Fig. 1.

Task illustrations. Top left: Visual Search Displays. In all three panels, the target is a blue vertical oval with a gap on the right or left. When shown with three red distracters (left panel) the Attend-Half and Attend-3 displays fully overlap. When the three blue ovals are the only blue items (Attend-3, middle panel), they attract attention automatically, whereas in the Attend-half (right panel), search requires top-down control. Top right: time-line of the change localization task (not drawn to scale). On every trial the color of one of the items is different on the test array than it was in the sample array. Bottom: examples of the 1–2 AX CPT trial structure, including both alphanumeric and picture stimuli for illustration. Participants only saw the picture stimuli. The two target sequences are 1-AX and 2-BY.