Reaction Time Test
Time is measured from the ready callback to your response with performance.now(), rounded to milliseconds. Early clicks record no attempt.
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Play, method and practical limits
Time is measured from the ready callback to your response with performance.now(), rounded to milliseconds. Early clicks record no attempt.
Limits and problems
Browser scheduling, display, sound and input latency affect results. Audio may be suspended or unsupported. Ratings are playful, not medical measurements.
In color mode the waiting color differs from the named target hue. A reset, early click or mode change invalidates the old ready callback.
Game data
Attempts stay in memory; the all-time best uses localStorage under reaction-best. A storage failure does not invalidate the measured attempt.
The clock starts in the scheduled callback, before a guaranteed paint or audible onset. Browser clock precision may be reduced; rounding to milliseconds does not establish millisecond accuracy. Hidden tabs cancel an active trial.
A very short value may reflect anticipation or timing artifacts. This game cannot verify that a score represents a human reaction.
About Reaction Time Test
The panel runs a single loop. You click once to arm it, it waits a random 1.5 to 5.5 seconds, and the moment the state changes the clock starts. Your next click stops it and the elapsed time is pushed into the session list. Because the delay is random you cannot learn a rhythm, and because a click during the wait is rejected with "Too early", guessing costs you the attempt rather than earning a fake score.
Classic changes the panel to green. Audio adds an 800 Hz tone for 0.15 seconds while the panel also changes visually. Color announces a target hue and shows a different waiting hue. These are game modes, not calibrated sensory or choice-reaction protocols.
Four figures sit under the panel. Attempts counts the rounds in this session, Best is the lowest of them, Average is their mean rounded to a whole millisecond, and Record is the lowest score this browser has ever stored, kept under the key reaction-best. The strip below shows your last attempts so a single lucky round does not flatter the picture. Reset clears the session list but leaves the record alone. Each result also gets a label: under 150 ms Incredible, 150-199 Excellent, 200-249 Great, 250-299 Good, 300-399 Average and 400 or more Keep practicing.
What this cannot do is separate you from your equipment. The measured number includes the time your mouse or touchscreen takes to report the click and the time your monitor takes to draw the new colour, so scores are comparable between your own sessions on the same hardware, not between people on different machines. It is a game and a training aid, not a medical or fitness-to-drive assessment.
The clock starts in the scheduled callback, before a guaranteed paint or audible onset. Browser clock precision may be reduced; rounding to milliseconds does not establish millisecond accuracy. Hidden tabs cancel an active trial. A very short value may reflect anticipation or timing artifacts. This game cannot verify that a score represents a human reaction.
Use Cases
Pro Tips
- Browser scheduling, display, sound and input latency affect results. Audio may be suspended or unsupported. Ratings are playful, not medical measurements. The clock starts in the scheduled callback, before a guaranteed paint or audible onset. Browser clock precision may be reduced; rounding to milliseconds does not establish millisecond accuracy. Hidden tabs cancel an active trial.
- A very short value may reflect anticipation or timing artifacts. This game cannot verify that a score represents a human reaction.
- Classic changes the panel to green. Audio adds an 800 Hz tone for 0.15 seconds while the panel also changes visually. Color announces a target hue and shows a different waiting hue. These are game modes, not calibrated sensory or choice-reaction protocols.
- Record survives a page reload because it lives in this browser under the key reaction-best, but Reset only clears the session list. Clearing site data is what wipes the record.
- A wireless mouse and a slow display both add milliseconds you did not spend reacting. Compare scores only against your own on the same machine, and use the space bar rather than a click if your mouse feels laggy.
Troubleshooting
The panel shows "Too early" and no time is recorded.
You clicked during the random wait, before the signal. The round is discarded on purpose so anticipation cannot produce a score. Click once more to arm a new round and wait for the actual change - the delay is redrawn every time, between 1.5 and 5.5 seconds, so there is no rhythm to learn.
Audio mode plays no sound.
The tone is generated with the Web Audio API, which browsers keep suspended until the page has received a real user gesture, and which is silenced entirely by a muted tab or muted system output. Click the panel once first, unmute the tab, then arm the round. If nothing comes through, use Classic mode instead - it needs no audio.
Every score is far slower than expected.
Classic changes the panel to green. Audio adds an 800 Hz tone for 0.15 seconds while the panel also changes visually. Color announces a target hue and shows a different waiting hue. These are game modes, not calibrated sensory or choice-reaction protocols. The clock starts in the scheduled callback, before a guaranteed paint or audible onset. Browser clock precision may be reduced; rounding to milliseconds does not establish millisecond accuracy. Hidden tabs cancel an active trial.
Record shows a number nobody in this session achieved.
Record is the lowest result this browser has ever stored, under the key reaction-best, and it outlives both the session and a page reload. Reset clears Attempts, Best and Average but deliberately leaves Record alone. Clearing the site data for this domain in your browser settings is what resets it.
The space bar does nothing.
The key handler is attached to the panel, so the panel must have keyboard focus. Click it once first, or tab to it, and the space bar then arms and stops the round exactly like a click. If the page has scrolled so the panel is off screen, the space bar scrolls the page instead.
How to use
Pick a mode in the row above the panel: Classic waits for green, Audio waits for a tone, Color waits for one named colour among decoys.
Click the panel once to arm the round; it turns to the waiting state and holds for a random 1.5 to 5.5 seconds.
Click - or press the space bar - the instant the signal arrives; the elapsed milliseconds and a rating appear on the panel.
Repeat at least ten times and read Average rather than Best, and watch the strip of recent attempts for consistency.
Check Record for the lowest score this browser has ever held, which survives reloads.
Press Reset to clear Attempts, Best and Average for a fresh session; the Record is deliberately left untouched.
Choose classic visual, audio or target-color mode. Click the area or press Space while it is focused to begin.
Wait for go, the sound, or the named target color, then respond once. Click again for another attempt; Reset clears the session.
Frequently Asked Questions
On this test, 200-249 ms is labelled Great and 150-199 ms Excellent. Published study figures describe their own participants and protocol. They are not norms for this browser game, driving fitness, or a personal diagnosis; direct score comparisons are not established here.
The largest figure worth quoting comes from Woods and colleagues in Frontiers in Human Neuroscience, 2015: a mean simple reaction time of 231 ms in 1,469 people aged 18 to 65, or 213 ms once their hardware delay was subtracted. The same study found reaction time rising by 0.55 ms for each year of age. Published study figures describe their own participants and protocol. They are not norms for this browser game, driving fitness, or a personal diagnosis; direct score comparisons are not established here.
The clock is started with the browser high-resolution timer at the instant the panel changes state, and stopped at your click, and the difference is rounded to a whole millisecond. Nothing is measured during the random 1.5 to 5.5 second wait, and a click in that window ends the round with "Too early" rather than recording a number.
Classic changes the panel to green. Audio adds an 800 Hz tone for 0.15 seconds while the panel also changes visually. Color announces a target hue and shows a different waiting hue. These are game modes, not calibrated sensory or choice-reaction protocols.
Browser scheduling, display, sound and input latency affect results. Audio may be suspended or unsupported. Ratings are playful, not medical measurements. The clock starts in the scheduled callback, before a guaranteed paint or audible onset. Browser clock precision may be reduced; rounding to milliseconds does not establish millisecond accuracy. Hidden tabs cancel an active trial.
The clock starts in the scheduled callback, before a guaranteed paint or audible onset. Browser clock precision may be reduced; rounding to milliseconds does not establish millisecond accuracy. Hidden tabs cancel an active trial. Browser scheduling, display, sound and input latency affect results. Audio may be suspended or unsupported. Ratings are playful, not medical measurements.
A very short value may reflect anticipation or timing artifacts. This game cannot verify that a score represents a human reaction.
Published study figures describe their own participants and protocol. They are not norms for this browser game, driving fitness, or a personal diagnosis; direct score comparisons are not established here. Browser scheduling, display, sound and input latency affect results. Audio may be suspended or unsupported. Ratings are playful, not medical measurements.
Reaction time is the interval between the signal and the start of your movement. Response time is that plus the time your movement takes to complete. This page measures the pair together, because it can only see the click that ends the movement - which is one more reason to compare your own runs rather than absolute figures from a laboratory.
Classic changes the panel to green. Audio adds an 800 Hz tone for 0.15 seconds while the panel also changes visually. Color announces a target hue and shows a different waiting hue. These are game modes, not calibrated sensory or choice-reaction protocols. The two are not usually equal: a 2010 study by Shelton and Kumar of 14 subjects reported a mean visual reaction of 331 ms against 284 ms for auditory. Published study figures describe their own participants and protocol. They are not norms for this browser game, driving fitness, or a personal diagnosis; direct score comparisons are not established here.
The measurement includes the device and browser pipeline. It does not isolate your nervous-system response or certify native audio latency.