Abstract
Recent evidence has been found for a top-down source of task-irrelevant oculomotor capture, in which an event draws the eyes away from a primary task. In these cases, an object memorized for a non-search task can capture the eyes when it appears during search (Sato, Heinke, Humphreys & Blanco, 2005; Olivers, Meijer & Theeuwes, 2006). Here, an experiment was conducted to investigate the interaction between memory-driven capture, goal-driven search, and capture by abrupt onsets. The use of eye tracking allowed us to determine the rate of capture by the different types of stimuli and explore the temporal dynamics of the various signals driving oculomotor guidance. This is important because we were able to distinguish between potential sources of capture and build a theoretical model of how visual working memory, top-down goals, and abrupt onsets can drive oculomotor orienting. The results of our experiments show that memorized objects capture the eyes at a higher rate than abrupt onsets when they are both present in the search display and in competition for the initial saccade. Additionally, when the abrupt onset and memorized color are the same object, this combination leads to even greater oculomotor capture away from the target. However, the degree of capture is less than additive, suggesting these are two independent sources of guidance signals. More importantly, saccade latencies differed between the three potential saccade targets, with saccades to the search target yielding the longest latencies, and saccades to memorized color singletons yielding latencies that were shorter than saccades to abrupt onsets. Results will be discussed in terms of a neural-computational model.