Smooth Pursuit

Smooth pursuit is a voluntary, continuous eye movement that matches gaze velocity to a moving target, keeping its image stable on the fovea for high-acuity tracking. Rashbass (1961) established that pursuit and saccadic systems are functionally distinct pathways rather than a single mechanism, showing that pursuit alone cannot fully match sudden velocity changes and depends on a brief predictive saccade to catch up when target motion outpaces the smooth system's gain. Pursuit gain, the ratio of eye velocity to target velocity, is a standard index of tracking quality and rarely reaches 1.0 even in skilled trackers.

Reference: Rashbass, 1961. The NeuroRank implementation holds the canonical form and scales interference via task-irrelevant stimulus density.

1. Keeping a crosshair locked on a strafing enemy in an FPS duel, where gaze and cursor must both match the target's velocity rather than just its position.
2. Following a moving ward or minion wave in a MOBA lane while planning the next action, a continuous tracking demand layered on top of decision-making.
3. Tracking a curved, Lissajous-style path in an aim trainer, where pursuit gain has to adapt continuously as the target's velocity changes direction.

NeuroRank's Tracking module is a direct behavioral analog of smooth pursuit: players follow a continuously moving target with the cursor, and avgNormDistance captures how tightly cursor position matches target position, closely mirroring the classic pursuit-gain measure.