Abstract
Tested alternative explanations for the apparent change in visual spatial organization produced by exposure to "adapting" or anchor stimuli: (a) change is perceptual (adaptation-level theory) and (b) change is the result of response bias (response-frequency-equalization theory). In Exp. I, judgments of spatial organization were obtained for 11 different matrices of dots in a series ranging from columnar organization to rowlike organization. 30 undergraduates were exposed on alternate trials to dot patterns of extreme horizontal (rowlike) organization, to extreme vertical (columnar) organization, or to neither (control group). As predicted by both theories, judgments were systematically affected by the adapting stimuli. In Exp. II with 33 Ss, the influence of response bias was nullified by a forced-choice procedure. Contrary to adaptation-level theory, once response bias was eliminated group differences vanished.