Interference between Orientation and Color, with Schematic Illustrations (Top [A,B]), and Stimuli/Data (Bottom [C–J])

<div><p>(A) Orientation segmentation with irrelevant color.</p><p>(B) Color segmentation with irrelevant orientation.</p><p>(A,B) Larger patch sizes of irrelevant color gives stronger interference, but larger patch sizes of irrelevant orientation do not make interference stronger.</p><p>(C–E) Small portions of the actual experimental stimuli for orientation segmentation, without color contrast (C) or with irrelevant color contrast in 1 × 1 (D) or 2 × 2 (E) blocks. All bars had color saturation <i>s_uv</i> = 1, and were ±5° from horizontal.</p><p>(F) Normalized RTs for (C–E) for four subjects (different colors indicate different subjects). The “no”, “1 × 1”, and “2 × 2” on the horizontal axis mark stimulus conditions for (C–E), i.e., with no or n × n blocks of irrelevant features. The RT for condition “2 × 2” is significantly longer (<i>p</i> < 0.05) than that for “no” in all subjects, and than that of “1 × 1” in three out of four subjects. By matched sample <i>t</i>-test across subjects, mean RTs are significantly longer in “2 × 2” than that in “no” (<i>p</i> = 0.008) and than that in “1 × 1” (<i>p</i> = 0.042). Each RT is normalized by dividing by the subject's mean RT for the “no” condition, which for the four subjects (AP, FE, LZ, NG) are 1170, 975, 539, and 1107 ms, respectively.</p><p>(G–J) Color segmentation, analogous to (C–F), with stimulus bars oriented ±45° and of color saturation <i>s_uv</i> = 0.5. Matched sample <i>t</i>-test across subjects showed no significant difference between RTs in different conditions. Only two out of four subjects had their RT significantly higher (<i>p</i> < 0.05) in interfering than in no interfering conditions. The un-normalized mean RTs of the four subjects (ASL, FE, LZ, NG) in “no” condition are: 650, 432, 430, 446 ms, respectively.</p>