Page:Popular Science Monthly Volume 35.djvu/771

Rh hear the question, you think of the answer, and you say it. Each of them has been separately measured, and takes from one tenth to one sixth of a second, so that the entire process requires from three tenths to one half of a second to complete it. People differ widely from one another in this rapidity of action, and the same person differs much at different times, and the explanation of this difference is found in the inherent power of activity in the brain. The effect of wine is to make these acts slower. The action as a whole calls into activity several parts of the brain, the nerve from the organ of sense to the brain, the part receiving the sensation, the tract from it to the motor area, and the part of that area which initiates the impulse and guides the movement and the nerve thence to the muscles. It is not surprising, therefore, that it should take some time; the astonishing thing is really the rapidity with which the brain acts, for modern measurements extend to thousandths of a second, and some mental processes in rapid brains take only a few hundredths of a second to be completed. Familiarity with a certain act lessens the time it requires. A lady was heard to say the other day, in alluding to the acting of the French comedians who have recently been seen here, that it was surprising how much faster French people talked than Americans. She would have thought it an act lacking in courtesy had it been insisted upon that it was not because they really talked faster, but because her English-speaking brain refused to think as rapidly in French, that had led her to the conclusion. Yet such was the fact.

There is one more process of mental activity to which allusion must be made, as it has thrown much light upon the theory of localization, and has now been fully explained by that theory—viz., the power of speech. There is perhaps no mental process which brings us more closely to the point of meeting of the physical and mental elements of the mind.

Language is so complex, as we survey it and as we constantly use it, that it seems at first impossible to unravel all its mysteries. But, if we watch its growth, we can get at some facts of not a little interest. Let us trace the way in which a baby learns its first word. As the baby looks about him he begins after a time to distinguish faces, and one face, his mother's, being constantly near, soon becomes most familiar. Mothers are constantly talking to their babies, and always speak of themselves as "mamma" or "mother," never using "I" or "me." After a time the baby begins to notice this sound "mamma" and to recognize it, and then the fact that a certain face and a certain sound usually come together finally establishes a fixed association between the sight-picture and the sound-picture, so that the one when brought to mind brings up the other. Then, if you ask the baby, "Where