. Psychology and the school. consider itfirst and deal with perception in the next chapter. Visual sensations. — There are as many classes ofsensations as there are kinds of sense-organs, and allof these will be briefly touched upon, beginning withvisual sensations, since these make up so large a partof human adult perception. As has been seen, the stim-ulation of the sense-organs constitutes an essentialcondition of sensation. It will therefore be necessaryfor us to take into consideration the nature of the vari-ous sense-organs and the way they function. In orderto make the description compl
. Psychology and the school. consider itfirst and deal with perception in the next chapter. Visual sensations. — There are as many classes ofsensations as there are kinds of sense-organs, and allof these will be briefly touched upon, beginning withvisual sensations, since these make up so large a partof human adult perception. As has been seen, the stim-ulation of the sense-organs constitutes an essentialcondition of sensation. It will therefore be necessaryfor us to take into consideration the nature of the vari-ous sense-organs and the way they function. In orderto make the description complete, the various sourcesof stimulation of the sense-organs must also be consid-ered. The latter constitute the physical conditions of 68 PSYCHOLOGY AND THE SCHOOL sensations; the former, together with the changes inthe nervous system, the physiological conditions. The eye (Fig. 13) is similar to a photographic camerain its construction and in the way it does its pupil, which is an opening in the iris (the colored. Fig. 13. Diagrammatic section of the human eye. 0, optic nerve;S, sclerotic; C, cornea; A, choroid coat; /, iris; R. retina; V, vitre-ous humor; H, aqueous humor; L, crystalline lens; X, optic centerof the lens; b, blind spot; /. fovea centralis; p, pupil; M, ciliarymuscles, which control the curvature of the lens; Ob, object outsideof eye; Im, image on the retina. (From Judd, after Wundt by per-mission of Ginn and Co.) part of the eye), admits the rays of light. The expan-sion of the pupil in dull light and its contraction inbright light is analogous to the wlorking of the dia-phragm of the camera. In front of the pupil is thecornea, a transparent covering shaped like a watch-crystal. Just back of the pupil is the lens of the eye,which refracts the rays of light and brings them to afocus on the retina. Between the lens and the retina SENSATION 69 is a mass of transparent jelly-like substance (the vitre-ous humor) which, with the aqueous humor in frontof th
Size: 2073px × 1205px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1921
