Cognition · ~2 minutes
Measure your reaction time.
Simple visual reaction time: wait for GO, press as fast as you can. One practice trial, five scored, median result against approximate adult norms — with your device's latency honestly acknowledged.
The panel below will say Wait… for a random moment, then flip to GO! — press it (or hit Space) the instant it does. Pressing early is a false start and the trial repeats. Your score is the median of five trials, so one slow tap won't sink you.
Wait for GO…
Your reaction time
Trials:
Percentiles are approximations against computer-administered adult norms (~N(284, 60) ms). Your screen, browser, and input device add real latency to every number here — so treat runs on different devices as different tests, and any single run as an estimate, not a verdict.
About this instrument
What this measures — and what it doesn't
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Measures
Simple reaction time
Processing speed at its rawest: register a signal, act. It's one of psychology's oldest measurements, correlates modestly with broader cognitive ability, and declines predictably with fatigue and age.
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Method
Five scored trials, median result
Random 1.5–3.5 s waits defeat rhythm-guessing; one practice trial burns off surprise; presses under 90 ms are treated as anticipatory and repeated; false starts are discarded, never scored. The median resists a single bad tap.
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Result
Milliseconds + approximate percentile
Your median lands against approximate computer-administered adult norms — about 284 ms at the middle, spread ~60 ms. Faster is better, so 220 ms sits near the 85th percentile and 360 ms near the 10th.
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Limits
Honest limits
Every number includes your device's input and display latency — often 30–80 ms — so absolute values aren't comparable across devices, and none of this is a clinical or driving-fitness assessment. Caffeine, sleep, and age all move the needle.
Go deeper
The science behind this instrument
Sleep, stress & test performance
Why a rough night measurably slows the same nervous system.
Read DataHow IQ changes with age
Processing speed is the domain that shifts most across a life — here's the shape of it.
Read DomainsPattern recognition & fluid reasoning
Where raw speed ends and reasoning begins.
ReadQuestions
Before you begin
What does a reaction time test measure?
Simple visual reaction time — how quickly you can respond to a single expected signal. It measures alertness and basic motor response, distinct from processing speed, which measures how fast you can perform an actual mental comparison across many items.
Why is the median used instead of the average?
One distracted trial can wreck an average. The median of five scored trials ignores a single outlier in either direction, which makes it the more honest summary of your true speed in a short test.
What counts as a good reaction time?
On computer-administered tests, typical adult medians cluster around 250–320 ms. We place your median against approximately N(284, 60) — so ~284 ms sits near the 50th percentile, ~220 ms near the 85th, and ~360 ms near the 10th. All of it is approximate: your device adds latency.
Why does my device matter?
Screens, browsers, mice, and touchscreens each add tens of milliseconds before your press is registered. That latency is inside every number this test reports, which is why percentiles carry a tilde and why comparing runs on the same device matters more than any single absolute value.
Speed is the tempo. See the whole score.
The full adaptive test maps reasoning across pattern, numeric, verbal, spatial, and memory domains.
Start the assessment