Reaction Time Challenge

Try five visual-signal rounds with pointer, touch or keyboard input. See your recorded milliseconds without a ranking or health label.

Available in Japanese and English

Wait for the signal

Choose one input method for this run. When the waiting message changes to GO, tap, click or press a key as instructed. Complete up to five valid rounds.

A browser game, not a clinical test or a measure of intelligence. Screen, browser, input device and accessibility tools affect these approximate times. There is no population ranking or pass mark.

The game keeps inputs and scores on this page; the site adds none to ad or analytics payloads. See Privacy & settings for advertising processing.

How it works

A random wait of 2–4 seconds is followed by a text-and-colour signal scheduled for a browser display frame. The browser clock measures from that callback to your chosen pointer-down or non-repeating key-down. This is not the physical time of photons reaching your eyes. Early presses, hidden/lost-focus tabs, scheduling delays over 750 ms and unanswered signals after 10 seconds are not scored. Five or fewer valid times produce a clearly counted median.