How fast do you correct while you're already tracking?
Keep the crosshair on the red target. Just track; don't guess. Each run is a 3 s warm-up plus 60 s, and Esc stops early.
Best in Chrome or Edge. Sanity check: add ?bot=120 to the URL and a simulated hand with a known 120 ms latency plays instead of you.
Finished runs are saved anonymously to work out percentiles: a random ID kept in this browser, your result, and your display and mouse rates.
Change in hand velocity around each event. Grey: single events. Green: average. Red: estimated onset, taken from where your average acceleration takes off.