Cognitive skill
Visual reaction time
How quickly your eye-to-decision-to-finger loop closes.
Visual reaction time measures the latency between a stimulus appearing in your field of view and your motor response. It's one of the most-studied cognitive metrics — and one of the most stable across decades.
What it is
Reaction time is the time from a visual stimulus appearing to a motor response being executed. Simple reaction time (one stimulus, one response) typically lands between 200 and 300 ms in healthy adults. Choice reaction time (multiple stimuli requiring discrimination) is longer because the discrimination adds processing. The single number is less useful than the variance — high variance often indicates fatigue, distraction, or, in clinical contexts, neural slowing.
Why it matters
- Driving — most road safety statistics correlate more strongly with reaction-time variance than with mean latency.
- Competitive gaming and sport — the difference between a top-1% and median performer is often only 30–50 ms.
- Workplace safety in any role involving moving machinery or rapid decision-making.
How it changes with age
Simple reaction time slows by roughly 0.7 ms per year after age 25. Choice reaction time slows faster — about 1.6 ms per year — because the discrimination step compounds with general neural slowing. Sleep deprivation and alcohol each add the equivalent of 5–10 years of ageing in a single session.
How to train it
Reaction time has a hard floor set by neural conduction speed — you can't drop below it. But most people sit 30–60 ms above their floor due to habit. Our Reaction-time drill in /train trains you toward your own floor by running 20 trials with random delays, then plotting your distribution against the population norm.