Imprinting in ethology and psychology

Editor's Notes

1. Mallard duck. Developmental Psychology
2. Why does a duckling follow the mother duck? How does it know which duck to follow? The answer is imprinting, which is an inherited instinctual tendency that new-born animals exhibit to respond to their environment. Imprinting is a form of learning in which an animal gains its sense of species identification. Birds do not automatically know what they are when they hatch – they visually imprint on their parents during a critical period of development. After imprinting, they will identify with that species for life. Imprinting for wild birds is crucial to their immediate and long-term survival. It allows baby birds to understand appropriate behaviours and vocalizations for their species, and also helps birds to visually identify with other members of their species so they may choose appropriate mates later in life. In psychology and ethology, imprinting is any kind of phase-sensitive learning (learning occurring at a particular age/life stage) that is rapid and apparently independent of the consequences of behaviour. It was first reported in domestic chickens, by Sir Thomas More in 1516 as described in his treatise Utopia, 350 years later by the 19th-century biologist Douglas Spalding. It was rediscovered by the early ethologist Oskar Heinroth, and studied extensively and popularized by his disciple Konrad Lorenz working with greylag geese.
3. Ethology combines laboratory and field science, with a strong relation to some other disciplines such as neuroanatomy, ecology, and evolutionary biology. Ethologists typically show interest in a behavioural process rather than in a particular animal group, and often study one type of behaviour, such as aggression, in a number of unrelated species. Ethology is a rapidly growing field. Since the dawn of the 21st century researchers have re-examined and reached new conclusions in many aspects of animal communication, emotions, culture, learning and sexuality, that the scientific community long thought it understood. New fields, such as neuroethology, have also emerged.
4. Lorenz studied instinctive behaviour in animals, especially in greylag geese and jackdaws. Working with geese, he investigated the principle of imprinting, the process by which some nidifugous birds (i.e. birds that leave their nest early) bond instinctively with the first moving object that they see within the first hours of hatching. As we have seen, although Lorenz did not discover the topic, he became widely known for his descriptions of imprinting as an instinctive bond. Together with Nikolaas Tinbergen, Lorenz developed the idea of an innate releasing mechanism to explain instinctive behaviours (fixed action patterns). Lorenz's approach to ethology derived from a scepticism towards the studies of animal behaviour done in laboratory settings. He considered that in order to understand the mechanisms of animal behaviour, it was necessary to observe their full range of behaviours in their natural context. Lorenz did not carry out much traditional fieldwork but observed animals near his home. His method involved empathizing with animals, often using anthropomorphization to imagine their mental states. He believed that animals were capable of experiencing many of the same emotions as humans.
5. On an estate near Vienna Lorenz divided a clutch of eggs laid by a graylag goose into two groups. One group was hatched by the goose; the other group was hatched in an incubator. The goslings hatched by the goose immediately followed their mother around the estate. The goslings hatched in the incubator, however, did not see their mother; the first living thing they saw was Lorenz. They then followed Lorenz about the estate! Lorenz now marked the two groups of goslings to distinguish them. He placed all the goslings under a large box, while the mother watched anxiously. When the box was lifted, the two groups of goslings streamed to their respective "parents“. Lorenz called this phenomenon, in which an early experience of the goslings determined their social behaviour, "imprinting“. Although earlier investigators had observed the effect, he was the first to name it and to point out that it appeared to occur at a critical period early in the life of an animal. He also postulated that the first object to elicit a social response later released not only that response but also related responses such as sexual behaviour. Although imprinting has been studied mainly in birds, (generally domestic fowl cannot be as clearly imprinted as wild birds) it also occurs in other animals. It has been observed in insects, in fishes and in some mammals. So far as mammals are concerned the phenomenon appears to be limited to those animals whose young are able to move about almost immediately after birth. For example, imprinting has been described in sheep, goats, deer and buffalo.
6. These observations have not been made under controlled laboratory conditions. In the 1950s, a young psychologist named Eckhard Hess devised an apparatus for just this purpose.
7. What is the critical age at which imprinting occurs? How long must young birds be exposed to the imprinting object in order to discriminate between it and similar objects? Hess and A O Ramsay. Maryland. Wild mallard ducklings. Circular runway about 5 feet in diameter and 12 inches wide. The walls were made of transparent plastic. Imprinting object was a model with a loudspeaker inside. Young mallard was placed a foot away from the male decoy duck which made a sound, “gock gock gock”. The imprinting period during which the duckling followed the decoy usually lasted 10 minutes. Later the ducklings were tested for imprinting by placing between two decoys 4 feet apart. The new female decoy differed only in coloration. One minute was allowed for the duckling to make a decisive response to the silent models. Later male decoy made the gock sound and the female decoy made the real bird sound. Four test situations were run off: Both stationary and silent Both stationary and calling Male stationary female moving both calling Male stationary and silent female moving and calling Positive response was noted every time it moved towards the male decoy.
8. What is the critical age at which imprinting occurs? 150 – 200 ft around the runway in a span of 10 minutes. Between 13 -16 made a maximum score. All were imprinted between 12 -17 hours.
9. How long must young birds be exposed to the imprinting object? Varied distance travelled and time. One group were made to travel 12, 25, 50 and 100 feet in same amount of time. At distances up to 50 feet the strength of imprinting increased with the distance travelled. Allowed other groups of ducklings to travel the same distance, but over different periods of time.
10. How long must young birds be exposed to the imprinting object? One turn around our runway is 12 feet; a duckling can walk this distance in something less than two minutes. They moved the decoy so that groups of ducklings made one turn around the runway in 2, 10 and 30 minutes. The scores of these animals were essentially identical. Moreover, there was no significant difference between the scores of ducklings which followed the decoy 100 feet in 10 minutes and those which traveled the same distance in 30 minutes. In other words, the strength of imprinting appeared to be dependent not on the duration of the imprinting period but on the effort exerted by the duckling in following the imprinting object. Two supplementary experiments 1. Four-inch hurdles -The birds which had to climb the hurdles, and thus expend more effort, made higher imprinting scores than those which travelled the same distance without obstacles. 2. Allowed the duckling to follow the decoy up an inclined plane - similar results.
11. Puzzled by the fact that the imprint ability of ducklings rapidly declines soon after they are 16 hours old. They had noticed that ducklings develop their first emotional response when they are 16 to 20 hours old. This response is an avoidance or fear of moving objects. Twenty-four hours after hatching almost 80 per cent of the ducklings exhibit this fear; the proportion increases to 100 per cent at about 32 hours. Does this fear response knock out imprinting? They administered meprobamate to 24-hour-old ducklings; their fear response was indeed reduced. Then imprinted the drugged birds 26 hours after hatching. Ducklings 26 hours old are of course imprinted very weakly, but they were surprised that the imprinting scores of these animals were even lower than normal. In other words, eliminating fear did not improve imprintability. Later they found that the tranquilizer also interfered with the imprinting of young mallards at an age when they were normally most imprintable. Their conclusion was that meprobamate, being a muscle relaxant, nullifies the effectiveness of the imprinting experience by relaxing muscular tension. This anxiety, from an admittedly human viewpoint, may merely be the fear of being left alone; the duckling might thus tend to follow the imprinting object as it moved away. They have also considered the genetic side of imprinting and have kept ducklings which were highly imprintable and bred them separately from ducklings which showed very little imprinting response. Significant differences appeared even in the first generation: the offspring of imprintable parents were easily imprinted; those of less imprintable parents were difficult to imprint. They also followed up those animals which have had experimental imprinting experiences to determine what influence, if any, these experiences have on their adult behaviour. The results are inconclusive, but they do suggest that experimental imprinting of mallards affects their adult behaviour, particularly with respect to courtship patterns. What does all this have to do with human behaviour? Of course it is not really necessary to relate their work to such behaviour; it is interesting and important in its own right because it tells us something about the way an organism adapts itself to the world. They felt, however, that the work had some implications which are relevant to humans. It has long been known, for example, that in order for a child to develop normally it must have a certain amount of attention and handling during a critical period of its infancy. This period is doubtless not as sharply defined as the imprinting period in birds, but it may lie within the first six months of life.
12. Through the work of Lorenz, Hess and others, imprinting research drew wide attention. It shed light on many important and controversial topics of 1950s psychology, most notably the problem of heredity and learning. Imprinting, it seemed, was different from most forms of learning. It appeared irreversible and confined to a critical period, and seemed not to require reinforcement. Later research (like Sluckin’s experiments with captive birds 36 hours and Kendric’s goats imprinted on sheep returned 3 years later to mix with goats) suggested that imprinting may in fact be reversible and may extend beyond the critical period. Regardless, their findings helped to usher in a new era of research on behaviours that appeared to be genetically determined and learned. Researchers continue to examine imprinting as an example of tightly constrained learning that involves genetic predispositions.
13. The earliest manifestation of learning in many bird species is seen in filial imprinting. Releasers: These are particular aspects of an animal’s morphology or behaviour which have signal value: the young are born with the instinct to respond to these signals. If releasing stimuli for imprinting are displayed by a mock parent the infantile responses will be directed to that mock parent. It is an error to suppose that a false parent-object will determine the kind of releasers to be efficacious; the young animal will react to the degree with which the false parent-object can supply the proper releasers, and will continue to so react when it is grown. In filial imprinting, once the young bird has formed an attachment to a particular object it avoids novel objects. This learning is thought to be advantageous either because it saves time and energy spent interacting with individuals which do not pose a threat, or because it enables a threat to be more readily recognized. The work done by Italian aviator Angelo d'Arrigo showed, imprinting research has practical applications for conserving endangered species. Because birds hatched in captivity have no mentor birds to teach them traditional migratory routes, D'Arrigo hatched chicks under the wing of his glider and imprinted on him. Then, he taught the fledglings to fly and to hunt. The young birds followed him not only on the ground (as with Lorenz) but also in the air as he took the path of various migratory routes. He flew across the Sahara and over the Mediterranean Sea to Sicily with eagles, from Siberia to Iran (5,500 km) with a flock of Siberian cranes, and over Mount Everest with Nepalese eagles. The peregrine falcon has also been known to imprint on specific structures for their breeding grounds such as cliff sides and bridges and thus will favour that location for breeding.
14. Sexual imprinting thus appears to be a result of learning about parents, and generalizing out from those parents to other similar individuals. Ex, male zebra finches prefer females with similar characteristics to their mother. The most important function of sexual imprinting is to enable the birds to recognize members of their own species and thus to ensure that, under natural conditions, sexual behaviour and pair formation displays are restricted to conspecific mates. The emphasis on species recognition suggests a key role for imprinting in the speciation process itself.
15. Reverse sexual imprinting is also seen in instances where two people who live in domestic proximity during the first few years in the life of either one become desensitized to later close sexual attraction. This phenomenon, known as the Westermarck effect, was first formally described by Finnish anthropologist Edvard Westermarck in his book The History of Human Marriage (1891). When proximity during this critical period does not occur, for example, where a brother and sister are brought up separately, never meeting one another, they may find one another highly sexually attractive when they meet as adults. This phenomenon is known as genetic sexual attraction. This observation supports the hypothesis that the Westermarck effect evolved because it suppressed inbreeding. This attraction may also be seen with cousin couples. Sigmund Freud argued that as children, members of the same family naturally lust for one another, making it necessary for societies to create incest taboos, but Westermarck argued the reverse, that the taboos themselves arise naturally as products of innate attitudes. Steven Pinker (famous for evolutionary psychology and the computational theory of mind) has written that Freud's conception of an urge to incest may have derived from Freud's own erotic reaction to his mother as a boy, and speculates that Freud's reaction may have been due to lack of intimacy with his mother in early childhood, as Freud was wet-nursed.
16. Research in the field of prenatal psychology undoubtedly show a direct correlation between our early experiences in life and the subconscious behavioral and emotional patterns in our adult lives. This mechanism is called “limbic imprint.” From conception, through gestation, at birth, and through the first formative years of life, the limbic system thoroughly registers every experience. If we are safe and receive tender, loving care as our first primal experience, our nervous system is “limbicly” imprinted with the undeniable rightness of being — good health, emotional stability, high self-esteem, ability to love, be creative, and responsible. If our first impressions are anything less than loving, then that “anything” imprints as our “basic settings,” acting as a surrogate for the love and nurturing, regardless of how painful it actually was: high levels of stress hormones in the maternal blood stream during pregnancy, inductions or any unnecessary interference with the natural process during labor, lack of immediate contact with the mother after birth, absence of breast milk, rough handling in the delivery room, needles, bright lights, loud noises. All of that sensory overload and excruciating pain becomes instantly wired into our nervous systems as our “comfort zone.” We are familiar with basic settings in our televisions. If a television is set with brightness is on “dim,” no matter how bright the image is, the picture on the screen will be dark. It is the same limbic imprint that has been used for thousands of years to train animals: elephants, camels, horses, and circus bears. When a baby elephant is chained to a small stick, it rages for a few days and then stops. When it grows up and has enough strength to pull this stick right out, it doesn’t happen as it never tries again. A new baby is an extremely sensitive being — in fact, more sensitive than he or she will ever be during adult life. Babies are not only able to have sensations and feelings, but also to remember them non-cognitively. Our early impressions stay with us for the rest of our life, for better or for worse. Three statements are usually made about the effects of early experience. The first is that early habits are very persistent and may prevent the formation of new ones. This, of course, refers not only to the study of experimental animals but also to the rearing of children. The second statement is that early perceptions deeply affect all future learning. This concept leads to the difficult question whether basic perceptions - the way we have of seeing the world around us - are inherited or acquired. The third statement is simply that early social contacts determine adult social behaviour. This, of course, is imprinting.
17. The tendency of users to adhere to the first experience when using, for example, digital products like browsing the site, using mobile applications, and so on. The users do not want to learn new programs and deal with a new interface, but instead, they willingly work with what is similar to the ones they already used.
18. In species not born at an advanced stage of neural and motor maturation there is a pre-learning period; the higher parts of the brain are immature, conditioning is not possible, and events that might otherwise be stressful have no demonstrable effect. This period sets a lower boundary for the imprinting period. The infant’s first social response is directed toward learning its parent. This process, as it has been described in lower animals, is called imprinting. Imprinting involves an innate disposition to learn the parent, or parent surrogate, at a certain early period in life and this learning has a permanency of effect. The critical period seems to have a gradient of effectiveness, only in the last part of the period does it appear that adequate learning is possible. Following this period is another, the period of infantile fear. The conditions of the fear period are little understood, but there is indication that there is unusual susceptibility to stressful circumstances which can become traumatic and remain so. The fourth identifiable period is an in-group learning, when the infant learns the non-parental individuals around it and is important for the individual’s social maturity.
19. Humana are one of the few animals unable to walk immediately after the neonatal stage. This uniqueness has forced the evolution of a different system of releasers and responses for imprinting. Social smile at 45 and 46 days. Kaila had discovered that between the third and fifth months the smile is to a stimulus configuration of two eyes, nose and forehead, with motion of the face itself necessary to hold the infant’s attention. Spitz wished to test if it is the human quality of the face or a configuration within the face which releases smiling. To accomplish this he used three stimulus situations: a rictus expression of the face, a human head covered with a grotesque mask, and a life-size dummy with the mask. As long as motion was present in the form of a nodding movement, the smile was rendered without discrimination until the fifth month when models would no longer elicit the response, although the human face continued effective as a releasing stimulus for another month.
20. Critical Period of Fear: Infants become shy, even fearful, of strangers soon after the sixth month. Beyond six months the smile is seldom given to other than familiar persons. Spitz and Wolf have spoken of the immediate symptoms of separation during the second half of the first year. These are depression, continual weeping, withdrawal, weight loss, and lack of health in general. In a word, the symptoms one could expect from an unprotected infant in a stage of innate fearfulness. Bowlby, on the basis of his own research, has hypothesized that it is these children deprived of parents and parental love at about this age who are most likely to become incorrigible delinquents
21. The study showed that neither purely hereditary nor purely environmental basis for GRSO is adequate. It appears that a persons GRSO becomes established, beginning at a very early age, as that person becomes acquainted with and deciphers a continuous multiplicity of signs that point in the direction of his being a boy or her being a girl, whether under the impact of deliberate training and inculcation or through the more casual and haphazard lessons of experience. These signs range all the way from nouns and pronouns differentiating gender to modes of behaviour, hair cut, dress, and personal adornment that are differentiated according to sex. The most emphatic sign of all is, of course, the appearance of the genital organs.
22. In organizational theory and organizational behavior, imprinting is a core concept describing how the past affects the present. Molecular imprinting is a technique to create template-shaped cavities in polymer matrices with memory of the template molecules to be used in molecular recognition
23. It is the last book of Konrad Lorenz, which is his lifetime’s study of the uncannily human behaviour of the greylag goose.