The essentials of psychology

Preface

The aim of this volume is to present clearly the accepted facts of psychology. Throughout, emphasis has been placed upon fact rather than theory. Where theories conflict, the better one has been chosen, the others merely neglected. This may seem dogmatic in places, but in a text dogmatism is preferable to confusion. The point of view is on the whole functional; more attention is given to what mind does than to what it is. With this goes an emphasis upon the outward manifestations of consciousness and upon the behaviour of others to the subordination of the individual consciousness. Nevertheless, use is made of the results of structural psychology wherever they throw light upon function or are interesting for themselves. The position, it is hoped, combines the advantages of the rival schools.

The content of a text-book in psychology is sufficiently agreed upon to require no comment. The general practice has been followed of introducing a brief exposition of the nervous system and its function. This is done with a full appreciation that it is no part of the task of the psychologist to teach neurology, but with the conviction that the beginning student in psychology is not likely to have acquired the knowledge elsewhere. In this treatment as little detail of structure has been given as is compatible with an understanding

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PREFACE of function. Large use has been made of the hypothesis of the synapse. Its convenience in explaining habit and association outweighs any scruples about its final position in physiology. For the rest, I have deviated from traditional usage only in introducing rather more of the results of recent experiment. A body of knowledge has been developing in connection with memory and action that seems ripe for embodiment in a text. Similar considerations have led to the introduction of chapters on fatigue and on the transfer of training.

The general arrangement followed is relatively novel. It consists in first developing a few simple principles and then making frequent application of them to the more complicated processes. Sensation, habit, retention, and selection or control are fundamental and appear repeatedly in mental operations of all kinds. When they are once understood, it is only necessary to develop their applications and interconnections to master the more developed operations. The method involves much repetition, but not more than the experience of the writer has proved necessary. What is not understood in one connection is made clear by the next application.

My obligations to psychological writers are so general and so apparent as to need no special acknowledgment. Dr. Rowe of the Central Normal School, Mt. Pleasant, Michigan, has read the manuscript and made many suggestions. Thanks are due also to my colleague. Dr. Shepard, for help at many points. I owe most to my wife, who has given constant advice in matters of expression, and has been of great service in the mechanical preparation of the book.

PREFACE

IX

I desire also to express my thanks to authors and publishers for permission to reproduce illustrations. I am indebted to The W. B. Saunders Company and Professor Howell for figures from ‘The Text-book of Physiology’ and the ‘American Text-book of Physiology’; to Dr. L. F. Barker for figures from his ‘Nervous System ’ ; to Henry Holt and Company and Professor Angell for cuts from his ‘ Psychology ’ ; to Houghton Miffiin Company and Professor Jastrow for figures from ‘Fact and Fable in Psychology’; to The Macmillan Company and Professors Titchener and Calkins, respectively, for figures from ‘ A Text-book of Psychology ’ and ‘ A First Book of Psychology ’ ; to Professor Swift for a Curve of Learning, and to Professor von Frey for permission to adapt his Temperature Scale.

Ann Arbor, Mich., '

V

The Self ....

XI

Chapter I Introduction

Psychology is traditionally defined as the science of mind. This is the translation of the two Greek words from which ‘ psychology ^ is compounded. The definition is now open to many objections. The most important of these is that the word ‘ mind ^ has in the course of long use taken on many meanings and implications which do not concern psychology as a science. Various terms have been suggested to avoid these objections. Psychology has been defined as the ^science of consciousness/ or as the ‘science of experience subjectively regarded.’ Each of these definitions has advantages, but none is free from objection. It is most satisfactory to give up the attempt to find a single word that will designate the facts covered by psychology, and to indicate the actual phenomena that it studies, — the evidences of mind. First of these is behaviour. We distinguish a man in the full possession of his senses from an imbecile by the character of his acts. We measure the intelligence of an animal by its accomplishments. Mind is known from man’s activities. Psychology may be most satisfactorily defined as the science of human behaviour.

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Man may be treated as objectively as any physical phenomenon. He may be regarded only with reference to what he does. Viewed in this way the end of our science is to understand human action. The practical end is to determine upon what human capacity depends and, in the light of this knowledge, to discover means of increasing man’s efficiency. In many fields of industry it is becoming more and more evident that an understanding of the laws of human efficiency is quite as important as a knowledge of mechanical laws, that it is quite as important to know what a man can do in a given time and how he should work to obtain the best results as to know the laws for the production of energy in boiler and engine. In fact, it is appreciated in many industries that further progress must wait upon increased knowledge of the human instrument. Psychology is concerned only indirectly with these practical problems. Science always endeavours to understand the laws of nature for themselves and is indifferent to the applications that may be made of them. Psychology is interested in the conditions of learning and forgetting, of imagining and reasoning, and in the methods of acquiring skill in various activities without any thought of the use that may be made of the knowledge. It is probable, however, that all suggestions for improving the efficiency of individuals must be based upon these laws. Indeed, many rules have already been developed from the psychological experiments and more are foreshadowed in the general principles now established.

If psychology is to be defined as the science of human behaviour, the term ‘behaviour’ must be used in the very widest sense. It must include everything from the simplest movements of walking or of fingering the pen to the activities involved in swaying an audience by speech or in carrying to completion some great engineering work. Certain of the very simplest acts, such as winking and other reflexes, are fairly within the range of physiology. But even these must be taken into consideration by psychology, because the most complicated act can be understood only when analysed into its components which are closely related to reflexes. Even the simplest forms of behaviour must be studied by the psychologist if he is to know the laws that govern the more complicated forms. No form of human behaviour, from the simplest to the most complex, falls outside of the province of psychology. As a science our knowledge of human behaviour must be organised and referred to a system of general principles. A science of human behaviour cannot be limited to a series of aphorisms or chance observations about man. ^Perseverance wins success’ is related to the psychology of conduct in very much the same way that * an east wind brings rain ’ is related to the science of meteorology. Each statement embodies the results of numerous observations, but it has no close connection with other facts or general laws. In a science these observations must be related to' other bits of knowledge and the whole organised into a consistent system that shall harmonise with the results of other sciences. Scientific laws are based on more carefully chosen data and in consequence possess wider validity and are less likely to be vitiated by popular prejudice or ill-founded tradition. They give each particular fact a perspective and make it easy to recall and to use each new observation.

Even if we regard the understanding of human behaviour as the ultimate end of psychology, consciousness must still play a very important part in our science. By consciousness we mean a man’s awareness of his own acts and their antecedents. While the reader might at this moment be observed by a friend to hold the book and move the eyes by jerks across the page with an occasional frown as a difficult sentence is met, the reader himself is aware of the sense of the material that is read, and thinks in some part ‘the ideas that are intended by the writer. The one appreciates the behaviour, the other consciousness. In this case behaviour is the immediate outcome of consciousness and can only be understood through it. The frown can be explained from the hesitation in getting the meaning of a sentence, and that is evident to the reader alone. While many kinds of activity are best known from the inside, others may be as well known from the outside. Thus the capacity of an individual for assimilating the material of this chapter may be determined as well by the instructor who assigns it and quizzes on it as by the student. This is particularly true if the reading is done under the observation of the teacher. The reasons for the differences in capacity to learn and repeat could be known either by the individual himself or by the observer only through long study of the individual in the light of earlier training and habits of work. In general, then, consciousness is always an important means of knowing behaviour. How important depends upon the sort of behaviour. The more complicated forms of behaviour can be understood only through consciousness; the simpler may be understood from without. Consciousness must have a very large place in psychology, not only because action may usually be explained through it, but also because of its own interest. There is nothing more interesting to the ordinary individual than the workings of his own mind. This interest alone would justify the existence of the science. Consciousness is at once an important means of understanding behaviour and an interesting object of investigation for itself. Consciousness and behaviour are closely related ; consciousness in others is known only through behaviour, behaviour in ourselves and ultimately in others is known only through consciousness. If one is made the end, the other must be the means; if either is understood in its completeness, the other will also be known. They are the inside and outside of the same organism. At the present stage in the development of psychology, it seems best to subordinate consciousness to behaviour. Psychology is the science of behaviour. Behaviour is to be studied through the consciousness of the individual and by external observation.

Mind, Consciousness, and Mental Process. — Before attempting any discussion of mental states it is necessary to define certain of the terms that are to be used. Viewed from within, psychology seeks to explain the experiences of the individual as they run their course, — to understand the various external impressions, memories, imaginings, and so on that together constitute the mental life. Any one of the states that may be regarded as detached from the mass for separate consideration is designated a mental process. Your idea of this book as you read it is a mental process, your memory of reading the book yesterday or of the assignment for study is a mental process as is the flitting thought that you would much rather be out for a walk than reading. Consciousness is the term ordinarily used to designate the sum total of mental processes at any moment. Thus, the perception of the book, the background of tactual and organic sensations that are receiving no particular attention at the moment, the vague emotional dissatisfaction that you are kept indoors on a pleasant day, and many other more or less definite mental processes combine to constitute your consciousness at this moment. Consciousness is also used less definitely for any sort of awareness, however great its duration, but this is not generally recognised as the technical meaning. Mind is the word that is ascribed to the entire series of conscious states of an individual from birth to death. It is the most inclusive of the series of terms and covers all processes, active and passive. Experience is used to designate practically the same mass of states, but it is a little more passive in its implications. All of these terms apply to the description of behaviour as observed from within, the mental antecedents and accompaniments of behaviour. The description of behaviour as it presents itself to the outside observer needs only the vocabulary of popular speech and requires no preliminary comment or definition.

The Methods of Psychology. — As has been said, behaviour can be studied in two ways ; by observation of another’s acts and by observation of one’s own conscious states. Observation of another, or what in psychology is known as observation, requires no special comment as a method. In all essential respects it follows the rules of observation that are common to all of the sciences. Selfobservation, known technically as introspection, seems at first sight to offer more difficulties and to require more safeguards. The question has been raised whether introspection is possible at all. The doubt arises from the assumption that the very observation of a mental state changes that state. One does not have the same mental state when questioning how one knows that the approaching footsteps are Smith’s, as when one interprets the sounds to mean that Smith is coming. One cannot at the same moment wonder what one is doing and do it to the best advantage. This objection proves to be less serious in practice than in theory. All mental states persist for a little time unchanged and it is possible to observe them during this persistence. One does not observe the mental state at the time it is happening, but examines it a moment later in memory. Observation in memory is accurate and does not alter the process investigated. Observation in any natural science requires the same reliance on momentary memory. One cannot make an observation and record it at the same time. If one tried, mistakes would be made. The reading is taken and held in memory until recorded, and then still later it is interpreted or used in the explanation of related facts. Introspection is no more difficult or uncertain than is observation of external phenomena.

Experiment.' — Within the last generation both introspection and observation have come to be largely carried on under experimental conditions and with the aid of instruments of precision. Experiment has aided both observation and introspection by making it possible to control accurately the conditions and antecedents of mental operations. It is possible now to remove from distracting stimuli the individual who is introspecting or being ob^ served and to measure accurately the stimuli that are permitted to affect him. The results obtained when observation is assisted by instruments are even more striking. It is a commonplace that a man who is embarrassed will blush. Delicate physiological instruments used in the psychological laboratory show that the blush is only a heightened effect of the changes in circulation that take place in all parts of the body in connection with almost all mental processes. Similarly it was first observed with the unaided eye that the eyes moved by jumps during reading. Later it was found possible to photograph the movements of the eyes, and these results brought out important points that could not have been attained otherwise. Introspection has been aided principally by recording the times that elapse between different parts of a mental operation. The times required have been combined and the results emphasised relations that were noticed in introspection. While experiment is only a means of increasing the accuracy of observation and introspection, it has through its wide application made possible important advances in nearly every field of psychology. To its great benefit psychology has become an experimental science.

But momentary introspection and observation combined, even with all the help that maybe had from experiment, do not exhaustively explain behaviour or consciousness. The observer sees the occasion for action and notes the response ; the actor sees the object and feels the response, but neither knows what happens in between nor appreciates fully the conditions of the act. For example, a wasp approaches, the man draws back or strikes. The observer notes the occasion for the movement and the movement itself, but nothing more. The man attacked sees the wasp and knows that he is moving or has moved, but nothing more. Neither can know why the movement takes place. One sees the stimulus vanish into the physical organism and movement result ; the other sees the insect, moves, and all the time is perturbed by an emotion, but neither can absolutely foresee the movement that results, neither knows why it results. These more fundamental explanations may be supplied in part on the basis of present knowledge. Two elements must be taken into consideration in the interpretation, — the character and nature of the action of the nervous system, and the past life and native endowment of the individual. One can understand what intervenes between the first excitation and the movement that results only if one can trace the course of connection through the nervous system. The earlier history of the individual and of the race plays a very large part in the determination of all sorts of behaviour. The man’s responses will differ according to the amount and nature of his experience with wasps. The influence of earlier experiences can be traced in many more subtle ways in the interpretation of any mental phenomenon. Both the nervous system and the effects of earlier life upon the acts of the individual can be known only through observation and introspection controlled and recorded, together with much experiment and reflection upon the connections of present with past activities. Human behaviour, then, can be understood by careful, long continued observation of man in action from the inside and lO from the outside, and by relating the results of these observations to the earlier experiences of the individual and to the facts concerning the nature and action of the nervous system that have been accumulated by the anatomist and the physiologist.

Relation of Psychology to Other Sciences. — The

relations of psychology to the other sciences are particularly close and important. The biological sciences shade over into psychology so gradually that it is not always possible to decide whether a problem belongs to psychology or to one of the biological sciences. The sciences that explain the nature and action of the human body, the sciences of anatomy and physiology, verge gradually over into psychology. One can understand behaviour only if one knows something of the organism that acts, of the sense organs that receive the impression from without, of the muscles that produce the actions, and of the nervous system that connects them. From the outside one can understand man’s behaviour most fully and easily by comparing it with the behaviour of animals and tracing the gradual development of man’s action in connection with the simpler forms of animal behaviour. Experimental biology gradually shades over into experimental psychology. The biologist has recently been devoting himself very largely to the problems of animal behaviour. The light cast upon human conduct by these experiments is only less important than that cast upon the actions of animals themselves. Still more general results of biological sciences have been profoundly important for the explanation of human consciousness. The very general acceptance in recent times of the doctrine of evolution has

II forced us to read the story of mind in the light of the development of the human organism from the lower forms of life. The result is a very much fuller understanding of many of the more fundamental phases of human activity. All of the physical sciences furnish some material for the psychologist, since the sense processes can be understood only in connection with the physical forces that act upon the organism.

The Related Sciences of Man. — In addition to the sciences from which it receives material and methods, psychology has come into a position where it may offer help to many sciences. If psychology can give information concerning human behaviour, it is evident that all the human and social sciences may look to it for aid in the solution of their problems. Sociology, or the study of man in the group, evidently must found its results upon a study of the individual. In less degree history, when it seeks to trace connections between its observed facts, must look to psychology for its fundamental principles. Economics, too, works with psychological materials. Its fundamental problems are essentially psychological. Values and human needs are largely mental. It must be said, however, that psychology is least well developed in the fields where it would be most helpful to the historian and to the economist. Last of all, the relations of psychology to philosophy are very numerous and are those of mutual helpfulness. Psychology was the last of the sciences to separate from philosophy, the parent of all of the sciences, and the bond is still very close. The history of psychology is still very largely a part of the history of philosophy. The results of psychology are in large part the foundation of philosophy, and on the other hand philosophy supplies the psychologist with general principles and sets very many of his problems for him.

Of the immediately practical subjects, education has probably made the largest demands upon the results of our science. Learning and teaching are both psychological operations. When any real attempt to understand either is made, education becomes an application of psychology. This is more and more appreciated in the modern schools, and in them psychology and education are coming closer and closer together. The psychologist is paying more attention to the problems of the educator, and the modern educational theorists are making more use of the results of psychological investigations. But the applications of psychology need not be confined to education. With the advance of knowledge all who have to deal with man will look to the psychologist to ever increase the knowledge that may be put at his disposal. The physician and the lawyer, the advertiser and the clergyman, are all dealing in one way or another with psychological problems. To the physician and the advertiser psychology has already given appreciable aid and it should be in a position at no distant day to offer help to the others. Too much of practical value is not to be expected from the science. In all of these fields there is a great difference between principles and practice. Often the rules that grow from daily practice are in advance of scientific principles. Science serves but to explain the truth of the practical precept. Theory does not always lag behind, and one can already see places in which psychological results point the way to improvement in practice. As a rule, however, established arts are more grateful for confirmation of the established custom than for the suggestion of improvements. This incomplete list of the relations of psychology may suffice to indicate how closely psychology is bound up with other fields of human knowledge. Any science that tells us anything of the nature of the physical universe or of the nature of the living organism will throw some light upon the problems of psychology. On the other hand, any science that deals in any way with human conduct, or that is dependent in any way upon human capacity (and what science is not?), can draw with profit upon the results of psychology. Either as creditors or debtors, all the sciences stand in some relation to psychology, the science of human behaviour.

Divisions of Psychology. — Each of the sciences that furnish material for psychology has given rise to a different sort of psychology, or at least to a different name for a psychological work. Psychophysics grew out of an attempt by Fechner to determine the quantitative relations between the physical stimulus and the intensity of the mental state. Physiological psychology is the name Wundt gives to his work, that has for its primary object the explanation of the relation between mental states and the bodily organism. Each of these treatments grew beyond its original scope to cover the entire field of psychology. The name indicates nothing more than the attitude that is taken toward the subject. Other branches of the subject are marked off by the part of the material of behaviour that is discussed. Genetic psychology treats of the development of behaviour. The behaviour of animals has given rise to a flourishing science and in the last few years has made much progress. Child study has made numerous contributions to the more theoretical problems. Each has thrown some light upon the nature of adult human behaviour, as well as collected many facts in its own field. Abnormal psychology, the study of abnormal and imperfect individuals, has also been a rich field for the psychologist and has given many important results. Each of these partial sciences may be considered by us only so far as it throws light on the behaviour of the adult normal man. A few years ago it was customary to classify psychological systems according to the methods of investigation. There was a rational psychology, an empirical psychology, an introspective psychology, and an experimental psychology. Now it is seen that no science can be developed by one of these methods alone, and all are used by any psychologist worthy of the name. At the most it can now be said that there is an empirical and a rational method in psychology, a method of introspection and a method of observation, both aided by experiment. The results of each method should be the same if the methods are adequate. And as a matter of fact the results are the same except that one method will be adequate for one problem, another for another. All the so-called branches of psychology, then, are closely related to the central science and at the most designate merely different fields for observation, or the preference of writers for different methods.

Our problem is to understand behaviour, and to investigate consciousness as the immediate antecedent and condition of behaviour. To understand either consciousness or behaviour it is necessary to know something of the character and action of the nervous system. As has been said, all knowledge of the world comes to consciousness through the nervous system and all expressions of consciousness in action are rendered possible by the nervous system. This is not psychology but is a necessary prerequisite for psychology. The psychological problem proper begins with an analysis of the elements of consciousness, both structural and functional. The structural elements are found in the qualities received through the senses, and the elements that are retained and revived in memory. The primary function is the capacity for selection that chooses the elements, both sensations and memories, that shall enter consciousness. To these may be added a third principle, that all elementary structures tend to arouse movements and that these movements are controlled by sensations. The fundamental facts and activities of consciousness and behaviour serve as a basis for the explanation of all of the more complicated concrete mental processes and operations. The analysis of consciousness and of behaviour consists, first, in determining the elementary states or activities, and then of seeing how they interact and unite in the constitution and control of the more complicated activities. The various partial prob-'' lems will be taken up in the order named : first, a brief statement of the facts of nervous physiology that have a bearing upon psychology; second, an analysis of the facts of consciousness and behaviour to discover the elementary components, and third, a study of the more complicated activities in the light of these simplest forms.

Chapter II

Behaviour must be explained in large part by the action of the nervous system. It does not follow that the action of the brain or of the nervous system is open to observation. On the contrary, one knows nothing under any circumstances of the nerves or of nerve-cells. All that is known is consciousness. The parts that act are altogether hidden, the effects alone are known. So completely is this true that even Aristotle, the most acute observer of antiquity, had no suspicion that the brain had anything to do with mental processes. He held that the brain was merely a gland for the secretion of tears. Its only function in thinking was to cool the animal spirits that originated in the heart and circulated through the brain.

Dependence of Consciousness on the Nervous System. — If one cannot observe the nervous system directly during its action, one may ask what right we have to assert that consciousness is related to it. Two facts bear most strongly in proof of the relation. The first is that behaviour increases in complexity with increase in the complexity of the nervous system. In the rudimentary organisms no nervous system can be distinguished. The same protoplasm that cares for the nutrition of the body

i6 also receives the stimulus and contracts. All parts are alike and each does all things that are necessary to its own welfare. The movements are correspondingly simple and

Fig. I. — Shows the development of pyramidal cells from the cerebrum of vertebrates. {A-D) neurones from an ascending series of vertebrates, (a-e) the stages in the development of cells in man. (A) frog ; (B) lizard ; (C) rat ; (D) man. (a) neuroblast without dendrites; (b) commencing dendrites; (c) dendrites further developed ; (d) first appearance of collaterals ; (e) further development of collaterals and dendrites. (From Howell: ‘Text-book of Physiology,’ Fig. 83, after Ramon y Cajal.)