Fig. 2. Task sequence.

(a) Observers performed a two-alternative forced-choice (2AFC) orientation discrimination task, contingent upon contrast sensitivity, while maintaining fixation. The target could appear at any one of four isoeccentric locations along the cardinals. Participants were either cued towards a single location (Valid cue) or to all four locations (Neutral cue). On every trial, four Gabor patches briefly appeared simultaneously at all stimulus locations. A response cue indicated the target, for which participants reported the tilt (left or right). Note that Gabor tilt angle, size of placeholders, fixation point, and response cue have been exaggerated for clarity. Subpanel: Group average stimulus contrast by location was the same for valid and neutral cue condition trials in each experiment, and are shown for (b) Experiment 1, same contrast across locations resulting in different performance across locations, and (c) Experiment 2, different contrast at different locations to equate performance across locations.