When the screen turns green, click or tap as fast as you can. Average human reaction time is around 250–284ms.
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Reaction time is the interval between a stimulus and your response to it. It's one of the most fundamental measures of cognitive and neurological speed. The average human visual reaction time is between 200–350 milliseconds, with trained athletes and gamers often scoring under 200ms.
Factors like age, fatigue, caffeine, and practice all influence your reaction time. Want to test other aspects of your cognitive speed? Try our Typing Speed Test or challenge your memory with the Number Memory Test.
Consistent practice, adequate sleep, and good hydration are scientifically proven to reduce reaction time. Professional gamers often train specifically to optimize their response latency. Take the test daily and watch your scores improve on your personal dashboard.
Simple visual reaction time (SRT) captures the entire chain from a photon hitting your retina to your finger completing a click. It is the most fundamental benchmark of neural processing speed, isolating the irreducible floor of human response. Franciscus Donders first measured it systematically in 1868; over 150 years of research have placed the population average at 250–284 milliseconds. Our web-based average of 284ms includes hardware variation that laboratory conditions exclude.
SRT differs from more complex variants: Choice Reaction Time adds a stimulus-identification step costing ~100ms extra, and Audio Reaction Time is typically 30–50ms faster because the auditory pathway has fewer synaptic relays than the visual pathway. This test isolates pure detection speed — nothing else.
Reaction time fluctuates by 15–40ms across sessions in the same individual. Sleep is the biggest lever — a single night of 5–6 hours slows RT by 20–40ms. Caffeine (100–200mg) provides a reliable 10–20ms improvement peaking 45 minutes after ingestion. Hardware matters too: a 60Hz monitor adds ~17ms of display lag versus ~7ms on a 144Hz screen, and wireless mice introduce 5–30ms of variable latency.
RT peaks in the early-to-mid 20s and slows by approximately 2–5ms per decade thereafter — reflecting reduced myelination efficiency and slower central processing speed. Athletes and competitive gamers often maintain faster RT into their 40s compared to sedentary peers, but the underlying biological decline continues regardless.
The single biggest RT lever. Sleep deprivation equivalent to 0.05% BAC after just 17 awake hours.
100–200mg, 45 mins before testing. Reliable 10–20ms improvement in controlled studies.
Removes 5–30ms of Bluetooth lag. Most effective hardware upgrade for accurate measurement.
10 mins/day for 3 weeks improves attentional readiness by 10–20ms. Gains plateau after ~100 trials.