Visual Perception of the Chick Volume 20

Visual Perception of the Chick Volume 20

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 edition. Excerpt: ...than size difference, it was necessary to employ various controls. There appear, in the stimuli themselves, three factors other than size that might provide a basis for correct response: (1) luminous intensity of the respective stimuli; (2) brightness of the respective stimuli; and (3) illumination of the respective electric compartments. Without adequate controls, it would be impossible to say definitely whether size or these-other characteristics were the bases of the responses which point to the above conclusion. Supposing the two stimulus areas to be 6 cm. and 3 cm. in diameter, the display surfaces equal in brightness, and a complete image of the larger formed on the retina, it follows that the chick would be stimulated by four times as much light from the larger as from the smaller stimulus. It is conceivable that the chick, under these conditions, might respond on the basis of pain or its physiological concomitant, or even of pupillary reaction. In addition to this possibility, the general illumination of the electric compartment containing the larger stimulus would differ from that of the other compartment. The chick might choose the lighter or darker compartment. Both of thesepossibilities might occur independently of the matter of brightness. As a portion of the controls used in this connection, an additional lamp was placed directly above the experiment box. This upper illumination (L of figure 3, p. 24), consisting of a 2 c.p. electric lamp enclosed in a vertically suspended cylinder of galvanized iron, was designed to hide the inequalities in the distribution of light in each compartment. It hangs about 120 cm. above the floor of the experiment box so that an equal amount of light is added to each compartment. The diameter more

Product details

  • Paperback | 34 pages
  • 189 x 246 x 2mm | 82g
  • United States
  • English
  • black & white illustrations
  • 1236918355
  • 9781236918352