Page:Popular Science Monthly Volume 67.djvu/496

490 And if I use an unfamiliar typewriter, I must assume a more attentive attitude to my manipulations, working out some of them deliberately anew; and I am quite likely to find myself intermittently attempting to perform on the new machine a manipulation that is proper only to the more familiar one. The relations are distinctly intensified when the coordination involved is more deep-seated, less consciously realized, more distinctively a function of the automatic centers. Activities guided primarily by the feelings accompanying muscular contractions, in contrast to those guided primarily by vision, furnish the most favorable instances of what is here involved. A very striking one is found in the attempt to ride a tricycle by one accustomed to the bicycle. The equilibration of the bicycle requires that one lean with the machine, to the right in turning to the right, to the left in turning to the left. This in itself is contrary to the normal walking habit of saving ourselves from falling by shifting to the opposite side, and had itself to be learned with some difficulty, because opposed to another ingrained tendency. Seated on a tricycle, the bicyclist unwittingly and in spite of himself maintains the bicycle-balancing habit, and is surprised to find the simple tricycle, which one without any experience with either can guide easily, quite beyond his control. The old habit persists and will not make way at once—though doubtless it would in time—for the new adjustment. What is distinctive of this experience is the strenuous persistence of the motor habit in spite of a considerable and conscious effort to check it—a relation that in turn is significant for the comprehension of unusual and pronounced lapses. Another example of such conflict of motor impulses may be arranged by attempting to write not by direct visual guidance of the pencil, but by following the tracing of the point (with the hand and pencil screened from direct sight) in a mirror or system of mirrors. The new and unusual visual guidance tells one to move the pencil in a given visible direction; but this direction of seen movement has always meant a certain kind of 'felt' movement; and when that type of 'felt' movement is set into action it proves to be, by the visual standard, completely and variously wrong. The struggle between trying to push the pencil in the direction one sees one ought to go, and also in the direction one feels one ought to move, may become so intense as to be quite agonizing; and the attempt must be abandoned as hopeless. Remove the mirrors and use the normal visual guidance, or close the eyes and use the normal muscular guidance, and the writing proceeds fluently, with but normal effort and attention. Oppose the two factors of the normal combined and harmonious synthesis, and confusion irresistible—a confusion, not of conscious intent, but of execution, of deep-seated automatic motor mechanisms—takes place. Likewise should it be noted that of all these modes of guidance are we normally but vaguely aware; so much is this the