Saccadic errors in the double-step task by a rhesus monkey. (a) Locations of initial fixation points (FP and FP′) at (−20°, 0°) and (+20°, 0°), respectively; first saccade target (A) at (0°, 0°); and second saccade targets (B and B′) at (−10°, 10°) and (10°, 10°), respectively. The red arrows represent the first saccade from FP′ to A and the second saccade from A to B′. The blue arrows represent the saccades in the other direction (to the left). (b) The graph plots horizontal saccadic error (eye position minus target position) against time from the disappearance of the stimulus to the beginning of the saccade. Data points are colored according to saccade direction. The red triangle is the mean error when the target disappeared 500 ms before the saccade. Error bars are standard errors of the means. The box denotes times at which the stimulus is on during the saccade. All the errors are in the opposite direction of the first saccade direction. Figure adapted from Jeffries et al. (2007) with permission.