CHAPTER III HABIT IN PREPARATION FOR EFFICIENCY WHEN we observe an animal or plant we are impressed with the similarity of its life from day to day. It does much the same thing under essentially the same conditions. The root of a plant always grows down into the earth and the stem seeks the light; cats mew beseechingly at the sight of milk and spit when a strange dog appears; and a man awakens at about the same time every morning, eats much the same things for breakfast, reaches his office at the same hour each day, and begins his work in the serial order of yesterday. The reason for this similarity of action is habit. As was pointed out long ago by various writers, habits are the result of changes in matter. It is because of this that we sometimes speak of the habits of plants. Indeed, one may go much further and refer to the "habits" of non-living matter. Shoes, for example, are more comfortable and flexible after having been worn for a few weeks, and the wood of a violin of an old master has acquired "habits" of vibrating that make it a more sensitive and delicate musical instrument. It will be observed that in some of these instances the changes are, in a sense, external. The creases of the shoes that make them more comfortable are visible. The alteration of the wood of the violin, however, is invisible. As a result of the skilful playing of the master the wood has acquired certain vibratory tendencies. It has become more flexible in certain ways; it responds more delicately to touch. To be able to adapt itself to new conditions— to have the capacity to change, the ability to adopt new habits a substance must be flexible enough to alter its form or its structure without losing its integrity. It must not go to pieces. Substances which have no plasticity or which break under alteration cannot acquire new habits. We are not accustomed, however, to speak of these responses of non-living matter as habits. Neither do we usually apply the word to the actions of plants. The term has been reserved for the relatively settled ways of behavior of animals-modes of action which have been acquired during the lifetime of the individual. Habit is thus distinguished from instinct. If we put it a little more technically, habit is a relatively organized and fixed nervous process, or series of processes, acquired by an individual, the repetition of which results in greater facility and better accommodation to the conditions that start the process. Objects and animals alike offer resistance to modification-to change; and, when the change has taken place, the new arrangement acquires a permanency of its own. It has taken on new habits and again it resists alteration. The justification for making habit analogous to the behavior of plants and the action of non-living matter is found in the fact already mentioned that habits are the result of changes in matter. A sprained arm, for example, is ever sensitive to strain. Some persons, again, are prone to sore throat, bronchitis, or tonsilitis. The tissues may be said to have the habit of easily becoming irritated. Functional diseases, again, are due to a predisposition of certain organs to function abnormally, and in such cases the purpose of medicine is to establish correct "habits" of action. "Tapering off" is another illustration. The purpose of this treatment is gradually to overcome old habits by starting and strengthening new ones. If we ask how habits are formed in animals we must turn to the nervous system for the answer. Nervous impulses started through the eye, ear, or other sense-organ run their course. They must find an exit; and their exit results in an adaptive response-in behavior of some sort― to an external situation, perhaps to an emergency. These nervous impulses in their course leave traces behind them. Some alteration occurs in the path which they have taken because of their passage over the route. There is some kind of a change in the nerves or in the connections between the neurones, by which a path once traversed is opened, and consequently offers less resistance to the next nerve-impulse that seeks an exit. What is this change? We do not know definitely, but the indications are that it is of a chemical nature. At any rate, a path once traversed by a nerve-impulse becomes an available outlet for succeeding ones, and a habit is thus established. Psychologists speak of "paths" being formed in the nervous system, and being made more easily traversible by the repeated passage of an impulse. This, of course, is an analogy, and analogies are likely to be misleading. But there seems to be truth in Carpenter's statement that an organ grows "to the mode in which it is habitually exercised." This is the case with muscle, as is seen in exercise, and there is no reason why it should not be true of the nervous system. Reconstructive changes are always going on, and these changes tend to emphasize and “fix” the sort of functional activity prevailing for the time. It is an instance of organic adaptation to demands. Exercise builds up muscle and lack of exercise is attended by gradual deterioration of the tissue. Activity always breaks down tissue which must be restored that the organ may not lose its power to function. This restoration, however, does not reinstate the original condition of the organ, for if it did the strengthening of a muscle would be impossible. The reconstruction is rather an adaptive process that tends to meet the demands put upon the organ, and in a nerve-unit this demand is for continued and improved accessibility to nerve-impulses that reach it over a previously travelled route. The need for an uninterrupted course exists, and the claim is made upon a particular nerve-unit because the path has already been traversed. In this way nutritional reconstruction of a neurone whose elements have been depleted by the passage of an impulse tends to conform to the demand of other impulses for free passage. If we inquire why the nerve-impulse first took the path which began the habit, perhaps the most that can be said is that there was no special reason why it should not. For reasons hidden in the structure of the nerves, or their connections, it was at the moment the path of least resistance, and there was no urgent need for taking another course. A man, for example, has rented a house in the middle of a block. The first time that he starts for the street-car he may turn to the right or to the left. Both cross-streets are equally near to his house and to the car. He does not know why he took one rather than the other, but the first act establishes the habit and, except for special reasons, he will always follow the same route in the future. We are now able to state the first practical advantage of habit and also to show its evolutionary significance. Habit makes movements exact and "sets" them, and it lessens fatigue. One need only watch a child who is learning to dress himself try to button his clothes to see the advantage of this. If movements once acquired by practice were not "set," learning acts of skill would have no meaning. It would be necessary continually to repeat the trial-anderror method, and man would have no time for anything beyond the simplest, most elemental needs of existence. The lessening of fatigue in habitual occupations is quite evident in physical labor. The bricklayer is unfatigued by his day's work, and the store clerk stands or walks about for ten or twelve hours with ease, but let these men exchange occupations and both are exhausted at the end. This is not merely a matter of muscles. The nerve centres and synapses-the functional connection between nerve-units are factors in even "muscular fatigue." It is much the same with mental activity. An accountant ends the day as fresh as the department manager, but neither could do the other's work without exhaustion at the close of day. In all of these cases it is habit that makes the work endurable-habits of muscles, of nerveconnections, and nerve-centres. The same reason that makes a change of occupation fatiguing applies in adopting a new method for the same work. Subjectively the resistance of the nervous system to an altered response may have all the signs of fatigue. Yet in many instances this feeling of weariness expresses the organic reluctance to drive through the first line of trenches, to overcome the first resistance; and it is because of this characteristic of the nervous system that what we have called the tendency to minimum effort prevails. Energy is required to overcome this inertia and the effort is not easily made. When once the habits that constitute the revised action are established everything again runs smoothly. The advantage of habit is the exactness of automatized movements, and its evolutionary explanation is the need of meeting emergencies in a definite manner. Having found a successful reaction, the act once performed becomes the line of least resistance. In the species, habit represents the prudent, "safe" manner of behaving. These "habits" of the species, however, are deeply ingrained in the organism and are called instincts. They are necessary for survival and have been established by the elimination of those individuals who did not conform. Man tends to do things in the simplest way, in the way that requires least expenditure of energy. "No one, not even a child, likes to take unnecessary trouble," was one of Rousseau's keen observations; and habits are troubleA certain result is desired, and we have found that only so much energy is expended as its attainment savers. |