Figure 2.

Time course of a trial. A trial started with presentation of a central fixation point. After a random interval between 0.5 and 1 s, the fixation point disappeared and a target appeared on the left or right to which participants were required to saccade. The probability of the target appearing on a particular side was constant within a block, but differed between the blocks. After the saccade, the target remained for a random period between 0.5 and 1.5 s, and then disappeared while the central fixation appeared. Once the participants saccaded back to the central fixation a new trial began.