Yale Psychological Studies Volume 1; New Series (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 Excerpt: ... The particular movements are never steady fixations of lines and figures. Dr. McAllister's report on some of the simpler fixations shows also that a movement is never a simple reaction. In successive cases the eye comes up to a given point in different ways. The fixation and refixation are accordingly matters of continually shifting balance. If one seeks for all the factors which contribute to the shifting of the balance, one will be likely to think first of certain varying sensory factors. Thus when a given area of the retina is for a time subjected to a given stimulation its sensitivity is gradually modified and a new balance will of necessity have to be set up because a gradual modification is taking place in the incoming stimulation. Or the muscles may, under the strain of fixation, begin to send sensations of strain to the central nervous system where they will tend by contributing new factors to disturb the balance. In addition to these factors it is perfectly clear from Dr. McAllister's figures (see Figs. 7 et seq.) that in many cases each successive movement is modified by the movements that preceded. The subject gradually fits the response to the sensation complex so that the two are more nicely balanced. It is wholly inadequate to describe the movements which the eyes make merely in terms of their consequent movement sensations or even in terms of the associated images of movement. As already pointed out, the revival of associated images can not mean exactly the same thing as the stimulation of sensory cells. The associations have certain necessary, nonsensory, motor relations. And when we see that the present sensory factors are not merely those of the muscle sense but also--and even chiefly--of vision proper and that all these factors are unifi...