Figure 1 .

Task design for Experiment 1. At the start of each trial, the memory array appeared, which consisted of four colored squares along the midline. Participants were told to remember the colors and locations of these squares over the brief delay. Following the memory array, the screen went blank. Then, either the screen remained blank the entire delay (no distractor condition) or the screen remained blank for 500 ms (distractor condition) followed by a series of distractors presented laterally. This distractor array consisted of either four colored squares or circles on one side of the screen and iso-luminant gray diamonds on the other side of the screen. When participants were in the “Ignore” condition, they were told to always ignore these task-irrelevant distractor objects. When they were in the “Discriminate” condition, they were told to determine the shape of the colored stimuli (squares vs. circles) in order to report whether the stimuli were circles. They were told to withhold their response until the response screen appeared. Following the distractor array, the screen then went blank for the rest of the delay. On the final screen, one square on the midline reappeared and could either be the same color as the original square or it could be a different color. In both conditions, participants had to report whether the square on the cued side of the screen changed colors. In the “Discriminate” condition, participants additionally had to report whether the distractor were circles, if there were distractor on that trial.