Visual parsing and response competition: the effect of grouping factors.

When the task is to categorize a target letter at a known location, subjects show more interference from incongruent distractors that are relatively close (B. A. Eriksen & C. W. Eriksen, 1974) or that share common motion with the target (Driver & Baylis, 1989). In eight experiments, we examined whether static factors other than proximity can affect the amount of interference. When distractors and the target letter were in the same color, the distractors interfered more than they did when they were in a different color, even when the latter were closer to the target. Good continuation between the target and distractors also led to more interference. These results suggest that the efficiency of selection is determined by several aspects of the relation between targets and distractors in addition to their proximity, and thus that visual attention is not directed on the basis of position information alone.