When does the timing start?

At lights out. The lights coming on are the countdown, not the signal: the time runs from the frame in which the lights were drawn off to the moment your press is reported, and the press counts rather than the release.

What counts as a jump start?

Any press while a light is still on. It is a false start: the trial is not recorded, the stage says so, and your next press runs it again. False starts are counted on screen for the run, so a fast median with several jump starts behind it shows them.

Is the pause the same as at a real race start?

It is not meant to copy any particular start. The pause after the fifth light is drawn at random between 0.5 and 3 seconds on every trial, so lights out can be seen but not counted.

Can I compare my time with someone else's?

Only loosely. The figure includes your screen drawing the lights going out and your device reporting the press, so two people on different hardware are not measured the same way. Run five trials on the same device on different days and compare the medians.

Are these times kept separately from the colour test?

Yes. Each test keeps its own five trials in this browser. Choosing Colour change at the top of the tool brings back that run, and choosing Start lights again brings this one back.

F1 Reaction Time Test

This test is modelled on a Formula 1 start. Press the stage and five red lights come on, one a second. After the fifth, all of them go out together following a random pause of 0.5 to 3 seconds, and you respond the moment they go out. Five trials give a median and a best, and a click, a tap, the space bar or Enter all count as a response.

Median so far

not yet

Best

not yet

Pause before lights out

0.5 to 3 s after the fifth light

The stage takes a click, a tap, the space bar or Enter, and the press is what is timed, not the release. A second press in the moment after a trial ends is ignored, so a double press cannot start the next trial while you are still reading the last one. Your times are kept in this browser and nowhere else. If you are using a screen reader, the signal is announced after it is painted, so the reading will be higher than what your hand did.

Responded before the signala false start
the trial does not count, and the page says why
Tab hidden mid-trialthe browser stopped drawing it
the trial is voided rather than timed
0 of 5 trials donemedian: the middle time
no trials recorded yet

What the number includes. This measures the whole loop: the screen drawing the lights going out, your eye and hand, and the browser reporting the press. Display and input lag sit inside that figure and nothing is deducted for them, so it is comparable between your own runs on one machine rather than against a laboratory instrument. A response that cannot be a reaction is refused rather than scored: one that arrives before the signal, which had nothing to react to, and one from a trial during which the tab stopped being visible, because a browser stops painting a hidden tab.

Common questions

When does the timing start?: At lights out. The lights coming on are the countdown, not the signal: the time runs from the frame in which the lights were drawn off to the moment your press is reported, and the press counts rather than the release.
What counts as a jump start?: Any press while a light is still on. It is a false start: the trial is not recorded, the stage says so, and your next press runs it again. False starts are counted on screen for the run, so a fast median with several jump starts behind it shows them.
Is the pause the same as at a real race start?: It is not meant to copy any particular start. The pause after the fifth light is drawn at random between 0.5 and 3 seconds on every trial, so lights out can be seen but not counted.
Can I compare my time with someone else's?: Only loosely. The figure includes your screen drawing the lights going out and your device reporting the press, so two people on different hardware are not measured the same way. Run five trials on the same device on different days and compare the medians.
Are these times kept separately from the colour test?: Yes. Each test keeps its own five trials in this browser. Choosing Colour change at the top of the tool brings back that run, and choosing Start lights again brings this one back.

Timed with the browser's high-resolution clock, to the millisecond it reports. The figure includes your screen or speaker presenting the signal and your device registering the press, so it is comparable between your own runs on one machine rather than against a laboratory instrument. A ruler drop time is free-fall arithmetic, only as precise as the mark you read at the catch.