What reaction speed means
Reaction speed is how quickly you respond once something happens. It is measured as a time, so the two words run in opposite directions: high speed means a low number. A typical person responds to a simple visual signal in about 250 ms, a quarter of a second.
Reaction speed in daily life
Catching a glass as it slips off a table is close to a simple reaction: one event, one response. Most everyday cases are not that clean. On the road, a driver first has to notice a hazard, work out what it is and choose what to do. Road engineers commonly allow 1.5 to 2.5 seconds for a driver to notice a hazard and begin braking, many times longer than a click test.
The gap comes from decisions. Hick’s law says that the more options there are, the longer a decision takes.
Reaction speed in sport
| Situation | What it shows |
|---|---|
| Sprint start | A start faster than 100 ms after the gun is a false start, so about 100 ms is treated as the human floor |
| Formula 1 start | Drivers typically react to the lights in roughly 0.2 seconds |
| Penalty kick | A goalkeeper has roughly 0.4 seconds, barely enough to react and dive |
Good keepers do not wait for the ball. They read the run-up and move early. That is anticipation, and it is where skilled athletes stand out.
Reaction speed in gaming
Games reward quick responses to things that appear on a screen, so the screen itself matters. A 60 Hz display refreshes every 16.7 ms and a 144 Hz display every 6.9 ms. A player on the faster screen sees each change sooner.
Age plays a part as well. A 2014 study of over 3,000 StarCraft 2 players found that response speed starts to slow from about age 24. The decline is gradual.
Measure your reaction speed
The test above measures the simple kind. The panel turns from red to green after a random wait, you click, tap or press Space, and five tries are averaged in milliseconds. Most people score 250 to 300 ms, and under 230 ms is fast.
For a focused test page with score bands, go to the reaction speed test. For the definition and the stages of a reaction, read reaction time. To combine speed with mouse movement, try the aim trainer.