Abstract
Recent work has highlighted how, during visual search, both irrelevant and relevant information within the focus of attention can influence attentional disengagement and the location of subsequent deployments of attention (Boot & Brockmole, 2010; Born, Kerzel, & Theeuwes, 2010; Brockmole & Boot, 2009). Participants in our studies began search by fixating an irrelevant item. Even though this item was never the target, saccades away from it were slowed when it shared the same color as the target. In a new series of experiments, we explored this attentional disengagement effect in depth. Specifically, we examined the time course of this effect, how the persistence of the item within the focus of attention influences disengagement, and whether similar effects could be observed when participants searched for targets defined by shape instead of color. Robust disengagement effects were observed when the color of the irrelevant fixated item matched the color of the search target, but only if the fixated item remained onscreen. Disengagement costs first appeared when the irrelevant item matched the target item approximately 70 ms before the search display, and grew stronger as the irrelevant item and search display approached simultaneous presentation. Non-persistent items produced no cost in terms of latency, but did bias eye movements to distractors that shared their features. This effect decreased as simultaneous presentation was approached. Thus, dissociable effects were observed on saccadic direction and latency. Furthermore, when participants searched for a target defined by shape, disengagement was delayed when this same shape was presented within the focus of attention, although disengagement effects were much smaller. Experiments confirm and extend findings suggesting a research focus not just on features that pull attention to a location, but also a focus on the features that hold it there as well. Both processes are critical determinants of visual processing.