Where the limit sits
A reaction cannot be instant. The signal has to be detected, passed to the brain, recognized and turned into a movement. Each step takes time, and together they put a floor under every score.
That floor is usually placed at about 100 ms. Athletics turns it into a rule: a sprinter who leaves the blocks less than 100 ms after the gun is ruled to have false started. A quicker start is assumed to be a guess.
The rule is about sound. Sound reactions are typically 30 to 50 ms faster than visual ones, so the practical floor for a visual test like this one sits higher.
Fast scores in context
| Time | What it is |
|---|---|
| About 100 ms | Treated as the floor for a real reaction |
| About 150 ms | Typical reaction to touch |
| About 170 ms | Typical reaction to sound |
| Under 200 ms | Exceptional on an online visual test |
| 250 to 300 ms | Typical online visual result |
Why sub 150 ms online scores are rare
An online score is your reaction plus the delay of your equipment. Hardware typically adds 20 to 50 ms. A 60 Hz screen refreshes every 16.7 ms and a 144 Hz screen every 6.9 ms, so even the green panel arrives slightly late.
Lab studies of young adults report about 200 to 250 ms for a simple visual reaction, with far less equipment delay. An online average below 150 ms would mean beating those lab figures while carrying extra lag. A number like that usually comes from a single try, not from a five-try average.
Anticipation is not reaction
The easy way to post an impossible number is to guess. If you start your click just before the change and it lands a few milliseconds after, the timer shows a tiny figure.
Here the wait before green is random, about 1.5 to 5 seconds, and a click before green cancels the try. Averaging five tries dilutes one lucky guess.
In sport, anticipation is a real skill. It is simply a different thing from the limit of reaction.
Finding your own fastest time
Use a wired mouse and a fast monitor, test when you are rested, and read your average, not your best try. More tips are in how to improve reaction time, and the wider picture is in human reaction time.