Harvard Psychological Studies, Volume 1 Containing Sixteen Experimental Investigations from the Harvard Psychological Laboratory.

PART III. AUDITORY REACTIONS OF FROGS.

Chapter 69,862 wordsPublic domain

X. HEARING IN THE FROG.

A. Influences of Sounds in the Laboratory.

After determining the simple reaction time of the green frog to tactual and electrical stimulation, I attempted to do the same in case of auditory stimuli. In this I was unsuccessful because of failure to get the animal to give a motor response which could be recorded. The animal was placed in an experimenting box with a string attached to one hind leg as in the experiments described in Part II., and after it had become accustomed to the situation a sound was made. A wide range of sounds were tried, but to none except the croak of another frog was a motor reaction frequently given. Even a loud noise, such as the explosion of a large pistol cap, caused a visible motor reaction only in rare cases. In fifty trials with this stimulus I succeeded in getting three reactions, and since all of them measured between 230 and 240[sigma] it is perhaps worth while to record the result as indicative of the auditory reaction time. As these were the only measurements obtained, I have no satisfactory basis for the comparison of auditory with other reaction times.

The remarkable inhibition of movement shown by the frog in the presence of strong auditory stimulation, at least what is for the human being a strong stimulus, led me to inquire concerning the limits and delicacy of the sense of hearing in frogs. In the vast quantity of literature on the structure and functions of the sense organs of the animal I have been able to find only a few casual remarks concerning hearing.

In approaching the problem of frog audition we may first examine the structure of the ear for the purpose of ascertaining what sounds are likely to affect the organ. There is no outer ear, but the membrana tympani, or ear drum, covered with skin, appears as a flat disc from 5 to 10 mm. in diameter on the side of the head just back of the eye and a little below it. In the middle ear there is but one bone, the columella, forming the connecting link between the tympanum and the internal ear. The inner ear, which contains the sense organs, consists of a membranous bag, the chief parts of which are the utriculus, the sacculus, the lagena, and the three semicircular canals. The cavity of this membranous labyrinth is filled with a fluid, the endolymph; and within the utriculus, sacculus and lagena are masses of inorganic matter called the otoliths. The auditory nerve terminates in eight sense organs, which contain hair cells. There is no cochlea as in the mammalian ear. The assumption commonly made is that vibrations in the water or air by direct contact cause the tympanic membrane to vibrate; this in turn causes a movement of the columella, which is transmitted to the perilymphatic fluid of the inner ear. The sensory hair cells are disturbed by the movements of the otoliths in the endolymph, and thus an impulse is originated in the auditory nerve which results in a sensation more or less resembling our auditory sensation. It is quite probable that the frog's sense of hearing is very different from ours, and that it is affected only by gross air vibrations. This conclusion the anatomy of the ear supports.

Although there does not seem to be a structural basis for a delicate sense of hearing, one must examine the physiological facts at hand before concluding that frogs do not possess a sense of hearing similar to our own. First, the fact that frogs make vocal sounds is evidence in favor of the hearing of such sounds at least, since it is difficult to explain the origin of the ability to make a sound except through its utility to the species. Granting, however, that a frog is able to hear the croaks or pain-screams of its own species, the range of the sense still remains very small, for although the race of frogs makes a great variety of sounds, any one species croaks within a narrow range.

Having satisfied myself that motor reactions for reaction-time measurements could not be gotten to any ordinary sounds in the laboratory, I tried the effect of the reflex croaking of another frog of the same species. In attempting to get frogs to croak regularly, I tested the effect of removing the brain. The animals are said to croak reflexly after this operation whenever the back is stroked; but for some reason I have never been successful in getting the reaction uniformly. In many cases I was able to make normal animals croak by rubbing the back or flanks, and to this sound the animals under observation occasionally responded by taking what looked like an attitude of attention. They straightened up and raised the head as if listening. In no case have other motor responses been noticed; and the above response was so rare that no reaction-time measurements could be made.

Again, while working with the green frog on habit formation, I one day placed two animals in a labyrinth from which they could escape by jumping into a tank of water. Several times when one frog jumped into the water I noticed the other one straighten up and hold the 'listening' or 'attentive' attitude for some seconds. As the animals could not see one another this is good evidence of their ability to hear the splash made by a frog when it strikes the water.

B. Influence of Sounds in Nature.

In order to learn how far fear and artificial conditions were causes of the inhibition of response to sounds in the laboratory, and how far the phenomenon was indicative of the animal's inability to perceive sounds, I observed frogs in their native haunts.

By approaching a pond quietly, it is easy to get within a few yards of frogs sitting on the banks. In most cases they will not jump until they have evidence of being noticed. Repeatedly I have noted that it is never possible to get near to any frogs in the same region after one has jumped in. In this we have additional proof that they hear the splash-sound. To make sure that sight was not responsible for this on-guard condition in which one finds the frogs after one of their number has jumped into the water, I made observations on animals that were hidden from one another. The results were the same. I therefore conclude that the splash of a frog jumping into the water is not only perceived by other frogs in the vicinity, but that it is a peculiarly significant sound for them, since it is indicative of danger, and serves to put them 'on watch.'

A great variety of sounds, ranging in pitch from a low tone in imitation of the bull frog's croak to a shrill whistle, and in loudness from the fall of a pebble to the report of a pistol, were tried for the purpose of testing their effects upon the animals in their natural environment. To no sound have I ever seen a motor response given. One can approach to within a few feet of a green frog or bull frog and make all sorts of noises without causing it to give any signs of uneasiness. Just as soon, however, as a quick movement is made by the observer the animal jumps. I have repeatedly crept up very close to frogs, keeping myself screened from them by bushes or trees, and made various sounds, but have never succeeded in scaring an animal into a motor response so long as I was invisible. Apparently they depend almost entirely upon vision for the avoidance of dangers. Sounds like the splash of a plunging frog or the croak or pain-scream of another member of the species serve as warnings, but the animals do not jump into the water until they see some sign of an unusual or dangerous object. On one occasion I was able to walk to a spot where a large bull frog was sitting by the edge of the water, after the frogs about it had plunged in. This individual, although it seemed to be on the alert, let me approach close to it. I then saw that the eye turned toward me was injured. The animal sat still, despite the noise I made, simply because it was unable to see me; as soon as I brought myself within the field of vision of the functional eye the frog was off like a flash.

Many observers have told me that frogs could hear the human voice and that slight sounds made by a passer-by would cause them to stop croaking. In no case, however, have such observers been able to assert that the animals were unaffected by visual stimuli at the same time. I have myself many times noticed the croaking stop as I approached a pond, but could never be certain that none of the frogs had seen me. It is a noteworthy fact that when one frog in a pond begins to croak the others soon join it. Likewise, when one member of such a chorus is frightened and stops the others become silent. This indicates that the cessation of croaking is a sign of danger and is imitated just as is the croaking. There is in this fact conclusive evidence that the animals hear one another, and the probability is very great that they hear a wide range of sounds to which they give no motor reactions, since they do not depend upon sound for escaping their enemies.

The phenomenon of inhibition of movement in response to sounds which we have good reason to think the frogs hear, and to which such an animal as a turtle or bird would react by trying to escape, is thus shown to be common for frogs in nature as well as in the laboratory. This inhibition is in itself not surprising, since many animals habitually escape certain of their enemies by remaining motionless, but it is an interesting phenomenon for the physiologist. We have to inquire, for instance, what effects sounds which stimulate the auditory organs and cause the animal to become alert, watchful, yet make it remain rigidly motionless, have on the primary organic rhythms of the organism, such as the heart-beat, respiration, and peristalsis. It is also directly in the line of our investigation to inquire how they affect reflex movements, or the reaction time for any other stimulus--what happens to the reaction time for an electrical stimulus, for example, if a loud noise precede or accompany the electrical stimulus.

For the purpose of determining the range of hearing in the frog, I was driven to study the influence of sounds upon respiration. Although the animals did not make any detectable movement, not even of an eyelid, in response to noises, it seemed not improbable that if the sounds acted as auditory stimuli at all, they would in some degree modify the form or rate of the respiratory movement.

C. Influence of Sounds on Respiration.[16]

[16] For full discussion of the normal respiratory movements of the frog see Martin, _Journal of Physiology,_ Vol. 1., 1878, pp. 131-170.

The method of recording the respiration was the direct transference of the movement of the throat by means of a pivoted lever, one end of which rested against the throat, while the other served as a marker on a revolving drum carrying smoked paper. The frog was put into a small box, visual stimuli were, so far as possible, excluded and the lever was adjusted carefully; a record was then taken for at least half a minute to determine the normal rate of respiration in the absence of the stimulus whose effect it was the chief purpose of the experiment to discover. Then, as soon as everything was running smoothly, the auditory stimulus was given. The following records indicate the effects of a few stimuli upon the rate of breathing:

1. Stimulus, 100 V. tuning fork.

Number of respirations for 10 cm. _before_ stimulus 18.0, 17.0; number of respirations for 10 cm. _after_ stimulus 19.0, 17.3.

The records indicate very little change, and contradict one another. For the same stimulus the experiment was tried of taking the normal respiration record for a complete revolution of the drum, and then at once taking the record for the same length of time (about two minutes) with the tuning-fork vibrating close to the frog. The following result is typical and proves that the sound has little effect.

Number of respirations in a revolution _before_ stimulus: First rev. 88; second rev. 88. Number of respirations in a revolution _during_ stimulus: First rev. 87; second rev. 88.

Concerning the influence of tuning-fork stimuli more will be said later in a consideration of the effects of auditory stimuli upon reactions to visual stimuli.

2. The influence of falling water as an auditory stimulus. Water was allowed to fall about two feet in imitation, first, of a plunging frog, and second, of water falling over rocks. In representing the effect of the stimulus on the rate of respiration, I have given the distance on the drum covered by the ten complete respirations just preceding the stimulus and the ten following it.

10 Respirations. 10 Respirations. _Before_ Stimulus. _After_ Stimulus. 1st Stim. 13.0 cm. 11.8 cm. 2d Stim. 12.7 cm. 12.7 cm.

With a smaller animal.

1st Stim. 5.4 cm. 4.8 cm. 2d Stim. 4.9 cm. 4.7 cm. Average for 5 5.00 cm. 4.86 cm.

_These records show a marked increase in the rate of respiration just after the auditory stimulus is given for the first time._ The stimulus has less effect when repeated after an interval of one or two minutes, and if repeated several times it finally causes no noticeable change. On the whole, the sound of falling water seems to arouse the animals to fuller life. The stimulus appears to interest them, and it certainly accelerates respiration. This is precisely what one would expect from a sound which is of special significance in the life of the animal.

3. In case of a loud shrill whistle inhibition of respiration resulted. This probably means that the frogs were frightened by the sound. Falling water served rather to excite their natural-habitat associations, whereas, the whistle, being an uncommon and unassociated sound, caused fear. It is evident to the casual observer that the frog sometimes inhibits and sometimes increases its respiratory movements when frightened, so the result in this experiment is in no way surprising. I am by no means certain, however, that a longer series of observations on several individuals would give constant inhibitory results. My immediate purpose in the work was to get evidence of hearing; the respiratory changes were of secondary importance, although of such great interest that I have planned a more thorough special study of them for the future.

A few sample results showing the influence of the whistle upon a small bull-frog follow:

Length of 10 Resps. Length of 10 Resps. _Before_ Stimulus in cm. _After_ Stimulus in cm. 1st Stim. 6.0 6.7 2d " 5.4 6.0 3d " 5.9 5.8 1st " 4.7 5.4 2d " 4.4 4.6

As a test-check observation for comparison, the influence of a visual stimulus upon respiration was noted under the same conditions as for the auditory. Effect of turning on electric light over box.

Length in cm. of 10 Resps. Length in cm. of 10 Resps. _Before_ Stimulus. _After_ Stimulus. 4.8 4.4 5.3 4.6 4.5 4.0

These results indicate an increase in the respiration rate due to the visual stimulus.

4. Of the other auditory stimuli used, the pistol-cap explosion gave very irregular results. For one animal it caused acceleration, for another inhibition. There is, however, good evidence that the sounds were heard.

5. The ringing of a bell gave results similer to those for a whistle, and the sound of a 500 S.V. tuning fork usually caused a slight increase in the rate of breathing. In these experiments I therefore have evidence, through their effects upon respiration, of the frog's ability to hear sounds ranging from 50 V. to at least 1,000 V.

The croak of the green frog ranges from 100 to 200 V., so far as I have been able to determine. That of the bull frog is lower, from 50 to 75; and in the leopard frog the range is from 80 to 125. The latter is very different from the green frog in its croaking, in that it croaks whenever disturbed, whereas, the green frog rarely responds in that way to a stimulus.

We are now in a position to say that the failure of frogs to give motor reactions to strong auditory stimuli is not due to their inability to be affected by the stimuli, but is a genuine inhibition phenomenon.

XI. THE EFFECTS OF AUDITORY STIMULI ON VISUAL REACTIONS.

Further experimental evidence of hearing was gotten from some work done to test the influence of sounds upon motor reactions to visual stimuli. Frogs, like most other amphibians, reptiles and fishes, are attracted by any small moving object and usually attempt to seize it. They never, so far as I have noticed, feed upon motionless objects, but, on the other hand, will take almost anything which moves. Apparently the visual stimulus of movement excites a reflex. A very surprising thing to those who are unfamiliar with frog habits is the fear which small frogs have of large ones. Put some green frogs or small bull frogs into a tank with large bull frogs, and the little ones will at once show signs of extreme fear; they jump about in the most excited manner and try hard to escape. The cause of their fear soon appears, since it is usually only a few minutes until the little ones are swallowed by their wide-mouthed, cannibalistic fellows.

It is, moreover, well known that a bit of red flannel fastened to a hook attracts frogs and is an excellent method of capturing them. Red seems to be the color which they most readily notice.

This tendency of the frog to attempt to seize any moving object I made use of to test the value of sounds. By placing a frog in a glass aquarium which was surrounded by a screen, back of which I could work and through a small hole in which I was able to watch the animal without being noticed by it, and then moving a bit of red cardboard along one side of the aquarium, I could get the frog to jump at it repeatedly. In each attempt to get the moving object, the animal struck its head forcibly against the glass side of the aquarium. There was, therefore, reason to think that a few trials would lead to the inhibition of the reaction. Experiment discovered the fact that a hungry frog would usually jump at the card as many as twenty times in rapid succession.

In this reaction to a visual stimulus there appeared good material for testing audition. I therefore arranged a 500 S.V. tuning fork over the aquarium and compared the reactions of animals to the visual stimulus alone, with that to the visual stimulus when accompanied by an auditory stimulus. The tuning-fork sound was chosen because it seemed most likely to be significant to the frog. It is similar to the sounds made by the insects upon which frogs feed. For this reason one would expect that the sight of a moving object and the sound of a tuning-fork would tend to reënforce one another.

The experiments were begun with observations on the effects of moving objects on the respiration. In case of a normal rate of 54 respirations per minute sight of the red object caused an increase to 58. Then the same determination was made for the auditory stimulus. The tuning-fork usually caused an increase in rate. In a typical experiment it was from 65 per minute to 76. The observations prove conclusively that the 500 S.V. sound is heard. My attention was turned to the difference of the environment of the ear in its relation to hearing. Apparently frogs hear better when the tympanum is partially under water than when it is fully exposed to the air.

Having discovered by repeated trials about how vigorously and frequently a frog would react to the moving red card, I tried the effect of setting the fork in vibration a half minute before showing the card. It was at once evident that the sound put the frog on the alert, and, when the object came into view, it jumped at it more quickly and a greater number of times than when the visual stimulus was given without the auditory. This statement is based on the study of only two animals, since I was unable to get any other frogs that were in the laboratory at the time to take notice of the red cardboard. This was probably because of the season being winter. I venture to report the results simply because they were so definite as to point clearly to the phenomenon of the reënforcement of the visual-stimulus reaction by an auditory stimulus.

Concerning the influence of this combining of stimuli on the reaction time, I am only able to say that the reaction to the moving object occurred quicker in the presence of the auditory stimulus. When the red card was shown it was often several seconds before the frog would notice it and attempt to get it, but when the sound also was given the animal usually noticed and jumped toward the moving card almost immediately.

Unfortunately I have thus far been unable to get chronoscopic measurements of the reaction times in this reënforcement phenomenon. I hope later to be able to follow out the interesting suggestions of these few experiments in the study of reënforcement and inhibition as caused by simultaneously given stimuli.

A few observations made in connection with these experiments are of general interest. The frog, when it first sees a moving object, usually draws the nictitating membrane over the eye two or three times as if to clear the surface for clearer vision. Frequently this action is the only evidence available that the animal has noticed an object. This movement of the eye-lids I have noticed in other amphibians and in reptiles under similar conditions, and since it always occurs when the animals have need of the clearest possible vision, I think the above interpretation of the action is probably correct.

Secondly, the frog after getting a glimpse of an object orients itself by turning its head towards the object, and then waits for a favorable chance to spring. The aiming is accurate, and as previously stated the animal is persistent in its attempts to seize an object.

XII. THE PAIN-SCREAM OF FROGS.

While making measurements of the frog's reaction time to electrical stimulation, I noticed that after a few repetitions of a 2-volt, .0001-ampère stimulus an animal would frequently make a very peculiar noise. The sound is a prolonged scream, like that of a child, made by opening the mouth widely. The ordinary croak and grunt are made with closed or but slightly opened mouth. The cry at once reminds one of the sounds made by many animals when they are frightened. The rabbit, for example, screams in much the same way when it is caught, as do also pigs, dogs, rats, mice and many other animals. The question arises, is this scream indicative of pain? While studying reaction time I was able to make some observations on the relation of the scream to the stimulus.

First, the scream is not given to weak stimuli, even upon many repetitions. Second, it is given to such strengths of an electrical stimulus as are undoubtedly harmful to the animal. Third, after a frog has been stimulated with a strong current (two volts), until the scream is given with almost every repetition, it will scream in the same way when even a weak stimulus is applied. If, for instance, after a two-volt stimulus has been given a few times, the animal be merely touched with a stick, it will scream. It thus appears as if the strong stimulus increases the irritability of the center for the scream-reflex to such an extent that even weak stimuli are sufficient to cause the reaction. Are we to say that the weak stimulus is painful because of the increased irritability, or may it be concluded that the reflex is in this case, like winking or leg-jerk or the head-lowering and puffing, simply a forced movement, which is to be explained as an hereditary protective action, but not as necessarily indicative of any sort of feeling. Clearly if we take this stand it may at once be said that there is no reason to believe the scream indicative of pain at any time. And it seems not improbable that this is nearer the truth than one who hears the scream for the first time is likely to think.

The pain-scream is of interest in this consideration of auditory reactions because it increases the range of sounds which we should expect frogs to hear if we grant the probability of them hearing their own voices.

It may be worth while to recall at this point the fact that a whistle from the human lips--the nearest approach to the pain-scream among the sounds which were used as stimuli in the experiments on respiration--caused marked inhibition of respiration. Perhaps this fact may be interpreted in the light of the pain-scream reaction. I may add that I have never seen a frog give a motor reaction to the pain-scream. Thinking it would certainly alarm the animals and cause them to make some movement which would serve for reaction-time measurements, I made repeated trials of its effects, but could never detect anything except respiratory changes.

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STUDIES IN PSYCHOLOGICAL THEORY.

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THE POSITION OF PSYCHOLOGY IN THE SYSTEM OF KNOWLEDGE.

BY HUGO MÜNSTERBERG.

The modern efforts to bring all sciences into a system or at least to classify them, from Bacon to Spencer, Wundt and Pearson have never, if we abstract here from Hegel, given much attention to those questions of principle which are offered by the science of psychology. Of course the psychological separation of different mental functions has often given the whole scheme for the system, the classification thus being too often more psychological than logical. Psychology itself, moreover, has had for the most part a dignified position in the system; even when it has been fully subordinated to the biological sciences, it was on the other hand placed superior to the totality of mental and moral sciences, which then usually have found their unity under the positivistic heading 'sociology.' And where the independent position of psychology is acknowledged and the mental and moral sciences are fully accredited, as for instance with Wundt, psychology remains the fundamental science of all mental sciences; the objects with which philology, history, economics, politics, jurisprudence, theology deal are the products of the processes with which psychology deals, and philology, history, theology, etc., are thus related to psychology, as astronomy, geology, zoölogy are related to physics. There is thus nowhere a depreciation of psychology, and yet it is not in its right place. Such a position for psychology at the head of all 'Geisteswissenschaften' may furnish a very simple classification for it, but it is one which cannot express the difficult character of psychology and the complex relations of the system of mental sciences. The historical and philological and theological sciences cannot be subordinated to psychology if psychology as science is to be coördinated with physics, that is, if it is a science which describes and explains the psychical objects in the way in which physics describes and explains the physical objects. On the other hand, if it means in this central position of mental sciences a science which does not consider the inner life as an object, but as subjective activity needing to be interpreted and subjectively understood, not as to its elements, but as to its meaning, then we should have two kinds of psychology, one which explains and one which interprets. They would speak of different facts, the one of the inner life as objective content of consciousness, as phenomenon, the other of the inner life as subjective attitude, as purpose.

The fact is, that these two sciences exist to-day. There are psychologists who recognize both and keep them separated, others who hold to the one or the other as the only possible view; they are phenomenalists or voluntarists. Mostly both views are combined, either as psychological voluntarism with interposed concessions to phenomenalism or as phenomenalism with the well-known concessions to voluntarism at the deciding points. Further, those who claim that psychology must be phenomenalistic--and that is the opinion of the present writer--do not on that account hold that the propositions of voluntarism are wrong. On the contrary: voluntarism, we say, is right in every respect except in believing itself to be psychology. Voluntarism, we say, is the interpretative account of the real life, of immediate experience, whose reality is understood by understanding its meaning sympathetically, but we add that in this way an objective description can never be reached. Description presupposes objectivation; another aspect, not the natural aspect of life, must be chosen to fulfill the logical purposes of psychology: the voluntaristic inner life must be considered as content of consciousness while consciousness is then no longer an active subject but a passive spectator. Experience has then no longer any meaning in a voluntaristic sense; it is merely a complex of elements. We claim that every voluntaristic system as far as it offers descriptions and explanations has borrowed them from phenomenalistic psychology and is further filled up by fragments of logic, ethics and æsthetics, all of which refer to man in his voluntaristic aspect. We claim, therefore, that such a voluntaristic theory has no right to the name psychology, while we insist that it gives a more direct account of man's real life than psychology can hope to give, and, moreover, that it is the voluntaristic man whose purpose creates knowledge and thus creates the phenomenalistic aspect of man himself.

We say that the voluntaristic theory, the interpretation of our real attitudes, in short teleological knowledge, alone can account for the value and right of phenomenalistic psychology and it thus seems unfair to raise the objection of 'double bookkeeping.' These two aspects of inner life are not ultimately independent and exclusive; the subjective purposes of real life necessarily demand the labors of objectivistic psychology. The last word is thus not dualistic but monistic and the two truths supplement each other. But this supplementation must never be misinterpreted as meaning that the two sciences divide inner experience, as if, for instance, the phenomenalistic study dealt with perceptions and ideas, the voluntaristic with feelings and volitions. No, it is really a difference of logical purpose of treatment and thus a difference of points of view only; the whole experience without exception must be possible material for both. There is no feeling and no volition which is not for the phenomenalist a content of consciousness and nothing else. There is, on the other hand, no perception and no idea which is not, or better, ought not to be for the voluntarist a means, an aim, a tool, an end, an ideal. In that real life experience of which the voluntarist is speaking, every object is the object of will and those real objects have not been differentiated into physical things under the abstract categories of mechanics on the one hand, and psychical ideas of them in consciousness on the other; the voluntarist, if he is consistent, knows neither physical nor psychical phenomena. Phenomenalist and voluntarist thus do not see anything under the same aspect, neither the ideas nor the will.

This difference is wrongly set forth if the antithesis to voluntarism is called intellectualism. Intellectualism is based on the category of judgment, and judgment too is a ideological attitude. Phenomenalism does not presuppose a subject which knows its contents but a subject which simply _has_ its contents; the consciousness which has the thought as content does not take through that the voluntaristic attitude of knowing it and the psychologist has therefore no reason to prefer the thought to the volition and thus to play the intellectualist. If the psychologist does emphasize the idea and its elements, the sensations, it is not because they are vehicles of thought but because their relations to physical objects make them vehicles of communication. The elements of ideas are negotiable and thus through their reference to the common physical world indirectly describable; as the elements of ideas are alone in this position, the psychologist is obliged to consider all contents of consciousness, ideas and volitions alike, as complexes of sensations.

The antithesis is also misinterpreted, or at least wrongly narrowed, if it is called voluntarism _versus_ associationism. Recent discussions have sufficiently shown that the principle of association is not the only possible one for phenomenalistic theories. If associationism is identified with objective psychology, all the well-founded objections to the monopoly of the somewhat sterile principle of association appear as objections to phenomenalism in psychology, and voluntaristic theories, especially those which work with the teleological category of apperception, are put in its place. But without returning to apperceptionism we can overcome the one-sidedness of associationism if full use is made of the means which the world of phenomena offers to theory. The insufficiency of associationism disappears if the content of consciousness is considered as variable not only as to quality and intensity but also as to vividness. This variation of vividness, on the other hand, is no exception from the psychophysical parallelism as soon as the psychical process is considered as dependent not only upon the local and quantitative differences of the sensory process but also upon the motor function of the central physical process. The one-sidedness of the physiological sensory theories has been the hidden reason for the one-sidedness of associationism. The sensory-motor system must be understood as the physical basis of the psychophysical process and the variations in the motor discharge then become conditions of those psychical variations of vividness which explain objectively all those phenomena in whose interest associationism is usually supplemented by apperceptionism. The association theory must thus be given up in favor of an 'action-theory'[1] which combines the consistency of phenomenalistic explanation with a full acknowledgment of the so-called apperceptive processes; it avoids thus the deficiency of associationism and the logical inconsistency of apperceptionism.

[1] H. Münsterberg, 'Grundzüge der Psychologie.' Bd. I., Leipzig, 1900, S. 402-562.

Only if in this way the sciences of voluntaristic type, including all historical and normative sciences, are fully separated from phenomenalistic psychology, will there appear on the psychological side room for a scientific treatment of the phenomena of social life, that is, for sociology, social psychology, folk-psychology, psychical anthropology and many similar sciences. All of them have been in the usual system either crowded out by the fact that history and the other mental sciences have taken all the room or have been simply identified with the mental sciences themselves. And yet all those sciences exist, and a real system of sciences must do justice to all of them. A modern classification has perhaps no longer the right as in Bacon's time to improve the system by inventing new sciences which have as yet no existence, but it has certainly the duty not to ignore important departments of knowledge and not to throw together different sciences like the descriptive phenomenalistic account of inner life and its interpretative voluntaristic account merely because each sometimes calls itself psychology. A classification of sciences which is to be more than a catalogue fulfills its logical function only by a careful disentanglement of logically different functions which are externally connected. Psychology and the totality of psychological, philosophical and historical sciences offer in that respect far more difficulty than the physical sciences, which have absorbed up to this time the chief interest of the classifier. It is time to follow up the ramifications of knowledge with special interest for these neglected problems. It is clear that in such a system sciences which refer to the same objects may be widely separated, and sciences whose objects are unlike may be grouped together. This is not an objection; it indicates that a system is more than a mere pigeon-holing of scholarly work, that it determines the logical relations; in this way only can it indeed become helpful to the progress of science itself.

The most direct way to our end is clearly that of graphic representation wherein the relations are at once apparent. Of course such a map is a symbol and not an argument; it indicates the results of thought without any effort to justify them. I have given my arguments for the fundamental principles of the divisions in my 'Grundzüge der Psychologie' and have repeated a few points more popularly in 'Psychology and Life,' especially in the chapter on 'Psychology and History.' And yet this graphic appendix to the Grundzüge may not be superfluous, as the fulness of a bulky volume cannot bring out clearly enough the fundamental relations; the detail hides the principles. The parallelism of logical movements in the different fields especially becomes more obvious in the graphic form. Above all, the book discussed merely those groups which had direct relation to psychology; a systematic classification must leave no remainder. Of course here too I have not covered the whole field of human sciences, as the more detailed ramification offers for our purpose no logical interest; to subdivide physics or chemistry, the history of nations or of languages, practical jurisprudence or theology, engineering or surgery, would be a useless overburdening of the diagram without throwing new light on the internal relations of knowledge.

Without now entering more fully into any arguments, I may indicate in a few words the characteristic features of the graphically presented proposition. At the very outset we must make it clear that phenomena and voluntaristic attitudes are not coördinated, but that the reality of phenomena is logically dependent upon voluntaristic attitudes directed towards the ideal of knowledge. And yet it would be misleading to place the totality of phenomenalistic sciences as a subdivision under the teleological sciences. Possible it would be; we might have under the sciences of logical attitudes not only logic and mathematics but as a subdivision of these, again, the sciences which construct the logical system of a phenomenalistic world--physics being in this sense merely mathematics with the conception of substance added. And yet we must not forget that the teleological attitudes, to become a teleological science, must be also logically reconstructed, as they must be teleologically connected, and thus in this way the totality of purpose-sciences might be, too, logically subordinated to the science of logic. Logic itself would thus become a subdivision of logic. We should thus move in a circle, from which the only way out is to indicate the teleological character of all sciences by starting not with science but with the strictly teleological conception of life--life as a system of purposes, felt in immediate experience, and not as the object of phenomenalistic knowledge. Life as activity divides itself then into different purposes which we discriminate not by knowledge but by immediate feeling; one of them is knowledge, that is, the effort to make life, its attitudes, its means and ends a connected system of overindividual value. In the service of this logical task we connect the real attitudes and thus come to the knowledge of purposes: and we connect the means and ends--by abstracting from our subjective attitudes, considering the objects of will as independent phenomena--and thus come to phenomenalistic knowledge. At this stage the phenomenalistic sciences are no longer dependent upon the teleological ones, but coördinated with them; physics, for instance, is a logical purpose of life, but not a branch of logic: the only branch of logic in question is the philosophy of physics which examines the logical conditions under which physics is possible.

One point only may at once be mentioned in this connection. While we have coördinated the knowledge of phenomena with the knowledge of purposes we have subordinated mathematics to the latter. As a matter of course much can be said against such a decision, and the authority of most mathematicians would be opposed to it. They would say that the mathematical objects are independent realities whose properties we study like those of nature, whose relations we 'observe,' whose existence we 'discover' and in which we are interested because they belong to the real world. All that is true, and yet the objects of the mathematician are objects made by the will, by the logical will, only, and thus different from all phenomena into which sensation enters. The mathematician, of course, does not reflect on the purely logical origin of the objects which he studies, but the system of knowledge must give to the study of the mathematical objects its place in the group where the functions and products of logical thought are classified. The arithmetical or geometrical material is a free creation, and a creation not only as to the combination of elements--that would be the case with many laboratory substances of the chemist too--but a creation as to the elements themselves, and the value of the creation, its 'mathematical interest,' is to be judged by ideals of thought, that is, by logical purposes. No doubt this logical purpose is its application in the world of phenomena, and the mathematical concept must thus fit the world so absolutely that it can be conceived as a description of the world after abstracting not only from the will relations, as physics does, but also from the content. Mathematics would then be the phenomenalistic science of the form and order of the world. In this way mathematics has a claim to places in both fields: among the phenomenalistic sciences if we emphasize its applicability to the world, and among the teleological sciences if we emphasize the free creation of its objects by the logical will. It seems to me that a logical system as such has to prefer the latter emphasis; we thus group mathematics beside logic and the theory of knowledge as a science of objects freely created for purposes of thought.

All logical knowledge is divided into Theoretical and Practical. The modern classifications have mostly excluded the practical sciences from the system, rightly insisting that no facts are known in the practical sciences which are not in principle covered by the theoretical sciences; it is art which is superadded, but not a new kind of knowledge. This is quite true so far as a classification of objects of knowledge is in question, but as soon as logical tasks as such are to be classified and different aspects count as different sciences, then it becomes desirable to discriminate between the sciences which take the attitude of theoretical interest and those which consider the same facts as related to certain human ends. But we may at first consider the theoretical sciences only. They deal either with the objectified world, with objects of consciousness which are describable and explainable, or with the subjectivistic world of real life in which all reality is experienced as will and as object of will, in which everything is to be understood by interpretation of its meaning. In other words, we deal in one case with phenomena and in the other with purposes.

The further subdivision must be the same for both groups--that which is merely individual and that which is 'overindividual'; we prefer the latter term to the word 'general,' to indicate at once that not a numerical but a teleological difference is in question. A phenomenon is given to overindividual consciousness if it is experienced with the understanding that it can be an object for every one whom we acknowledge as subject; and a purpose is given to overindividual will in so far as it is conceived as ultimately belonging to every subject which we acknowledge. The overindividual phenomena are, of course, the physical objects, the individual phenomena the psychical objects, the overindividual purposes are the norms, the individual purposes are the acts which constitute the historical world. We have thus four fundamental groups: the physical, the psychological, the normative and the historical sciences.

Whoever denies overindividual reality finds himself in the world of phenomena a solipsist and in the world of purposes a sceptic: there is no objective physical world, everything is my idea, and there is no objective value, no truth, no morality, everything is my individual decision. But to deny truth and morality means to contradict the very denial, because the denial itself as judgment demands acknowledgment of this objective truth and as action demands acknowledgment of the moral duty to speak the truth. And if an overindividual purpose cannot be denied, it follows that there is a community of individual subjects whose phenomena cannot be absolutely different: there must be an objective world of overindividual objects.

In each of the four groups of sciences we must consider the facts either with regard to the general relations or with regard to the special material; the abstract general relations refer to every possible material, the concrete facts which fall under them demand sciences of their own. In the world of phenomena the general relations are causal laws--physical or psychical laws; in the world of purposes theories of teleological interrelations--normative or historical; the specific concrete facts are in the world of phenomena objects, physical or psychical objects, in the world of purposes acts of will--specific norms or historical acts. If we turn first to phenomena, the laws thereof are expressed in the physical sciences, by mechanics, physics, chemistry, and we make mechanics the superior as chemistry must become ultimately the mechanics of atoms. In the psychological sciences the science of laws is psychology, with the side-branch of animal psychology, while human psychology refers to individuals and to social groups. Social psychology, as over against individual psychology, is thus a science of general laws, the laws of those psychological phenomena which result from the mutual influence of several individuals.

On the other hand, we have as the special concrete products of the laws, the objects themselves, and the most natural grouping of them may be from whole to part. In the physical world it means that we start from the concrete universe, turning then to the earth, then to the objects on the earth, inorganic and organic. There is here no logical difficulty. Each one of these objects can be considered in three aspects, firstly as to its structure, secondly as to its special laws, that is, the special function of the object as related to the general sciences of physics and chemistry, and thirdly as to its natural development. If we apply these three methods of study to the whole universe we have astronomy, astrophysics and cosmology, to the whole earth, geography, geophysics, geology, to animals, zoölogy, physiology, comparative anatomy, and so on.

The special phenomena in the framework of the psychological sciences group themselves in the same logical order, from the whole to the part. The psychological totality is empirical mankind, and as we select the earth as the one part of the universe which is the habitat of man, so our scientific interest must move from the whole psychical humanity to those phenomena of human life which are the vehicle of our civilization, from mankind to its most important function, the association of man; and as we moved from earth to the special objects on earth, so we may turn from association to the special phenomena which result from association. If we separated further the inorganic from the organic, we must here separate the products of undifferentiated and of differentiated association. The science of mankind is race psychology, the science of the association of man is sociology, the science of the results of undifferentiated association is Völkerpsychologie, folk psychology. The science of products of differentiated association has no special name; its subject matter is the whole of historical civilization considered as a psychological naturalistic phenomenon. As soon as we follow the ramification still further we have to do with the special kinds of these products, that is, with the volitions, thoughts, appreciations and beliefs. In the undifferentiated associations they give us morals and habits, languages and enjoyments and mythological ideas, while the individually differentiated association gives political, legal and economic life, knowledge, art and religion: all of course merely as causal, not as teleological processes, and thus merely as psychological and not as historical material. Here, as with the physical phenomena, the structure, the special laws and the development must be everywhere separated, giving us three sciences in every case. For instance, the study of mankind deals with the differences of mental structure in psychical anthropology, with the special psychical laws in race psychology and with the development in comparative psychology. The chief point for us is that social psychology, race psychology, sociology, folk psychology, etc., are under this system sharply differentiated sciences and that they do not at all overlap the real historical sciences. There is no historical product of civilization which does not come under their method but it must be conceived as a causal phenomenon, not as related to the purposes of the real man, and thus even the development means merely a growing complication of naturalistic processes and not history in the teleological sense.

We turn to the normative sciences. The general theory of the overindividual purposes is metaphysics; the special overindividual acts are those which constitute the normative volitions, connected in the philosophy of morals, the philosophy of state and the philosophy of law, those which constitute the normative thoughts and finally those which constitute the normative appreciations and beliefs, connected in æsthetics and the philosophy of religion. Especial interest belongs to the philosophy of thought. We have discussed the reasons why we group mathematics here and not among the phenomenalistic sciences. We have thus one science which deals critically with the presuppositions of thought, _i.e._ the theory of knowledge or epistemology, which can be divided into the philosophy of physical sciences, the philosophy of psychological sciences, the philosophy of normative sciences and the philosophy of historical sciences. We have secondly the science of the processes of thought dealing with concepts, judgments and reasoning, _i.e._, logic, and we have finally the science of those objects which the thought creates freely for its own purposes and which are independent from the content of the world, _i.e._, mathematics, which leads to the qualitative aspect of general mathematics and the quantitative aspect of concrete mathematics. For our purposes it may be sufficient to separate externally algebra, arithmetic, analysis and geometry. In this way all the philosophical sciences find their natural and necessary place in the system, while it has been their usual lot to form an appendix to the system, incommensurable with the parts of the system itself, even in the case that the other scheme were not preferred, to make ethics, logic, æsthetics, epistemology and metaphysics merely special branches of positivistic sociology and thus ultimately of biology.

In the historical sciences the general theory which stands over against the special acts has a special claim on our attention. We may call it the philosophy of history. That is not identical with the philosophy of historical sciences which we mentioned as a part of epistemology. The philosophy of historical sciences deals with the presuppositions by which historical teleological knowledge becomes logically possible. The philosophy of history seeks a theory which connects the special historical acts into a unity. It has two branches. It is either a theory of the personality, creating a theory of real individual life as it enters as ideological factor into history, or it seeks the unity of entire humanity. The theory of personality shows the teleological interrelation of our purposes; the theory of humanity shows the teleological interrelation of all nations. The name philosophy of history has been used mostly for the theory of humanity only, abstracting from the fact that it has been often misused for sociology or for the psychology of history or for the philosophy of historical sciences--but the name belongs also to the theory of personality. This theory of personality is exactly that second kind of 'psychology' which does not describe and does not explain but which interprets the inner teleological connections of the real man. It is 'voluntaristic psychology' or, as others call it who see correctly the relation of this science to history, 'historical psychology.' It is practically 'apperceptionistic psychology.' The special activities of the historical man divide themselves again into volitions, thoughts, appreciations and beliefs, with their realization in the state, law, economical systems, knowledge, art and religion. Each of these special realizations must allow the same manifoldness in treatment which we found with the special physical or psychical objects; we can ask as to structure, relation to the general view and development. But in accordance with the teleological material the study of the structure here means 'interpretation,' the study of the general relations here means study of the relation to civilization, and the study of the development here means the real history. We have, thus, for the state or law or economy or knowledge or art or religion always one science which interprets the historical systems of state, etc., in a systematic and philological way, one science which deals with its function in the historical world and one which studies biographically and nationally the history of state, law, economical life, science, art or religion.

In the sphere of the practical sciences the divisions of the theoretical sciences must repeat themselves. We have thus applied physical, applied psychological, applied normative and applied historical sciences, and it is again the antithesis of psychological and of historical sciences which is of utmost importance and yet too often neglected. The application of physical sciences, as in engineering, medicine, etc., or the application of normative knowledge in the sciences of criticism do not offer logical difficulty, but the application of psychological and historical knowledge does. Let us take the case of pedagogy or of penology, merely as illustrations. Is the application of phenomenalistic psychology or the application of teleological voluntarism in question? Considering the child, the criminal, any man, as psychophysical apparatus which must be objectively changed and treated, we have applied psychology; considering him as subject with purposes, as bearer of an historical civilization whose personalities must be interpreted and understood and appreciated, then we need applied historical knowledge. In the first case the science of pedagogy is a psycho-technical discipline which makes education mechanical and deprives the teacher of the teleological attitude of inner understanding; in the second case it is a science of real education far removed from psychology. All the sciences which deal with service in the system of civilization, service as teacher, as judge, as social helper, as artist, as minister, are sciences which apply the teleological historical knowledge, and their meaning is lost if they are considered as psycho-technical sciences only.

NOTE: The letters _a, b, c_ below the sciences of Special Objects and Special Acts indicate the three subdivisions that results from the threefold aspects;--of structure(_a_), of relation to the general laws or theories(_b_), and of development(_c_). With regards to physical phenomena, for instances, we have astronomy(_a_), astrophysics(_b_), and cosmology(_c_); or geography(_a_), geophysics(_b_), geology(_c_); or botany(_a_), plant physiology(_b_), phylogenetic development of plants(_c_). In the same way for psychical objects; for instance: structural sociology(_a_), functional sociology(_b_), comparative sociology(_c_); or structure (grammar and syntax) of languages(_a_), psychology of languages(_b_), comparative study of languages(_c_). With regard to the telelogical historical sciences the study of structure takes on here the character of intrepretation; the relation to the general view is here the dependence on civilization and the development is here the real history. We have thus, for instance, the intepretation of Roman law(_a_), dependence of Roman law upon civilization(_b_), history of Roman law(_c_).

End of Project Gutenberg's Harvard Psychological Studies, Volume 1, by Various