Figure 1.

Examples of reactive and anticipatory pursuit. (A and B) Eye position (lower) and smooth eye velocity (upper) responses (blue traces) to ramp (A) and step-ramp (B) target motion stimuli (black traces) with velocity of 20 (blue)°/s. Gaps in smooth eye velocity traces represent locations of saccades removed in analysis. (C and D) Eye position (lower) and smooth eye velocity (upper) during target occlusion occurring 400 ms after target motion onset ( from Bennett and Barnes, 2003). In (C) target always reappears after 800 ms occlusion, whereas in (D) target never reappears but subject is instructed nevertheless to continue pursuit as if it will reappear. (E) Anticipatory smooth eye velocity responses made in response to target motion cues during presentation of randomized target velocities. Each cue comprised a digit (1, 2, 3, or 4) representing speed (10, 20, 30, or 40°/s, respectively) and a directional indicator (< or >) and occurred 600 ms before target onset. Anticipatory velocity markers () indicate eye velocity 50 ms after target onset (V50), prior to visual feedback. V50 increased as target speed increased (Jarrett and Barnes, 2005) as shown in these examples. In the catch presentation, target motion was unexpectedly delayed by 160 ms, resulting in earlier initiation of anticipatory movement and attainment of higher than normal V50.