Task setup.

<p><b>Top panel:</b> Setup of a single trial sequence in the attention-demanding task. Here, the target stimulus is a horizontal rectangle on either side of the center cross. In each trial sequence, the cross is presented, followed by a cue (arrow) giving probabilistic information about whether and where the target stimulus wil appear, and finally by the stimuli, displayed for approximately 50 ms. The target will either appear as cued, appear in the uncued location, or not appear at all; subjects are required to choose which of these possibilities occurred. <b>Bottom panel:</b> Setup of the memory-demanding tasks (same format for word and face memory). In the study session, subjects are presented with a sequence of stimuli. During the test session, another sequence of stimuli is presented; subjects are required to distinguish whether each test stimulus is novel or identical to a stimulus from the study session. Colors of lexical stimuli and colored borders of face stimuli (not pictured) indicate the probability that the test stimulus has been seen before.