Movement and Mental Imagery
Chapter 8: The Problem or Purpose
Margaret Floy Washburn
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In the preceding chapter we have considered some of the ways in which movement systems may interact with each other, and associative dispositions, the tendencies of one movement to excite another, may influence one another when they are simultaneously set into action. Upon such mutual influences the wandering of our thoughts at random, the play of fancy, depends. But much of our thinking is not random; it is, rather, directed toward a definite end. Is it possible to explain directed, controlled, purposeful thought, without introducing any new principles and laws beyond those which govern the mutual relations of associative dispositions?
Psychologists in the last few years have been much occupied with this subject of the exact nature of the problem or purpose, as directing the course of mental phenomena. It was Watt (148) who in 1903 first used in the sense which has recently become technical the German word to indicate the idea of a problem to be solved, as affecting the associative dispositions that follow upon its acceptance. The term was used in the same year by Ach (2) to designate certain features of the reaction experiment. For instance, it has long been customary to distinguish in such experiments between the sensorial reaction and the muscular reaction: in the former the reagent's attention is beforehand directed towards the stimulus, which he is instructed to expect and to discriminate accurately when it occurs; in the latter his attention is directed beforehand wholly towards the movement that he is to make when the stimulus occurs. Ach pointed out that this is a difference in the problem, the Aufgabe, which in the sensorial reaction is, "React when the stimulus is fully apprehended," and in the muscular reaction is, "React as quickly as possible." The
( 152) influence of the problem, once attended to, upon subsequent associative dispositions and movements Ach explained by saying that to associative dispositions and perseverative dispositions we must add a third kind of disposition in the nervous system, namely, determining dispositions or tendencies. A determining tendency proceeds from the idea of an end, and is responsible for the fact that the same stimulus may suggest different ideas under the influence of different problems. The strength of determining tendencies differs with individuals; it is modified by opposing associative and perseverative tendencies. An ingenious method of measuring the strength of certain determining tendencies was devised by Ach and has already been mentioned.[1] Associative dispositions between certain syllables were formed by a number of repetitions of the syllables. The observer was then given certain syllables of the series as stimuli, having been previously instructed that instead of responding by the next syllable of the series he was to give a new syllable that rhymed with the stimulus syllable. That is, he was to overcome an associative disposition by means of a determining tendency proceeding from his instructions. If he failed to carry out the instruction, and simply gave the syllable associated with the stimulus in the series learned, then the determining tendency was too weak to overcome the associative disposition. The strength of the associative disposition was measured by the number of repetitions used to form it, and the strength of a determining tendency could be measured by the number of repetitions needed to found an associative disposition that just overcame the determining tendency.
The question for us is evidently, `What is the physiological basis of determining tendencies?' If associative tendencies or dispositions are based on lowered synaptic resistances between the kinesthetic centres excited by the performance, either tentative or full, of one movement and the motor centre belonging to another movement, upon what are determining
( 153) tendencies based? And a necessary step towards the solution of this question is as evidently a consideration of what constitutes a problem idea.
It would seem that the distinguishing characteristic of a problem idea, which differentiates it from other kinds of ideas, is the persistence of its influence. In disordered revery, we fly from one thought to another: each thought is responsible for the occurrence of the next, but beyond the next its influence hardly reaches, except occasionally. Thus we find at the end of our train of fancy that we have reached a conclusion we never anticipated: we started with the thought of the European war and we have arrived at a mental picture of a barn where we hunted for eggs in our childhood. A problem idea, on the other hand, exerts its influence often for a very long time: the problems connected with writing a book pursue us for months and years.
The degree of persistence required of a problem idea's influence of course varies within wide limits. The shortest duration of such influence is demanded when the problem is simply that of attending to a particular aspect of a stimulus about to be given. If an observer is told to notice especially the color of a design that is to be placed before him, the influence of this problem or task need persist only a few seconds. If all problems could be solved so quickly. we might need nothing but the memory after-image to explain their influence. As a matter of fact, Groos (45) in 190-2 suggested that what he called the 'after-function' or `secondary function' of nervous elements accounts for the difference between ordered thought and revery, and prevents us from being always the sport of wandering ideas. His pupil Schaefer (121) undertook to measure the strength of a person's secondary functions as a general individual characteristic, by calling out a stimulus word and requiring the observer to write all the words he thought of during one minute. The number of times the observer broke away from the influence of the starting word was, taken as a measure of the strength of that word's after-effect. But the secondary
( 154) function, or the memory after-image, is something that belongs to ideas whether they are problem ideas or not : for instance, Schaefer finds that ideas with emotional suggestion have much stronger secondary functions than ideas without it. If it is said that problem ideas have stronger secondary functions than ideas that are not problems, the question remains as to the reason for this difference; and besides, the conception of the secondary function or memory after-image process as the source of a problem idea's persistent influence would hold only for very short-lived problems. One could not explain the hold of a complicated mathematical difficulty on the mind, whereby it works itself out through months of labor, by anything so fleeting as the secondary function of the original putting of the question.
Müller (89) and Offner (98) both think that the persistent influence of the problem idea is to be explained by perseveration. It has a spontaneous tendency to recur to the mind, through considerable intervals of time, and not merely immediately after it has first been attended to. But obviously the point to be explained is why problem ideas as such have this perseverative tendency. It is not as uncertain an affair as the perseverative tendency of a tune which `happens' to run in one's head: the human mind would be a very inefficient instrument if its plans and purposes had as fitful a tendency to recur and persist in their influence as the perseverative tendency of a tune. What is it that gives the problem idea such an especially good chance of recurring and persisting? Watt (148) said that the problem idea was simply a greater and stronger `reproduction motive' than other ideas, and that he did not know its physiological basis. Müller appears to think that its relatively permanent influence is due to a combination of associative tendencies; to `constellation.' That is, the problem idea is one which starts into action a movement system so complicated that it naturally takes some time to work itself out. The activity of such a system has a strong tendency to recur. This conception seems to apply well enough to certain kinds
(155) of problems, but not so well to others. It describes the case of a problem which like a complicated mathematical theorem has to be developed step by step, but not the case of the addition of a long column of figures: here the associative system is not complicated at all. The same simple kind of association has to be made to each of the figures in the column and the one before: the constellation involves only three factors, the two numbers and the problem of their sum. If we say that the performance of such a task as this is due simply to the persistent aftereffect of the preceding step in the addition, to the fact that, as it were, we get in the habit of adding, that adding runs in our head, we evidently do injustice to the steady purpose that is in our mind. We do not add because we have got into the habit of adding, simply, but because we formed the `resolution' at the outset to add. In this `resolution' something more than ordinary associative processes, whether simple or complicated, and something more than the perseveration of associative processes, seems to be at work. Thus we find several authorities implying that there is an affective or emotional aspect to the problem idea. Claparède (22) declares that logical thought is distinguished by the presence of a "sentiment of the end." Meumann (81, 82) says that the capacity of fixing attention on the idea of the end is connected with affective life. and has developed this conception most ably in his "Intelligenz and Wille."
We shall take it for granted that the most essential thing about a problem idea, as distinguished from other ideas, is the persistence of its influence, and that to explain this persistence we need to invoke something over and above ordinary associative dispositions: in other words, that an associative tendency becomes a determining tendency through the operation of some factor that is not itself an ordinary associative tendency.
Let us take a very simple case of the operation of a problem idea, that where a person is instructed to direct his attention towards a particular aspect, say, the color, of an impression that is to be given him, and to note whether the impression
( 156) contains a particular color, red. Now, according to our general theory, the words of the instruction set up the tentative movements belonging to the color red. These tentative movements, however, are not set up merely for an instant, but persist until the impression to be judged is actually given; or if they lapse momentarily, when there is a long wait between the giving of the instructions and the presentation of the impression, they renew themselves spontaneously. We may call tentative movements which thus endure and recur, persistent tentative movements. I thin], we shall find that they are characteristic of all cases where a problem idea is operative; of all cases, that is, where mental processes are directed and not random.
If we pass from this very simple problem to the consideration of complexer problems, we shall find it convenient to divide them into two classes. In one class of problems, we have to do with what we have called `sets of movements'; in the other class with what we have called `systems of movements.' In a set of movements, it will be remembered, a number of different movements are associated, each in the same way, with one and the same movement. For instance, all the names of colors are associated with the same word, namely, `color.' The word `color' will call up any or all of the particular color names, such as `red,' `green,' `blue.' These names have no connection with each other except through the common name color or through other common features: there is no necessity that when one thinks of red one should also think of blue or of green unless the movements belonging to color in general are exerting an influence. In a set of movements, the movement associated with all the members of the set is like the string tied around a bundle of straws: without the string, there is no unity. Now in a movement system, on the other hand, the movements are linked among themselves, either in simultaneous or in successive systems. For instance, many persons know the names of the colors in their spectral order: violet, indigo, blue, green, yellow, orange, red. Such a series of words is a movement
( 157) system: the performance of one movement leads directly to the performance of another, and so on.
A simple illustration of a problem that involves sets of movements rather than systems of movements would be the case where a person is instructed to observe the color of a picture to be shown him. He is not told to look out for a particular color, but just to note what color or colors may be present. The persistent tentative movements belonging to `color' tend to excite all the motor centres connected with particular colors: many of these movements are incompatible, of course, so they cannot be actually executed at the same time, even as tentative movements, but they may be excited in rapid succession and thus all be in a state to recur readily when the colors of the impression to be judged actually appear.
Again, suppose a person is put to adding a column of figures. The word `add ' similarly places in readiness a set of tentative movements, those connected with the adding process: for instance the words `two and three are five,' `three and seven are ten.' Or suppose that the task is one that is familiar in the psychological laboratory: suppose a series of words is given to an observer with the instruction that he is to react to each word by giving the word expressing the opposite idea. To ' hi` h' he is to respond `low,' to 'short.' 'long,' and so on. Here. too. evidently, the persistent movements connected with the word `opposite' put in readiness the motor responses connected with a whole set of opposite words.
On the other hand, perhaps the simplest illustration of a problem idea which involves a system of movements rather than a set of movements is the effort to recall a forgotten name. Here one usually tries to reinstate entire situations in which the name was formerly experienced; that is, one tries to recall a whole context, and the parts of the context are linked with each other in the interdependent fashion of movement systems. Of course, one may try to get the name by reconstructing several situations in which the only common element was the name in question: in such a case the systems themselves form a set of
( 158) movements; but each situation is itself of the nature of a movement system. The persistent tentative movements are those of the system, and `constellation,' or the operation of simultaneous systems, is the best means of effecting recollection. The process is the same, only more complicated, in the highest operations of creative thought. When the inventor solves his problem, he does so through the persistent influence of certain tentative movements that set in activity whole systems of movements: each step of his reasoning is dependent, not only on the step immediately before it, but upon the whole series that has preceded. Upon the power of forming such very complicated movement systems creative power rests in part; but also on the power of sticking to one's problem until one has got it solved. This latter capacity relates, evidently, to the same character of persistence in the influences set at work by the problem idea.
Persistent tentative movements, then, are characteristic of the problem idea. Whence do they get their persistence? Partly from perseveration and the memory after-image, but largely from another source.
In the chapter on types of association between movements, we distinguished movement systems as phasic and static. The former are simply complex movements, requiring the coöperation of a number of innervations. The latter are not movements but attitudes, that is, what is required in them is the steady maintenance of innervation. Holding up the head is a static movement system: it requires not only the simultaneous but the continued innervation of a whole set of muscles. In such cases, as Sherrington has pointed out (126, pages 338-39), the stimuli to the continued innervation of the muscles are the kinaesthetic excitations resulting from the innervation of the other muscles in the system, and these kinaesthetic or 'proprioceptive' excitations, instead of ceasing to be effective as stimuli according to the law of sensory adaptation by which the effectiveness of a long-continued stimulus is reduced, seem to be able to preserve their influence unimpaired for long peri-
(159) -ods of time. Two causes, in fact, limit the duration of a static movement system. The first is fatigue. The second is the occurrence of a stimulus which demands of the organism a motor response prepotent, that is, having by inherited arrangement the right of way, over the motor innervations involved in the static system. In the case of those typical static movement systems, the external bodily postures, such as standing or sitting erect, a stimulus leading to actual movement always tends to be prepotent over the static system stimuli. An internal static movement system, not involving the muscles of locomotion, would be less liable to interruption from prepotent stimuli. If an internal static movement system, relatively permanent by virtue of its essential character, can be associated with any other motor excitation, it would have the effect of making the latter persistent, and constantly tending to renew it. In other words, if the motor excitation on which an idea is based can be associated with an internal static movement system, it will acquire the persistence needed to transform the idea into a problem idea.
Now, what happens at the critical moment when an idea is adopted as a problem idea? What, in other words, is the nature of a resolve? What is the difference between merely having the idea of an act occur to one, and deciding that the act shall be carried out?
According to Ach (3) the adoption of a purpose, -that is, the making of a resolve, - which constitutes the difference between the directing or problem idea and an ordinary idea, is characterized by four factors, which lie terms the image moment, the objective moment, the actual moment, and the zuständliche moment, a term that is difficult to translate, but may perhaps be appropriately rendered as `affective moment.' The image moment consists of strain sensations. The objective moment, which may also, rather confusingly, consist of an image, is the idea of the end, and of the means, oftenest verbal, sometimes merely an awareness.[2] The actual moment involves an activity of the self. The I-side of the psychic process be
(160) comes prominent in quite a different way than is the case in other experiences, and in the moment where the will-act is present in its energetic form, a uniquely determined change in the state of the I is experienced. Moreover, this consciousness of the activity of the self involves not merely an `I will,' but an `I really will,' which excludes every other possibility. Finally, the affective moment consists of a conscious attitude of effort. What relation this bears to the strain sensations which formed the image moment is not stated, but we may suppose that the difference is simply that the conscious attitude of effort is unanalyzable, and not to be located as strain sensations are.
It will he seen that the actual moment introduces a factor which cannot he reduced to sensation, image, or affection. The discovery of this factor rests simply upon Ach's interpretation of the introspections of his observers. - o suggestion as to the possible psychophysical basis of this activity of the self is offered.
Meumann's (82) analysis of the resolve also introduces, or discovers, a unique factor. For Ach's actual moment, he substitutes a process of inner assent to the end of the action. Besides the idea of the end and of the means of reaching it, we judge this end and give our assent to it. Moreover, and this is an addition to Ach's actual moment, we must be conscious that this inner assent is the real cause of the voluntary act; that without the assent the act would not be performed. The inner assent is the symptomatic manifestation of "an elementary active reaction of the Ego." Again we are left wholly without any clue as to the physiological process involved.
The fact is that in order for an idea to be accepted as a problem idea, and in consequence to obtain relatively lasting influence upon associative processes, it has in ordinary language to appeal to a need, a desire. All desires are ultimately connected with the great motor outlets of instincts. If we examine introspectively what happens when an idea `arouses a desire' that cannot immediately be gratified, we find, I think, that motor effects of either or both of two different kinds are produced. The one effect (not necessarily first in time) is that we
( 161) `feel restless,' `uneasy.' The restlessness seems to he produced by diffused and shifting motor innervations, which apparently have no useful connection with each other, and seem rather to be the effects of a common cause than to form a true movement system. The other effect that may be connected with the arousal of desire I shall call the activity attitude. In its intenser degrees it is revealed to introspection as the `feeling of effort,' which is recognized as the accompaniment of active attention. Introspection further indicates that it is not due to shifting innervations, but rather to a steady and persistent set of innervations. It appears from introspection, also, to be in its intenser forms a bodily attitude, involving a kind of tense quietness, a quietness due not to relaxation but to a system of static innervations. We should then class it under the head of `static movement systems.'
The writer would like to suggest that a problem idea becomes the starting-point of effective and directed thought towards its solution only when the incipient motor innervation which the problem involves connects itself, not simply with general restlessness and uneasiness, but with the steady innervations of the activity attitude. Through their inherent and characteristic persistence, as members of a static movement system, the problem innervation is kept from lapsing and may continue to exert an influence upon associated motor innervations and to arouse imagery which bears on its solution.
We must, indeed, if such a view be accepted, go a step beyond introspection. The `feeling of effort,' the form in which the activity attitude reveals itself most clearly to introspection, is connected not with smooth and easy thinking but with interruptions and obstacles to the course of thought. If such obstacles are insurmountable, the activity attitude either resolves itself into the shifting movements of restless desire, or drops into an attitude of relaxation. But if the obstacle is successfully surmounted, the activity attitude, we must suppose, does not cease because it is less evident to introspection, but is most effective in securing the persistent influence of the Aufgabe
( 162) when the kinaesthetic sensations to which the activity attitude itself gives rise are not themselves the objects of attention. In fact, just in proportion as it is evident to introspection, that is, attended to for its own sake, it is less effective in securing the persistence of the problem system. Is this only another way of saying that thinking implies active attention and that active attention is characterized by the presence of the consciousness of effort, or the feeling of activity? Yes; but it is saying more: namely, that the motor innervations underlying the 'consciousness of effort' are not mere accompaniments of directed thought, but an essential part of the cause of directed thought. It is the static, mutually reinforcing innervations of an organized movement system which, associating themselves with the incipient innervation set up in connection with the problem idea, keep that excitation effective and prevent it from lapsing. What is required to transform an idea into a problem idea or Aufgabe is the association of the incipient motor excitation which it involves with some excitation relatively static and enduring in its nature. And a determining tendency is an associative disposition one of whose exciting influences is the activity attitude.
All students of the learning process report the great influence of effort, the `determination to improve.' Thus Bryan and Harter (17) say, "It is intense effort that educates"; Johnson (58) ascribes plateaus or periods of no improvement in the learning to pauses in the effort, and Book (13) says that "less effort was actually put into the work at all those stages of practice where little or no improvement was made." Now the actual causative influence of effort on learning has usually been regarded as due to a more or less mysterious will process, of which the bodily attitude characteristic of activity or effort was merely the accompaniment. The theory here suggested is the first, so far as I know, to explain how a bodily attitude like that of effort can actually be the cause of improved mental work, by prolonging, through its own persistent nature, the influence of the problem on associative processes.
( 163)
In the section on "The Effect of Repetition on the Strength of Associative Dispositions," we left unexplained the fact that in learning a series of words or nonsense syllables, a recitation from memory does much more to strengthen the associative dispositions which it brings into play than a new presentation or reading of the series. The reason for this difference would be found, we said, in the different attitudes involved in reciting from memory and merely reading. Following a suggestion from Katzaroff, we find that it is in fact the activity attitude that is, in large measure at least, responsible for the great value of recitations in memorizing. "In the readings," Katzaroff says (61, page 257), "the subject is passive, calm, indifferent; in the recitations he is active, he has to seek, he rejoices when he has found and gets irritated at the syllables which evade his call. Hence a crowd of sentiments of affection for certain syllables, of antipathy for others, which contribute to enrich the associative nexus and favor conservation and reproduction.... When a pupil has read a fable many times without ever reciting it, he is thrown off the track when he has to say it by heart before the teacher: the active attitude in which he finds himself at the moment of the recitation, being different from the passive attitude in which he found himself at the time of the reading, is an obstacle to the revival of his memories." There can be no doubt that while one may not be wholly passive during the reading of a series to be memorized, one has much less of the activity attitude than during the effort to recite. Thus an attempted recitation forms an association between the series as a whole and the attitude of activity, which is of the utmost value when the final recitation is made that is the test of the learning: while a mere reading forms such an association either not at all or in a much less degree.
On this theory it is possible to explain, or at least to find a plausible description of, certain individual variations in the effectiveness of directed thought. The activity attitude, we may suppose, will not ordinarily be set up in connection with an idea that does not, directly or indirectly, appeal to some
( 164) instinct. An idea that does so appeal may stir up merely a state of unrest, involving diffuse and shifting innervations. In certain individuals, this is the common result. Owing to causes lying in his physiological constitution and not accessible to his consciousness, ideas in such a person habitually set up unrest rather than activity attitudes: they come
" Close enough to stir his brain
And to vex his heart in vain."
In other natures, unrest quickly yields place to the fruitful and useful attitude of activity; while still others are so phlegmatic that even those ideas whose connection with instinctive outlets is fairly close will not so much as stimulate to unrest.
In the same individual, readiness to assume unrest attitudes and the activity attitude varies from day to day. Our physiological condition determines the intensity of instinctive appeals: where these are weak, both unrest and activity attitudes will fail to be aroused. A constant crux of discussion has been the lack of correlation between unrest and the activity attitude. In debates on the determination of the will, the `strength of motives' has commonly referred to the intensity of the unrest set up by certain ideas. And it has often been pointed out that we sometimes act on a motive weaker than that which at another time fails to move us to action. Hence the illusion that we act without a cause; that will is not determined by the strongest motive. The facts, in my opinion, are as follows. Our physiological condition at certain times is unfavorable to the production of the activity attitude. The instincts may be alive: the motor pathways connected with them may be ready for use. The unrest aroused by an idea indirectly connected with an instinctive outlet may be intense. But the activity attitude is not assumed; and if the idea's connection with the instinctive outlet be so indirect that `thinking' is necessary to willing, then the `will' is lacking despite the strength of motive. Since no introspection can certainly determine whether the organism is or is not in the proper physiological state for the assumption of
( 165) the activity attitude, the relation of motive and will is uncertain, contingent. At another time an idea that stirs up a far weaker unrest attitude may give rise to the attitude of activity and so dominate associative processes to a successful working out of its problem.
The question naturally occurs as to how on this theory the influence of a particular problem idea is terminated. Obviously we stop mental work on a problem under two conditions: when the problem is solved and when it is not. If a problem reaches its solution, the persistent tentative motor processes find their fulfillment. The result is of course that if the problem idea is later suggested, there will be no suspension of the motor processes, but the passage to the solution will be immediate: only if the solution has been forgotten, through the effect of time in heightening resistances at synapses, will the motor innervation remain obstructed, and if conditions are favorable, the activity attitude will come into function and the problem be worked through again.
But a problem is often dropped without having reached a solution. And the dropping may be temporary or final. A problem that requires a long train of thought for its solving is usually dropped and resumed several tinges before it is finally worked out, if it ever is. On our theory, the interruption of mental work on a problem before the solution is reached must be due to relaxation of the activity attitude. The usual causes bringing about such a relaxation are (1) the occurrence of a prepotent stimulus demanding an entire shift of attitude (the dinner-bell calling the thinker to food), or (2) fatigue. Really the second is but a special case of the first, since the stimuli produced by fatigue are prepotent when they reach a certain degree of intensity.
The relaxing of the activity attitude, and consequent interruption of directed thought on a given problem, may be followed after an interval by the resumption of active work on the task. Judging from introspection, such a resumption may be started either by the associative suggestion of the problem to
( 166) our minds once more, or by the `spontaneous' or perseverative recurrence of the activity attitude itself, which recalls the problem. We resume our task either because some other idea or something in our surroundings recalls the task to our minds and the task sets up the activity attitude; or because we `feel like work,' and casting about for something to work at, we find that the activity attitude, thus recurring `spontaneously,' suggests either the task most recently associated with it, or the task which the context and surroundings combine to suggest. If the activity attitude recurs when I enter my study, the unfinished task it suggests is that which belongs to those surroundings; if it recurs in the laboratory, it sets in excitation the centres connected with my unfinished laboratory tasks. This spontaneous recurrence or perseveration is familiar in the case of organic movements such as desires or regrets: it often happens that we have in consciousness first the `awareness' of wanting something, or that something pleasant or unpleasant has happened, and these recurring motor states call up the idea of their own cause. We remember in a few moments what it was that we wanted, or that pleased or displeased us.
The experience of extreme unpleasantness in connection with any problem seems to break the connection between the incipient motor innervations connected with that problem and the activity attitude. A special and practically very important case of this occurs when work on the problem has been pushed to the point of great fatigue. The fatigue of mental work is rather generally acknowledged to be essentially the same as that resulting from physical work. We may assume that it is fatigue induced by too long continuance of the activity attitude. The worker has dropped his uncompleted task because the fatigue poisons, acting as prepotent stimuli, compel an interruption of the activity attitude. If the fatigue is moderate in amount, an attitude of relaxation supplants the attitude of activity. But if the fatigue is great, the stimuli which it produces give rise not merely to an attitude of relaxation but to the general negative response accompanying marked
( 167) unpleasantness. The negative response, as many phenomena connected with the learning process in man and the loner animals inform us, has the ability to substitute itself for responses that produce it. So a task, dropped in the midst of the unpleasantness of great fatigue, will later call up not the activity attitude that would ensure its continuance, but a reaction of aversion: we `want never to think of it again.'
The efficiency of a mental worker is thus directly connected with his sensitiveness to fatigue stimuli. Not merely is the too fatigable individual, whose activity attitudes relax before the problem has governed associative processes long enough to progress towards solution, a failure; but the worker who is insensitive to fatigue until its products have accumulated so that the reaction when it does occur is violently unpleasant, is in danger of still greater disaster from the point of view of efficiency. For the problem that is dropped under the influence of a slight degree of fatigue may be resumed, but the problem dropped under the influence of profound fatigue is likely to be abandoned permanently.
When fatigue puts an end to the activity attitude too soon for the highest degree of efficiency in work, it may be because the fatigue processes are really intense, owing to some temporary or permanent physiological weakness on the worker's part, or it may be because he has the bad habit of paying too much attention to fatigue sensations. As it is disastrous for efficiency when a worker disregards fatigue influences until they have become very intense, so it is in a less degree unfortunate if his limen for a special reaction to fatigue sensations is too low. There are some persons, and the present writer is one of them, who can never work without giving a disproportionate amount of attention to the fact that they are working. Hence, indeed, they avoid nervous breakdowns and do not tend to abandon unfinished tasks finally and forever, as do some of their too enthusiastic friends after uninterrupted long periods of work; but they waste a good deal of time by dropping their tasks after very short periods of work because their attention is
(168) directed to slight sensations of fatigue. I do not know whether any reader can verify this experience from his own introspection, but I have repeatedly noted that on a morning when I am generally fatigued after loss of sleep, I produce an unexpectedly large amount of work; and I am inclined to lay this to the fact that, starting out tired, I take my fatigue sensations for granted, as it were, and pay less attention to them than usual. Thus I am enabled to avoid the many needless breaks in my work ordinarily caused by the fact that I am distracted by the sensations caused by the activity attitude.
It would seem highly probable that to differences in innate and acquired or habitual permanence of the activity attitude and the proper amount of fatigability and attention to fatigue sensations are due differences in `general ability.' There is more and more accumulated evidence in favor of the supposition called by Spearman (47) the theory of two factors; namely, that individual excellences in various kinds of mental work are due partly to special ability and partly to general ability. There can surely be no single condition so important for all kinds of work where mental ability is involved as the proper degree of persistence of the activity attitude.
Our theory is, then, that the persistence of the motor innervations connected with a problem idea is connected with the persistence of the activity attitude, a static movement system which associates itself, under favoring physiological conditions, with the attitude of unrest stirred up by the partial inhibition of a motor innervation connected with an instinct. It is a well known fact that a problem idea's influence will continue to be exerted after the idea itself has dropped out of consciousness. When the task is, for instance, the adding of a column of figures, the worker does not have constantly to remind himself to add. Several careful studies have been made of the stages in the disappearance of the directing idea from consciousness, under various conditions. A comparative examination of the results of these studies indicates that such stages are of three different types. There is, first, the case where the problem idea
( 169) is fully conscious at the time when it exerts its effect: the observer says to himself, `I must add,' or, `I must think of an opposite,' whatever the case may be. In the second type of effectiveness of the problem idea, it appears somehow fused with the stimulus that is to be responded to, and the stimulus is apprehended in a particular way, or has certain features added to it, as the result of the problem idea's operation. Thus in Ach's (2) experiments where the task consisted of simple arithmetical operations, the numbers were visualized with a plus sign between them, or one over the other to facilitate the operation of subtraction. The third type of case differs from the second rather in degree than in principle: it occurs when, with more complicated problems, a certain means of solving them, a certain method which aids in the fulfilling of the task, is adopted: this method may be in consciousness while the problem idea itself is not. Thus in Grünbaum's (46) experiments, where very complicated sets of figures were shown for a very brief interval and the observers had to detect similar figures in the groups, they devised various schemes to help themselves. The second and third types are only cases where some other innervation has substituted itself for the innervation which the problem idea originally involved, and this substitute motor process persists in the place of the original one. Thus instead of saying each time, `I must add,' the verbal formula, 'and are ,' remains in readiness, or the plus sign persists, or the more elaborate scheme which aids in solving a more complicated problem remains in a state of persistent readiness to be excited. Of course the processes underlying the memory after-image and perseveration, the readiness of movements to be repeated, are strong factors aiding in the solution of problems, but the peculiar feature that distinguishes either the original problem idea, or the surrogate that later comes to replace it, is association with the activity attitude.
There are cases where apparently the whole physiological process underlying directed thought ceases to have a conscious accompaniment and yet proceeds effectively, as later conscious
( 170) processes show. In many such cases the activity attitude persists: there are times when I am puzzling over a difficulty, and remain for an appreciable interval conscious of the activity attitude, of strained attention, but of little else in the way of imagery, verbal or otherwise; yet at the close of the interval I find my associative dispositions have combined in a new pattern. Sometimes the activity attitude itself is absent: a new idea, the solution of a problem, flashes on one in the midst of idle revery on other subjects. Here it is evident, since there is no persistent attitude to help the persistence of the problem's influence. that it must be due entirely to perseveration.
Clearly the more practised a set of movements is, the more it will tend spontaneously to repeat itself, or to perseverate. Thus it is along lines in connection with which we have done much thinking that unconscious 'thinking' goes on: we do not have sudden inspirations on subjects about which we have done little conscious meditation. So the simpler tasks, such as adding or rhyming or thinking of opposites, very quickly come to depend entirely on perseveration, because they are tasks already so familiar and so well practised. So, too, when a task is set that can be solved in a number of different ways, not only does delay occur because a variety of movements is set in readiness, but such a task has to depend longer on the activity attitude than does a task that can be solved by only one set of movements, for in the latter case the single set of movements through being repeated and practised gets much help from perseveration. The fact that a fully determined problem is performed with greater ease and speed than a vaguely determined one is called by Ach (2) the `Law of Special Determination,' and lie derived it from experiments by the following methods. His observers were required to make one set of reactions with predetermination. These were as follows: simple reactions to white cards as stimuli; reactions where sometimes other stimuli were given to which no reaction was to be made ; discrimination reactions, where two kinds of stimuli were intermingled and the observer was to react as soon
( 171) as he recognized what a particular stimulus was; reactions where one kind of stimulus was to be responded to by a movement of the right hand and the other by a movement of the left hand; reactions where there were four different kinds of stimuli to be responded to by four different movements. Another set of reactions was made without determination. These included two classes, those where the stimulus was indeterminate and those where the response was indeterminate. In the first case, two stimuli were shown together, and the observer's instructions were to choose which one he would respond to, but always to make the same movement in response to the same kind of stimulus. Thus if a red card and a blue card were shown together, he might respond to either one, but if he chose to respond to the red card he must do so by a movement of his right hand. In the second case, cards with numbers were shown to the observer, who might perform any of several different arithmetical operations he chose with the numbers presented. The more complete and particular the instructions, the less liberty of choice left to the observer, the shorter was the reaction time.
Just the same law is shown in experiments on so-called `forced associations.' When a word is given to an observer and he is told to answer with the first word that occurs to him, it regularly takes him a little longer to do so than if he is instructed beforehand that he must respond with a particular kind of word, for instance a rhyme, or a word denoting the class to which the object named by the stimulus word belongs. This at least is the testimony most generally given by those who have compared `free association times' with `forced association times': thus Wells (150) says that controlled associations, if simple, are always shorter than free ones. Wreschner (159), on the other hand, says that a given type of association occurs more rapidly when it is free than when it is prescribed: that is, for example, an observer would respond to the word `dog' with the word `animal' more quickly if he just `happened' to do so than if he had been previously instructed to think of a superior
( 172) concept to dog. "Every Aufgabe," says Wreschner, "exerts a certain inhibiting influence, in consequence of which the idea corresponding to it comes to consciousness a little late." Wreschner does not limit this statement to the complexer tasks, but it would certainly appear that he should do so. If a problem is simple, it certainly ought to be performed more quickly when the movements which it involves are set in readiness beforehand. If it is complex, one can see why the more complicated set of movements should involve delay as compared with a free reaction. The Law of Special Determination holds without exception: if a forced association means that only a few movements have been set in readiness, and a free reaction means that a great many movements have been set in readiness, then the free association will take longer than the forced one. But as a matter of fact the reactions given under the instructions to say the first word that comes into one's head are often not free at all in the sense that many possibilities are previously excited: for in the first place, when the stimulus word is not known, the expectation is wholly vague, and in the second place the reaction word that is given is often based on an associative disposition of such strength through much repetition that no other possibility can claim the field. The person who is given the stimulus word `black' is likely to respond `white' with no interference of other associative dispositions, because no other disposition is of anything like equal strength. The Law of Special Determination is clearly illustrated in the fact that it regularly takes longer to pass from a more general idea to a less general one, as from `animal' to `dog,' than from a less general to a more general idea. `Animal' may suggest many subordinate classes besides `dog,' but `animal' is by far the most obvious superior concept to `dog.'
The advantage of definite preparation and of the perseverative tendency that is involved in having a special and fully determined problem at the outset is further shown by the fact that when a person is given vague and indefinite instructions he very soon helps himself out by adopting a stereotyped
( 173) concept to dog. "Every Aufgabe," says Wreschner, "exerts a certain inhibiting influence, in consequence of which the idea corresponding to it comes to consciousness a little late." Wreschner does not limit this statement to the complexer tasks, but it would certainly appear that he should do so. If a problem is simple, it certainly ought to be performed more quickly when the movements which it involves are set in readiness beforehand. If it is complex, one can see why the more complicated set of movements should involve delay as compared with a free reaction. The Law of Special Determination holds without exception: if a forced association means that only a few movements have been set in readiness, and a free reaction means that a great many movements have been set in readiness, then the free association will take longer than the forced one. But as a matter of fact the reactions given under the instructions to say the first word that comes into one's head are often not free at all in the sense that many possibilities are previously excited: for in the first place, when the stimulus word is not known, the expectation is wholly vague, and in the second place the reaction word that is given is often based on an associative disposition of such strength through much repetition that no other possibility can claim the field. The person who is given the stimulus word `black' is likely to respond `white' with no interference of other associative dispositions, because no other disposition is of anything like equal strength. The Law of Special Determination is clearly illustrated in the fact that it regularly takes longer to pass from a more general idea to a less general one, as from `animal' to `dog,' than from a less general to a more general idea. `Animal' may suggest many subordinate classes besides `dog,' but `animal' is by far the most obvious superior concept to `dog.'
The advantage of definite preparation and of the perseverative tendency that is involved in having a special and fully determined problem at the outset is further shown by the fact that when a person is given vague and indefinite instructions he very soon helps himself out by adopting a stereotyped
( 173) method and sticking to it; that is, he adds self-imposed tasks to the one he has been set. In the very interesting experiments of Koffka (63), where the instructions were quite general, such as, "React, by making a signal, when the stimulus word has suggested an idea to you"; or, "React when it has suggested an idea and this idea has suggested another"; the observers imposed on themselves more special tasks, such as those of reacting as quickly as possible, or of reacting only with words, or of reacting always with synonyms, or of thinking of individual examples. Koffka therefore adds to Ach's conception of `determining tendencies,' or the influences which proceed from problem ideas, that of `latent attitudes' which have the effect of determining tendencies but do not proceed from problem ideas. It seems to me that these self-imposed problems can be explained simply in the following way. A very general problem sets in readiness a number of methods for its solution. One of these methods happens to be the first one adopted, and simply perseverates: since the influence of perseveration involves so much less fatigue than the influence of the activity attitude, it is not interfered with and becomes increasingly strong.
