Dwelling on distractors varying in target-distractor similarity.

Present day models of visual search focus on explaining search efficiency by visual guidance: The target guides attention to the target's position better in more efficient than in less efficient search. The time spent processing the distractor, however, is set to a constant in these models. In contrast to this assumption, recent studies found that dwelling on distractors is longer in more inefficient search. Previous experiments in support of this contention all presented the same distractors across all conditions, while varying the targets. While this procedure has its virtues, it confounds the manipulation of search efficiency with target type. Here we use the same targets over the entire experiment, while varying search efficiency by presenting different types of distractors. Eye fixation behavior was used to infer the amount of distractor dwelling, skipping, and revisiting. The results replicate previous results, with similarity affecting dwelling, and dwelling in turn affecting search performance. A regression analysis confirmed that variations in dwelling account for a large amount of variance in search speed, and that the similarity effect in dwelling accounts for the similarity effect in overall search performance.