Abstract
In orientation repulsion, a vertical target appears tilted against the orientation of a surrounding inducer. There is psychophysical evidence that the internal representation supporting orientation repulsion gradually evolves before conscious awareness. Here we quantified the repulsion when a flanker sped up the awareness of the target. To induce the repulsion, eight circularly arranged Gabor patches were presented both to the right and left of the fixation point. A target Gabor patch was flashed at the center of either inducer. Participants reported whether the target appeared tilted clockwise or counter-clockwise from the vertical. In Experiment 1, the repulsion was smaller with a local flanker (five dots) preceding the target by 100 ms than with the same flanker presented simultaneously. The same reduction occurred when flankers were presented not only on the side of the target but also on both sides. In Experiment 2, the results were the same even though a central directive cue provided 600 ms before the target indicated the target’s side. In Experiment 3, three horizontally aligned Gabor patches were sequentially presented with various SOAs. Participants reported whether the patches appeared to move leftward or rightward. When the preceding flanker locally surrounded the outermost patch, an illusory motion away from it was induced and the SOA of 40 ms was necessary to cancel this motion, demonstrating that the flanker actually sped up awareness by 40 ms. In Experiment 4, instead of local dots, concentric circles presented at four corners of the display served as the flanker. Even this remote flanker preceding the target by 100 ms reduced the repulsion. The results suggest that the process promoting the emergence of conscious awareness is neither content-specific nor spatially selective, and that this process can finalize the appearance of orientation repulsion even when contextual modulation has not yet been saturated.