Popular Science Monthly/Volume 43/October 1893/The Progress of Psychology
By Prof. JAMES McKEEN CATTELL.
FOUR hundred years ago it was possible for Columbus to discover a new world. The circle of the earth is long since complete, but in the presence of each man is an unexplored world—his own mind. There is no mental geography describing the contents of the mind, still less is there a mental mechanics demonstrating necessary relations of thought. Yet the mind is the beginning and the end of science. Physical science is possible because the mind observes and arranges, and physical science has worth because it satisfies mental needs. The mind being thus the center from which we start and to which we return, there is reason for wonder that we know so little concerning it. Each of the physical and biological sciences includes a large mass of facts admitted by all students, and many theories which by general consent are accepted as working hypotheses. In psychology, on the other hand, there seems to be no common ground continually increasing. The text-books contain speculations which are unverifiable, and often have little to do with psychology. They include descriptions of things which no one could understand from the description, but which every one understands without it. There are often anecdotes, which belong to the nursery. Then, in more recent times, we find accounts of the eye and brain, which are sometimes good physiology, but which seldom increase our knowledge of sensation and thought. It may be added that in the popular mind psychology consists largely of ghosts and mesmeric exhibitions.
But in the midst of confusion there are signs of order. Psychologies are now written which do not range at large through metaphysics, logic, ethics, and aesthetics, or, if they do, the writers at least know where they are wandering. Description and analysis become of greater value as introspection is more careful and words are more exactly defined. When works on physics, physiology, and pathology are sifted, there is found to be a considerable remnant which belongs to psychology. Even "telepathy" and hypnotism contribute their modest quota of facts. Comparative zoölogy, anthropology, philology, history, and art discover interrelations with psychology. Lastly, the attempt has recently been made to apply the methods of natural science, and even the measurements of exact science, in the study of the mind.
The backwardness of psychology is not indeed surprising. Certain material needs must be satisfied before there is time for self-observation. Even the lower animals are concerned with the changes of day and night and the return of summer and winter, with the growth of plants on which they feed and the habits of beasts which prey upon them. Astronomy, physical geography, botany, and zoölogy have their first foundation in remote, prehuman times. When the savage appears, he needs must attend to the external world, whereas self-observation would profit him but little. If his life depend on killing a bird with a stone, he must know the habits of the bird, and even something of the course of projectiles. Should he stop to consider the relation between sensation and movement, he would not survive to tell his thought. Even nowadays, when every one must have exact knowledge of some part, however small, of the material world, there are but few who have time to study their mental life, which indeed goes on none the better for being watched.
The elements of physical science are not only more necessary to life than knowledge of the mind—they are also more easily obtained. The facts of the material world are comparatively constant and accessible to observation. The stars return daily in their courses, and the plants repeat yearly their monotonous lives. Inert matter may be observed and measured more readily than the living body; physics consequently preceded biology in its development. The changes of mental life are more fleeting and obscure than those of the body. It is natural, therefore, that, as biology is more backward than physics, so psychology should be more backward than biology. There was a time when all the sciences were nourished by philosophy. In Greece the philosopher and the man of science were identical, and those who most advanced mathematics and science in the revival of learning are called philosophers. With the increase of knowledge division of labor became necessary, and the separate sciences were defined. Those sciences were first developed which found data ready in the common knowledge of daily life, and which embraced subjects where experiment and measurement could be most readily used. The close relation in which psychology still stands to philosophy is thus explained by its comparative backwardness. This relation is not essentially different from that of the other sciences. Philosophy is not the arithmetical sum of the special sciences, but has a peculiar task. It seeks to investigate the conditions of knowledge, and to form a theory of the ultimate nature and meaning of things. Psychology is no more concerned with these matters than is physics. Experimental and mathematical physics need not and should not investigate the origin and ultimate nature of matter, nor should psychology as a natural science concern itself with the origin, destiny, and meaning of mind. The subject-matter of psychology corresponds exactly to that of any other natural science. As physiology studies the phenomena of the living body, so psychology studies the phenomena of mind. It is often urged as an objection to psychology that the student can observe one mind only, but it is equally true that the student of physics can observe with one mind only. Were mental processes so irregular and idiosyncratic as is sometimes assumed, there would be no science of psychology, but physics would be equally out of the question. Psychology is not concerned with individual peculiarities, but with the laws to which all mental processes are subject. Its position is similar to that of physiology, which studies individual organisms in order to learn general truths concerning nutrition, movement, etc. The problems of psychology are evidently complicated by the fact that individual minds differ. But this difference is largely a matter of comparatively unimportant detail. The position of psychology is not very different from that of other sciences. Should astronomy seek to determine the orbits of all the satellites, of all the planets, of all the suns in the universe, it would have a hopeless task; but, if we understand one solar system, we have an astronomy to a large extent universal.
The methods of psychology are the same as those of other sciences. Science has its beginnings in common knowledge of daily life collected for practical ends. This knowledge is systematized, often in an artificial manner, and facts, often fancies, more remote from daily experience and usefulness are added. Attempts are made to simplify and explain, usually by arbitrary hypotheses. Thus it was thought by the early Greek physicists that the earth is explained by saying that it all consists of water or air or tire. Even in recent times it was thought an explanation to say that water rises in the pump because Nature abhors a vacuum, or that life is explained by the presence of a vital fluid. But as science advances it depends more and more on experiment and measurement. Data are seldom admitted which can not be verified by any competent observer, and mere matters of fact take a subordinate place. Exact science consists almost exclusively of measurements and the relations of quantities.
Psychology until very recently was in the position of science before experiment and measurement had been used. It consisted largely of useless descriptions, artificial classifications, and verbal explanations. A preference was given to matters which are extraordinary and unverifiable. But in the progress of science it has at last become possible to apply experiment and measurement to the mind. We have to-day laboratories of psychology where facts may be discovered, measurements made, and the results verified by every trained student.
To prevent misunderstanding, it may be worth while to notice what is not done in laboratories of psychology. They are not intended for the study of physiology. The functions of the nervous system may throw light on the workings of the mind, but the debt is reciprocal. We know, indeed, more concerning attention, memory, and thought than concerning the cerebral processes which may precede or accompany them. The commonly used term physiological psychology is awkward. There is a science of physiology and a science of psychology, and there are relations between body and mind. But these relations are wider than this—they are between matter and mind. Thus we know that vibrations of a special sort may be accompanied by a sensation which we call blue, but we know almost nothing concerning the corresponding processes in the eye and brain. The, world is one world, and all science is interdependent, but the development of psychology has drawn a sharper line between mental and physical processes than was ever recognized before. The distinctions of material science are comparatively artificial, resting on our ignorance rather than on our knowledge. Whether bodies be as large as planets or as small as atoms is not a matter of great consequence. If we but knew the laws of matter in motion, they would obtain equally in astronomy and chemistry. The phenomena of the living body must in the end be subject to the principles of physics, and physics must in the end become mechanics. But sensation, attention, and feeling can never be reduced to matter in motion. A complete correlation between mental and physical changes. may be established, but the most perfect knowledge of the processes of the brain would of itself throw no light on the nature of thought. The blind man will not learn to see by studying the changes taking place in the combustion of a candle. Psychology can never be made a branch of physiology.
Laboratories of psychology are for the study of mental processes. It would not be possible in a single article to give an account of what has been accomplished by experimental psychology, nor would tables, curves, and mathematical formulæ prove interesting reading. "The plain man," in Bishop Berkeley's phrase, "undebauched by learning," is apt to ask. What is the good of all this? It may, therefore, be better to give several examples of the practical application of the results of experimental psychology. Pure science is not, indeed, an art whose end is to produce changes in the course of Nature. Astronomy is commonly regarded as the noblest of the sciences, but we can not alter the orbits of the planets, and the higher astronomy is not useful in the affairs of daily life. Science is an end in itself, as are the fine arts. It is good because it satisfies mental needs, and makes life better worth the while. But material science, while searching for truth, has not failed to contribute to the practical needs of society. Its applications in the arts and manufactures have guided the course of civilization. One man to-day can do the work which required ten men a hundred years ago, and the poor have now comforts and opportunities which were formerly not within the reach of the rich. In like manner we shall probably find that more exact knowledge of the mind will have many applications in pedagogy, in political science, in medicine, in the fine arts, and, indeed, in the whole conduct of life.
Let us consider pedagogy. Our methods of education have been greatly altered in the past few years, and more changes will follow. But we go forward blindly, not seeing the way, often retracing our steps. The poor children contribute to the progress of educational methods somewhat as the frog contributes to the progress of physiology. But we may hope to replace vague surmises with exact knowledge. In our laboratories of psychology we can test the senses and faculties of children. We can determine whether the course of study is developing or stunting fundamental characteristics, such as accuracy of perception, quickness of thought, memory, reasoning, etc. We can learn what methods best strengthen each of these faculties without injuring the others. The overtasked teacher finds a child slow, and places it with more backward children, which increases its slowness. A more exact test of the child's mind may show that it is indeed slow, but that the slowness is more than counterbalanced by intensity and range. Methods must be applied which will shorten the time of thought, and will not interfere with its force and extent. We can determine what size and composition of class, what length of lesson, session, and term are most favorable. We can learn whether it is better for the student to do a thing, to see it, to hear it, or to read about it. We can never build a road to learning which need not be traveled by the student, but we can build a royal road in the sense that it is the shortest and best of roads. Above all, our tests and measurements will demonstrate the value of learning itself, and tell us whether under given circumstances it is secured by the development or sacrifice of more essential qualities, such as health of body, serenity of mind, common sense, honesty, and kindliness.
In laboratories of psychology not only children but every one can be tested, and small defects or changes in the senses and faculties can be discovered. Psychology may thus become an ally of medicine. Degenerations which escape common observation, and even the practiced eye of the physician, can be detected and measured by scientific methods. The overstrained clergyman or man of business can be told when a holiday is necessary, how long it must last, whether rest or amusement be required. As an example of the co-operation of psychology and medicine, surgery of the brain can be given. The part of the brain which is diseased is determined by psychophysical methods, the skull is opened, the diseased part of the brain is removed, and the patient may be cured. Psychological methods are useful not only in the diagnosis but also in the cure of many diseases. We know much better than formerly how the insane, the vicious, and the criminal should be treated. We know, for example, that social work is far better than solitary confinement. Even diseases not directly dependent on the nervous system may be cured by psychophysical methods—for example, suggesting to the patient in the hypnotic state that he will be cured.
Those in good health may also profit from an examination in a laboratory of psychology. Valuable traits can be determined as well as defects, and the profession and mode of life most suitable to the person can be indicated. As has been suggested by Mr. Galton, such tests would be peculiarly useful in civil-service examinations. They would determine the real qualities and fitness of the candidate in addition to (or in place of) the superficial knowledge temporarily acquired by "cram." While we have but little power to alter the individual character, we could exert great influence on the future of the race. If we determine what traits are valuable, and how these can be developed by suitable marriage, and made universal by early marriage, we may hope for practical results of immense importance. By the development of a code of honor, or by direct encouragement of the parents or the State, degenerative tendencies could be eliminated, and valuable traits could be developed much more rapidly than occurs in the slow course of natural selection. Mr. Galton has shown that the offspring of early marriages will soon supplant the offspring of later marriages. But as things go at present the thoughtless and criminal are apt to have offspring early, while the reliant and mentally endowed postpone marriage until a long course of education is accomplished and a social position is secured.
It is not necessary to dwell on other applications of psychology. Its relation to the fine arts is evident. The external form of art is directly fitted to the senses and its inner essence to the mind. In political economy we need to know more concerning the interest, passions, and needs of the people. Ultimately, we shall be able to determine what distribution of labor, wealth, and power is the best. Indeed, the measurements and statistics of psychology, which at first sight may seem remote from common interests, may in the end become the most important factor in the progress of society. The whole course of life will move forward in straighter and broader channels when we no longer depend on instincts developed by the beast and savage, but on knowledge and reason guiding to an end.
Dr. Baumann, in his recent journey in countries north of Lake Tanganyika, discovered the source of the Kagera or Ruvuvu River in about latitude 3° south, in a lofty range of mountains known as the Mountains of the Moon. The Warundi—whose ancient kings bore the title of Mwezi (Moon), and who looked upon Dr. Baumann as one of their descendants just returned from the moon, and consequently received him with noisy demonstrations expressive of their joy—look upon this spot as sacred. Within a wood close by they used to celebrate the funeral rites of their kings, whom they buried on the top of a mountain rising above the Mountains of the Moon.
Dr. D. G. Brinton has made a study of the Song of the Arval Brethren, a priestly sodality of ancient Rome, of presumed Etruscan origin, which was sung at their annual festival, and has found in it the name of a divinity which is also a divine name among the Libyan tribes of northern Africa, and is perhaps the root of the name of those (the Berber) tribes. This hint of connection between the Etruscans and these peoples is supported by the discovery of the name of "a man of the Tursha" at Gurob, near the Libyan boundary of Egypt, and of an Etruscan ritual book in the same region. The stem Adur, equivalent with that of Tur in Tursha, and with Etrur in Etruria, occurs also in the name Adurmachides—the fighting Adurs—given by Herodotus to a tribe living in the same region."