Page:American Journal of Psychology Volume 21.djvu/536

524 highest brains in such a way as to be relatively isolated from each other and from the motor area. The association areas which link these widely separated sensory centres are clustered in unmistakable fashion around the motor area." (Psy. Rev. Mon. Supp. 7, 1905, "Movement and Consciousness," p. 207.) Judd holds that all paths lead to the motor area through the associational tracts; that the higher senses do not "reach the motor areas through tactual centres." (p. 209.) He points out that muscular and tactual sensations are unrefined and that "requirement of sensory control and refinement of movement go hand in hand. Why, then, should the conscious processes in which visual factors are fused be continually referred back to a primitive form of sensation for their explanation?" (p. 218.)

The bearing of Judd's contention upon the problem of this paper is evident. All impulses move toward the motor area; sensations do not arouse other sensations but motor responses. The higher and phyletically later sense processes are more "refined" than the older tactile sensations. The later acquisitions, therefore, more accurately represent the situations to which adjustments are made. There is, therefore, no reason why images of these later and more refined sense acquisitions should not, so far as any imagery at all may be concerned, play as original and important a role in volitional acts as any other imagery.

In the language of James, "All consciousness is motor," a fact so frequently demonstrated as to be a commonplace. But if the image theory of voluntary action is strictly interpreted some elements of consciousness under volitional conditions require the presence of additional conscious data in order to become effectually motor. To put it in the physiological terms in which Judd has expressed the situation, some sensory impulses cannot pass over into motor impulses without first arousing certain other sensory activities which are the physiological correlates of previous sensory experiences obtained under involuntary conditions. In fine, if the image theory is interpreted in accordance with the scientific usage of psychological terms it involves a serious modification of the proposition that 'all consciousness is motor' in case of all reactions above the level of the involuntary and the habitual. Here once more we are face to face with a break between the voluntary and involuntary which in turn involves a gap in the image theory not yet bridged over by its supporters.

There is a third concept current in the psychology of movement which is apparently difficult to explain on the basis of the image theory. This is the notion of sensory and motor forms of reaction. When the subject is making reactions that