Classics in the History of Psychology

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Christopher D. Green
York University, Toronto, Ontario

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Animal Intelligence

Edward L. Thorndike (1911)



The statements about human nature made by psychologists are of two sorts, -- statements about consciousness, about the inner life of thought and feeling, the 'self as conscious,' the 'stream of thought' and statements about behavior, about the life of man that is left unexplained by physics, chemistry, anatomy and physiology, and is roughly compassed for common sense by the terms 'intellect' and 'character.'

Animal psychology shows the same double content. Some statements concern the conscious states of the animal, what he is to himself as an inner life; others concern his original and acquired ways of response, his behavior, what he is an outside observer.

Of the psychological terms in common use, some refer only to conscious states, and some refer to behavior regardless of the consciousness accompanying it; but the majority are ambiguous, referring to the man or animal in question, at times in his aspect of inner life, at times in his aspect of reacting organism, and at times as an undefined total nature. Thus 'intensity,' 'duration' and 'quality' of sensations, 'transitive' and 'substantive' states and 'imagery' almost inevitably refer to states of conscious- [p. 2] ness. 'Imitation,' 'invention' and 'practice' almost inevitably refer to behavior observed from the outside. 'Perception,' 'attention,' 'memory,' 'abstraction,' 'reasoning' and 'will' are samples of the many terms which illustrate both ways of studying human and animal minds. That an animal perceives an object, say, the sun, may mean either that his mental stream includes an awareness of that object distinguished from the rest of the visual field; or that he reacts to that object as a unit. 'Attention' may mean a clearness, focalness, of the mental state; or an exclusiveness and devotion of the total behavior. It may, that is, be illustrated by the sharpness of objects illumined by a shaft of light, or by the behavior of a cat toward the bird it stalks. 'Memory' may be consciousness of certain objects, events or facts; or may be the permanence of certain tendencies in either thought or action.  'To recognize' may be to feel a certain familiarity and surety of being able to progress to certain judgments about the thing recognized; or may be to respond to it in certain accustomed and appropriate ways. 'Abstraction' may refer to ideas of qualities apart from any consciousness of their concrete accompaniments, and to the power of having such ideas; or to responses to qualities irrespective of their concrete accompaniments, and to the power of making such responses. 'Reasoning' may be said to be present when certain sorts of consciousness, or when certain sorts of behavior, are present. An account of 'the will' is an account of consciousness as related to action or an account of the actions themselves.

Not only in psychological judgments and psychological terms, but also in the work of individual psychologists, this twofold content is seen. Amongst writers in this country, for example, Titchener has busied himself almost [p. 3] exclusively with consciousness 'as such'; Stanley Hall, with behavior; and James, with both. In England Stout, Galton and Lloyd Morgan have represented the same division and union of interests.

On the whole, the psychological work of the last quarter of the nineteenth century emphasized the study of consciousness to the neglect of the total life of intellect and character. There was a tendency to an unwise, if not bigoted, attempt to make the science of human nature synonymous with the science of facts revealed by introspection. It was, for example, pretended that the only value of all the measurements of reaction-times was as a means to insight into the reaction-consciousness, -- that the measurements of the amount of objective difference in the length, brightness or weight of two objects that men could judge with an assigned degree of correctness were of value only so far as they allowed one to infer something about the difference between two corresponding consciousnesses. It was, for example, pretended that experimental methods were not to aid the experimenter to know what the subject did, but to aid the subject to know what he experienced.

The restriction of studies of human intellect and character to studies of conscious states was not without influence on a scientific studies of animal psychology. For one thing, it probably delayed them. So long as introspection was lauded as the chief method of psychology, a psychologist would tend to expect too little from mere studies, from the outside, of creatures who could not report their inner experiences to him in the manner to which he was accustomed. In literature of the time will be found many comments the extreme difficulty of studying the psychology of animals and children. But difficulty exists only in the case of their consciousness. Their behavior, by its simpler [p. 4] nature and causation, is often far easier to study than that of adults. Again, much time was spent in argumentation about the criteria of consciousness, that is, about what certain common facts of behavior meant in reference to inner experience. The problems of inference about consciousness from behavior distracted attention from the problems of learning more about behavior itself. Finally, when psychologists began to observe and experiment upon animal behavior, they tended to overestimate the resulting insight into the stream of the animal's thought and to neglect the direct facts about what he did and how he did it.

Such observations and experiments are, however, themselves a means of restoring a proper division of attention between consciousness and behavior. A psychologist may think of himself as chiefly a stream of consciousness. He may even think of other men as chiefly conscious selves whose histories they report by word and deed. But it is only by an extreme bigotry that he can think of a dog or cat as chiefly a stream or chain or series of consciousness or consciousnesses. One of the lower animals is so obviously a bundle of original and acquired connections between situation and response that the student is led to attend to the whole series --situation, response and connection or bond -- rather than to just the conscious state that may or may not be one of the features of the bond. It is so useful, in understanding the animal, to see what it does in different circumstances and what helps and what hinders its learning, that one is led to an intrinsic interest in varieties of behavior as well as in the kinds of consciousness of which they give evidence.

What each open-minded student of animal psychology at first hand comes thus to feel vaguely, I propose in this essay to try to make definite and clear. The studies [p. 5] reprinted in this volume produced in their author an increased respect for psychology as the science of behavior, a willingness to make psychology continuous with physiology, and a surety that to study consciousness for the sake of inferring what a man can or will do, is as proper as to study behavior for the sake of inferring what consciousness he can or will have. This essay will attempt to defend these positions and to show further that psychology may be, at least in part, as independent of introspection as physics is.

A psychologist who wishes to broaden the content of science to include all that biology includes under the term 'behavior,' or all that common sense means by the 'intellect' and 'character,' has to meet certain objections. The first is the indefiniteness of this content. The indefiniteness is a fact, but is not in itself objectionable. It is true that by an animal's behavior one means facts about the animal that are left over after geometry, physics, chemistry, anatomy and physiology have taken toll, and that are not already well looked after by sociology, economics, history, esthetics and other sciences with certain complex and specialized facts of behavior. It is true that the boundaries of psychology, from physiology on the one hand, and from sociology, economics and the like on the other, become dubious and changeable. But this is in general a sign of a healthy condition in a science. The pretense that there is an impassable cleft between physiology and psychology should arouse suspicion that one or the other science is studying words rather than realities.

The same holds against the objection that, if psychology is science of behavior, it will be swallowed up by biology. When a body of facts treated subjectively, vaguely [p. 6] and without quantitative precision by one science or group of scientists comes to be treated more objectively, definitely and exactly by another, it is of course a gain, a symptom of the general advance of science. That geology may become a part of physics, or physiology a part of chemistry, is testimony to the advance of geology and physiology. Light is no less worthy of study by being found to be explainable by laws discovered in the study of electricity. Meteorology had to reach a relatively high development to provoke the wit to say that "All the science in meteorology is physics, the rest is wind"

These objections to be significant should frankly assert that between physical facts and mental facts, between bodies and minds, between any and all of the animal's movements and its states of consciousness, there is an im-passable gap, a real discontinuity, found nowhere else in science; and that by making psychology responsible for territory on both sides of the gap, one makes psychology include two totally disparate group of facts, things and thoughts, requiring totally different methods of study. This is, of course, the traditional view of the scope of psychology, reiterated in the introductions to the standard books and often accepted in theory as axiomatic.

It has, however, already been noted that in practice psychologists do study facts in disregard of this supposed gap, that the same term refers to facts belonging some on one side of it and some on the other, and that, in animal psychology, it seems very unprofitable to try to keep on one side or the other. Moreover, the practice to which the study of animal and child psychology leads is, if I understand their writings, justified as a matter of theory by Dewey and Santayana. If then, as a matter of scientific fact, human and animal behavior, with or without con- [p. 7] sciousness, seems a suitable subject for a scientific student, we may study it without a too uneasy sense of philosophic heresy and guilt.

The writer must confess not only to the absence of any special reverence for the supposed axiom, but also to the presence of a conviction that it is false, the truth being that whatever feature of any animal, say John Smith, of Homo sapiens, Is studied -- its length, its color of hair, its body temperature, its toothache, its anxiety, or its thinking of 9 X 7 -- the attitude and methods of the student may properly be substantially the same.

Of the six facts in the illustration just given, the last three would by the traditional view be all much alike for and all much unlike any of the first three. The kind of science, physical science, would be potent for the first three and impotent for the last three (save to gives about certain physical facts which 'paralleled' them). Conversely one kind of science, psychology, would by the traditional view deal with the last three, but have nothing about the first three.

But is there in actual fact any such radical dichotomy of these six facts as objects of science? Take any task of science with respect to them, for example, identification. A core of scientific men, including John Smith himself, are asked to identify John's stature at a given moment. Each observes it carefully, getting, let us say, as measures: 72.10 inches, 72.11, 72.05, 72.08, 72.09,72.11, etc.

In the case of color of hair each observes as before, there being brown, light brown, brown, light brown, between light brown and brown, and so forth.

In the case of body temperature, again, each observes as before, there being the same variability in the reports; but John may also observe in a second way, not by observing [p. 8] a thermometer with eyes, but by observing the temperature of his body through other sense-organs so situated that they lead to knowledge of only his own body's temperature. It is important to note that for efficient knowledge of his own body-temperature, John does not use the sense approach peculiar to him, but that available for all observers. He identifies and measures his 'feverishness' by studying himself as he would study any other animal, by thermometer and eye.

In the case of the toothache the students proceed as before, except that they use John's gestures, facial expression, cries and verbal reports, as well as his mere bodily structure and condition. They not only observe the cavities in his teeth, the signs of ulcer and the like, but they also ask him, tapping a tooth, "Does it hurt?" "How long has it hurt?" "Does it hurt very much?" and the like. John, if their equal in knowledge of dentistry, would use the same methods, testing himself, asking himself questions and using the replies made by himself to himself in inner speech. But, as with temperature, he would get data, for his identification of the toothache, from a source unavailable for the others, the sense-organs in his teeth.

It is worth while to consider how they and he would proceed to an exact identification or measure of the intensity of his toothache such as was made of his stature or body-temperature. First, they would need a scale of toothaches of varying intensities. Next, they would need means of comparing the intensity of his toothache with those of this scale to see which it was most like. Given this scale and means of comparison, they would turn John's attention from the original toothache to one of given intensity, and compare the two, both: by his facial expression, gestures and the like, and by the verbal reports made. John would [p. 9] do likewise, reporting to himself instead of to them. The similarity of the procedure to that in studying a so-called physical fact is still clearer if we suppose a primitive condition of the scales of length and temperature. Suppose for example that for the length of a man we had only 'short' or 'tall as a deer,' 'medium' or 'tall as a moose,' and 'tall' or 'tall as a horse'; and for the intensity of the toothache of a man 'little' or' intense as a pin-prick,' 'medium' or 'intense as a knife-cut,' and 'great' or 'in-as a spear-thrust.'  Then obviously the only difference between the identification of the length of a man's body and identification of the intensity of his toothache would be that the latter was made by all on the basis of behavior as well as anatomy, and made by the individual having it on the basis of data from an additional sense-organ. In actual present practice, if observers were asked to identify the intensity of John's toothache on a scale running from zero intensity up, the variability of the reports would be very great in comparison with those of stature or body-temperature. Supposing the most intense toothache to be called K, we might well have reports of from .300 K to .450 K, some observers identifying the fact with a condition one and a half times as intense as that chosen by others. But such a variability might also occur primitive men's judgments of length or temperature.

It is important to note that the accuracy of John's own identification of it depends in any case on his knowledge scale and his power of comparing his toothache therewith. Well-trained outside observers might identify the intensity of John's toothache more accurately than he could.

In the case of John's anxiety, the most striking fact is the low degree of accuracy in identification. The quality of [p. 10] the anxiety and its intensity would both be so crudely measured by present means that even if the observers were from the score of most competent psychologists, their reports would probably be not much better than, say, the descriptions now found in masterpieces of fiction and drama. Science could not tell at all closely how much John's anxiety at this particular time resembled either his anxiety on some other occasion or anything else. This inferiority is due in part to the fact that the manifestations of anxiety in behavior, including verbal reports, are so complicated by facts other than the anxiety itself, by, for example, the animal's health, temperament, concomitant ideas and emotions, knowledge of language, clearness in expression and the like. It is due in part to the very low status of our classification of kinds of anxieties and of our units and scales for measuring the amount of each kind. Hence the variation amongst observers would be even greater than in the case of the toothache, and the confidence of all in their judgments would be less, and far, far less than their confidence in their judgment of John's stature. The best possible present knowledge of John's anxiety, though scientific in comparison with ordinary opinion about it, would seem grossly unscientific in comparison with knowledge of his stature or weight. Knowledge of the anxiety would improve with better knowledge of its manifestations, including verbal reports by John, and with better means of classification and measurement.

John's knowledge of his own anxiety would be in part the same as that of the other observers. He too would judge his condition by its external manifestations, would name its sort and rate its amount on the basis of his own behavior, as he saw his own face, heard his own groans, and read the notes he wrote describing his condition. But he would [p. 11] also, as with the toothache, have data from internal sense-organs and perhaps from centrally initiated neural actions. In so far as he could report these data to himself for use in scientific thought more efficiently than he could report them to the other observers, he would have, as with the toothache, an advantage comparable to the advantage of a criminologist who happened also to be or to have been a thief, or of a literary critic who happened to have written what he judged. It is important to note that only in so as he who has 'immediate experience' of or participates in or is 'directly conscious' of the anxiety, reports it to himself as thinker or scientific student, in common with other nineteen, that this advantage accrues. To really be or have the anxiety is not to correctly know it. An insane man must become sane in order to know his insane condition. Bigotry, stupidity and false reasoning can be understood only by one who never was them or has ceased to be them.

In our last illustration, John's thinking of '9 x 7 equals 63' the effect on John's behavior may be so complicated other conditions in John, and is so subject to the particular conditions which we name John's 'will,' that the observers would often be at loss except for John's verbal report. Note that the observer is restricted to that. If John does the example

in the usual way, it is a very safe inference that he thought 9 x 7 equals 63, regardless of the absence of a verbal report from him. But often there little else to go by. To John himself, on the contrary, it is easier to be sure that he is thinking of 9 x 7 equals 63 than that he has a particular sort and strength of toothache. Consequently if we suppose John to be thinking of that fact while under observation, and the twenty ob- [p. 12] servers to be required to identify the fact he is thinking of, it is sure that there might be an enormous variability in their guesses as to what the fact was and that his testimony might be worth far more than that of all the other nineteen without his testimony. His observation is influenced by the action of the neurones in his central nervous system as theirs is not, and, in the case of the thought '9 x 7 equals 63,' the action of these neurones is of special importance. Our examination of the way science treats these six facts shows no impassable cleft between knowledge of a man's body and knowledge of his mind. Scientific statements about the toothache, anxiety and numerical judgment are in general more variable than statements about length, hair-color and body-temperature, but there is here no difference save of degree. Some physical facts, such as hair-color, eye-color or health, are, in fact, judged more variably than some mental facts, such as rate of adding, accuracy of perception of a certain sort and the like. So far as the lack of agreement amongst impartial observers goes, there is continuity from the identification of a length to that of an ideal.

Scientific judgments about the facts of John's mind also depend, in general, more upon his verbal reports than do judgments about his body. But here also the difference is only of degree. The physician studying wounds, ulcers, tumors, infections and other facts of a man's body may depend more upon his verbal reports than does the moralist who is studying the man's character. Verbal reports too are themselves a gradual and continuous extension of coarser forms of behavior. They signify consciousness no more truly than do signs, gestures, facial expression and the general bodily motions of pursuit, retreat, avoidance or seizure. [p. 13]

Nor is it true that physical facts are known to many observers and mental facts to but one, who is or has or directly experiences them. If it were true, sociology, economics, history, anthropology and the like would be physical sciences or represent no knowledge at all. The kind of knowledge of which these sciences and common judgments of our fellow men are made up is knowledge possessed by many observers in common, the individual of whom the facts is known, knowing the fact part in just the same way that the others know it.

The real difference between a man's scientific judgments about himself and the judgment of others about him is he has added sources of knowledge. Much of what goes on in him influences him in ways other than those in which it influences other men. But this difference isn't coterminous with that between judgments about his 'mind' and about his 'body. As was pointed out in the case of body-temperature, a man knows certain facts about his own body in such additional. ways.

Furthermore, there is no more truth in the statement a man's pain or anxiety or opinions are matters of direct consciousness, pure experience, than in the statement his length, weight and temperature are, or that the sun, moon and stars are. If by the pain we must mean the pain as felt by some one, then by the sun we can mean only the sun as seen by someone. Pain and sun are equally subjects a science of 'consciousness as such.' But if by the sun is meant the sun of common sense, physics and astronomy, the sun as known by any one, then by the pain we mean the pain of medicine, economics and sociology, the pain as known by any one, and by the sufferer long after he was or had it.

All facts emerge from the matrix of pure experience; [p. 14] but they become facts for science only after they have emerged therefrom. A man's anxiety may be the anxiety as directly felt by the man, or as thought of by him, or as thought of by the general consensus of scientific observers. But so also may be his body-temperature or weight or the composition of the blood in his veins. There can be no valid reason other than a pragmatic one for studying a man's anxiety solely as felt by him while studying his body-temperature as thought of by him and others. And the practical reasons are all in favor of studying all facts as they exist for any impartial observer. A man's mind as it is to thinking men is all that thinking men can deal with and all that they have any interest in dealing with.

Finally, the subject-matter of psychology is not sharply marked off from the subject-matter of physiology by being absolutely non-spatial. On the contrary, the toothache, anxiety and judgment are referred unequivocally, by every sane man who thinks of them, to the space occupied by the body of the individual in question. That is the surest fact about them. It is true that we do not measure the length, height, thickness and weight of an animal's pain or anxiety, but neither do we those of his pulse, temperature, health, digestion, metabolism, patellar reflex or heliotropism.

Two noteworthy advantages are secured by the study of behavior. First, the evidence about intellect and character offered by action and the influence of intellect and character upon action are given due attention. Second, the connections of conscious states are studied as well as their composition.

The mind or soul of the older psychology was the cause not only of consciousness, but also of modifiability in thought and action. It was the substance or force in man [p. 15] whereby he was sensitive to certain events, was able to certain movements, and not only had ideas but connected them one with another and with various impressions acts. It was supposed to account for actual bodily action as well as for the action-consciousness. It explained connections between ideas as well as their internal composition. If a modern psychologist defines mind as the a total of consciousness, and lives up to that definition, omits the larger portion of the task of his predecessors. To define our subject-matter as the nature and behavior men, beginning where anatomy and physiology leave off, is, on the contrary, to deliberately assume responsibility for the entire heritage. Behavior includes consciousness and action, states of mind and their connections.

Even students devoted to 'consciousness as such' must admit that the movements of an animal and their connections with other features of his life deserve study, by even their kind of psychologist. For the fundamental means of knowing that an animal has a certain conscious state are knowledge that it makes certain movements and knowledge of what conscious states are connected with those movements. Knowledge of the action-system of an animal its connections is a prerequisite to knowledge of its stream of consciousness.

There are better reasons for including the action-system animal in the psychologist's subject-matter. An animal's conscious stream is of no account to the rest of world except in so far as it prophesies or modifies his action. [1] There can be no moral warrant for studying man's nature unless the study will enable us to control his acts. If a psychologist is to study man's consciousness without relation to movement, he might as well fabricate [p. 16] imaginary consciousnesses to describe and analyze. The lovers of consciousness for its own sake often do this unwittingly, but would scarcely take pride therein!

The truth of the matter is, of course, that an animal's mind is, by any definition, something intimately associated with his connection-system or means of binding various physical activities to various physical impressions. The whole series -- external situations and motor responses as well as their bonds -- must be studied to some extent in order to understand whatever we define as mind. The student of behavior, by frankly accepting the task of supplying any needed information not furnished by physiology, and of studying the animal in action as well as in thought, is surer of getting an adequate knowledge of whatever features of an animal's life may be finally awarded the title of mind.

The second advantage in studying total behavior rather than consciousness as such is that thereby the connection of mental facts one with another and with non-mental facts receive due attention.

The original tendencies to connect certain though feelings and acts with certain situations -- tendencies which we call reflexes, instincts and capacities -- are not themselves states of consciousness; nor are the acquired connections which we call habits, associations of ideas, tendencies to attend, select and the like. No state of consciousness bears within itself an account of when and how it will appear, or of what bodily act will be its sequel. What any given person will think in any given situation is unpredictable by mere descriptions and analyses of previous thoughts each by itself. To understand the when, how and why of states of consciousness one must study other facts than states of consciousness. These non - [p. 17] conscious relations or connections, knowledge of which informs us of the result to come from the action of a given, situation on a given animal, may be expected to be fully of the subject-matter of mental science.

As was noted in the early pages of this chapter, the psychologist commonly does adopt the attitude of treating mind as a system of connections long enough to give some account of the facts of instinct, habit, memory, and the like. But the dogma that psychology deals exclusively with the inner stream of mind-stuff has made these accounts needlessly scanty and vague.

One may appreciate fully the importance of finding outer the attention-consciousness is clearness or is something else, and whether it exists in two or three discrete degrees or in a continuous series of gradations, and still upon the equal importance of finding out to what facts and for what reasons human beings do attend. There would appear, for example, to be an unfortunate limitation study of human nature by the examination of its consciousnesses, when two eminent psychologists, writing elaborate accounts of attention from that point of view, tell us almost nothing whereby we can predict what any given animal will attend to in any given situation, or can cause in any given animal a state of attention to any given fact.

One may enjoy the effort to define the kind of mind-stuff in which one thinks of classes of facts, relations between facts and judgments about facts, and still protest that a balance in the study of intellect demands equal or greater attention to the problems of why any given animal thinks of any given fact, class or relation in any given situation and why he makes this or that judgment about it.

In the case of the so-called action-consciousness the [p. 18] neglect of the connections becomes preposterous. The adventitious scraps of consciousness called 'willing' which may intervene between a situation productive of a given act and the act itself are hopelessly uninstructive in comparison with the bonds of instinct and habit which cause the situation to produce the act. In conduct, at least, that kind of psychology which Santayana calls 'the perception of character' seems an inevitable part of a well-balanced science of human nature. I quote from his fine description of the contrast between the external observation of a mind's connections and the introspective recapitulation of its conscious content, though it is perhaps too pronounced and too severe.

"Perception of Character. -- There is, however, a wholly different and far more positive method of reading the mind, or what in a metaphorical sense is called by that name. This method is to read character. Any object with which we are familiar teaches us to divine its habits; slight indications, which we should be at a loss to enumerate separately, betray what changes are going on and what promptings are simmering in the organism . . . The gift of reading character . . . is directed not upon consciousness but upon past or eventual action. Habits and passions, however, have metaphorical psychic names, names indicating dispositions rather than particular acts (a disposition being mythically represented as a sort of wakeful and haunting genius waiting to whisper suggestions in a man's ear). We may accordingly delude ourselves into imagining that a pose or a manner which really indicates habit indicates feeling instead.

"Conduct Divined, Consciousness Ignored. . . . As the weather prophet reads the heavens, so the man of experience reads other men. Nothing concerns him less than [p. 19] their consciousness; he can allow that to run itself of when he is sure of their temper and habits. A great master of affairs is usually unsympathetic. His observation is not in the least dramatic or dreamful, he does not yield himself to animal contagion or reënact other people's inward experience. He is too busy for that, too intent on his own purposes. His observation, the contrary, is straight calculation and inference, and it sometimes reaches truths about people's character and destiny which they themselves are very far from divining. Such apprehension is masterful and odious to weaklings, who think they know themselves because they indulge in copious soliloquy (which is the discourse of brutes and madmen), but who really know nothing of their own capacity, situation, or fate. [2]

Mr. Santayana elsewhere hints that both psychology and history will become studies of human behavior considered from without, -- a part, that is, of what he calls physics, -- if they are to amount to much.

Such a prediction may come true. But for the present there is no need to decide which is better -- to study an animal's self as conscious, its stream of direct experience, or to study the intellectual and moral nature that causes its behavior in thought and action and is known to many observers. Since worthy men have studied both, both are probably worthy of study. All that I wish to claim is that the right of a man of science to study an animal's intellectual and moral behavior, following wherever the facts lead -- to "the sum total of human experience considered as dependent upon the experiencing person," to the self as conscious, or to a connection-system known to many observers and born and bred in the animal's body.

[1] Unless one assumes telepathic influences.

[2] 'Reason in Common Sense,' p. 154