Imprinting and Early Learning

Wladyslaw Sluckin

• Publisher: Routledge
• Year: 2017
• ISBN:
  9781351513180
• Edition: 2
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

What is imprinting and what role does it play in the early development of the individual? What is its theoretical importance for understanding the mechanisms of instinct and learning? What is its significance in the development of the young of our own species? This book attempts to answer all these questions.

In recent years imprinting has attracted much interest. This has been in no small measure the result of the admirable writings of Konrad Lorenz. The continued interest in this field of research has been bound up with the realization among students of behavior that imprinting and imprinting-like processes may be highly significant in the ontogenetic development of very many species, possibly including our own. The study of imprinting has become an area of collaboration between zoologists, who were the initiators of the research, and psychologists, who promptly took it up and extended it.

Imprinting and Early Learning is a compendium of the data and experimental reports on the youthful study of imprinting and early learning-a progress report that traces the history of interest in the theory of imprinting and similar processes, considers imprinting side by side with related concepts and empirical studies, reviews the full range of experiments that illuminate the characteristic nature of imprinting, elucidates the relationship of imprinting to conditioning and early learning, and points out the implications of imprinting for work in educational, social and abnormal psychology.

Chapter 1
A Historical Introduction

The young of many species stay for a time with their begetters; if they did not, their survival would be imperilled. The close proximity of parents and offspring is brought about in part by parental care and in part by an affiliation tendency in the young. In many species, including man, the neonate is largely helpless, requiring care or nursing. In such altricial species, as they are called, the tie between the parents and their offspring is necessarily due less to the activity of the young than to the activity of the adults. In non-altricial species, sometimes called precocial, infant individuals possess well-developed sense organs, are capable of locomotion, and themselves contribute substantially to the establishment of the bonds between them and their parents.

In this category are the young of ungulates, such as lambs, kids and calves, as well as the young of some other mammalian species. Among birds, fledgelings of the so-called nidifugous species, mostly groundnesting, can run or swim very soon after hatching. Such young birds - domestic chicks, ducklings and goslings, to name a few - tend to follow their parents almost as soon as they are out of the egg. The initial tendency in the young to cling to, or to follow, parent-figures may be described as instinctive or innate, by which is meant that the young are not trained and do not have to learn to behave in this filial manner.

Approach and following on the part of the new-born or newly hatched creature are responses to stimulation. What is it, then, that evokes these responses in the agile neonate, and under what conditions? Some early systematic observations were reported by D. A. Spalding in 1873, who coupled his interesting observations with some venturesome speculations about the nature of instinct. Spalding’s studies were brought to the notice of the present generation by the late Professor J. B. S. Haldane, who arranged for the paper by Spalding, called ‘Instinct, with Original Observations on Young Animals’, to be reprinted in full in 1954 in the British Journal of Animal Behaviour. While considering some ‘manifestations of instinct’, Spalding (1873) wrote as follows:

Chickens as soon as they are able to walk will follow any moving object. And, when guided by sight alone, they seem to have no more disposition to follow a hen than to follow a duck, or a human being.

Spalding was concerned to establish that certain features of the behaviour of chicks, including the following of moving objects, were instinctive rather than learned. To this end he devised an ingenious procedure whereby newly hatched chicks were largely deprived of visual experiences so that they could scarcely learn anything about their visual environment. To exclude the possibility that the eye ‘may have had opportunities of being educated’, Spalding ‘had recourse to the following expedient’.

Taking eggs just when the little prisoners had begun to break their way out, I removed a piece of the shell, and before they had opened their eyes drew over their heads little hoods, which, being furnished with an elastic thread at the lower end, fitted close round their necks. The material of the hoods was in some cases such as to keep the wearers in total darkness; in other instances it was semi-transparent.

The experimental procedure, in Spalding’s own words, was as follows.

In this state of blindness - the blindness was very manifest - I allowed them to remain from one to three days. The conditions under which these little victims of human curiosity were first permitted to see the light were often carefully prepared.

Spalding then observed the behaviour of his chicks after unhooding them. From his observations he concluded that pecking, entailing the ability to perceive direction and distance, was an instinctive act rather than a learned skill. With regard to the tendency to follow moving objects these were Spalding’s remarks :

The unacquired power of following by sight was exemplified in the case of a chicken that, after being unhooded, sat complaining and motionless for six minutes, when I placed my hand on it for a few seconds. On removing my hand the chicken immediately followed it by sight backward and forward and all round the table.

Another chick ‘was unhooded when nearly three days old’. This chick was placed about half-an-hour later ‘within sight and call of a hen with a brood of its own age’. ‘After standing chirping for about a minute, it started off towards the hen .. A

So much for the conditions of following. Spalding also had something to say about the circumstances in which following will not occur. ‘ Something curious’ - he reported -

came to light in the case of three chickens that I kept hooded until nearly four days old - a longer time than any I have yet spoken of. Each of these on being unhooded evinced the greatest terror of me, dashing off in the opposite direction whenever I sought to approach it. The table on which they were unhooded stood before a window, and each in its turn beat against the glass like a wild bird. One of them darted behind some books, and squeezing itself into a comer, remained cowering for a length of time. We might guess at the meaning of this strange and exceptional wildness; but the odd fact is enough for my present purpose. Whatever might have been the meaning of this marked change in their mental constitution - had they been unhooded on the previous day they would have ran to me instead of from me - it could not have been the effect of experience; it must have resulted wholly from changes in their own organization.

Some years later, referring to Spalding’s work, William James (1890) asserted in his Principles of Psychology, Vol. II, Ch. 24, that ‘These little creatures show opposite instincts of attachment and fear, either of which may be aroused by the same object, man’. James could have said, to render Spaldings’ view faithfully, that the tendencies to approach or fear might be aroused by any moving object, according to the time of the chick’s first confrontation with that object. For Spalding appears to have suggested that, as a rule, chicks up to about three days of age will approach and follow the first moving object seen, but at about four days of age the first moving object encountered will be avoided rather than approached. It is open to doubt whether this could be generally true, considering the striking individual differences in behaviour among chicks (see Chapter 3), and the very small number of subjects actually observed by Spalding. Nevertheless, the view that timidity gradually develops in the very young animal, and that it eventually overcomes or inhibits the tendency to approach and follow moving objects, might be substantially true.

It is interesting to note that many years after Spalding’s observations and James’s remarks, Fabricius (1951a), studying in Finland the behaviour of several different species of wild duck, observed likewise that the very same moving objects that would be approached and followed by his ducklings were also capable at other times or in other circumstances of evoking fear in them. Later, Ramsay and Hess (1954) confirmed this; and Hinde, Thorpe and Vince (1956) found that objects which elicit following in moorhens and coots may also elicit fear in these birds; cf. Hinde (1961). How following and fear are related is a challenging problem. Experimental studies bearing on its solution are surveyed and discussed later, in Chapter 7.

It appeared to Spalding that the chick would follow its mother provided it had the opportunity to do so while it was young enough. If confronted for the first time with its mother when the opportune time had passed, the chick would be quite indifferent to her. Spalding gives the following account of the behaviour of a chicken that was first confronted with its mother at ten days of age.

The hen followed it, and tried to entice it in every way; still it continually left her and ran to the house or to any person of whom it caught sight. This it persisted in doing, though beaten back with a small branch dozens of times, and indeed cruelly maltreated. It was also placed under the mother at night, but it again left her in the morning.

The implication of such observations could simply be that an instinctive act can occur at some periods of the animal’s life but not at others. There may be a special time for the display of each innate tendency. At an early age the chick approaches and follows moving objects. Later, it flees from moving objects. Very much later the fowl displays sexual behaviour. Likewise young mammals cling to their mothers while very young, play at a later stage, and so on. However, a more important conclusion to be drawn from Spalding’s observations could be that there is in the life of an animal a critical period for acquiring or learning certain kinds of behaviour. If during such a critical period the chick did not experience the proximity of its mother, then the chick could never subsequently develop a lasting attachment to her. More generally, certain forms of behaviour must be acquired during the critical period, or they will not be acquired at all.

William James (1890) in his Principles of Psychology, Vol II, Ch. 24, refers to ‘the inhibition of instincts by habits’ and to what he calls the Taw of transitoriness’. The latter states that ‘Many instincts ripen at a certain age and then fade away’. He develops this theme as follows:

... during the time of such an instinct’s vivacity, objects adequate to arouse it are met with, a habit of acting on them is formed, which remains when the original instinct has passed away; but that if no such objects are met with, then no habit will be formed; and, later on in life, when the animal meets the objects, he will altogether fail to react, as at the earlier epoch he would instinctively have done.

James then refers specifically to the tendency to follow and to the lasting ties to the objects of following. He writes :

In the chickens and calves,... it is obvious that the instinct to follow and become attached fades out after a few days, and that the instinct of flight then takes its place, the conduct of the creature toward man being decided by the formation or non-formation of a certain habit during those days.

James suggests that the behaviour involving following, and thereby becoming attached to the thing followed, is at once innate and acquired. This combination of instinct and learning is the interesting feature of the development of following in an animal such as the domestic chicken. Now, many types of behaviour are purely innate and need not be learned at all. Equally, many kinds of behaviour are characteristically acquired or learned. Developing an attachment through following, as Spalding and James have described it, combines the instinctive and acquired factors; for following is instinctive, but the attachment to, or the preference for, a particular class of objects is acquired. This type of behaviour has excited great interest in recent times: Thorpe (1956, 1963) in his book Learning and Instinct in Animals (see also Thorpe, 1951) judged this behaviour to be of‘rather exceptional theoretical interest’; the study of it, in Thorpe’s view, promised to shed a good deal of light on the relationship of instinct to ‘plastic processes in general’.

It would be perhaps misguided to build too much on the limited observations and theorising by Spalding and William James. In the first decade of this century fresh studies of the following response and the formation of attachments of young nidifugous birds were made by O. Heinroth in Germany. Heinroth read a paper in 1910 (published in 1911) about his work; and this paper received much publicity twenty- five years later when it was cited by the pioneer ethologist, Konrad Lorenz. Heinroth (1911) reported his studies of swans, geese and ducks from a variety of angles. Among other things, Heinroth found that incubator-hatched graylag goslings showed no fear when the incubator was opened and thereafter would follow people about. In Heinroth’s own words:

They look at you without betraying any sign of fear; and, if you handle them even briefly, you can hardly shake them off. They peep pitifully if you walk away, and soon follow you about religiously. I have known such a little creature to be content if it could just squat under the chair on which I sat, a few hours after I had taken it from the incubator ! If you then take such a gosling to a goose family with young of the same age, the situation usually develops as follows. Goose and gander look suspiciously at the approaching person, and both try to get themselves and their young into the water as quickly as they can. If you walk towards them very rapidly, so that the young have no chance to escape, the parents, of course, put up a spirited defence. This is the time to place the small orphan among the brood and leave in a hurry. In the excitement, the parents at first regard the newcomer as their own, and show an inclination to defend it as soon as they see and hear it in human hands. But the worst is yet to come. It does not even occur to the young gosling to treat the two old birds as geese. It runs away, peeping loudly, and, if a human being happens to pass by, it follows him: it simply looks upon humans as its parents.

Thus, a gosling can become attached to a human being if, soon after hatching out, it encounters only human beings and not geese. This is not altogether surprising. Hens have often been used for incubating duck eggs, the ducklings that hatch from under a hen follow the hen around just as her own chicks do. Old folk tales tell us about the difficulties to which such mutual attachments of hen and ducklings may lead.

Lorenz (1935, 1937a) was impressed by the fact that a young bird does not instinctively recognise adult members of its own species. Its instinctive endowment merely predisposes it to follow the first moving thing it encounters - usually its mother, sometimes another member of its own species, occasionally a member of another species. But after having had some little experience of its mother, or of some other animal, or perhaps of a human being, the young animal forms a lasting attachment to the individual, or the class of individual, it has initially followed. We say that the young animal has become imprinted with, or imprinted to, this individual or this type of individual; and the phenomenon itself is known as imprinting. The word ‘imprinting’, used by Lorenz (1937b) in a paper which appeared in English, is a translation of the German word ‘Pragung’, used by Lorenz on other occasions (1935, 1937a).

It has been pointed out by Gray (1961a) that the term ‘ imprinting’, or ‘Pragung’, used by Lorenz, and the ‘einzuprâgen’, used earlier by Heinroth, have strong affinities to such well-known English phrases as ‘to stamp in’ or ‘stamping in’. (Spalding himself - it may be noted - has used the phrase ‘the stamp of experience’.) Gray thinks that Heinroth’s ideas about instinct may have been influenced by the German eighteenth-century philosopher, Reimar (called in Latin, Reimarus), who is said to have contended that rapid early learning complements instinctive behaviour. Whatever Reimar’s views may have been, he was not an observer of animal behaviour, and he probably knew nothing about the phenomenon of imprinting. This is apparent from the account of Reimar’s writings by his French contemporary, the naturalist Leroy (see the English edition of Leroy’s letters published in 1870 under the title ‘The Intelligence and Perfect- ability of Animals from a Philosophic Point of View’), as also from the account by Brett in his ‘ History of Psychology ’ (cf. Brett, 1912 and 1921, and Peters (Ed.) 1953).

Now, Spalding observed the tendency in the newly hatched domestic chick to follow the first-seen moving object; and William James adumbrated the study of imprinting by noting that by following some objects early in life the animal ‘forms a habit’ of attachment to that class of objects. Lorenz went further: he specified, rather boldly, the characteristics of imprinting. Lorenz’s writing is clear and vivid; and the present-day interest in imprinting, including its important implications in psychology, derives almost entirely from Lorenz’s early observations of, and theorising about, this form of animal behaviour. Lorenz’s early conception of imprinting was quite definitive; no wonder, therefore, that, as factual findings began to accumulate, this conception became the target of much severe criticism. But the later criticisms, fundamental and valid as they have been, only enhance Lorenz’s very great initial contribution.

What then, precisely, were Lorenz’s original views concerning imprinting? Lorenz (1935) wrote:

The process of imprinting differs radically from the acquisition of the objects of other instinctive acts whose releasing mechanism is not innate. Whereas in the latter case the object seems always to be acquired by self- training, or learning, imprinting has a number of features which distinguish it fundamentally from a learning process. It has no equal in the psychology of any other animal, least of all a mammal. However, I would point out certain analogies in human psychology, which appear in the form of pathological fixations on the object of an instinct.

First among the points that distinguish imprinting from ordinary learning is that the object acquisition in question can only take place within a brief critical period in the life of an individual. In other words, a very specific physiological state in the young animal’s development is required to accomplish it.

Secondly, once the physiologically critical period is over, the animal knows the imprinted object of its innate reactions to a fellow member of the species exactly as though this knowledge were innate. It cannot be forgotten ! Yet, as C. Bühler (1927) in particular points out, it is essential to anything learned that it can be forgotten ! Of course, since our knowledge of this field is in its infancy, it is too early to claim definitely that the imprinting process is irreversible. I infer that it is so from a fact frequently observed in hand-raised birds. Once their instinctive social reactions are transposed to a human being, their behaviour does not change in the least even if they are later kept for years with other members of their own species and without human company.

To quote further Lorenz’s own phrases, ‘ later behaviour is determined at a critical period’, and “this process of determination is irreversible’. It could, of course, be said that these features of the development of behaviour may be characteristic of all learning. In the first place, any acquired behaviour is sometimes acquired at some critical stage of the individual’s life; for example, it appears that in learning a foreign language a true ‘ native accent’ can be acquired only in childhood. Secondly, much ordinary learning is irreversible; the acquired ability to swim or to ride a bicycle is never really forgotten. However, in his earlier writings Lorenz stressed that imprinting had “none of the essential earmarks of training’. Lorenz (1937a), in fact, wrote :

The animal does not act according to the principle of trial and error, as it does when acquiring an instinct-training interlocking, nor is it led by reward and punishment. Instead, an exposure to certain stimuli, very limited in time, determines its entire subsequent behaviour, without - and this is essential - this behaviour having necessarily been practised before the stimuli become effective. It is especially apparent in cases where considerable time elapses between the operation of the object-determining stimuli and the discharge of the instinctive act. Thus, as far as I have been able to observe, the object of the jackdaw’s (Coloeusmonedula spermolugus) innate mating behaviour is already determined during the young bird’s nesting period. Youngjackdaws that are taken over by humans around the time they become fledged, will tran...