How to Improve Reaction Time: What Works and What Does Not

Every reaction has three stages: perception (the signal reaches the brain), decision (the brain selects a response) and movement (the command travels to the muscles and the finger moves). What you are measuring depends on how much work the middle stage has to do.

• Simple reaction time has one signal and one response: the screen turns green, you click. A sprinter leaving the blocks at the gun is doing a simple reaction task.
• Choice reaction time has several possible signals, each with its own response: press left for red, right for blue. Braking for a pedestrian, returning a serve or choosing which way to swerve are choice tasks.

Choice reactions are always slower, and they get slower as options are added. Hick's law, from experiments by William Hick and Ray Hyman in the early 1950s, describes the pattern: decision time rises roughly with the logarithm of the number of equally likely choices, so each doubling of the options adds about the same extra delay.

Task	Typical time
Simple visual, online test with a mouse	about 250 ms
Simple visual, laboratory equipment, young adults	about 200 ms
Simple auditory (a beep instead of a light)	about 150–170 ms
Two-choice visual	about 300–400 ms
Sprinter leaving the blocks	about 120–180 ms
Braking in a car after an unexpected hazard	about 1–1.5 s

Hearing beats sight: sound signals take a shorter path to the brain and are processed faster. World Athletics treats any start under 100 ms as a false start, on the basis that nobody can genuinely react that quickly. Driving is slow because it combines detection, a choice and a large movement of the foot.

Online scores run higher than laboratory ones partly because of the hardware. A 60 Hz screen only redraws every 16.7 ms, and monitors, wireless mice, TVs and touchscreens each add their own delay, together often tens of milliseconds. A 280 ms result on a phone and a 240 ms result on a gaming PC may reflect the same person.

• Sleep loss. This is the largest everyday factor. In a 1997 study published in Nature, Drew Dawson and Kathryn Reid found that 17 hours without sleep impaired psychomotor performance about as much as a blood alcohol concentration of 0.05 per cent, and 24 hours about as much as 0.10 per cent. Chronic restriction is sneakier: in a 2003 study led by Hans Van Dongen, people sleeping six hours a night for two weeks showed attention lapses comparable to a night or two without sleep, while rating themselves only slightly sleepy.
• Alcohol. It slows responses and, more importantly, makes them inconsistent and error-prone, with effects measurable well below typical legal driving limits.
• Age. Simple reaction time is fastest in the twenties and slows gradually, more noticeably after about 50. Choice reaction time slows more, and the variation between attempts widens. Healthy older adults remain well within the range needed for everyday life.
• Divided attention. Talking on a phone, even hands-free, slows drivers' responses, because the decision stage is busy with something else.
• Sedating medicines, such as older antihistamines and sleeping tablets, can slow reactions the next morning.

1. Sleep. Recovering lost sleep restores most lost speed, and regular sleep and wake times keep it there. When you cannot sleep more, a 10 to 20-minute nap improves alertness for a few hours without leaving you groggy; the nap timer has a 20-minute preset. Waking up on time covers the other end of the night.
2. Task-specific practice. Reaction time for a particular signal and response improves with repetition, especially in choice tasks, as the brain learns the mapping and starts reading early cues. Experienced goalkeepers and tennis players are faster mainly because they anticipate better, not because their raw reflexes differ much. Gains transfer poorly: studies of commercial brain-training games have found improvement on the trained games with little carry-over to other tasks. Practise the thing you want to be faster at.
3. Moderate caffeine. About 75 to 200 mg, one or two cups of coffee, reliably improves reaction time and vigilance, most noticeably when you are tired. It takes effect within 30 to 60 minutes. Larger doses add little except jitter, and daily users partly adapt.
4. Exercise. A bout of moderate exercise tends to sharpen reaction times for a short period afterwards, and regular aerobic exercise is linked to faster, more consistent reactions in later life.
5. Readiness. Warm, alert and in position beats cold and distracted. Responses are faster when you know roughly when the signal is coming, which is why good tests randomise the delay.

Players of fast action video games also react faster in lab tasks without losing accuracy, and some training studies suggest play contributes to this, though the size of the effect is still debated.

A single attempt tells you very little. Scores can vary by 30 ms or more from trial to trial, and one lucky anticipation can produce a number you will never repeat. For a meaningful result:

• Take at least five trials after two or three warm-ups, and look at the average as well as the best.
• Discard anticipations and distractions. A result under 100 ms is a guess; one far slower than the rest means your attention slipped.
• Keep the setup identical: the same device, browser, input method and screen. Wired mice and keyboards are more consistent than wireless ones and touchscreens.
• Test at the same time of day, and compare yourself with yourself, not with someone else's hardware.

The reaction timer shows each recent attempt alongside your best and average, which is exactly what you need to spot a trend across days. For a different kind of speed, the typing speed test measures a practised motor skill. For sport drills, a partner with the stopwatch or lap timer can time sets of starts, but hand timing includes the timekeeper's own reaction, roughly a quarter of a second, so use those numbers only for comparing one session with the next.