Reaction time, explained properly
Everything we figured out building the tests: the real numbers, what they mean, and how much of it you can actually change, with the studies cited so you can check us.
Fifteen guides, written while building the tests on this site rather than collected from elsewhere. Two rules apply to all of them. Every number that could be checked is linked to the study it came from, and where our own figures are estimates rather than measurements we say so on the page instead of borrowing someone else's authority for them. If you find a claim you think is wrong, tell us and point at a source. We would rather fix it than defend it.
Start here
If you have just taken a test and want to know what the number means, read these three first. Between them they cover what is being measured, whether your score is any good, and what to do if it is not.
What Is Reaction Time? A Plain-English Definition
The definition, the four stages a reaction actually goes through, and where the milliseconds go.
Read → GuideWhat Is a Good Reaction Time?
Straight answers for 200, 250 and 300 ms, broken down by age and by what you play.
Read → GuideWhy Is My Reaction Time So Slow? The Honest Reasons
Six things that genuinely slow you down, and which of them you can do anything about.
Read →How a reaction actually works
A reaction is not one event, it is a chain: light hits your retina, a signal crosses your brain, a decision gets made, a muscle fires. These four take that chain apart and show which stage each millisecond belongs to.
The Science of Reaction Time: What Really Happens
Retina to muscle, stage by stage, with the timing of each step.
Read → ScienceAuditory vs Visual Reaction Time: Why Sound Wins
Sound beats sight by roughly 40 ms, and the reason is chemistry in your eye.
Read → ScienceSimple vs Choice Reaction Time and Hick's Law
Why four options cost you more than one, and how Hick's law predicts by how much.
Read → ScienceWhat Affects Your Reaction Time? Sleep, Caffeine, Age
Sleep, caffeine, age, alcohol and fatigue, ranked by how much they actually move the number.
Read →Getting faster, honestly
Training claims are where reaction-time writing goes worst. These two separate what has evidence behind it from what is being sold to you, and are blunt about the ceiling: most people have far less room to improve than the adverts suggest.
How to Improve Your Reaction Time: What Actually Works
What the evidence supports, what is marketing, and the ceiling biology puts on all of it.
Read → How-toHow to Test Your Reaction Time: 5 Ways, Click to Ruler
Five methods from a ruler drop to a click test, and what each one really measures.
Read →Where it actually matters
Reaction time only becomes interesting when something depends on it. On a track, in a duel, at a set of brake lights. A recurring theme here: in the fastest situations the raw reflex is barely the deciding factor.
Reaction Time for Gaming: FPS, Aim and the Real Numbers
Where trained players actually sit, and why raw reaction decides less than you think.
Read → SportHow Do F1 Drivers React So Fast?
The start procedure, the ~200 ms launch, and how much of it is reflex versus rehearsal.
Read → SportReaction Time in Sports: The Numbers, by Sport
Eight sports, the time available in each, and what the athlete is really doing with it.
Read → SafetyDriving Reaction Time and Stopping Distance, Explained
Milliseconds turned into metres of tarmac, and where the 1.5 second figure comes from.
Read →The numbers people argue about
Two topics that generate more heat than data: the fastest reaction ever recorded, and whether men really react faster than women. Both have real research behind them and both are routinely overstated online.