Limited capacity for contour curvature in iconic memory.
We measured the difference threshold for contour curvature in iconic memory by using the cued discrimination method. The study stimulus consisting of 2 to 6 curved contours was briefly presented in the fovea, followed by two lines as cues. Subjects discriminated the curvature of two cued curves. The cue delays were 0 msec. and 300 msec. in Exps. 1 and 2, respectively, and 50 msec. before the study offset in Exp. 3. Analysis of data from Exps. 1 and 2 showed that the Weber fraction rose monotonically with the increase in set size. Clear set-size effects indicate that iconic memory has a limited capacity. Moreover, clear set-size effect in Exp. 3 indicates that perception itself has a limited capacity. Larger set-size effects in Exp. 1 than in Exp. 3 suggest that iconic memory after perceptual process has limited capacity. These properties of iconic memory at threshold level are contradictory to the traditional view that iconic memory has a high capacity both at suprathreshold and categorical levels.
Sakai
Koji
K
Department of Human Relations, Kyoto Koka Women's College, Japan. rb064@mail.koka.ac.jp
D000328:Adult; D003463:Cues; D004192:Discrimination, Psychological; D004538:Eidetic Imagery; D005260:Female; D005556:Form Perception; D006801:Humans; D008297:Male; D008568:Memory; D011930:Reaction Time; D012858:Size Perception