Reaction Time Test
Wait for the target to light up, then tap as fast as you can — 5 rounds, about half a minute, free and with no account. You get your fastest time in milliseconds, and a straight answer about how much of that number is you and how much is your equipment.
Take the test
Tap the target the moment it lights up. Not before.
READY
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ms, your fastest
Simple reaction time — how fast you can act on a signal you were already expecting. Published figures for adults usually land somewhere around 200–300 ms, but on a web page your display and input device are inside that number.
Every round was a false start. Wait for the target to change before tapping, and the run will measure something.
- Best
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- Average
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- Valid trials
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Nothing is uploaded; your times stay in this tab. Tapping early is a false start and the round is repeated.
What a reaction time test measures
The gap between a signal appearing and your finger moving is not one thing. Light has to reach your retina, a signal has to travel, something has to recognise it as the event worth acting on, and a command has to reach your hand.
Simple reaction time — this test — strips out every decision: there is one signal and one response, and you already know what to do. What is left is close to the floor of how fast you can act on the world at all.
That floor is why the measurement matters. Every more interesting task, from choosing between two answers to naming an ink color, is built on top of it — so knowing your baseline is what lets a slower number elsewhere mean something other than “I am slow today”.
Where it comes from
- 1868
Donders times a thought
Franciscus Donders measures how long a mental step takes by timing two tasks and subtracting one from the other: react to any signal, versus react only to a particular one. The difference is the cost of deciding. It is the founding trick of mental chronometry, and the reason a bare reaction time is the baseline everything else is measured against.
- Since
The most measured number in psychology
Simple reaction time turns up everywhere: sports screening, sleep-deprivation studies, drug trials, ageing research. It is trivial to collect and it moves in response to almost anything that affects the nervous system, which is both its usefulness and its weakness.
- On the web
The hardware joins in
A browser test measures your nervous system plus your screen plus your input device plus whatever the browser is doing. That does not make it worthless — it makes it a measurement of you-on-this-device, comparable to itself and to nothing else.
How to read your result
Three numbers, and the interesting part is the distance between the first two.
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Your best round
The headline. Best rather than average on purpose: a single distraction inflates an average, while your fastest clean round is closer to what you are actually capable of.
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The average
Shown next to it because the gap between the two is informative. A best far below your average usually means attention wandered on some rounds, not that you are secretly faster.
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Valid rounds
Out of 5. Tapping before the signal is a false start: the round is thrown away and repeated, because guessing the timing is not reacting.
What this version cannot tell you
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Your screen adds time
A 60 Hz display can sit on a finished frame for up to about 17 ms before showing it, and touchscreens add more. Tens of milliseconds of what you measure here belong to the hardware, not to you.
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Mouse, keyboard and finger differ
The three input paths do not cost the same. Switching device mid-comparison is enough to invent an improvement that never happened.
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This is simple, not choice, reaction
One signal, one response, nothing to decide. Choice reaction time — where you must pick the right response — is a different and slower measurement, and the two are not interchangeable.
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It is not a diagnosis
Reaction time shifts with sleep, caffeine, mood, illness and age all at once, which is exactly why a single number cannot tell you which of them caused it.
Questions about reaction time
What is a good reaction time?
Published laboratory figures for adults on a simple visual reaction task usually land somewhere around 200 to 300 ms. On a web page, add whatever your display and input device contribute, which is often tens of milliseconds. That makes a browser number fine for tracking yourself and poor for comparing yourself to anyone else.
Why is the wait before the signal random?
So you cannot learn the rhythm. With a fixed delay you would start moving before the target changed and measure your timing rather than your reaction. The wait here is a random 1.5 to 3.5 seconds, and tapping during it is treated as a false start.
Why does it use my best round instead of the average?
Because a single lapse of attention drags an average down in a way that says more about that moment than about you. Your fastest clean round is the better estimate of your ceiling — and both numbers are shown, so you can see how far apart they are.
Can I train my reaction time?
A little, and mostly early on: some of what looks like improvement is you learning the task and settling into a rhythm of expectation. Sleep, caffeine and simple alertness move the number more than practice does. Anyone promising you a dramatic, lasting drop is selling something.
Do I need an account?
No. Everything runs in your browser, nothing is submitted, and your times are shown to you and then gone when you close the tab.
If it is the trend you want, that needs an app
A single number tells you about one afternoon. NEURA measures processing speed across several games, tracks it as one Focus Index and shows you the line over weeks — which is the part no single page can do, whatever it measures.