Distinguishing influences of overt and covert attention in anticipatory attentional target tracking.

This study investigated the relative contributions of overt and covert attention on the apparent anticipatory nature of attention in two experiments, using two different object tracking tasks, both combined with a probe detection task. In Experiment 1, we investigated the distribution of attention for overtly and covertly tracked targets separately at low tracking load using a single-object tracking task (one target, one distractor). We found anisotropic distributions of probe detection rates for both overtly tracked and covertly tracked targets, with highest detection rates at locations ahead of the target's movement. In Experiment 2, we investigated the distribution of attention in overt and covert tracking at a relatively higher tracking load using a multiple-object tracking task (two targets, two distractors) in which viewers overtly tracked one target while simultaneously covertly tracking a second target. We found anisotropic distributions of probe detection rates around covertly tracked targets only. We conclude that covert attention always anticipates motion when keeping track of moving objects, while overt attention is more flexible and its anticipatory nature depends on the tracking task.