Figure 1.

Experimental procedure. A, Representation of the four possible types of search arrays used in the task. In 50% of trials, all display items were of the same color (e.g., red; distractor-absent condition); whereas in the remaining 50% of trials, three items were of the same color (e.g., red) and the fourth item (additional singleton) was of the alternative color (e.g., green; distractor-present condition). The target, indicated with a dashed circle for graphical purposes only, was defined as the unique double-arrowhead item. B, Timeline of an experimental trial. Three TMS pulses were delivered at 10 Hz (pulse gap of 100 ms) starting 100 ms after search array onset. C, Schematic representation of the stimulated sites: Talairach coordinates were x = −36, y = −1, z = 48 and x = 36, y = −1, z = 48 for left and right FEF, respectively, and x = −30, y = −53, z = 49 and x = 30, y = −53, z = 49 for left and right IPS, respectively (red circles). The two sham conditions (white circles) were in a region on the scalp located halfway between IPS and FEF of the left and right hemisphere, respectively.