Introduction to Physiological Psychology (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER II. SENSATION, ASSOCIATION, ACTION. We have become acquainted with " constancy " as characteristic of reflex action, at least as regards quality. As a criterion of automatic acts, we fixed on " the modification of a motion by external intercurrent stimuli" Let us recall to mind the frog, deprived of its cerebrum, that is still able to avoid an obstruction. Neither reflex nor automatic acts have a psychical correlative; in other words, both are performed unconsciously. At least we found no authority for the assumption of concomitant psychical processes. Let us now analyze a simple conscious action resulting from an external stimulus. We see a friend, for example, and greet him. In this case the visual sensation, or the image of the friend, is the external stimulus; the salutation with the hand is the resulting action, or, as it has been termed, reaction. What was it that co-operated in the production of just this motion ? It is obvious that a sufficient cause is not to be found in the external stimulus alone, for if it had been some other person not our friend, the salutation would not have taken place. It is plain that the memory of having already seen this same person occurs to us. A mental image stored up in some manner in the brain, the image of our friend as it is carried with us in memory, has influenced or modified the motor process. If it had been our enemy, we might possible have turned away or looked elsewhere. But the memory tells us that it is our friend; we recognise him as such and the salutation follows. In this case, therefore, the course of the reaction is influenced by intercurrent mental images, which have been called forth from their state of latency by thesensation itself. We shall designate the mental image by / (idea) (Fig. 3), and indicate the ...