Psychology

Preface

The present text aims to give a comprehensive view of the facts, principles, and theories of human psychology. Accordingly, the student will find that it represents 'the various points of view of modern psychology — the analytic and the descriptive, the structural and the functional, the genetic and the physiological. At the same time the empirical results of experimental psychology are used as far as possible. Thus at the beginning the student is given a broader foundation for the understanding of mental life than could be given by a more limited point of view.

From the very outset an attempt has been made to differentiate the metaphysical and the empirical tendencies in psychology. It is important that the student should know when he is indulging in naive metaphysical speculation, and when he is dealing with the results of scientific observation or the theories based upon such observation.

While I am in sympathy with the present attempt now being made in some quarters to emphasize the objective and quantitative aspects of consciousness, nevertheless I confess the beHef that the quahtative aspect is still worthy of psychological consideration, and that, in order to get at this quahtative aspect, the method of introspection is still a valid method of psychological procedure.

I am very much indebted to Mr. Schachne Isaacs, Instructor in Psychology, University of Cincinnati, for preparing the index, for reading the manuscript and proofs, and for many helpful suggestions in the preparation of the text.

Acknowledgments are due for the use of illustrations taken from the following text-books: Villiger's "Brain and Spinal Cord," J. B. Lippincott Co.; Quain's "Elements

VI PREFACE

of Anatomy," Longmans, Green and Co.; Angell's "Psychology," Henry Holt and Company; Howell's "Text-Book of Physiology," W. B. Saunders and Company; Pillsbury's "Essentials of Psychology" and Titchener's "Text-Book of Psychology," The Macmillan Company; Thorndike's "Elements of Psychology"; Ladd and Woodworth's "Physiological Psychology" and Judd's "Psychology," Charles Scribner's Sons.

B. B. B.

University of Cincinnati, June, 191 7,

Contents

I. Introductory

Divisions of Psychology. The Procedure of Psychology. Consciousness. Subject-Object Nature of Consciousness. Soul. Mind. Self.

II. The Nervous System

Chapter I Introductory

Psychology is that study whose task it is to point out and organize the observable facts of conscious life, and to formulate the theories, or hypotheses, necessary to explain these facts. In this study it is important that the student should distinguish clearly between fact and hypothesis — between what is obtained through scientific observation and what is logically constructed through speculation. Psychology was in its earliest stages a branch of philosophy, and was more inclined to speculate about the nature of consciousness than to observe and systematize the facts connected with it. This is illustrated in the attempts to explain consciousness in terms of the soul, a metaphysical being beyond actual observation. Modern psychology concerns itself more with the facts and less with the ultimate nature of consciousness.

If we consider all the facts which come from actual observation we may put them into three groups:

1. Facts about matter.

2. Facts about life.

3. Facts about consciousness.

The first group forms the subject-matter of the material sciences; the second group forms the subject-matter of the biological sciences; and the third group forms the subject-matter of psychology.

Divisions of Psychology. — There are a number of special forms of psychology determined by the fields of mental life from which the psychologist draws his material, and by the methods and points of view he employs in his study. With respect to the fields of consciousness we have:

1. Adult human psychology.

2. Child psychology.

3. Social psychology.

4. Abnormal psychology.

5. Animal psychology.

With respect to methods and special points of view we have :

1. Descriptive psychology.

2. Experimental psychology.

3. Genetic psychology.

4. Functional psychology.

5. Physiological psychology.

6. Psychophysics.

7. Comparative psychology.

Adult Human Psychology considers the consciousness found in the adult human being. It points out the common qualities, processes, and modes of activity found in human beings generally. Since individuals differ from each other in mental characteristics, a study of these differences is also important. This study has been termed individual psychology.

Child Psychology deals with the conscious states of the child. It takes account of the stages of mental development through which the child passes. Since the genesis of consciousness is important here, child psychology is a part of genetic psychology; and since a large part of the child's Hfe is spent in school under a formal educational system, child psychology and genetic psychology often take the form of educational psychology.

Social Psychology has to do with conscious experiences which are made possible by the presence of an individual mind in a group of other minds. Such experiences are due to what has been termed social consciousness. Out of it spring language, laws and customs, myths and religion — all of which are dependent upon the existence of a community of individuals. The use of the terms "social consciousness" and "collective mind" must not be understood to indicate the assumption of the existence of another kind of consciousness other than that found in individuals. These terms refer only to the conscious states in individuals which are due to a community of minds. Communities of people have the same language, customs and fashions, religion and mythology. The conscious experiences back of these institutions we assume to be the same in all individuals. Since much of our mental life is social, social psychology overlaps normal adult psychology and draws its material from it. A subdivision of social psychology, variously named as race psychology, ethnic psychology, or folk psychology, is interested in the mental characteristics of different races or peoples. It may include the comparison of the mental traits found in different peoples. We may compare the Japanese, on the one hand, with the Russians on the other; or the primitive races, like the American Indians or Malays, with the more civilized races. A still further subdivision might take up the study of classes, professions, and occupations.

Abnormal Psychology deals with abnormal mental states, such as hypnotism, double or multiple personahty, fixed ideas, hysterias, mania, melancholia, dementia, paranoia, idiocy. Here also should be included the study of deficient and exceptional minds — the weak-minded and the genius. The criminal mind belongs in this list, because most criminals are abnormal.

Animal Psychology takes as its subject-matter the mental states of animals. The absence of language in animals limits the possibilities of studying the consciousness which we know exists there. Man can describe his experience in language, but animals cannot. However, the behavior of the animal is a clew to the kinds of consciousness it has. We may therefore study its behavior and so, indirectly, its consciousness. Since we may proceed from the lowest animal forms to the highest, animal psychology may be genetic in its point of view.

Descriptive Psychology is really a method of studying consciousness. It analyzes, describes, and classifies conscious experiences.

Experimental Psychology is laboratory psychology. Laboratory methods and physical apparatus are used as means of controlling and studying mental states. Of course, the psychologist cannot measure or weigh the conscious states of his subjects. He cannot even observe them directly. He may, however, measure the time during which a conscious state exists. He may measure or weigh the physical stimuli and correlate the results with the intensities of the conscious experiences. He may also note the physiological changes which take place in the body while the conscious states are going on. For all this he uses instruments of precision, but nowhere in his laboratory has he an instrument that will measure a mental state itself. A large part of this study depends upon the introspective report given by the subject.

Genetic Psychology considers the successive stages of mental growth and the evolution in the individual and in the race. We may use a pair of terms that are common to biology and psychology to designate the two lines of development — phylogenesis, or racial development, and ontogenesis, or individual development. These terms really refer to the growth and development of organisms as a whole — both mind and body. Mental development in phylogenesis includes all the stages of conscious life which appear in the evolution of animal forms from the lowest to the highest. These stages of development may be considered either as a series now existing, or as a series constituting the successive stages of evolution from the earliest time to the present. Mental development in ontogenesis includes the stages of development which take place in an individual from birth to death. The biologist finds a relation between ontogenesis and phylogenesis which he states as the principle of recapitulation. According to this principle, the individual in embryo passes through the same stages of development that the race has passed through. Thus, biological recapitulation suggests a problem for genetic psychology: Does the child in his mental development pass through the stages of mental development that the race has passed through ? ^ The chief problem of genetic psychology, however, is that of making out the stages of mental development of the individual.

Functional Psychology looks upon consciousness as a process. Formerly the mind was supposed to possess the functions of knowing and willing. Later a third function, that of feeling, was added. Knowing, feeling, and willing are, from the point of view of functional psychology, the functions of the mind. A more recent functional point of view asserts the presence in the mind of a purposive factor which determines the direction and nature of conscious processes. While external conditions (stimuli) do this to a certain extent, it is claimed that these factors are not sufficient to explain conscious activity adequately. A conscious agency, therefore, is assumed to account for the character of our conscious states.

Physiological Psychology considers consciousness as either the direct outcome or the correlate of brain activity. Physiological psychology does not, however, necessarily commit itself to a materialistic philosophy. For consciousness may be non-material or spiritual in its nature and yet be dependent upon the brain for an opportunity to manifest itself. The brain may be only the medium or agent for consciousness and not its real cause. But whether its philosophy is materialistic or spiritual, it bases its particular point of view and its method upon the observable fact of correlations between consciousness and nervous processes in the brain. It accordingly takes the activity of the nervous tissue as its starting-point, acquaints itself with the facts of the anatomy, histology, and physiology of the nervous system, and at-

'For a discussion of this question the student is referred to "Mental Development in the Child and the Race," by James Mark Baldwin.

tempts to find out what happens in the brain when we are conscious, or, more exactly, to find out what the correlations are between the nervous activities on the one hand and mental states or activities on the other. It really combines a large part of neurology (that which has to do with the higher brain centres and their connections) with psychology proper. One of its important problems is the localization of brain centres for the different conscious processes. For example, it finds the centre for sight in the occipital lobes of the brain, the centre for hearing in the superior convolution of the temporal lobes, and so on. In the present state of knowledge of the physiology of the nervous tissue there is relatively little known concerning the nervous action in the brain. At the present time, then, physiological psychology can be little more than the statement of a series of neurological facts on the one hand, and of conscious facts on the other.

Psychophysics is the study of the relations which exist between consciousness and the world of physical objects which are capable of acting as sense-stimuli. It is a partnership between physics and psychology, and is included under experimental psychology as now carried on in the psychological laboratory.

Comparative Psychology has taken at least two directions. In some quarters it has been identical with animal psychology and has occupied itself with the comparison of the mental life found in the various types of animals. This might well include a comparison of the mental life of the animal forms with that of man, but this is a problem for the future. A wider significance has been given in other quarters to comparative psychology in that it is considered as a comparison of the normal human adult consciousness with that found in the child, in abnormal man, in social groups, and in animals respectively.

The Procedure of Psychology. — Although the array of psychologies seems rather long and perplexing, the matter becomes really very simple when we remember that they are all studies of consciousness, and that consciousness is found only in human beings and animals. Nearly all these forms of psychology are simply special methods, or points of view, used in the study of animal and human consciousness. A general psychology, such as we are entering upon, takes for its subject-matter the highest type of consciousness — that of the adult human being. But it may make use of any of the different special methods and points of view, or even of the subject-matter of the different psychologies, in so far as it is helpful in understanding the mental life of normal man.

The fundamental method of psychology is observation: first, the observation of the mental states and processes taking place in our own minds, and second, the observation of the behavior of others by means of which we may infer the presence and nature of their mental states. These two forms of observation are necessary in psychology. Without the first we could never have an intimate first-hand acquaintance with the facts of consciousness, and without the second we would know nothing of consciousness outside our own minds.

The first form of observation gives us direct knowledge of our own conscious life and has been termed — introspection, i. e., looking within. Introspection is the observation of our own mental states. This self-observation does not, however, presuppose a new process or method of observation introduced by the psychologist. Introspection does not differ fundamentally from the observation employed in the other sciences. The difference lies only in the material upon which it works. Introspection in psychology is observation of mental facts, while observation in the other sciences is observation of material facts. Introspection has sometimes been taken to be an inner consciousness in distinction to an outer consciousness which knows the outer world of objects. But there is no valid ground for such a distinction. All consciousness, whether it be awareness of mental states or of material objects, is of the same character. The distinction of inner and outer has no meaning when applied to consciousness itself. The awareness of a material object is just as much inner consciousness as the awareness of a mental state. Both are contents of consciousness. The ability to introspect improves with training and practice. The novice in psychologyis quite as helpless as the beginning student in biology when given his first high-power microscope. Expertness is needed no less for the accurate observation of mental states than for the accurate observation of material specimens in biology, physics, or chemistry.

Objections have been urged against introspection as a scientific method on the ground that its results cannot be verified. The claim has been made that the results of introspection cannot be confirmed because no one can observe directly the conscious states of another. On the other hand, the objects of material sciences are said to be common property. Any one may observe them and confirm the reports of others. This distinction of the private nature of consciousness and the public nature of objects is not as far-reaching as it seems at first sight. All the sciences are built up by means of observation. But every observation is the observation of some one person. The observation itself is always a private and personal affair. Different observations can be brought together and made to agree only when reduced to a common unit of measurement. By means of this unit of measurement uniformity may be established, and this is the most important thing in all observation. In the material sciences the uniformities are found in terms of units of quantity — the millimetre, the gram, et cetera. In psychology the uniformities are in the terms of quality — quality of experience. The units of quality are descriptive units, or language symbols. The facts of consciousness discovered by means of introspection may be reduced to the common terms of descriptive language. If when measured by these common terms the experiences of different observers show uniformity, that is sufficient verification.

Restating this point, we may say that the so-called material objects of the sciences always fall within some one's private experience. The material object which I observe is my object, and the material object which you observe is your object. You can never experience my object and I can never experience your object. They become common to both of us only when they are described in the same terms, i. e., reduced to the same symbols. Likewise, my consciousness and your consciousness become common property when described and communicated through the medium of language. The reliability of these descriptions depends, of course, upon the degree of accuracy with which the symbols of language are used. There is, to be sure, greater opportunity for variation and error in the language description of psychical facts than in the quantitative units of measurement of the material sciences. But even in the material sciences there is variation and error. No two observers report exactly the same results from the observation of material objects. The method of introspection in psychology and the method of observation employed in the material sciences are alike in their fundamental procedure. They both reduce the results of individual and personal observation to the common terms of measurement or description, and by means of the uniformities discovered verify the facts. When a number of investigators co-operate and compare the results of their introspection, and repeat them again and again, a mass of cumulative evidence is obtained that is entirely trustworthy.

Another objection to introspection has been offered on the ground that the observation of mental states cannot take place without changing their nature. This objection is based upon the assumption that the consciousness of mental states is not the same as the consciousness of material objects. This assumption, as we have seen, is not well founded. We have spoken of this before, but let us remind ourselves again that the observation of mental states is not a different kind of observation from that by which we know the material world. The physicist interprets his experience in one way lO PSYCHOLOGY

and the psychologist in another, hut the interpretation is a construction which is put upon the experience after it is over. In the one case we are interested in the experience as an object belonging to an independent material world. In the other case we are interested in the experience as a part of our consciousness. At the moment of observation both the object and the mental state are given in our awareness.

The second form of observation in the procedure of psychology supplements introspection. It is the observation of behavior. From these external manifestations we may not only infer the presence of consciousness, but its nature. When a man smiles we judge that he is pleased. When a young child cries we know that it is experiencing pain. We can establish the fact that there is a large number of correspondences between the two series of events. Bodily movements and attitudes are the outward signs of conscious states. The quiver of the eyelid, the tremor of the muscles about the mouth, the faint blush upon the cheek, the peculiar quaHty and intonation of the voice, all betray to the practised observer the nature of the conscious states back of them. In young children and animals observation of behavior is the only means we have of gaining knowledge of their mental states.

Consciousness. — What consciousness ultimately is we do not know any more than we know what life ultimately is. Many theories have been formed about its real or intrinsic nature, but so far these theories have been of little value to the science of psychology.'

When the psychologist asserts his inability to define consciousness ultimately he does not intend to imply that psy-

' Such inquiry really belongs within the province of metaphysics and not in psychology. We may, however, note two opposing theories concerning the ultimate nature of consciousness that have been generally held:

1. The spiritualistic hypothesis.

2. The materialistic hypothesis.

The spiritualistic hypothesis holds consciousness to be states of an unextended permanent being of immaterial or spiritual nature. The materialistic

INTRODUCTORY II

chology is different from the other sciences in respect to the definition of its fundamental subject-matter. No science is able to define its subject-matter ultimately. What matter really is remains as great a mystery as ever, even though the sciences of physics and chemistry attempt to define it variously in terms of energy, or in terms of the atom* the ion, or the electron. These are metaphysical conceptions, and they tell us no more about the real nature of matter than the spiritualistic or the materialistic hypothesis tells us about the real nature of consciousness. Biology, too, is unable to define life ultimately, although it has been tempted into metaphysical speculation about it. This is illustrated by the attempt in some quarters to conceive life as a manifestation of "vital force" — a principle of mysterious and unfathomable essence thought to be the cause of life phenomena. Even the attempt to reduce life to some form of refined chemical reaction is none the less pure speculation. Just as the material and biological sciences have now given up speculation about the transcendental nature of matter and life, so psychology no longer speculates about the transcendental nature of consciousness.

While we are unable to reduce consciousness to anything more fundamental than itself, we are able to define it as observable fact. When we say that we are conscious we mean that we have experiences that we know directly. Every moment of our waking lives we are conscious: we see lights and colors, or hear sounds, or taste foods, feel pleasures or pains, perceive objects, image forms, remember past events, or form judgments, reason, feel glad or sad, or angry, love or hate, resolve, decide, and experience impulses to act. Any or all of these are states of consciousness. We can observe them directly. We can analyze those that are complex into

hypothesis regards consciousness as a form of nerve-energy which, so far, we have not been able to observe and measure. But whatever the metaphysical basis of consciousness may be, the facts of consciousness remain the same as far as observation of them goes.

simple conscious states and can weave them into a system of relationships.

Some of the earlier English psychologists used the term consciousness to signify awareness of one's own mental states and processes. Locke defined it as the "perception of what passes in a man's own mind," and Reed as "that immediate knowledge which we have of all the present operations of our own mind." But more recently that meaning has been discarded and now the term consciousness is used to indicate any and all mental experience; not only the awareness of our own mental states, but also awareness of objects and relations in the outer world; not only the mental experience of man but the mental experience of all sentient beings.

Subject-Object Nature of Consciousness. — One of the most troublesome points to keep clear in discussing the nature of consciousness is the distinction which we are logically forced to make between the subject side of consciousness and the object, or content, side. To be conscious impHes some one who is conscious. To have a sensation or thought seems logically to involve a subject to which the sensation or thought is presented. What thinks the thought? What has and owns the sensation? Professor James's answer, "that the thoughts themselves are the thinkers," does not satisfy the logical need of our thinking. This question appears in vari ous forms in the study of conscious phenomena. We cannot attempt really to answer it without entering the field of metaphysics, but psychology has the right to make any assumption concerning it that is in accord with the facts of consciousness. The spiritualistic hypothesis of consciousness assumes a being of psychical nature, a permanent ego, or knower, to which all consciousness as content is presented. This double aspect of consciousness has given rise to two different points of view concerning consciousness:

1. Consciousness as the act of the subject.

2. Consciousness as content of experience.

It is important for the student to keep clearly in mind these two possible meanings of consciousness, because in psychology the term is sometimes used in one sense and sometimes in the other, and often the meanings are confused. The first meaning considers only the subject and its activity in attending, perceiving, feeling, willing, et cetera. The second meaning considers only the content of experience, or, in common terms, that which is experienced — a sensation, a percept, a memory image, an emotion, et cetera. For example, the content of consciousness is that which is presented to us as different experiences. The experience of red is different from that of green. The experience of the taste of sugar is different from the experience of the sound of middle C on the piano. The experience of an emotion is different from the experience of a memory image. Such experiences make up the content of consciousness.

It is not possible in an introductory psychology to avoid the use of consciousness as subject and consciousness as content, but it. is possible to know when we are using the one and when the other. As an illustration of the two meanings of consciousness found in the literature of psychology we may instance the widely differing definitions offered for some of the most common concepts. For example, if the student will read the definitions of attention in a number of text-books on psychology, he will find that in some attention is defined as the "power of the mind to concentrate, select, and prolong consciousness," while in others it is defined as "clearness, vividness, or distinctness of mental content, accompanied by a complex of muscular strain and effort." It is plain that in the former case consciousness is conceived as a subject or agent manipulating the contents of its experience, while in the latter case consciousness is merely content.

It is the content side of consciousness which furnishes the facts of scientific psychology, because the content of our experience is the only part of consciousness that lends itself to observation. It is the only part about which we can have definite, empirical knowledge. On the other hand, the so-called subject of consciousness always lies outside the world of observable facts. It is a logical construction which should be used in psychology only as a convenient hypothesis. In referring to the subject of consciousness as a logical construction, we mean that it is a factor which appears only after we begin to think about the facts of consciousness and attempt to explain them rationally. It is, therefore, a product of thought, and not a directly observable reality.

Those who have attempted to avoid the hypothesis of a spiritualistic subject of consciousness or have denied its existence, usually substitute for it the assumption that consciousness is really some form of nervous energy. They assert that there is no necessity of assuming anything more than this nervous energy in a living and acting brain to account for the phenomena of consciousness. Whether we accept the hypothesis of a psychical or spiritual subject of consciousness, or that of the material nature of consciousness, really makes little difference within psychology itself so long as we are consistent in holding to one or the other. The observable facts remain the same in either case. The sensation of red is just what it is experienced to be, whether it is referred to a psychical subject or to a form of nervous energy. If consciousness is a form of nervous energy, then the brain or nervous system is the unifying principle which has and owns the conscious states. Now, we know by actual observation that conscious states as content of experience exist only at the moment of their experience. Then, according to the materialistic conception, they become, when they cease to be experienced, merely states or conditions of the nervous system. They may be revived again when the nervous material which has given rise to them is stimulated into activity. This conception tacitly assumes a mode of transformation between material brain processes and conscious experience that is beyond the realm of observable fact. Even if it were possible to observe all the details of the brain-cell processes, and to follow them to their last chemical or physical activities, they would still be just what they are — material processes. The particular manner or mode of their transformation into conscious states is never revealed to us as observable fact. The central point in this materialistic hypothesis is the assertion that conscious states are really and ultimately some form of nervous energy in the brain, and that therefore the brain is the ultimate ground of existence for all consciousness.

The student should not confuse this assumption with the observable fact of the dependence of conscious phenomena upon the brain or nervous system in a living organism. The assumption attempts to explain the ultimate or real nature of consciousness by reducing it to nervous energy. On the other hand, the establishment of the fact of the dependence of consciousness upon the nervous system does not involve the question of what its ultimate ground of being is, but rests its case upon the observable facts of consciousness on the one hand, and the observable facts of brain states and activities on the other.