(A) Large attention field (High uncertainty). Each bar represents performance for a different range of stimulus orientations. Red, valid pre-cues. Blue, invalid pre-cues. Error bars, ±1 s.e.m. (n=4 observers). Similar performance for all orientations indicated that observers spread their attention across orientations. (B) Small attention field (Low-uncertainty). Performance corresponding to each of 3 orientation ranges, combining right- and left-tilted orientations. Red, valid pre-cues. Blue, invalid pre-cues. Error bars, ±1 s.e.m (n=4 observers). * p<0.05, t-tests, Wilcoxon test.