The first time a specific sensation is conveyed to a center, it is problematic which efferent or motor nerve will carry the outgoing impulse, but the choice is of great significance, for a habit is thereby begun. The second time the same sensation is conveyed, it will be easier for the same outgoing path to be followed. Thus habits are formed. Each repetition fixes it more firmly and makes more difficult the forming of a new manner of reaction to that stimulus.
Every sensation and thought tends thus to express itself in action. The little child is therefore especially susceptible to suggestion. Inhibition is the intervention of a second thought or stimulus which sends a counter impulse that prevents the action. If the expression of the action is continually prevented, or if through weakness of will or low vitality the expression is deferred, or not made, the power to express may become weak, and the individual thus degenerate into a mere dreamer. In extreme cases this becomes a condition known as dementia praecox.
Nerves completely developed (and therefore efficient for functioning) are covered by a sheath of tissue which may be compared to the insulation cover of an electric wire. At birth, few, if any nerves involved in voluntary action or thought are completely sheathed. This process requires many years, some nerves becoming sheathed earlier, others later. A regular evolutionary order is apparently followed, those nerves that control the racially older sensations or movements becoming sheathed and mature before the racially younger. This is the biological basis of the stages of development, and of the manifestations of different interests. It is useless, often injurious, to attempt to train a muscle or an interest before the nerves are ready. When they are ready, ample exercise must be permitted; this is the nascent stage of that interest. If exercise is now neglected, the golden opportunity for its education is passed. For instance, there is a stage, from about ten months to six years, when the special senses, as hearing, touch, sight are ripening. This is the time for training in sense accuracy and discrimination. The child’s spontaneous interests and activities furnish the best clue we now have to this development of nascent interests and the time for their exercise.
In the brain there are apparently special centers which receive the sensations from any one part of the body and which send back to that part the motor impulse. Thus there is a center for the arm, the hand, the fingers, another for the ear, another for the eye. Language has its special centers. This is the localization of functions in the brain. At birth these centers are undeveloped. In a right-handed child the language centers develop in the left hemisphere, and in the left-handed child in the right hemisphere. Ambidexterity is frequently found with stuttering and with low-grade mentality, and is not considered advantageous to foster.
At birth, also, there is little or no development of association fibers between the centers in the brain, or between related centers in the brain and in the spinal cord. These centers and the association fibers develop through attempted use, as the baby receives stimuli from without and attempts to respond. As a matter of experience, the child learns to associate the several qualities that are found together in one object, as the taste, odor, color, “feel”, shape, of a piece of bread. He also associates with an object his emotional states at the time, as bread with the comfort of feeding, a hot iron with the smart of pain, a ball with playful moods, a church with awe or reverence, a thunderstorm with fear or confidence. These early associations become ingrained and remain with him throughout life or with great difficulty are supplanted; they form his prejudices, his basis of morals and religion, his subconscious self.
The reference of a stimulus from a spinal nerve center to a brain center, and its transference in the brain to a motor nerve, requires thought. Thought is necessary for mental development, but it would be very exhausting if every sensation had thus to be consciously responded to. Nature is always working out short cuts. When a response is uniformly through one motor nerve, and a sensation is therefore uniformly followed by the same action, the stimulus, instead of journeying to the brain, transfers to the efferent nerve directly from the center in the spinal cord,—that is, the action becomes automatic. Not only thought but time and nervous energy are thereby economized.
The time required between stimulus and response is the reaction time. In an individual of phlegmatic temperament the reaction time is slow; in the active temperament it is quick, often impulsive. By a tonic régime (involving cold baths, laxative diet, vigorous physical exercise) the too phlegmatic may be developed into more alert responsiveness. By a quieting, sedative physical régime (increased sleep, rhythmic exercises, freedom from stress) the too active temperament may be toned down. Other temperamental changes may be developed, especially during infancy and early childhood, while the nervous system is still plastic.
The nervous system needs the stimulus of environment for its development. If the eyes of a normal baby were bandaged and his ears stuffed with cotton, so he could receive neither sight nor sound stimuli, and his arms and legs were kept bound tight so he could not move, his mental development would be hindered. If too many or too severe stimuli are presented, the nervous system is irritated, confused, overworked, and development is retarded. The child himself will select from a normal environment the stimuli that he needs. Others should not be forced upon him.
Whatever stimulus is exerting the strongest impression will hold the child’s attention and direct his emotions and action. If a child is himself absorbed with some normal object or interest, it is tactless to attempt to divert this to some imposed academic interest. If he is in physical discomfort, it is a waste of time to attempt to give him instruction until the discomfort is removed. On the other hand, if a discomfort cannot be removed, or if the object of his attention is morbid or unworthy, the supplying of a more attractive counter-stimulus (as the telling of an absorbing story or the observation of activities out of the window, or doing some other work with his hands) is the natural and constructive method.
The Psychological Basis of Education. Self-activity is the natural method of education. This is Froebel’s term. Rousseau called it learning to do by doing; Dewey calls it education by development; Montessori’s term is auto-education. Free play is the child’s self-activity, when he chooses what he shall play, how, and with what implements. Montessori calls this work, when it is doing something useful or intellectually educative.