Chapter II: Front Matter (2)

Glorious had been the triumph of Positivism in the middle of the eighteenth century when the French encyclopædists were at work, those men who wrote the decrees for the French Revolution. But before the last consequences of the Positivism of the eighteenth century were drawn, the idealistic counter-movement had started. Immanuel Kant gave the signal, he fired the shot heard round the world; and Fichte followed, whose ethical Idealism changed the map of Europe, and his spirit went over the Channel to Carlyle, and finally over the ocean to these shores of New England and spoke with the lips of Emerson. It is unimportant whether Emerson studied the great transcendental systems in the original; he knew Kant and Schelling probably at first through Coleridge, and Fichte through Carlyle. But in the mean time Idealism too had exaggerated its claims, it had gone forward to Hegel, and while Hegelian thought, about 1830, held in an iron grasp the deepest knowledge of his time, his neglect of positive experience demanded reaction, a counter-movement became necessary, and in the midst of the nineteenth century the great idealistic movement with all its philosophical and historical energies went down, and a new Positivism, full of enthusiasm for natural science and technique and full of contempt for philosophy, gained the day. With logical consistency, the spirit of empiricism went from realm to realm. It began with the inorganic world, passed into physics, then forward to chemistry, became more ambitious and conquered the world of organisms, and when biology had said its positivistic say, turned from the outer nature of being to the inner nature. The mind of man was scrutinized with positivistic methods; we came to experimental psychology, and finally, as the highest possible aim of naturalism, to the positivistic treatment of society as a whole, to sociology. But naturalism again has overdone its mission, the world has begun to feel that all the technique and all the naturalistic knowledge makes life not more worth living, that comfort and bigness do not really mean progress, that naturalism cannot give us an ultimate view of the world. And above all, the reaction has come from the midst of the sciences themselves. Twenty years ago scientific work received its fullest applause for the neglect of philosophical demands. Ten years ago the feeling came up that there are after all problems which need philosophy, and to-day philosophers, with good or bad philosophy, are at work everywhere. The physicists, the chemists and the biologists, the astronomers and the mathematicians, the psychologists and the sociologists, the historians and the economists, the linguists and the jurists, all are to-day busily engaged in philosophical enquiries, in enquiries into the conditions of their knowledge, into the presuppositions and methods of their sciences, into their ultimate principles and conceptions; in short, without a word of sudden command, the front has changed its direction. We are moving again towards philosophy, towards Idealism, towards Emerson.

Does all this mean that we are to forget the achievements of natural science, and ignore the results of empirical labor, of labor which has given us an invincible mastery of stubborn nature and an undreamed-of power to calculate all processes of the physical and of the psychical world? No sane man can entertain such a notion. Yes, such ideas would contradict the laws which have controlled the alternation of Idealism and Positivism through the ages of the past. Whenever Positivism returned, it always showed a new face, and the teaching of the intervening period of Idealism was never lost. The naturalism of the middle of the nineteenth century was not at all identical with the naturalism of the middle of the eighteenth; and so Idealism too, as often as it returned to mankind after periods of neglect and contempt, had every time gained in meaning, had every time found increased responsibilities, had every time to do justice to the new problems which the preceding period of Positivism had raised. If Idealism to-day wants to gain new strength, nothing must be lost of all that the last fifty years have brought us, no step must be taken backward, the careful scientific work of the specialists must be encouraged and strengthened, and yet the totality of this work must be brought under new aspects which allow a higher synthesis; yes, a higher synthesis is the problem of the philosopher of to-day. He does not want to be ignorant of natural science and simply to substitute idealistic demands in the place of solid, substantial facts; and he should feel ashamed of the foul compromise with which half-thinkers are easily satisfied, a compromise which allows science its own way till it comes over the boundaries of human emotions, a compromise which accepts rigid causality but pierces little holes in the causal world, making little exceptions here and there that human freedom may be saved in the midst of a world-machinery; a compromise which accepts the social origin of ideals, but claims a mystic knowledge that just our own private pattern will remain in fashion for eternity. No philosophy can live by compromises. If natural science is to be accepted and Idealism is to hold its own, they must be combined, they must form a synthesis in which the one no longer contradicts the other. Just such synthetic harmonization, and not at all a stubborn ignorance of the other side or a compromise with cheap concessions, was the aim of the period from Kant to Emerson. It is merely the naturalistic period which ignores its idealistic counterpart, which delights in its one-sidedness, which is afraid of harmony because it is suspicious of demands for concessions. It is naturalism only which thinks that mankind can walk on one leg.

If we ask where such harmonization can be found, where the great Idealists of the beginning of the last century have sought it, and where our modern philosophy is seeking it again, well aware that by the progress of science in the mean time the difficulties have been multiplied, the logical responsibilities have become gigantic, we cannot do more here than to point out the direction; we cannot go the way. And it is clear, of course, too, that such an answer has its individual shape, and that no one can promise to give a bird's-eye view of the marching movement while he is himself marching among his comrades. But the individual differences are non-essential. The one great tendency, the Emersonian spirit, if it is rightly understood, is common to them all. What has modern philosophy all over the world to say about that threefold claim concerning Nature, Freedom, and Oversoul? What has it to say when natural science has fully said its say and had its fair hearing, and has been approved as sound and welcome?

A philosopher might answer, perhaps, as follows: You Positivists have done wonderfully with your microscopes and your telescopes, with your chronoscopes and spectroscopes; you have measured and weighed and analyzed and described, and finally explained the whole world which you perceive, and there is nothing in space and time and causality which can escape your search. But did not all that work of yours involve certain presuppositions which you had accepted and which it was not your business to look on critically, but which, nevertheless, may be open to enquiry? Your first claims granted, all may follow; but how is it with the first claims? You examine all that is in space and time, but what are space and time? You examine the material substances and the contents of consciousness, but what is consciousness, and what is matter? You seek the special applications of causality, but what is causality? Well, you reply, you give the facts just as you find them; but do you do that really? And what do you mean by saying that you find the facts? Let us look, at least for a moment, at the very simplest facts with which your work begins. You say there are physical objects made up of atoms, and you describe them as a physicist; and there are mental ideas in consciousness made up of sensations, and you describe them as a psychologist; and both, you say, you are finding. But what does it mean, that you find the physical object outside there and the mental idea of the object inside in you; is that really a statement of your immediate experience? The physicist speaks of this table here before me, outside of me; and the psychologist speaks of my idea of this table, enclosed in my consciousness. Both may do well to speak so; but will you make me believe that I find that doubleness in my experience? If I see this table and want to use it, I am not aware of one table of wooden stuff and another in me of mental stuff. I am not aware of a two-ness at all, and if the physicist says that this wooden table is made up of molecules and has in itself no color and no continuity, and that the mental idea in me furnishes all those qualities of color and smoothness, but has no solidity, then they speak of two interesting worlds about which I am anxious to know, but certainly neither of them is the world I live in. If I lean on this table I am not aware of a table in my mind at all. I know the one table only, and this one table has its color and its smoothness.

I know what you will answer. You will say, in your immediate experience there are indeed not two worlds of objects, a physical and a psychical; the real thing to which our interests in life refer is not differentiated into a molecular object outside of us and a sensational object in us, but it is clear that every real thing allows a kind of double aspect; we can consider this table in so far as it is common to all of us, in so far as it is a possible object for every one of us, and in so far as it becomes an object for the individual, and we can then call the objects, in so far as they are common property, physical; and in so far as we take the aspect of individual relations, psychical; and as it must be of the highest importance for our practical purposes to discriminate between those two aspects, we have clearly the right to consider the world from the point of view of both the physicist and the psychologist. It is, of course, an abstraction if we leave out in the one case the one side, in the other case the other side of our objective experience; but we gain by that the possibility of constructing two closed causal systems of which each one must have its special conditions of existence, inasmuch as the one is conceived as related to individuals and the other as independent of individuals.

Very true, we should answer. Something like that saves you completely, justifies fully your claim to separate the physical and the psychical worlds of objects, the world of matter and the world of ideas; but can you deny that you have lost your case, are you not now yourself in the midst of philosophical, methodological discussions, which your physics and psychology themselves cannot settle, yet which must be settled before they can enter into their rights; and above all, do you not yourself see now that your whole physics, for instance, is not at all an account of reality, but merely a certain logical transformation of reality; that you do not find the world of physics at all, just as little as you find the psychical ideas, but that you can merely work over and reshape the reality which you find till you construct out of it your world of matter and your world of consciousness? What you believed you would find you have never found, while your construction of physical things may have been most necessary for your purposes; but do not deny that you have left reality far behind you.

And so it is with all your doings. You tell us proudly, for instance, that you show us the deepest nature of the world by showing us the elements which the object contains, and that you thus bring us at least nearer to the essence of things; and yet if we begin to look into your real achievements, we are disappointed again to find that you are far away from even attempting anything of the kind. You tell us that water is hydrogen and oxygen, and if we say "Prove it," you show us simply that you can transform the water into hydrogen and oxygen, and that you can transform these two elements again into water. Is that really what you promise? We want to know what the thing is, and you show us simply how the one thing can be transformed into another thing; and whenever we turn to your wisdom, it is always the same story. You show us always, and most nicely, how the one goes over into the other, but you never show us what the one or the other really is in itself. For your practical purposes the first may be the most important aspect, but do not make us believe, therefore, that it is the only possible aspect. In short, whether science describes or explains, it never gives us what we find in reality, but makes out of reality a new ideal construction in the service of certain purposes, and never gives us the things as they are, but merely the effects and changes which they produce. Are we still, then, to be deeply impressed with the claim of the naturalist that he alone has the monopoly of knowing reality, while we see now that every step of his leads us away from reality? And have we still to be afraid to raise the voice as philosophers with the claim that reality itself must find its expression, that there must be a science which shall give account of reality as we really find it, of nature before it is made up and repolished for the purposes of the physicist? Only if we have such other account of nature, then only do we speak of that nature in which we live and in which we act, and compared with such an account of the fuller reality, the constructed schematism of the physicist must appear, indeed, as Emerson said, "barren like a single sex." Not the slightest result of natural science is depreciated, not the slightest discovery ignored, if we insist that all these so-called facts have a meaning only under certain artificial conditions which set them apart from the reality of our life; and in this reality lies the interest of the philosopher. We have thus no reason to reproach the scientist so long as the scientist does not fancy that his science gives an account of nature as it really is. Both kinds of work are necessary, and the scientist may well speak, as the squirrel in Emerson's poem:

"Talents differ,
All is well and wisely put;
If I cannot carry forests on my back,
Neither can you crack a nut."

Natural science has to crack our nuts, but philosophy has to carry on its back the flourishing forests of life, in which we wander and breathe. And if Emerson is right, to-day and forever, in claiming that the facts of natural science are not expressions of reality, it is only a small step to see that he was not less right in saying that man is free. Consider man as a particle in the physical universe, consider his actions from the point of view of a causal science, and there is no possibility of escaping materialism and fatalism. We must understand every activity as a necessary outcome of foregoing conditions. Psychology must do so, and physics must do the same. The empirical sciences would be disloyal to their own principles if they allowed the slightest exception. The noblest gesture, the greatest word, the bravest action, must be considered by them under the category of causality. They are necessary effects of all the preceding causes. It may be interesting, it may be fascinating to follow such lines with the enthusiastic energy of scholarly research. But are we really obliged to accept the outcome as an ultimate word concerning the meaning of our freedom? "Forever wells up the impulse of choosing and acting in the soul." Is it really merely an illusion? Has responsibility still its moral value, are we the actors of our actions, are we still good, are we still guilty, when every deed follows as necessary effect? Is not, then, the whole constitution of the world, which has made us, responsible whenever we move our hand for good or for bad?

But we know now where we are standing; we know now that the world of objects, of psychical as well as of physical, is a constructed world, constructed for the purpose of satisfying our demand for causal connection; for that world holds causality because it is the world seen from the point of view of causality; and just as there cannot be anything in that world of physical and psychical objects which is not causally connected, just so it cannot have any meaning at all to ask for causal connection before the world is conceived in the service of this artificial construction. Reality in itself is not causal, and to ask for the causes of the real experience of our inner life has not more meaning than to ask how many pounds is the weight of a virtue, and how many inches is the length of our hopes. But we must go farther. To apply the question of cause and effect to our real will means not only that we apply to the real object a standard which belongs to the artificial or constructed object, but it means above all that we consider as an object something which in reality is not an object at all. The will which the psychologist describes and must describe, the will which has causes and which is thus not free, is a will conceived as an object found in our mind like an idea, something of which we are aware, something whose happening we perceive, and yet if anything is sure it is the immediate experience that we are aware of our will in a way which is absolutely different from the way in which we perceive objects. We do not perceive our will at all, we will it, we strive it, we fight it; yes, we feel ourselves, only in so far as we are the subjects of will. Our will is our personality, which we do not find but which we are, and which stands opposed and separated by the deepest gulf from the world of objects. Those objects are means and purposes of our will, are ends and aims and instruments; but they come in question for us only as we will them, as we like and dislike them, as we approve and reject them. And if we take this world of objects and reconstruct it into the artificial world of physical and psychical things connected by causality, in this very act of reconstruction we feel ourselves as willing, deciding, approving, aiming personalities, whose wills decide, who think the world as causally connected, whose freedom guarantees the value of our conception of a world not free. There is no knowledge but in our judgments; there is no judgment but in our affirming and denying; there is no affirming and denying but in our will. Our will chooses for its purposes to conceive reality as if it were unfree. What a climax of confusion to think that this conception of an unfree world, the conception of science, can itself now condemn the freedom of the will which has chosen. "Freedom is necessary," said Emerson. We can add, necessity itself is merely a purpose determined by freedom. "Intellect annuls fate," Emerson says. We may add, fate is merely an idea of intellect. Let us be psychologists if we want to analyze, to calculate, to explain the unfree man; but let us be philosophers to understand what it means to be a psychologist. Now the synthesis is reached; the real world is free, but we choose for our purposes to conceive the world as unfree, and thus to construct causal sciences.

And if we understand that in reality man is free and that the psychological aspect of man as unfree is a special way of looking on man for special purposes, then suddenly there opens itself before us the vast field of history, and the historical life, which seemed deprived of all interest by the psychological, iconoclastic mood, suddenly wins again a new importance. We feel instinctively that this free man of reality, this man who is a responsible actor of his actions, he only is the agent of history; and history is falsified and cheapened when it is brought down to a causal explanation of psychological man instead of real man. History had become an appendix of sociology, and what great historians aimed at in the interpretation of the few "stout and earnest personalities" seemed lost in favor of a construction in which the great man and the genius rank with the fool as mere extreme variations of psychological averages. Now suddenly do we understand that history has to deal with the world of freedom, that it has not to explain, but to interpret, that it has not to connect the facts by linking causes and effects, but by understanding the meaning of purposes, their agreement and disagreement, their growth and liberty. Now we understand why Fichte, why Carlyle, why Emerson believes in heroes and hero-worship, why Idealism has been at all times the fertile ground for writing history and for making history, while Naturalism has made technique, and thought in an anti-historical spirit. Our time begins again to think historically. It can do so because it again begins to emancipate itself from its positivistic disbelief in man's freedom and from its unphilosophic superstition that causal science alone is science, that we know only when we explain.

And when we at last stand man to man in full freedom, no longer as psycho-physical constructions but as free personalities, and when we debate and try to convince each other, will you deny that Jove stands behind each of us and Jove nods to Jove when we meet? Would it even have a meaning for us to go on with our talk, should we try at all to convince each other if you thought and I thought, each one for himself, that our will is only our personal will, that there is no over-individual will, no Oversoul behind us? Can we discuss at all if we do not presuppose that there is really a truth which we are seeking in common, that there are certain judgments which we are bound to will, which we are obliged to affirm, which we will, but not as individuals, and of which we take for granted that every one whom we acknowledge at all as a personality must will them too; and if you come with the flippant air of the sceptic and tell me, "No, there is no truth, all is only as it appears to me, there is no objective truth," do you not contradict yourself, are you not saying that at least this, your own statement, expresses objective truth; that you will this with a faith and belief that this will of yours is an over-individual will which is, as such, a duty, an obligation for every one who thinks? Every escape is futile. And all the over-individuality that lives in our will towards truth comes to us again in our will towards morality. Do not say sceptically that there is no absolute obligation, that you do not feel bound by an over-individual will in your action, that you will do in every moment what pleases you individually. You cannot even speak this sceptical word without contradicting yourself again, as you demand through the fact of your saying it that we believe that you speak the truth and that you thus feel yourself bound not to lie. If you leave us doubtful whether your word was not a lie, the word itself cannot have any meaning. Do not try to dodge the Oversoul. Men live and fight in its purposes, and men descend to meet. It is as Emerson said, "At first delighted with the triumph of the intellect, we are like hunters on the scent and soldiers who rush to battle; but when the game is run down, when the enemy lies cold in his blood at our feet, we are alarmed at our solitude." Let the sociologists triumphantly reduce the ideals to necessary social products of evolution in the same spirit in which the psychologist eliminates the freedom of the individual; but let us never forget that such a social mechanism is as much an artificial construction necessary for its purposes as is the psycho-physical mechanism of individuality. In that reality with which history deals, in which our freedom lies, there our over-individual will comes from deeper ground than from the soil and the food and the climate. Our logical obligations, our ethical duties, our æsthetic appreciations, our religious revelations, in reality they do not come from without, they come from within; but from within as far as we are souls in the Oversoul. There is no duty in the world but the duty which we will ourselves; no outer force, no training, no custom, no punishment can make us have duties. Duty is our will, it may be the duty to think for the ideal of truth, the duty to feel for the ideal of æsthetics, the duty to act for the idea of morality, the duty to have faith in the ideal of religion; but it is always our own will, and yet not our fanciful, personal, individual will. It is a system of purposes upon whose reality all knowledge of the world, and thus the world as we know it, is dependent forever. The wave of Idealism is rising. The short-sighted superstition of Positivism will not lurk under the roof of a new hall of philosophy. To be a true student of the most scientific, of the most scholarly, of the most insistent philosophy means to respect and to study the sciences, the physical and the psychical sciences, but at the same time to understand that natural science is not the science of reality, that psychology does not touch the freedom of man, that no life has a meaning without the relation to the Oversoul. We cannot write a whole system and a whole text-book on the front of the new building. It must be enough to write there a symbolic word; happy, forever happy, the university which can write over the door of its temple of philosophy the name: Ralph Waldo Emerson.

IV. THE PLACE OF EXPERIMENTAL PSYCHOLOGY

[At the opening of Emerson Hall, December 27, 1905, the American
Psychological Association discussed the relation of psychology to
philosophy; I opened the discussion with the following remarks:]

From the whole set of problems which cluster about psychology and its relation to neighboring sciences, this hour, in which Emerson Hall is completed, and this room, in which I hope to teach psychology to the end of my life, suggest to me most forcibly to-day the one question: Have I been right in housing psychology under this roof? I might have gone to the avenue yonder and might have begged for a psychological laboratory in the spacious quarters of the Agassiz Museum, to live there in peaceful company with the biologists; or I might have persuaded our benefactors to build for me a new wing of the physical laboratory. But I insisted that the experimental psychologists feel at home only where logic and ethics, metaphysics and epistemology keep house on the next floor.

I certainly do not mean that the psychologist ought to mix the records of his instruments with the demands of his speculations, and that he may seek help from the Absolute when the figures of the chronoscope or the curves of the kymograph are doubtful. Experimental psychology is certainly to-day and will be for all future an independent exact discipline with its own problems and methods. No one can insist more earnestly than I do on the demarcation line between the empirical study of mental phenomena and the logical enquiry into the values of life.

Yet I deny that it is a personal idiosyncrasy of mine to try to combine vivid interest in both. There is no antagonism between them; a man may love both his mother and his bride. I am devoted to philosophy, just as I love my native country; and I am devoted to psychology, just as I love the country in which I do my daily work; I feel sure there is no reason for any friction between them.

Of course, on the surface a psychological laboratory has much more likeness to the workshop of the physicist. But that has to do with externalities only. The psychologist and the physicist alike use subtle instruments, need dark rooms and sound-proof rooms, and are spun into a web of electric wires. And yet the physicist has never done anything else than to measure his objects, while I feel sure that no psychologist has ever measured a psychical state. Psychical states are not quantities, and every so-called measurement thereof refers merely to their physical accompaniments and conditions. The world of mental phenomena is a world of qualities, in which one is never a multiple of the other, and the deepest tendencies of physics and psychology are thus utterly divergent.

The complicated apparatus is therefore not an essential for the psychologist. Of course, we shall use every corner of our twenty-four laboratory-rooms upstairs, and every instrument in the new cases--and yet much of our most interesting work is done without any paraphernalia. Three of the doctor-dissertations which our psychological laboratory completed last year consisted of original research in which no instruments were involved; they dealt with memory-images, with associations, with æsthetic feeling, and so on. Yes, when, a short time ago, a Western university asked me how much it would cost to introduce a good practical training-course in experimental psychology, I replied that it would cost them the salary of a really good psychologist, and besides, perhaps, one dollar for cardboard, strings, rulers, colored paper, wire, and similar fancy articles at five cents apiece.

On the other hand, I do not know a psychological experiment which does not need a philosophical background to bring its results into sharp relief. Of course, you will say, the psychologist deals with facts, not with theories, and has to analyze and to describe and to explain those facts. Certainly he has to do all that; only he must not forget that the so-called "fact" in psychology is the product of complex transformations of reality. A will, an emotion, a memory-image, a feeling, an act of attention, of judgment, of decision--these are not found in the way in which stones and stars are noticed. Even if I choose perceptions or sensations as material for my psychological study, and still more when I call them _my_ perceptions and _my_ sensations, I mean something which I have found at the end of a long logical road, not at its starting-point, and that road certainly leads through philosophy. Emerson said wisely, "A philosopher must be more than a philosopher;" we can add: A psychologist must be more than a psychologist. First of all, he must be a philosopher.

What would be the result if our laboratory had moved to the naturalistic headquarters? It would be the beginning of a complete separation from philosophy. Our graduate students would flock to psychological research work without even being aware that without philosophical training they are mere dilettantes. And soon enough a merely psychological doctorate would be demanded. I do not deny at all that such pure psychologists would find enough to do; I should doubt only whether they know what they are doing. There are too many psychologists already who go their way so undisturbed only because they walk like somnambulists on the edge of the roof; they do not even see the real problem; they do not see the depths to which they may fall.

But does the laboratory itself gain from such divorce? Just the contrary. It is evident that everywhere in the world where the psychological laboratory turns to natural science, the experiments deal mostly with sensation, perception, and reaction; while those laboratories which keep their friendship with epistemology emphasize the higher mental functions, experimenting on attention, memory, association, feeling, emotion, thought, and so on. But is it not clear that only the latter work gives to the psychological laboratory a real right to existence, as the former is almost completely overlapped by the well-established interests of the physiologists? If psychology cannot do anything else than that which physiologists like Helmholtz, Hering, Kries, Mach, Bowditch, and the rest have always done so successfully, then experimental psychology had better give up the trade and leave the study of the mind to the students of the organism.

I have said that we ought not to depend on authorities here. Yet one name, I think, ought to be mentioned gratefully in this hour in which the new psychological laboratory is opened for work. I think of Professor Wundt of Leipzig. The directors of the psychological laboratories in Columbia, and Yale, in Clark and Chicago, in Pennsylvania and Cornell, in Johns Hopkins and Washington, in Leland Stanford and Harvard, and many more are his pupils. Some weeks ago, when I did not foresee our present discussion, I told him of Emerson Hall; and a few days ago I got an answer from which, as my closing word, I may quote in translation. Professor Wundt writes to me: "I am especially glad that you affiliated your new psychological laboratory to philosophy, and that you did not migrate to the naturalists. There seems to be here and there a tendency to such migration, yet I believe that psychology not only now, but for all time, belongs to philosophy: only then can psychology keep its necessary independence." Mr. Chairman, these are the words of the father of experimental psychology. I hope they indicate the policy to which Harvard University will adhere forever.

V. THE PSYCHOLOGICAL LABORATORY IN EMERSON HALL

A monumental staircase leads from the first--the lecture-room--floor of Emerson Hall to the second, the library floor; at the two ends of its broad corridor smaller staircases lead to the third floor, the laboratory. Its general division of space is seen at a glance from the sketch of the ground plan (opposite page 1). Eighteen rooms of various sizes with outside windows form a circle around the central hall which is well lighted by large skylights; but at each end of the hall itself two large windowless spaces are cut off and each of these is divided into three dark rooms. We have thus twenty-four rooms, besides coat-room, toilet-rooms, etc. A further stair leads to the wide attic which is mainly a store-room for the institution.

In order that the laboratory should be adaptable to the most diverse purposes, the permanent differentiation of the rooms has been kept in narrow limits. It seemed unwise to give from the first every room to a special line of research, as the preponderance of special interests may frequently shift; there are years when perhaps studies in physiological and comparative psychology make the largest demand and others in which studies in æsthetical and educational psychology stand in the foreground. A thorough-going specialization, by which special rooms are reserved for tactual studies and others for chronoscope work or for kymograph researches, allows of course certain conveniences in the fixed arrangement of instruments and a certain elaboration of equipment that is built in, but it very much impairs the flexibility of the whole laboratory, and has thus not seemed advisable for an institution whose catholic attitude welcomes investigations as different as those contained in this volume.

To be sure certain constant requirements have demanded a special fitting up of one room as a workshop, one room for the more delicate instruments, one for the beginning course in experimental work, a lecture-room for the courses in comparative psychology, a photography-room, a battery-room, a sound-proof room, the chief animal rooms, and the dark rooms. We have seven light-proof rooms, finished in black, of which two have outside windows for heliostats; of the others, four can be used for optical research; the longest one contains the photometer. Six other rooms, including the lecture-room, may be darkened by opaque blinds. One contains a partition with door and a grooved window-frame fitted with screens in which openings of any desired size and shape may be cut. This window is opposite the main door of the room, and opposite this, across the central hall, some sixty feet away, is the door of another dark room; optical stimuli can thus be given from this window to a subject over seventy feet away.

Several rooms are fitted up with special reference to the investigation of the various forms of organic movement, animal behavior and intelligence. As one result of several investigations in animal psychology already pursued here, the laboratory has a considerable number of devices for testing and making statistical studies of the senses and intelligence, methods of learning and emotional reactions of animals.

Adequate provision is made for the keeping of animals in a large, well-lighted, and well-ventilated corner room. Instead of having aquaria built into the room, an aquarium-table eighteen feet long has been constructed to support moveable aquaria of various sizes. Whenever it is desirable for the purposes of an investigation, any of these aquaria may be moved to the research-room of the investigator or to such quarters as the special conditions of the experiment demand.

The vivarium-room contains, in addition to provisions for water-inhabiting animals, cages of a variety of forms and sizes. The largest of these cages, six and a half feet high, six feet wide, and four feet deep, may be used for birds, monkeys, or any of the medium-sized mammals. Cages for rabbits, guinea-pigs, and other small animals are arranged in frames which support four double compartments. Similarly, small cages suitable for mice, rats, and other small rodents are in supporting frames which carry four of the double cages, each of which is removeable and may be carried to the experimenting-room at the convenience of the experimenter.

In a large unheated room above the main laboratory are tanks for amphibians and reptiles. These tanks, since they can be kept at a low temperature during the winter, are very convenient and useful for frogs, tortoises, and similar hibernating animals.

In view of the prime importance of electricity to a modern psychological laboratory, a rather elaborate system of wiring has been designed and built in. The unit of this system is a small delivery-board six inches wide by eight inches high, which carries the following five circuits: _a_, a time-circuit for running magnetic signals; _bb_, two low-tension circuits for chronoscope, bells, signals, etc.; _c_, a high-tension alternating current (110 v. and 60 phases) for alt. current motors, to be used where great constancy of speed is desired; _d_, a high-tension direct current (110 v.) for dir. current motors, where it is desired to vary the speed continuously (by the introduction of resistance). Two such delivery-boards have been set on opposite walls of all except the smallest rooms, which have but one board. Circuits _a_ and _b_ are represented on the board by binding-posts, while the high-tension currents, _c_ and _d_, appear as flush, protected sockets that take a double-pole plug.

Circuit _a_ is a single circuit led from a time-pendulum permanently set in the battery-room, and carried once around the laboratory. It is connected with the _a_ binding-posts of the individual delivery-boards in parallel. It follows that the time-circuit is alike for all the rooms at any one time; but in different hours the pendulum can be adjusted to give various impulse-rates. If an investigation requires some special rate of impulse, the special time-apparatus is set up in the investigator's room and current for it taken from one of the _b_ pairs of posts.

Each _b_ pair goes directly from the delivery-board to the battery-room and ends at a double-pole (telephone type) socket on a large switch-board. Thus every room has two or four direct and independent connections with the battery-room.

The _c_ and _d_ circuits do not come from the battery-room, but from their respective generators that are stationed outside of the building. They are of course connected at the delivery-boards in parallel.

The large switch-board in the battery-room consists of an upper and a lower part. The upper part bears the double-pole sockets from the _b_ posts in all the rooms; the lower part carries some fifty pairs of single-pole sockets that are connected with the batteries stationed near by. These pairs are labelled, and some give a current from cells of the Leclanché type, others of a gravity type. The student has merely to choose the kind and number of cells that he needs, from the lower part, and connect them with one of the double-pole sockets of the upper part which runs to a _b_ pair in his own room. By connecting two double-pole sockets with each other, the student can establish a circuit between any two rooms of the laboratory,--this for purposes of telephonic or other communication. Since every room has two, and most of the rooms have four of the _b_ circuits, the greatest variety and elasticity of service is attained.

The large switch-board further carries a voltmetre and an ammetre, both of the Weston make, which are reached (electrically) from double-pole jacks (sockets) on the upper part of the board. Thus before connecting the current with his room, the student can in a moment measure its amount and intensity. These instruments are of the flushface type, and dead-beat.

All of the rooms are lighted by electricity, and the lighting system is independent of the delivery-boards. Nine of the rooms are provided with soapstone sinks, and six (not including the lavatories and service-room) with enamelled iron or porcelain sinks. All the sinks have two taps and each of these ends with a screw-thread so as to take a tip and rubber hose. The soapstone sinks were specially designed with soapstone drip-boards. This is probably the best material for a research-room, and the porcelain and enamel sinks were put only where a neater appearance was desired, or where chemicals were to be frequently used--as for instance in the battery and photographic rooms. Gas is not used for illumination, but six rooms are provided with jets for the smoking of drums, soldering, brazing, etc.

The instrument-room is equipped with large dust-proof cases for holding the more delicate and valuable instruments. The larger unused pieces are stored, out of sight but readily accessible, in an attic which has a clear floor-space of something more than half the total area of the laboratory. Dust-proof cases for demonstration and class-work material are provided in the lecture- and class-rooms.

The shop contains a wood-working bench with two vices, tool-racks, shelves, drawers, cupboards, and stock-racks, for the use of students; and a 9-in. lathe, circular saw, grinding- and buffing-machine, separate bench, vice, racks, and drawers for the use of the mechanic. The machinery is run by a 5 h.p. electric motor suspended from one of the outside brick walls, on brackets. One who selects the equipment of such a shop has to weigh carefully the respective merits of circular and band saws; the latter undoubtedly lends itself to a greater variety of uses, but it is also a far more dangerous machine to have running in a room to which students are to be given access. This latter consideration determined in the present case the choice of a circular saw. It is quite dangerous enough, and may be used only by, or under the supervision of, the mechanic.

It has been stated on competent authority that a truly sound-proof room cannot be built except under ground. This has not been attempted, but the laboratory contains one room (no. 17) which is virtually sound-proof. A double door separates it from the adjoining experimenter's room, and double doors also separate this from the main hall. The wall between these two rooms consists of two layers of plaster with special deadening material inserted between. Two small tubes, ordinarily stuffed with felt, connect these rooms. When the acoustical stimulus is a tuning-fork, it is placed in a distant room, connected with one of the _b_ circuits of the sound-proof room, and then with a telephone receiver near the subject's ear.

The photographic-room contains the ordinary sink, red lights, shelves, etc. The indirect entrance is light-tight when the door is not closed, so that the experimenter may pass in and out even when developing is going on. This room, like all the others which have no window (except the sound-proof room), has forced ventilation.

The class-room is designed for the experimental training-courses. It has eight of the regular delivery-boards, ten tables, instrument-case, blackboard, and sink.

The lecture-room for specialized courses in comparative and experimental psychology seats eighty students. It is provided with two Bausch and Lomb electric projection-lanterns, horizontal and vertical microscope attachments, and attachment for the projection of opaque objects. On the lecturer's platform, besides the blackboard, projection-screen, and chart-racks (capable of holding twenty charts), is a large demonstration-table provided with a delivery-board, water, gas, sixteen chart-drawers, two other drawers, and three cupboards.

As has been said before, the general psychology course of the University is not given on the laboratory floor, but downstairs in the large lecture-hall with about 400 seats. A number of large demonstration instruments of the laboratory serve the special purpose of this course; this hall too has its own stereopticons.

Our instrumentarium is, of course, in first line, the collection of apparatus bought and constructed through the fourteen years of work. Yet with the new expansion of the institute a considerable number of psychological, physical, and physiological well-tested instruments has been added. Especially in the departments of kymographic, chronoscopic, and optical apparatus the equipment presents a satisfactory completeness; its total value may be estimated to represent about twelve thousand dollars. Yet the place of the laboratory which we appreciate most highly is not the instrument-room but the workshop, in which every new experimental idea can find at once its technical shape and form. Whether those experimental ideas will be original and productive, whether their elaboration will be helpful for the progress of our young science, in short, whether the work in the new laboratory will fulfil the hopes with which we entered it, may be better decided as soon as a few further volumes of the Harvard Psychological Studies shall have followed the present one, which is still from cover to cover a product of Harvard's pre-Emerson-Hall period.

OPTICAL STUDIES

STEREOSCOPIC VISION AND THE DIFFERENCE OF RETINAL IMAGES

BY G. V. HAMILTON

The question which the Laboratory proposed to me for experimental enquiry was one which demanded a definite reply of yes or no. The positive answer seemed a necessary consequence of the traditional psycho-physiological theories, while a certain practical consideration seemed to suggest the negative solution. The question which seems to have been overlooked so far was this: According to the theory of stereoscopic vision two points of light which are seen by each of the two eyes under the same angle appear to lie in the same plane; as soon as the angle for the right eye is larger than that for the left, that is, as soon as the two stimulated retinal points in the right eye are more distant than the two retinal points stimulated in the left eye, the right light-point seems to be farther away than the left one. If we relate them to planes vertical on the ideal binocular fixation-line, the right point lies in a more distant plane. This principle, which, of course, controls all arrangements for stereoscopic effect, is deduced from experiences in which the fixation-line is vertical to the line that connects the nodal points of the two eyes; the plane in which the equally distant points lie is then parallel to the forehead. If, on the other hand, the eyes are turned to the side, that is, if the ideal fixation-line forms an acute angle with the line connecting the eyeballs, the two fixated light-points, which lie in a plane perpendicular to the fixation-line, cannot be seen by the two eyes under the same angle. Any object on my right side is somewhat nearer to my right eye than to my left, and therefore must throw a larger image on my right retina. The two light-points of a plane vertical to the fixation-line give thus with the eyes turned to the right two unequal pairs of retinal stimuli; and the difference of the retinal stimulations is evidently just the same as if the eyes were looking straight forward but the two lights were at different distances. If difference of retinal images really produces the conscious experience of seeing the lights in differently distant planes, vertical to the fixation-line, it follows that with the eyes turned to the right, lights which objectively lie in the same plane must appear subjectively to lie in different distances. The question arises whether the facts correspond to this conclusion. If we look with eyes turned sidewise towards a plane vertical to the direction of seeing, do the points of that plane remain in it for consciousness or do we see them in different planes? We see that practical considerations suggest a "No" to this question, because it would mean that everything which does not lie exactly in front of us must change its plastic form, and this the more strongly the more we see it on our right or our left, and this of course again the more strongly the nearer it is to the eyes, inasmuch as the relative difference of the retinal images must increase with the nearness of the object. If a short-sighted person fixates an object a few centimetres from the eyes strongly turned to the side, the distances in the retinal image of the one eye may be almost the double of those in the other. Under normal conditions the differences would be smaller, but yet everything would be necessarily distorted in its three-dimension shape as soon as it is seen in indirect vision or with sidewise fixation. On the other hand, if the objects keep their three-dimensional relations in spite of sidewise movements, it is evident that the accepted psycho-physiological theory of stereoscopic vision is incomplete and must be revised in a very essential way. The experiment had to decide. Of course the question might be approached experimentally in different ways. It would have been possible, for instance, to study the stereoscopic synthesis of two separate flat pictures seen with the eyeballs in different positions. But we preferred the simplest possible way, seeking the threshold of distance for two parallel vertical edges with eyes turned forward and to the side. We chose edges instead of hanging threads for the purpose of avoiding the possible influence of the apparent thickness of the threads on the judgment of distance. Of course, distance is here never distance from the one or the other eye, but from the centre of the line which connects the two nodal points of the eyes; the two vertical planes whose edges were to be compared stood always vertical on the ideal line of fixation which starts from that central point between the two eyeballs.

The apparatus used in these experiments consists of three parts, viz.:

(1) A plank 2.5 metres x 9.5 centimetres x 4 centimetres, set on edge and screwed to a table at either end.

(2) A head-rest 45 centimetres high, 35 centimetres broad and 15 centimetres deep. Attached to the centre of the lower strip of the frame is a concave trough for the chin. Another trough, shaped to fit over the vertex and with a strip of wood fastened to the front of it for the forehead, slides up or down within the frame. The attachment for the forehead can be moved and fixed at various positions antero-posteriorly. By means of these devices the head can be securely fixed in any position desired without discomfort to the subject.

In order to have the eyes always in the same plane and at a known distance from the apparatus at the other end of the plank, a hole was made in either side of the frame with its centre at a level of the eyes. Extending through the vertical diameter of each hole is a fine wire. Fitted into the inner portion of each hole is a cardboard tube 10 centimetres long: the inner end of each tube contains a vertical wire so arranged that the four wires all fall into a plane at right angles to the long direction of the plank. A mirror at the outer exit of either hole enables the experimenter to align the tips of the subject's corneæ with the wires.