At this point it is that child psychology is more valuable than the study of the mind of animals. The latter never become men, while children do. The animals represent in some few respects a branch of the tree of growth in advance of man, while being in many other respects very far behind him. In studying animals we are always haunted by the fear that the analogy from him to man may not hold; that some element essential to the development of the human mind may not be in the animal at all. Even in such a question as the localization of the functions of the brain described later on, where the analogy is one of comparative anatomy and only secondarily of psychology, the monkey presents analogies with man which dogs do not. But in the study of children we may be always sure that a normal child has in him the promise of a normal man.
3. Again, in the study of the child's mind we have the added advantage of a corresponding simplicity on the bodily side; we are able to take account of the physiological processes at a time when they are relatively simple—that is, before the nervous system has grown to maturity. For example, psychology used to hold that we have a "speech faculty," an inborn mental endowment which is incapable of further analysis; but support for the position is wanting when we turn to the brain of the infant. Not only do we fail to find the series of centres now known to be the "speech zone," but even those of them which we do find have not yet taken up this function, either alone or together. In other words, the primary object of each of the various centres involved is not speech, but some other and simpler function; and speech arises by development from a union of these separate functions.
4. In observing young children, a more direct application of experiment is possible. By "experiment" here I mean both experiment on the senses and also experiment directly on consciousness by suggestion, social influence, etc. In experimenting on adults, great difficulties arise through the fact that reactions—such as performing a voluntary movement when a signal is heard, etc.—are complicated by deliberation, habit, custom, choice, etc. The subject hears a sound, identifies it, and presses a button—if he choose and agree to do so. What goes on in this interval between the advent of the incoming nerve process and the discharge of the outgoing nerve process? Something, at any rate, which represents a brain process of great complexity. Now, anything that fixes or simplifies the brain process, in so far gives greater certainty to the results. For this reason experiments on reflex actions are valuable and decisive where similar experiments on voluntary actions are uncertain and of doubtful value. Now the child's mind is relatively simple, and so offers a field for more fruitful experiment; this is seen in the reactions of the infant to strong stimuli, such as bright colours, etc., as related further on.
With this inadequate review of the advantages of infant psychology, it is well also to point out the dangers of the abuse of it. Such dangers are real. The very simplicity which seems to characterize the life of the child is often extremely misleading, and this because the simplicity in question is sometimes ambiguous. Two actions of the child may appear equally simple; but one may be an adaptive action, learned with great pains and really very complex, while the other may be inadaptive and really simple. Children differ under the law of heredity very remarkably, even in the simplest manifestations of their conscious lives. It is never safe to say without qualification: "This child did, consequently all children must." The most we can usually say in observing single children is: "This child did, consequently another child may."
Speaking more positively, the following remarks may be useful to those who have a mind to observe children:
1. In the first place, we can fix no absolute time in the history of the child at which a certain mental process takes its rise. The observations, now quite extensively recorded, and sometimes quoted as showing that the first year, or the second year, etc., brings such and such developments, tend, on the contrary, to show that such divisions do not hold in any strict sense. Like any other organic growth, the nervous system may develop faster under more favourable conditions, or more slowly under less favourable; and the growth of the mind is largely dependent upon the growth of the brain. Only in broad outline and within very wide limits can such periods be marked off at all.
2. The possibility of the occurrence of a mental state at a particular time must be distinguished from its necessity. The occurrence of a single clearly observed fact is decisive only against the theory according to which its occurrence under the given conditions may not occur. For example, the very early adaptive movements of the infant in receiving its food can not be due to intelligence and will; but the case is still open as to the question what is the reason of their presence—i.e., how much nervous development is present, how much experience is necessary, etc. It is well to emphasize the fact that one case may be decisive in overthrowing a theory, but the conditions are seldom simple enough to make one case decisive in establishing a theory.
3. It follows, however, from the principle of growth itself that the order of development of the main mental functions is constant, and normally free from great variations; consequently, the most fruitful observations of children are those which show that such an act was present before another. The complexity becomes finally so remarkable that there seems to be no before or after at all in mental things; but if the child's growth shows a stage in which any process is clearly absent, we have at once light upon the laws of growth. For instance: if a single case is conclusively established of a child's drawing an inference before it begins to use words or significant vocal sounds, the one case is as good as a thousand to show that thought may develop in some degree independently of spoken language.
4. While the most direct results are acquired by systematic experiments with a given point in view, still general observations carefully recorded by competent persons, are important for the interpretation which a great many such records may afford in the end. In the multitude of experiences here, as everywhere, there is strength. Such observations should cover everything about the child—his movements, cries, impulses, sleep, dreams, personal preferences, muscular efforts, attempts at expression, games, favourites, etc.—and should be recorded in a regular daybook at the time of occurrence. What is important and what is not, is, as I have said, something to be learned; and it is extremely desirable that any one contemplating such observations should acquaint himself beforehand with the principles of general psychology and physiology, and should seek also the practical advice of a trained observer.
As yet many of the observations which we have in this field were made by the average mother, who knows less about the human body than she does about the moon or the wild flowers, or by the average father, who sees his child for an hour a day, when the boy is dressed up, and who has never slept in the same room with him—let alone the same bed!—in his life; by people who have never heard the distinction between reflex and voluntary action, or that between nervous adaptation and conscious choice. The difference between the average mother and the good psychologist is this: she has no theories, he has; he has no interests, she has. She may bring up a family of a dozen and not be able to make a single trustworthy observation; he maybe able, from one sound of one yearling, to confirm theories of the neurologist and educator, which are momentous for the future training and welfare of the child.