justments' are made, such as the control of the eye movements, formation of systematic habits of study, ways of looking up words in the dictionary, etc., which can be directly used in acquiring skill in certain.other functions. These part adjustments have been called "identical elements" by Woodworth and Thorndike. Where there are no identical elements in the two functions, training in one does not hasten the process of acquisition in the other.
Increasing the Complexity of the Object Beyond the Point Where Adequate Reaction Can Be Made. — In a narrow sense this problem has been investigated in the laboratory by means of the tachistoscope. This is a device for exposing a series of words, figures or objects simultaneously for a period of time less than that of the reflex eye movement. The experimenter begins by exposing two letters, figures, words or numbers. If the subject can name those correctly or write them down or draw them, the number of objects exposed is increased until his limit is reached. As might be expected, considering the way our word habits and other habits are formed, as many separate words can be reacted to correctly as isolated letters. In general, it has been found that no more than six items can be properly reacted to. The limit, as a rule, ranges between four and six. In hearing, a EXPLICIT BODILY HABITS 291 practical test can be made by getting the subject to repeat a list of numerals given to him orally. The number of numerals pre- sented is increased to the point where errors (omissions, dis- placements, wrong numerals) begin to appear. In the case of normal adults 6-8 numerals can be correctly repeated; in the case of children, defectives, and of certain psychopathic individuals this number cannot be attained. In making any of these tests upon a sense organ the stimuli may be presented either simulta- neously or successively without materially changing the results. The contact sense may be tested by touching the body simul- taneously at several different places. The number of separate points stimulating the individual can be correctly enumerated if they are not in excess of six.
The Number of Habits Which Can Function Simul- taneously.— The inability of the subject to react adequately to a; stimulus which has more than a certain complexity leads us at once into the discussion as to the number of separate activities or habits which can be exercised simultaneously. The fact seems to be that in the broadest sense since the individual acts as a unit only one thing can be done at a time. There seems to be an obvious contradiction in fact in this statement. It will be immediately remarked that women can knit, quilt or sew while engaging in a lively conversation. The answer to this is that the knitting and talking have been learned together and hence they form a part of an organized system. It is more difficult to talk and tele- graph or to talk and play the piano, yet this, too, can be done. It is extremely difficult to talk and typewrite at the same time, yet possibly if the activities were originally learned in that way it could be done. In making all of the finer coordinations as in rifle shooting, expert balancing or trapeze work the final adjust- ment is always made without conversation.
Such considerations lead almost at once into the field of auto- matic writing. So far as the principles in automatic writing are concerned, there is no theoretical difficulty in holding that they are closely similar to knitting and talking, although, of course, the reaction system as a whole is far more complicated. The process of double acquisition, or, better, double functioning, has 292 PSYCHOLOGY 9 been experimentally studied by Downey and Anderson. After considerable work they acquired some skill in the double process of writing a stanza previously memorized while maintaining either silent reading or reading aloud. Two years after acquir- ing this skill the function was retested. There was considerable retention with rapid re-learning. It is safe to say that on account of the effort and tremendous strain involved in simultaneous double acquisition such learning will never become popular.
In psycho-pathology we find many examples of the indepen- dent exercise of part reactions, some of which become highly systematized. We see this systematization possibly in the so- called cases of "multiple personality" or "split personalities": nearly every human being has something in his organization both of Dr. Jekyll and Mr. Hyde. If we assume that for one reason or another the more socialized reactions of Dr. Jekyll so come in conflict with one another that inhibition of reaction on that plane occurs, action will take place through the outlets which are not in conflict. If this goes on for a sufficient length of time there seems to be no reason, according to the general principles of habit formation, why the individual should not become organized upon the level of Mr. Ifyde. (Indeed, if enough suggestions are given to the patient, he may systematize on two or three such levels.) If by the alteration of the individual's environment or by his reeducation, the conflicts in the socialized reaction tend- encies of Dr. Jekyll are removed, we may once more see him reacting permanently as Dr. Jekyll.
There is a purely practical question possibly involved in this discussion. For example, in the cotton mills of the South, chil- dren from fourteen years of age and on are taught to run one loom. As they grow older and become more adept in their work they are given more and more looms to manage. The adjust- ment required is fairly simple, but it involves great eye-strain and extreme nimbleness of movement. There are a number of duties in the electrical world which demand a similar type of adjustment. The question as to the possible number of such operations which can be carried out at one time is, of course, important. In the first place the larger the number of separate EXPLICIT BODILY HABITS 293 operations the individual can conduct simultaneously and effi- ciently the greater is the advantage to the manufacturer, and to the employee if paid on a piece-work basis. On the other hand, it may be extremely detrimental to the organization of the indi- vidual himself. So far no investigations have been made which show just how many such operations can be carried out without loss in efficiency; or whether the number can be increased by the adoption of special training methods; and finally whether the effect of such a splitting of activity is detrimental to the indi- vidual himself.
Habit Fixation. — At the present time there is no satisfactory way of giving an account of the formation of a habit in terms of cause and effect, A good many monographs and special chapters have been devoted to its explanation, but although we know a great deal about the factors which influence the formation of habits, as we shall see later, we cannot state in detail what the course of events is in the inception of any individual habit. Habits! start, as we have seen, with the so-called random move- ments (if the object fails to arouse either positive or negative reaction tendencies no habit can be formed). Among those random movements is one group or combination which, completes the adjustment, the "successful" one. All others, from a super- ficial standpoint, seem to be unnecessary. But it must be remem- bered that the organism cannot respond in any other way than his equipment allows him to. When put in front of a problem the solution to which cannot be effected by an immediate instinc- tive act or by one belonging to his past habit acquisitions, the whole organism begins to work in each and every part but with- out working together. Not only are the arms, legs and trunk active but the heart, stomach, lungs and glands as well. We know that when the new habit is formed the organism as a whole acts smoothly, each part reaction hangs together with every other part reaction, all tending to facilitate and make possible the smooth working of the group of acts effecting the final adjust- ment. The formation of the simplest habit is an enormously com- plicated affair. We are prone to think that the successful act is only a small group of movements involving, for example, only 294 PSYCHOLOGY the hands and the fingers. This is not true. Even so apparently simple a thing as firing a rifle successfully requires many facil- itating part adjustments all over the body. As the right hand picks up the rifle the body parts begin to fall into line — a certain stance is taken so as to brace the body, the back muscles take on a greater tone, the left hand and arm begin to take on the posi- tion of grasping the end of the barrel, the shoulder muscles con- tract, finally the instant before firing respiration is blocked and as the trigger is pulled the body gets ready to withstand the recoil.
The production of such a close-fitting and well-timed group of activities all working together, the end result being- the hitting of the bull 's-eye or the felling of the deer, requires in the begin- ning naturally the display of a large number of "useless? move- ments. But probably on each succeeding attempt to hit the bull 's- eye some 'of these part reactions fall together in such a way as to facilitate succeeding movements. The whole learning stage is thus an active one and something is gained each time the indi- vidual goes through the process. Hence the so-called useless movements are useless only when looked at from the standpoint of the completed habit. They are all necessary in view of the fact that the successful movements could not have appeared in any given trial unless they had been preceded by just those acts which did precede.
Some attempted causal explanations of the process of fixa- tion are as follows: (1) In most cases where random activity finally leads; to success the successful group of acts is always the last one to appear; hence when the next trial is given the last group active in the preceding test (the successful one) is thus the one most recently exercised, therefore, other things being equal, it will be the one most likely to occur first or at least early in the second trial. (2) In view of the fact that the random acts are infinitely varied the successful act is the only one per- formed each time the stimulus is presented. It, therefore, be- comes the most frequently performed movement. (3) By reason of the fact that the final group of acts always brings food, water, removes an irritating object, lessens emotional tension, etc., the new state (attained by the result of the action of the final group) EXPLICIT BODILY HABITS 295 brings heightened metabolism. It is conceivable that those neuro- muscular elements which have just been active, in completing the adjustment have a slightly dilated system of blood-vessels, con- sequently they share more generously than the group functioning earlier in the increased and bettered blood supply. (4) It is possible tha^t when the final group of movements functions and the adjustment is completed, the situation as a whole becomes an emotion-producing one; internal glandular secretions are set free which serve as reinforcers. It is possible to suppose, due to the increased dilatation of the blood-vessels in the elements which have just functioned, that they receive a slightly greater "rein- forcement" (possibly increase in metabolic rate as a result of the increased blood flow to the parts in active use) from the auta- coid agencies than the groups which functioned earlier. One pictures here, of course, the possible action of adrenin in neu- tralizing fatigue products. It should again be emphasized that these are little more than mere speculations. The fact, however, that we must confess to no ready-made explanation of this prob- lem should detract in no way from our zeal in studying the other factors involved in habit formation.
Neural Basis of Habit. — Man is principally a visual and aural animal so far as the acquisition of habits is concerned. We mean by this that these two sense organs initiate the majority of the impulses to which he reacts in a motor way during the acquisition stage of all habit. This is far from saying that the other sense organs are not utilized in the same way or that they may not be. Certainly the contact and the k'inaesthetic senses are important factors in every habit even in the initial stages. Nevertheless, the human animal, if left alone, brings vision to bear wherever possible in forming a habit. When considered purely schematically the relationships involved are quite simple. Watch any adult try to use a visible typewriter for the first time. Give him the printed word CAT. He looks over the keyboard and as soon as C stimulates the eye he strikes the key and looks at the result. He looks back at the copy, repeating the procedure until each letter is written. The activity is initiated at every step by vision. Some activities are necessarily always largely 296 PSYCHOLOGY • executed in the terms in which they were learned, but most acts, regardless of the sense organ used in acquisition, tend as time goes on to approach the kinaesthetic stage. An accomplished piano player rarely looks at his instrument. The "touch" ste- nographer never looks at the keys but only at the copy. Her hands literally run themselves (practically segmental reflexes) unless a breakdown occurs. The moment the wrong letter is struck the chain as a whole is broken and visual-motor adjust- ment takes place. On page 58 we called attention to the fact that every muscle is both -a sense organ and a motor organ. The facts we studied there will explain how activities of great com- plexity can be executed wholly or largely in motor terms. Con- sider the following purely schematic illustration. Let A^ B, C, D, E, F, etc., represent a series of visual objects to each of which we respond with a given group of movements; movements 1 to A, movements 2 to B, movements 3 to C, etc. If the series of re- sponses is learned in an invariable way, the individual after a time gets to the point- where only the first member of the visual series is necessary to produce the responses 1, 2, 3, 4, 5, etc., in their proper order.4 How does this come about? What change has there been in the system? When visual stimulus A is pre- sented movement 1 occurs. But when response 1 is made there arises a kinassthetic impulse. This kinsesthetic impulse has been associated so long with the visual impulse B that it can rouse movement 2 without the visual object B actually striking the eye (substitution of stimulus). Similarly, movements in muscle 2 arouses the kingesthetic impulse which throws muscle 3 into activ- ity. We have outlined the matter so far with respect to normal individuals. The acquisition of habits in defectives of the blind deaf-mute type is very different. Cutaneous impulses take the place of vision and audition during the process of acquisition. This principle which we have so briefly discussed is one of 'the most important in the whole of psychology. By means of im- 1 The so-called touch methods of teaching typewriting abbreviate learn- ing apparently from the start. Contact and kinsesthesis take care of the movements from the beginning of learning, and the eyes are left free to follow the copy. There is no loss in time due to shifting the eyes from, copy the keys and vice versa* EXPLICIT BODILY HABITS 297 pulses from the muscles themselves man becomes partially inde- pendent of the impulses from the so-called higher senses. We see the advantage of this when we have to act in the dark or when we actually lose the use of one of the higher senses. We see the final perfection of the process in thought where we have a substituted word process for practically every object in our environment. These substituted word processes can initiate gen- eral bodily movements exactly as do the visual or auditory stimuli for which they stand.
Possible Short-Circuiting in the Central Nervous Sys- tem.— The question arises, of course, as to whether there is a sim- ilar short-circuiting process in the central nervous system, whether the cortex is involved in both the acquisition and the performance stage of habit. It is conceivable, of course, that the cortex is involved in the acquisition stage, but that as training goes on the lower centers may short-circuit the process. We can- not answer this question definitely at the present time. It is cer- tainly generally assumed that in the acquisition of a habit the so-called sensory (and motor) areas in the cortex are involved, and further that those parts of the brain must remain intact if the habit is to exist undisturbed. For example, it is assumed that in a visual-motor habit the visual and motor areas in the cortex must be intact, that in an auditory-motor habit the audi- tory and motor areas must be without lesion. From some work which Franz and Lashley are doing we are called upon to modify to some extent this general view. Franz has shown that in indi- viduals of the aphasic and paralytic types with serious destruc- tion of nervous (brain) tissue a fairly respectable group of habits may be built up — the subjects can be taught to speak, to knit and sew and to play baseball. This is true even though their speech and motor habits may have been lost for years. Lashley and Franz, working upon the formation of habit in the rat, present the view that one-third of any portion of the cortex as a whole (motor area excluded) can be destroyed without interfering seri- ously with the animal's ability to form habits. If large portions of the cortex are destroyed after the habit is formed, far less serious disturbance is caused than we have been led to believe 298 PSYCHOLOGY hitherto. This view is indicated in the earlier work of Franz on the frontal cerebral lobe of cats and monkeys which was later confirmed by Swift. Franz observed that if parts of the frontal lobes of an animal (cat) that had acquired a habit were extir- pated this previously learned habit was lost, but that the animal could re-acquire this habit and learn new ones. While these facts tend to disprove the early strict views of cortical localization, teaching rather that the brain as a whole is more adaptable than we have believed and that each part is tolerant of a varied type of function, it should not be assumed that the cortex is useless or that its functions are not less important than we had hitherto been led to believe: nor is it possible to conclude from such work that the cortex has the same function over the whole cerebral hemisphere or that the whole fabric of cortical localization has been destroyed. We know beyond question that the precentral gyms is mainly responsible for the cerebral control of motor functions, and that in man at least the cortical representations of the sense organs (sensory areas) cannot be too seriously tam- pered with without bringing grave trouble to the habits which have previously been formed. Our interest here in the problem centers around the possibility of reestablishing certain basal habits connected with the care of the person (eating, drinking, talking), and those connected with simple occupations in indi- viduals who have suffered grave cortical lesion. A few years ago the thought of retraining a paralytic of long standing would not have been seriously entertained.
The Determiners of Acts. — In adult life each single object or situation can call out more than one response. The sight of a dog can cause me to run and climb a tree or to whistle for it to come and be petted. Likewise, the sight of this animal may lead me to go and get food for it, or to muzzle it, or to get my gun and go shooting. The more highly educated the man the larger the number of responses any object can call out. When explicit and implicit vocal responses are considered we can gather some idea of the enormous number of reactions that center around each situation and object. It is this possibility of multiple re- sponse to a single stimulus that makes man's reactions hard to predict in a particular instance. These habits are flexible in EXPLICIT BODILY HABITS 299 the sense that man is prepared to meet any slight change in the situation or object with an appropriate change in the response. The constant shifting of response is seen to best advantage in the verbal parrying and fencing of two men in argument, in the airy persiflage of a conversational kind that goes on between a witty man and woman, or in the encounters between two wrest- lers, fencers, or boxers. So varied is the shading of response that habit seems at first sight to be a poorly chosen term to apply to it. But we neglect the long years of training the individual must gc through with before such varied activity can take place. If we could watch the growth of such conduct we should see that its development is gradual and orderly. In view of the fact that there are so many responses possible, the question as to which will appear upon the incidence of a given stimulus becomes one which we must consider. We can answer this only in a general way and in probable terms. (1) The response most likely to appear is the one which was most recently called out by the object. (2) When recency is not pertinent, the act which has been most frequently connected with the object is the one most likely to be called out. (3) The act called out is likely to be one which is most closely connected with the general setting of the situation as a whole. For example, one taking an ocean voyage with agreeable men and women companions might begin to hop about and dance at the sight of a man with a violin. But if earlier in the morning several conventional ladies had remarked that "to-day is Sunday, no dancing1 will be tolerated," the sight of the man with the violin may lead merely to verbal railing against the blue laws enforced beyond the three-mile limit. We are expected to display churchly behavior, funereal behavior and wedding behavior upon certain occasions. The situation as a whole envelops us and each object in that situation can call out for the time being only a narrowly appropriate and conven- tional type of act. (4) The most important determiners are the situations which the individual has had to come up against during the hours preceding the incidence of the stimulus to which he must now react, and the amount of emotional tension those previous activities have aroused. The usual reactions to a revolver lying on the dresser are possibly to polish and clean it periodi- 300 PSYCHOLOGY ^H cally, but if some one has been rifling your cash drawer or safe from day to day you may, on reaching home, pick up the weapon, load it, return to your office and lie in wait for the intruder. (5) Temporary intra-organic factors tremendously influence our re- actions. The onset of toothache, headache, or indigestion or the beginning of seasickness may temporarily make out of an ordi- narily cheerful individual one from whom normal reactions can- not be obtained. (6) The most important determiner,.of course, is the life history of the individual in the sense that his general and special training, illnesses, disappointments, hobbies, family training and the like develop within him definite attitudes, trends, or slants — to the religious man each new discovery in science is a direct evidence of the beneficence of the Creator; to the scientific man it is an evidence of the keenness and assiduity of the research worker; to the down-trodden each new thing is an added burden which will merely serve to overtax him further.
We thus see that although the possibility of varied response is almost unlimited, yet definite factors are always present which rationalize behavior and give it a causal basis. In the normal individual these factors are so powerfully operative that no other line of conduct at the moment is open to him as long as he remains balanced: it is all but impossible for a balanced human being to be so torn by circumstances that he will throw a brick into his neighbor's window, steal his purse or automobile or kidnap his child. It is alike impossible for him to commit suicide or mutilate himself or others. All of these acts are possible to him in the sense that the necessary coordinations used in committing such crimes are in his repertoire. Yet his total systems of responses are so tied together that the moment he starts to perpetrate any one of them a new situation is created which immediately leads to a different act. Psychologically the individual can act only in line with his training and in conformity with his inherited points of weakness and strength. (We would recall here such factors as constitutional inferiority occurring from many causes but seen most frequently in the offspring of alcoholic, syphilitic and feeble-minded parents.)
EXPLICIT BODILY HABITS 301 B. EETENTION OR "MEMORY" OF EXPLICIT BODILY HABITS.
Introduction. — The term "memory" in psychology, when properly denned, is useful, and can be made to cover a wide series of facts. Take the case of explicit motor habits such as we are now considering*. An individual may learn after a short but varying number of hours of practice to write on the type- writer thirty words of ordinary copy per minute; to send ten words by wireless per minute; or to play eighteen holes of golf in eighteen strokes above bogey. The learner then stops practice for a period of time, either for experimental reasons, or because his environment changes. At the end of that time he again begins to practice. The original learning score is kept and compared with the new score now being obtained. It is found that the last score in the original series (or average of the last several scores) is higher than the present initial score (or average of the first several scores). There has been a certain loss in the efficiency of the function. We might divide all such acquisitions which are allowed to lie fallow, and are then re-learned, into three periods: (1) the learning period (original acquisition), (2) the no-practice period (the interval during which the habit was laid aside), and (3) the re-learning period. The learning period we