Attention and size in a global/local task

Two-letter stimuli, consisting of one small letter inside a much larger one tin Experiments 1A, 1B, and 2) or inside a "blob" tin Experiment 3), were used to examine the role of size difference in global/local tasks. The smal l letter was placed at locations that avoided contour interactions. The res ults showed no identity interference. in that the specific identity of the large letter did not differentially affect identification of the small one. However. there was evidence of global advantage, in that the presence of a large letter hindered identification of the small one, The magnitude of th e global advantage effect, as measured by the difference in performance bet ween the small-single and small-embedded conditions, was largest (about 200 ms reaction time (RT) difference) when the large letters were the same as the small ones, lower (a 63 ms difference in Experiment 1B. and 89 ms in Ex periment 2) when the large letters were unrelated to the small ones, and lo west (a 25 ms difference) when the large stimuli were blobs. It is proposed that the amount of interference depends on the overlap between the feature s of the large stimuli, as a set, and those of the small ones, also as a se t. (C) 2001 Elsevier Science B.V. All rights reserved.