Abstract
Certain results during a check of Kohler''s distance paradox were at variance from those predicted. It was hypothesized that Gibson''s "adaptation to the norm" might also the effective under conditions of non-symmetry other than the linear situations that have so far been investigated. The problem then became to find the amount of figural after-effect when a symmetrical situation was used, and compare this amount with the results already found. Expt. I (12 subjects): Using the task of setting two dots (T figure) to the apparent horizontal, figural after-effects were measured to the nearest 0.1 mm. following 1.5 minutes of exposure to two solid rectangles situated, respectively, one above and one below each dot. Ten trials were used for each subject for every position of the rectangles, which were displaced different distances from the median horizontal. Expt. II (7 subjects): Using a rectangle whose varying size reproduced the distances tested in expt. I, but symmetrically placed with respect to the fixation point, each subject was required to set 4 dots to asymmetrical rectangular position. Figural after-effects were observed in both cases. Under the conditions of expt. II figural after-effects were in agreement with "satiation" theory for all positions of the rectangle''s edges. In expt. I the non-symmetry had produced an amt. of figural after-effect in excess of that in expt. II, point for point This excess is attributed to the action of "adaptation to the norm" in Gibson''s sense, interacting with, and adding to, the effect of "satiation.".
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