So far the extensive development. On the side of intensive centralization Wundt's doctrine of apperception provides the necessary hypothesis. To these aspects of the subject I can only refer now.
Turning at once to the "Physiological Psychology," we find that it proceeds, as scientific method dictates, from the simple to the complex. After an introduction, Part I. discusses the bodily Substrate of the Mental Life; Part II. the Elements of the Mental Life; Part III. the Formation of Sensory Ideas; Part IV. the Affective Process and Volitional Action; Part. V. the Course and the Connection of Mental Processes; Part VI. adds Final Considerations. Thus, we pass from the functions of the nervous system, by way of sensation, feeling and presentation, to consciousness in the formation of ideas and in the train of ideas, which, in turn, involves attention, apperception, and will, not forgetting phenomena such as association, imagination and emotion. Two reasons make it hard to select this or that, and to say, Here Wundt excels. First, profuse wealth of suggestion and result is scattered everywhere. Second, the successive editions of the "Physiological Psychology "constitute the life history of Wundt's own mind in relation to the subject as a whole; and only psychologists von Fach can supply the necessary light and shade. It appears to me that special interest attaches to his discussion of Müller's theory of specific energies, because it reveals Wundt's view of the part played by the nervous system in the psychological organization; to his criticism of the Young-Helmholtz theory of color, because it attacks the "mystery" of space-perception; to the treatment of sensation, the duration of mental processes, and association, because they afford typical instances of the new data which experimental psychology can bestow upon analyses of psychical phenomena. Doubtless, professed psychologists would insist upon other points. For my part, the central interest still attaches to Wundt's theory of apperception and will. I take the former as a typical illustration of the direction in which physiological psychology moves.
In apperception the conscious being brings his entire unity of experience to bear on the object now in the field of his attention. We light upon an inner and elaborative activity which "bears the stamp of spontaneity." Evidently, a process complex in the highest degree! My expert colleague, Professor Pillsbury, has analyzed it as follows: Apperception involves four elements. "(1) Increase of clearness in the idea directly before the mind, accompanied by the immediate feeling of activity; (2) inhibition of other ideas; (3) muscular strain sensations, with the feelings connected with them, intensifying the
- "Physiol. Psych.," Vol. I., pp. 5-6 (Eng. trans.).