What Is a Good Reaction Time? Making Sense of the Numbers

A quarter of a second is about normal, and your device eats some of it. A plain guide to reaction time and what our speed games really measure.

Speed games make people curious about their own reflexes. Are mine fast? Slow? Getting worse? The honest answer needs a little unpacking, because "reaction time" is not one thing.

The simple kind

The basic measurement is called simple reaction time. One signal, one response: a light comes on, you press a button. For healthy adults, a typical result is somewhere around a quarter of a second, often a little faster for young people who are concentrating. Responses to sound tend to be quicker than responses to light.

There is a floor. In athletics, a sprinter who leaves the blocks less than a tenth of a second after the gun is judged to have false started, on the grounds that nobody can genuinely react that fast. They must have guessed.

So the realistic human range for a simple reaction is narrow: from a bit under two tenths of a second on a very good day to three or four tenths when you are tired.

The choosing kind

The moment you have to decide something, everything slows down. This is choice reaction time, and it is what most games really test.

In the early 1950s the psychologists William Hick and Ray Hyman showed that the time taken to respond rises steadily with the number of options. More choices, more time, in a regular and predictable way. It is usually called Hick's law.

Quick Pads is a four-choice reaction test wearing an arcade costume. You see a shape and have to hit the matching pad out of four. Nobody does that in a quarter of a second. Half a second is already sharp. And when the pads shuffle after every fifth point, you can feel yourself slow down while your brain redraws its map.

The stopping kind

A third skill is holding back. Green Light is built on what psychologists call a go/no-go task. Most of the shapes are green and need a tap. A few are red and need nothing. Because green is far more common, tapping becomes automatic, and the red square arrives just when your finger has stopped asking permission.

Being fast and being able to stop pull in opposite directions. The players who score well in Green Light are rarely the quickest. They are the ones who give up a little speed to stay in control.

Your device takes a cut

Here is the part most online reaction tests leave out. The number you see is not only you. Between the game deciding to show something and your tap being counted, the machine adds its own delays:

The screen takes time to draw the new picture.
A touchscreen or mouse takes time to report the press.
The browser handles the press on its next frame.

Together these can add several hundredths of a second, and the amount varies from device to device. A result of 280 on one phone and 240 on another does not mean you improved.

The useful comparison is with yourself, on the same device, on different days.

What changes your result

Far more than talent, these move the number about:

Sleep. A bad night shows up immediately.
Warm-up. The first two or three rounds are nearly always the slowest.
Attention. A conversation in the room is worth a tenth of a second.
Caffeine and time of day. Small effects, but real ones.
Expecting the signal. If you can predict when it is coming, you are no longer reacting. You are timing.

That last point is why Tap Sprint is not a reaction test at all. Nothing surprises you. It measures how fast your finger can move, which is a different limit entirely.

So what is "good"?

For the games here, we would put it like this. If you can reach thirty in Quick Pads, your choice reactions are quick. If you can reach forty in Green Light, your self-control is better than most. If your scores in both fall apart at eleven at night, you are normal.

What these HTML5 games cannot do is diagnose anything. They are short, fun and unscientific. Treat the scores as a game, and if you have a real concern about your reactions or attention, that is a question for a doctor.

For everyone else: play three rounds to warm up, then see what you can do.