What the number contains
Not just your nervous system. The measurement includes the time for the screen to show the change, for your eye and brain to process it, for your hand to move, and for the input to be registered.
A 60Hz screen adds up to 16 milliseconds of uncertainty on its own, and a wireless mouse a few more. That is why a gamer on a 144Hz monitor scores better than the same person on an office laptop — partly reflexes, partly equipment.
Averages, and why several attempts matter
Typical visual reaction time is 200–250 milliseconds. Under 200 is fast; under 150 usually means you anticipated rather than reacted.
A single attempt says almost nothing — attention fluctuates second to second. Five or more, with the outliers visible, is a far more honest picture, which is why the spread is shown alongside the average.
Frequently asked questions
What is a good reaction time?
200–250 milliseconds is typical for visual reaction. Under 200 is fast; under 150 usually means anticipating rather than reacting.
Does my equipment affect the score?
Yes. A 60Hz screen adds up to 16ms of uncertainty, and a wireless mouse adds more. The number is you plus your hardware.
Why does it vary so much between attempts?
Attention fluctuates second to second. Take several — the spread is as informative as the average.
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