Page:Popular Science Monthly Volume 42.djvu/24

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14
THE POPULAR SCIENCE MONTHLY.

quent on this anatomical delimitation of brain areas is very important. Apart from this it is not possible to conceive of that restriction of the attention to one kind of sensory impressions that is essential to clear perceptions. All teachers know the importance of securing attention; but, unfortunately, this is too often confounded with a constrained attitude and other non-essential accompaniments.

But a sound physiology and psychology should correspond to Nature. About the best way to test them will be to ascertain how they fit into human nature before it is influenced by any methods whatever, for all methods are liable to hamper and modify. It is hopeful to notice that so many psychologists of the modern school are turning to infant psychology, or the study of the mental development of the very young child, which is of course closely related to its physical development. The behavior of the infant is in accordance with the brain structure and function of which I have been speaking.

The infant from birth is the subject of almost constant movements during the waking hours of its life—movements which are spontaneous and not voluntary. Some of these movements, at all events, are reflex—i. e., the nervous discharges from the central cells of the brain and spinal cord which cause them are not due to the will, but to some sort of external stimulus; and so great is the tendency to these nervous discharges in the young animal that but the slightest stimulus is required. Some of these movements may be considered a continuation of those of the pre-natal period.

It is doubtful if the newly born infant executes any voluntary movements, because will proper it does not then seem to possess.

Though the child at this stage neither sees nor hears probably in the true sense of the term, it is not uninfluenced by light and sound. Gradually it gets clear perceptions from all its senses, and then it becomes more than ever a reflex mechanism, its nervous system being responsive to all external things, and its motor system expressing this condition. In other words, sensations are streaming in through all the avenues of sense, and these have their outward expression in movements by which, as from the first, the muscular sense on which all exact voluntary movement depends, and the cutaneous sense, the most fundamental of all, and that on which the perfection of all the others depend, are exercised.

At first, sounds though heard can not be localized. Objects are perceived by the eye, but the infant has no idea of their distance. It will reach for a light across the room as readily as if it were but a foot away.

It is clear that the human being at this stage is on a par with