The role of the gap effect in the orienting of attention: Evidence for express attentional shifts

The “gap effect” refers to the finding that saccadic latencies are typically reduced when the fixation point is removed just prior to the presentation of a target. One explanation for this effect is that the removal of the fixation point causes the disengagement of covert attention and allows for extremely rapid movements of attention (express attentional shifts). However, previous research regarding express attentional shifts has yielded equivocal results. The present study used a variation of a peripheral cueing paradigm with a discrimination task (Experiment 1) and a detection task (Experiment 2) to further examine this issue. The results from eye movement and keypress latencies indicated that there were express attentional shifts with the discrimination task but not in the detection task. This pattern of results may have been due to differences in how attention was allocated between the two tasks. Thus, evidence for express attentional shifts was found, but only under certain conditions.