Page:Philosophical Review Volume 4.djvu/441

425 the child's motor response (reaching for the color), stood thus: Blue, White, Red, Green, Brown. This result is quite different from that of Preyer, who puts Blue last on the list. Using the same method to investigate the rise of right- or left-handedness, it was found that dextrality developed "under pressure of muscular effort in the sixth and seventh months, and showed itself also under the influence of a strong color stimulus to the eye" (p. 65). It does not seem to be the product of differences of experience in the use of the hands, for it arose before there were any such differences; and, moreover, when it arose, the right hand was employed when the left would have been more convenient. An interesting point is the relation of speech to right-handedness: both are controlled by the same hemisphere; both are expressive functions; neither is found in the lower animals. They are evidently parts of the same function. It is likely that dextrality in children "is due to differences in the two half-brains reached at an early stage in life, that the promise of it is inherited, and that the influences of infancy have little effect upon it" (p. 74).

Suggestion (which, by the way, is only another name for the fundamental fact of Dynamogenesis), shows itself in the child under three leading aspects: (a) physiological suggestion, conveyed by repeated stimulation under uniform conditions; (b) sensori-motor suggestion, shown, e.g., in the child's joyful response to the sight of her food-bottle, and in her making the proper "ducking" movements while being dressed; (c) ideo-motor suggestion, in which the stimulus is a clearly-pictured idea. So far, we see the fact of Dynamogenesis,—stimulus, followed by movement,—but the question now arises: What kind of action follows each special kind of stimulus? And in answer we have two possibilities: (a) the organism may simply do what it has done before (Habit); or (b) it may adapt itself to a new stimulus by a new reaction (Accommodation). The first is not difficult to understand, but Habit alone would not account for growth and life-history. Accommodations are essential to development, but how can Accommodation take place, seeing that it flies in the face of Habit and tends to break it up? To answer this question is the main business of the remaining ten chapters of the book. Put briefly, the theory is that these new accommodated reactions can take place only through the action of the stimulations themselves, which so modify the reactions of the organism that these modified reactions serve to hold or repeat the new stimulations, so far as they are good. So we have an interaction of stimulation and reaction, the former leading