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Reaction Time Test

Wait for green, then click as fast as you can. Five trials, and you get your average in milliseconds along with how it compares to everyone else who has clicked through a browser.

Click to start

Wait for the panel to turn green, then click as fast as you can. Five goes.

What you are actually measuring

Simple reaction time is the interval between a signal appearing and you responding to it. It sounds like it should be a pure measure of nerve speed, and it mostly is not. The interval includes detecting the change, deciding it is the signal, sending the instruction to your hand, and the hand moving. Perception and decision take up more of it than the movement does.

A browser adds its own tax on top. Your monitor waits for the next refresh, your mouse reports on its own polling interval, and the browser has to schedule the event. Together these usually add 30 to 80 milliseconds that have nothing to do with you, which is why browser results run slower than the sub-200ms figures reported in laboratory studies. It is also why comparing yourself against someone on different hardware is only loosely meaningful.

Reaction time and intelligence

There is a genuine relationship, and it is smaller than people expect. Simple reaction time, the kind measured here, correlates weakly with general cognitive ability. Choice reaction time, where you have to decide between several possible responses, correlates more strongly, which is the clue about what is going on: the part that tracks intelligence is the deciding, not the moving.

So a fast result here is worth something, and it is not an IQ score. Processing speed is one component of cognitive performance, and reasoning, verbal, numerical and spatial, is most of what a full-scale score is made of.

Frequently asked questions

What is a good reaction time?

Measured in a browser, most adults land between 230 and 330 milliseconds, clustering a little above a quarter of a second. Under 200ms is genuinely quick. Those figures include display and input latency, so they run slower than laboratory measurements of the same thing, which typically come in under 200ms.

Why is my browser reaction time slower than lab figures?

Because you are not only measuring yourself. Between the screen refreshing and your click registering there is monitor latency, input latency and browser event loop delay, which together usually add 30 to 80 milliseconds. A 60Hz display alone can add up to 16ms just waiting for the next frame. This is why the comparison here is against other people clicking in browsers rather than against published norms.

Does reaction time relate to intelligence?

There is a real but modest relationship. Simple reaction time correlates weakly with measures of general cognitive ability, and choice reaction time, where you must decide between responses, correlates more strongly. Neither is a substitute for an intelligence test. Speed is one small component of cognitive performance and reasoning is most of what a score is made of.

Why does clicking early not count?

Jumping the gun is a failure of inhibition, not a fast reaction. If early clicks were scored they would produce impossibly low times and reward guessing the interval rather than responding to the signal, so those trials are replayed instead. The wait before green is randomised between roughly 1.2 and 4.5 seconds for the same reason.

How can I improve my reaction time?

Most of the easy gains are situational rather than trained: being rested, caffeinated within reason, sitting properly, using a wired mouse and a high refresh rate display. Practice produces a genuine but small improvement that plateaus quickly. Reaction time also slows gradually with age from the mid twenties onward, which is one of the most reliable findings in the area.

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