Figure 1.
a, Baseball configuration, showing eight possible strike-zone locations, bluish fixation, and target moving from the center toward the strike zone (trajectory indicated by arrow, not part of stimulus display). b, Subjects fixate on a blue central fixation point between 0.54 and 3.46 s. The fixation point then changes color and increases in size for 1 s to inform the subject of the task to be performed. Green, Always-go; red, always-nogo; white, ocular baseball. Next, the fixation point returns to its original size and color, and a target begins to move away from this central fixation point at an average speed of 1.75°/s (see Materials and Methods). A strike zone appears in a pseudorandomly determined location 10° from the fixation point. Subjects were instructed to maintain fixation during this phase for all trial types. Three seconds after stimulus onset, a green response cue at fixation appears, informing subjects to respond. Subjects then continue to fixate or pursue for the remainder of the trial (1 s). The target never crosses the strike zone, reaching only 7° eccentricity from the fixation point.