How to use this test
Start on the target
Click the blue button, then wait for green and the words Click now. The delay varies between 1.2 and 3.4 seconds.
Respond to the change
Click, tap or press Enter or Space when the cue appears. An early response does not count; try that attempt again.
Complete five attempts
Start each attempt when ready. After five valid responses, read the median, fastest time and individual samples.
What we check
Timing uses the browser’s performance clock from the animation-frame callback that sets the green cue to the input event. It is an estimate of this browser interaction, not the exact instant light reaches your eyes.
The median is the middle of five sorted samples. Device latency, display refresh, browser scheduling and input method all affect the result. Keep your setup consistent when comparing runs.
What this test can’t tell you
This is a practice game, not an IQ test, health screening or clinical assessment. The score describes this run, not your overall ability. There are no population rankings.
Something not working?
I clicked too soon
Start a new attempt and wait for the colour change.
My result varies
That is expected. Try a few relaxed attempts rather than drawing a conclusion from one.
Common questions
What is a good reaction time?
This site does not publish a population average or percentile. Use repeated runs on the same setup to explore your own consistency.
Why use a median?
The middle sample is less affected by a single unusually slow attempt than an average. All five values remain visible so the summary does not hide the run.
Can I use a phone?
Yes. Tap the target, but compare touch runs separately from mouse or keyboard runs.
Does this test fitness to drive?
No. This is a simple timing game, not a safety assessment or medical test.