Figure 2.

Illustration of the relation between fixation interval between saccades and time delay between gaze and finger position. a, Assume that a subject is instructed to move the finger along a straight line at a constant velocity and that the subject does so by a sequence of saccades (gray line) with constant fixation times between saccades. Also assume that gaze moves to a new position as soon as the finger (solid black line) reaches the gaze position. A relatively small number of fixations (3 in this example) with long fixation times between saccades results in a relatively large effective lead time (dashed line) of gaze relative to finger position. b, A relatively large number of fixations (6 in this example) with short fixation times results in a relatively small effective lead time of gaze relative to finger.