворона не будут проявлять реакцию следования по отношению к человеку, потому что у него нет некоторых специфических черт, присущих облику взрослого ворона. К таким чертам относятся способность летать и черная окраска, возможно, также форма тела.

Very interesting is the phenomenon of the so-called “multiple imprinting”. R. Hind, V.G. Thorpe and T. Viné describe such a capturing of coot and moorhen chicks. These birds at the age of three to six days can be imprinted several different subjects. In this case, the follow-up reaction develops not in relation to any one subject, but to any of them. But if the chicks during the first days of life did not see the moving object to follow, then the reaction of following them is disturbed. Such chicks run away at the sight of any moving model.

Наблюдения показывают, что у животного могут запечатлеться определенные детали предмета, а не весь его облик. Например, известны наблюдения за поведением индюка, которого выкормил мужчина – служитель зоопарка. До возраста одного года этот индюк не видел никаких птиц. Уже во взрослом состоянии он начал проявлять половое повеление, а точнее реакцию ухаживания по отношению к воспитавшему его смотрителю. Любопытно, что при виде женщин, а также мужчин в одежде с развевающимися полами индюк убегал. Видимо, помимо запечатления облика воспитателя, такая реакция была связана с тем, что развевающаяся одежда вызывала у птицы врожденную защитную реакцию, поскольку была похожа на позу, которую индюк принимает при угрозе нападения: расправляет крылья, распластывает их по земле и волочит за собой. В этом примере можно проследить сочетание врожденной реакции и запечатления необычного объекта.

Наиболее часто импринтинг происходит в скором времени после рождения, при этом он приурочен к короткому периоду времени, имеющему четкие временные границы, – чувствительному, или сенсибельному. Лоренц считал, что сам процесс запечатления в данном случае определяется исключительно внутренними факторами (факторами эндогенной природы), однако позднее стало известно, что длительность и время начала чувствительного периода зависят от жизненного опыта животного. Были высказаны предположения, что эти сроки связаны с появлением у животного новых движений, а также с созреванием органов зрения и некоторых областей головного мозга.

Сразу после вылупления из яйца птенцы, как правило, не боятся никаких новых для них объектов и стремятся исследовать их. Однако уже по прошествии нескольких дней они начинают проявлять реакцию страха при таких встречах и стараются избегать незнакомых объектов. Интересно, что время наступления такого перелома в поведении зависит от условий содержания птенцов. Отмечено, что цыплята меньше пугаются предметов, окрашенных в те же цвета, что и стены инкубатора, где они содержались. Таким образом, в первые дни после вылупления, когда для птенцов еще не существует разделения на незнакомые и знакомые предметы, они выделяют из окружающей среды какие-либо свойственные ей характеристики. Эти характеристики помогают им отличить «знакомое» от «незнакомого». В результате такой птенец уже может выделять знакомые объекты, избегая при этом незнакомых. Например, при содержании цыплят вместе с курицей очень скоро и родительская особь, и братья с сестрами становятся знакомыми объектами, и реакция страха на них не развивается.

An English biologist, anthropologist and philosopher G. Beitson (1904–1980) proposed an interesting model (the Bateson model),which is built on the analogy of the development of the body with the movement of the train. The initial station from which the movement begins is associated with the moment of conception. Each compartment of this train is a specific system of behavior. Open compartment windows indicate the sensitivity of behavior to environmental factors at a certain stage of development. At the beginning of the journey, the windows in the train are closed; there is no connection with the outside world yet. Then the windows begin to open slightly, passengers can get acquainted with the outside world. Then the windows can either close or remain open. In this case, during the journey, the passengers themselves may change, and the external environment is constantly changing. Different systems of behavior that are formed in ontogenesis (coupe) can change their essence, their nature, that is, passengers. These behaviors can be programmed toto respond to external factors (to get acquainted through open windows with the outside world) at various points of ontogenesis (the path).

Чувствительный период может быть не один, животное может проходить несколько вариантов сенсибельного периода. Например, эксперименты на цыплятах показали, что чувствительные периоды для полового и «сыновнего» поведения у них не совпадают по времени. Половой импринтинг осуществляется позднее. Были проведены эксперименты, в ходе которых молодым петушкам в разные возрастные периоды показывали движущуюся модель. Цыплята в возрасте 31–45 суток, которым предъявляли такую модель, демонстрировали по отношению к ней половое поведение, в то время как «сыновнее» поведение было слабым. Напротив, цыплята в возрасте 1—30 суток, импринтированные на ту же модель, проявляли по отношению к ней сильное «сыновнее» поведение.

К. Лоренц считал, что импринтинг относится к формам поведения, принципиально отличным от других форм научения. Большинство современных исследователей относят запечатление к формам научения. Импринтинг – научение организма тому, каким образом он должен реагировать на предмет, который запечатлелся. Импринтинг имеет отношение к формам перцептивного научения. В пользу этого утверждения говорят эксперименты, в которых животное получает специфический опыт при помощи особых стимулов. В качестве примера можно рассмотреть развитие песни у зяблика. Для того чтобы песня нормально сформировалась, необходимо, чтобы птица прослушала ее в раннем онтогенезе, а также имела возможность попрактиковаться в этом на поздних стадиях развития. Фазу, когда птица запечатлевает новую песню, можно рассматривать как перцептивное научение. Другой пример – запечатление птенцами зебровой амадины облика воспитавшей их бронзовой амадины. В этом случае зебровые амадины после нескольких лет изоляции будут реагировать на нее как на полового партнера. Примером участия перцептивного научения в процессе импринтинга могут послужить также наблюдения за цыплятами, которые легче запечатлевают те объекты, с которыми ранее встречались.

Кроме того, импринтинг имеет отношение и к инструментальному научению. Например, утятам через день после вылупления демонстрировали движущийся игрушечный поезд. Впоследствии таких птенцов можно было научить клевать столбики, если сразу после клевания мимо будет проезжать этот поезд. Важно отметить, что при демонстрации поезда на более поздних стадиях развития такая реакция у утят не вырабатывалась. Г. Бейтсон и К. Риз описали наблюдения за утятами и цыплятами, которые могут научиться нажимать на педаль, чтобы включить мелькающий свет. Такое обучение важно провести в период, чувствительный для запечатления.

Бейтсон и Уэнрайт исследовали поведение цыплят в специальном устройстве, которое позволяло количественно оценить степень предпочтения тех или иных стимулов. Они экспериментально показали, что по мере ознакомления птенца с запечатленным им стимулом он начинает отдавать предпочтение другим стимулам, не знакомым для него. Ученые предположили, что в естественных условиях это помогает цыпленку всесторонне изучить мать, ознакомиться со всеми ее признаками. В итоге на основе всех характеристик у птенца выстраивается ее комплексный портрет.

Нельзя однозначно сказать, что импринтинг необратим, вероятно, у некоторых видов животных он может быть обратимым. Так, К. Лоренц приводит пример с попугаями, у которых произошло запечатление облика самого ученого. Птиц долгое время держали в изоляции от людей, они нормально спаривались с особями своего вида, растили птенцов. Однако через два года, оказавшись с Лоренцем в одной комнате, попугаи тут же принялись «ухаживать» за ним, бросив самок своего вида. Николаи отмечает, что снегирь, которого вырастил человек, ведет себя с ним, как с половым партнером, но осенью или зимой, при встрече со снегирем противоположного пола, он может нормально общаться с ним и не проявляет никаких реакций по отношению кчеловеку. Однако если птица не видит особей своего вида, половое запечатление на человека сохраняется.

Follow-up reaction. In this reaction, capturing is most pronounced. Its essence lies in the fact that young calves of mature animals, shortly after their birth, move relentlessly after their parents and at the same time - one after another. The reaction is typical for both domestic and wild animals. For example, a female gogol before hatching chicks leaves its nest, which is located in the hollow of a tree at a height of about 15 m from the ground and flies away. Upon her return, she, no longer flying into the hollow, emits drafts calls, prompting the chicks to leave the nest. Chicks approach the entrance, and then rush down. They land, immediately begin to move actively and follow the mother. Mother waits for the whole brood to be on the ground, after which she goes to the reservoir, the average distance to which is about 2 km. Nestlings relentlessly follow her, moving with rather high speed. When the birds reach the reservoir, the mother enters the water, and the chicks follow her. The same reaction is inherent in other birds. For example, peganok, which nest in burrows at a height of 3-4 m from the ground, call for chicks, which jump to them from this height. Chicks for caribou birds jump from nesting sites (high cliffs) already at the age of 19 days.

The replication reaction is manifested in mammals. It is well expressed in mature animals, especially in ungulates. Their young acquire the ability to move within a few hours or even less than an hour after birth. For example, a newborn camel makes its first attempts to get up within 10 minutes after it is born, and after 90 minutes it can freely stand on its feet; the reaction of following is formed in him within 24 hours. Imprinting in mammals occurs both on optical and acoustic, and on olfactory signs - the smell of the parent individual. In young cubs isolated from mothers, imprinting may occur on a person who cares for them in captivity if the cub first sees him during a sensitive period. (However, there is an opinion that other factors besides imprinting form the basis of attachment to the mother.) The replication reaction is expressed not only in ungulates, it is well traced in rodents, for example, in mature guinea pigs. The following is described in detail in other mammals, such as seals, as well as in fish.

The value of the formation of the reaction of following is great, it is focused on the parent and on other pups of the same brood. Due to the formation of this reaction, the young immediately after birth keep close to the parent, which in such a situation is easier to direct, control and protect them. Cubs learn to distinguish their mother from others, try to keep up with her. Thus, according to K. Fabry, “the quick concrete definition of the instinctive behavior of cubs on individually identifiable objects (parents, fellows) provides here the formation of vital adaptive reactions in the shortest possible time.” ^[22]

Like other cases of imprinting, the follow-up reaction is confined to the sensitive period during which it forms. For example, Gogol chicks jump out of a hollow within 12 hours from the time of hatching, these are hours of a sensible period. In chicks and ducks, the sensitive period begins immediately after hatching and ends in about 10–15 hours. In some animals, this period is longer, for example, in guinea pigs, it is extended from the sixth to the 30–40th day of life. Imprinting occurs very quickly, often a meeting with an object is often enough.

Reinforcement is not necessary to form a follow-up reaction. E. Hess gives the results of his experiments, when following an object from the chicks was artificially difficult, for example, causing pain stimuli. In this case, the reaction not only did not disappear, but, on the contrary, became more intense.

Imprinting refers to the obligatory form of learning, so it does not depend on any components of the environment, even on those that could serve as a reinforcement of the reaction. Imprinting is too important for an individual, its vital activity, it must be carried out in any conditions, even in the absence of the possibility of reinforcement. However, it is likely that when imprinted, “internal” proprioceptive reinforcement occurs. In this case, the source of reinforcements are the sensations from the movements themselves.

Sexual imprint. Imprinting can affect the sexual partner’s choice in the adult animal. This phenomenon has received the name of sexual imprinting. It provides individuals a future communication with a sexual partner.

The difference of sexual imprinting from all other forms of imprinting is that its result appears much later. In this case, the animal learns to recognize the typical distinguishing features of the future sexual partner in the early stages of postnatal development.

Most often, sexual imprinting occurs in males; they “memorize” the signs of the maternal specimen as an example of an individual of its own species. Thus, there is a sort of “refinement” of the future sexual behavior. At the same time, recognition of female type-typical signs is superimposed on the innate recognition of common types of typical signs.

Sexual imprinting is established in different animals, but it is especially pronounced in birds. For example, Warriner and staff conducted experiments with black and white species of domestic pigeons. In the experiments, 64 pigeons were used that had not previously mated and were raised by either black or white parents. The results showed that in 26 cases out of 32 males mated with females of the same color as the adoptive parents. In the remaining five of the six cases, the females preferred to mate with the males, which had a coloring of adoptive parents. Thus, the results of the study showed that the preferences of males are more significant than those of females.

The ethologist F. Schugz showed that in males of wild ducks the optimal period of sexual imprinting is limited to 10–40 days. It is at this time that the duck family disintegrates under natural conditions. Schutz noted that male ducks choose a sexual partner that resembles in appearance the female that raised it. Females prefer to mate with males of their own species, regardless of early experience. This was confirmed experimentally. Of the 34 males of the mallard, which were raised by birds of another species, 22 were mated with females belonging to the species of adoptive parents, and 12 with females of their own species. In contrast, out of 18 female mallards raised by other species of birds, all but three mated with males of their own species. At the same time, it is noted that males of species with sexual dimorphism (differences in animals of different sexes in appearance) should rely more on early experience in order to recognize birds of their own species.

Sexual imprinting has also been studied in mammals, especially in ungulates and rodents. Olfactory stimuli play a large role in sexual imprinting. Experiments were conducted on mice: during the experiments they were sprayed with odorous substances. As a result, the cubs of such mice at puberty could not distinguish the sex of other individuals, so they did not find a sexual partner. Similar experiments were conducted with other rodents, for example, with rats and guinea pigs. If males of rodents are separated from the mother during the first week of life and given to feed a specimen of another species, they can observe the effect of sexual imprinting on the alien species.

Sexual imprinting does not always occur in childhood, it can also be observed in adulthood. For example, according to the statements of the Swedish ethologists A. Ferne and S. Sjelander, the males of the Swordtail fish prefer the females of the color that they saw within two months after the onset of maturity.

Thus, in the course of capturing, rapid postnatal completion of the innate mechanism of behavior occurs at the expense of individually acquired components. Due to this, the instinctive behavior is clarified, which ensures the effective execution of instinctive actions.