Page:Popular Science Monthly Volume 46.djvu/746

726 the rapidity of the association processes can be altered by the use of certain drugs. Thus alcoholic beverages make the sensory perceptions and the process of thought slower than normal. They increase the rapidity of motor acts for a short time, but finally retard these, too. Tea has just the opposite effect, making sensations and intellectual acts more rapid, while it delays the motor actions. Morphine has at first much the same effect as tea, but soon after it delays all mental acts.

I have noticed that one of the early signs of beginning disease in the brain is a decided lengthening in the processes of association, even where none of these processes are absolutely suspended.

The number of associations permanently established with any given idea has been made the subject of tests, and it has been said that it is a better measure of the mental capacity of an individual to ascertain the number of associations which he possesses with any given subject than to require him to pass an examination upon his knowledge of the subject.

Among the curiosities of thought we may mention some queer disturbances in these processes of association. We may find that association tracts are apparently blocked so that a perception which should call up a certain concept fails to do so.

I have seen a man look at his own son and yet fail to recognize him—that is, the perception of the face no longer resulted in the quick spreading outward over a thousand associated tracts to other parts of the brain of impulses calculated to call up the numerous memory pictures usually associated with that face. Not long ago I asked a man who had one of these forms of defective association what his occupation was. He replied: "What I do? My business? I know just as well as I know all of it, but I can't tell," The idea of his occupation was unable to carry him on to its name. He was a printer. He assured me that he could call to mind his office with its presses and frames, but he could not name his occupation; yet he recognized the word printer at once when I spoke it, and knew it was what he wanted to say. One process of association, at least, in his brain was suspended.

Some of the extraordinary disturbances of consciousness in which an individual's personality appears to be divided, instances of which I shall give later, seem to be explicable only on the theory of the cessation of activity of the association fibers of the entire brain for a time.

I may mention here an unexpected association, a sort of spontaneous association between unrelated perceptions, which is observed in some minds. You may have heard that there is such a thing as color-hearing—i. e., persons subject to this forced association find that certain colors awaken forcibly the memory of certain sounds, which memory may be so vivid as to be a