Inhaltsangabe
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.1907 Excerpt: ... Chapter IV. The Organ1zat1on Of Ret1nal Elements. § 1. The Function of Extra-foveal Vision in Space Perception. Since no object, however minute it may be, is confined during fixation to the fovea alone, and since most objects of regard actually clear up as a result of stimulation which is largely outside the macula, while even the peripheral retinal areas regularly add their part to the complication of the central processes; the function of extra-foveal vision refuses to be regarded as merely preparatory and secondary. On the contrary in at least one typical and rather exacting visual process, i. e., that involved in reading, we have seen that extra-foveal vision is an integral and invaluable factor in the total product of each fixation; without which each successive reading pause would add only a relatively insignificant detail to a relatively unorganized mass of experiences. The very length of the ocular reaction bore testimony to our general contention. Even when the object of regard happens to lie entirely within the fovea, foveal vision is never isolated and distinct from the extra foveal. Ordinary observation gives no adequate clue to the position of the point of regard. Every object of regard is seen as a part of a simultaneous field. And the field, real or imaginary, is a significant factor in the perception and interpretation of every discreet object of regard. Moreover, the field is not a mere mosaic of previous foveal stimuli; for each foveal stimulation is only a part of a whole in which a distinction between the foveal and extra-foveal never appears. Physiologically and psychologically, the only functional distinction between different zones of the retina is determined anew in each act of vision, according to the adequacy of the resultin...
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