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CHAPTER 1
Early and Later Learning
One of the centres of interest in modern psychology is the problem of the significance of early learning. Learning, in a broad sense, is regarded by many as peculiarly important in infancy. Learning at that stage of development is thought to be laying the foundations for the individualās characteristic behaviour later in life. Yet it is by no means self-evident that learning in infancy must be exceptionally influential. It may, in fact, be thought that infants, human and animal, learn but little, learn inefficiently, and forget quickly. However, debate at this level of generality is sterile: research findings can tell us little about the general importance of early learning; but they do tell us a great deal about the developmental significance of particular learning processes early in life. Even so, in the light of recent extensive animal and human studies, certain broad conclusions about the character of behavioural development may be reached. It is our aim to survey the salient research findings in this wide field, and to consider the extent of present-day understanding of early learning and its effects in both animals and man.
I. Early learning and early experience
Some types of research come under the heading of early learning while others are said to be concerned with early experience. Can a valid distinction be drawn between the two? When in everyday language we refer to early experiences, we are talking about the memory which we have of past events. If experiences are to be studied, they must be regarded as observable events, namely the effects of stimulation on the organism. (1) Early experience refers, then, to all effects of stimulation in infancy, both immediate and long-lasting. By contrast, the connotation of early learning is rather narrower; thus certain kinds of early experience involve no learning, although all early learning constitutes early experience.
Consider such environmental conditions as high or low temperatures. When continuously experienced early in life, these conditions may markedly influence the organismās physical development and consequently its later behaviour. However, such effects have little or nothing to do with early learning (and yet changes of temperature can act as rewards and punishments, and be instrumental in bringing about learning to approach and avoid certain features of the environment). Other experiences early in life, although they would not normally be described as learning, may well lie behind the acquisition of a variety of modes of behaviour. The experience of insufficiency of food, for instance, may be at the back of habitual persistent calling or searching for food later in life, and of other types of activity which would be atypical of individuals without some early experience of food deprivation. And then there are those early experiences that are quite manifestly conditioning or learning. Whenever, for example, a human or animal infant acquires a preference for some type of food as a result of pertinent experience, learning has occurred. Likewise, learning takes place when the young individual acquires ways of escaping from, or avoiding, painful situations.
The survival of the individual and species would be imperilled unless some learning took place early in life. However the young of altricial species, being initially immobile and helpless, and normally getting all the essential parental care in early infancy, may be expected to learn very little during the first stages of development. It is only somewhat later that failure to learn begins to carry a heavy penalty. The position is different in precocial species, that is, in those whose young have well-developed sense organs and are capable of locomotion soon after birth. If such young are to survive they must learn fairly quickly; at least, there are certain things which they are capable of learning and there is some urgency that they be learned. Passerine birds, rats, cats and dogs are examples of altricial animals; ground-nesting birds, sheep, cattle and horses are typical of precocial animals. Pigs and primates, including the human species, are altricial rather than precocial, but are physically sufficiently well developed at birth to be capable of some very early learning.
We shall not be concerned here with all early environmental influences, but only with those which, for one reason or another, may be said to produce early learning. And so certain experimental studies of later effects of early experience are outside the scope of this book, while others are of border-line interest or perhaps only just within our purview. To the latter categories belong investigations involving the handling or shocking of infant animals, such as mice and rats. In fact young animals so stimulated have been found to be less reactive later in life (it used to be said, less emotional) than control subjects. Does such stimulation entail early learning? The right answer may be semantic rather than substantive in character. Broadly conceived, learning would include effects of this kind; but whether it would be advisable to think of learning in such broad terms is a somewhat controversial matter. At any rate, we shall consider early experiences that are marginally learning much more briefly than early learning in the narrow sense. The reader will notice that we are not tackling the thorny problem of the definition of learning. The term ālearningā appears often to be used inconsistently even by learning theorists. It will be seen that, along with others who study aspects of learning empirically, we shall use the term in a descriptive way to refer to certain, but not all, changes of behavioural potentiality.
II. Learning early and later in life
As said earlier, the question as to whether early learning differs substantially from later learning may be too broad and too vague to be capable of eliciting a simple answer. In the first place it is uncertain what the criteria for assessing the differences between early and later learning should be. Secondly, any discernible differences may, of course, be characteristic of some species but not of others. Yet, the view that developmental changes in the character of learning are profound and that first learning differs sharply from later learning has been widely accepted.
The age factor had certainly been considered by early students of animal and human learning. The very early view was that young animals, though not those in their infancy, learn faster than older ones. Then in the late 1920s it was reported that such differences disappeared when differences in motivation were allowed for. The implication was that the learning mechanism was essentially the same at all ages, though it was recognized that there would be changes in learning abilities in relation to the development and decline of sensory powers. On the whole, however, differences in the learning abilities of subjects of different ages reported by experimentalists tended until more recent times to be ascribed to motivational changes occurring in the course of the life cycle. (2) Only in the 1940s and 50s did other developmental changes in learning behaviour begin to be considered and investigated experimentally.
Hebb (3) believed that later learning builds upon, rather than replaces, initial learning; and this in itself would make the characteristics of the two different. He believed that much early learning tended to be permanent. While early learning has been shown, at least in the higher mammals, to be very slow, it could nevertheless be foundational both in furnishing the organism with essential perceptual and motor skills and in providing the basis for subsequent transfer of learning. And Hebb expressed the view that āthe learning of the mature animal owes its efficiency to the slow and inefficient learning that has gone before, but may also be limited and canalized by itā (op cit., p. 109).
More recently, research findings have tended to qualify and specify statements of this kind, rather than confirm or refute them. Various learning capabilities of young subjects and mature subjects have been compared and differences have been reported and evaluated; but the interpretation of such differences has not been easy. Many studies confirmed Hebbās view that restriction of the range of initial experiences tends to affect adversely much later learning; and some of these studies will be considered in Chapter 5. One important outcome of the progress in developmental studies of learning has been the view that the concept of learning, as an entity, may be too general and too crude to allow an adequate investigation of changes of learning capacity with age. (4)
Vince, who arrived at this conclusion, studied and analysed the learning of young and adult passerine birds: chaffinches, titmice, greenfinches and canaries. She trained them in tasks involving the pulling of strings, the lifting of lids, and so on. She considered two features of the learning process: the acquisition, when reinforced, of the appropriate response, and the suppression of the tendency to continue to respond in the absence of reinforcement. Vince found juveniles to be more generally responsive, and capable of acquiring the correct responses more quickly, than mature birds. The latter were, however, found to be better able to inhibit incorrect responses, i.e. to learn not to respond inappropriately. Either the young or the adults could learn more quickly, depending on the character of the task. What is important is not that early learning is less or more efficient than later learning but that early and later learning can differ in certain features. It may, thus, be misleading to adopt any single unitary criterion of learning efficiency.
This view, as Vince points out, is consistent with findings concerning the learning of simple sensory-motor skills by children. Long ago Luria reported studies of children, ranging in age from 2 to 7 years, indicating that young children do not lack in responsiveness; what they do lack is the ability to control their activity, i.e. to suppress unwanted or unhelpful responses. (5) Other students of child development have also drawn attention to developmental changes in learning. Bruner, for instance, following Piaget, emphasizes the role of cognitive growth in children, entailing changes with age of modes of acquiring knowledge. The childās growing understanding of the world may be regarded as model-construction and model-modification. Such models as are being formed are tested against reality only partially and intermittently; and they develop as a function of the uses to which they are being put. (6) Thus the character of model-formation, or knowledge-acquisition, or learning, depends on the level, of cognitive development (the level attained in the progression of modes of representation) which in part depends on the nature of the childās experience of interaction with the environment.
A suggestion has been made that what is learned by a young child will not, in many instances, ever be lost, whereas adult learning is essentially rather unstable. The near-irreversibility of childhood learning might occur whenever an association is formed between stimuli of a particular class and a given response before the child is capable of making differentiations within that class. An example is quoted of a child terrorized by his father at a very early stage of development, before the child is capable of discriminating between father and other men. Such a child might react for ever with some fear to all men, or at least to a broad class of men of whom father was initially a member not distinguishable from other members. (7) This is, of course, no more than an interesting suggestion; but it is one of many that emphasizes the differences between early and later learning, and one that may conceivably lead to some fruitful investigations.
III. A comparative approach
The view, or assumption, of the Hebbian tradition is that, irrespective of species, failure to learn early may prevent effective learning later in life. It is also thought that relatively little later learning may greatly consolidate early learning, so that the total effectiveness of the learning experience depends on the conjoinment of the early and late phases. While some early learning is exceptionally durable, some appears to be entirely lost; this differential retention is a remarkable and, presumably, advantageous feature of human learning in infancy.
Some of the traditional aims of comparative psychology, including the comparative psychology of learning, have been criticized in recent years on the ground that learni...
