RunTheTests
/

Reaction Time Test

Measure your visual reaction time, with the display and input latency accounted for separately.

How this test works

The panel turns green after a randomised wait between 1.5 and 5 seconds, and you click as soon as you see it. The timestamp is taken on the frame the green is actually painted rather than when the state changes, because the gap between those two is a whole frame and would otherwise be charged to you. The refresh rate is measured in the background so the result can state how much of your score belongs to the machinery: half a frame of display hold plus half a polling interval is the part that can be computed, and the rest of the chain is named rather than estimated. The median across attempts is reported rather than the mean, so one distracted go does not decide the result.

What the results mean

Median
The middle of your attempts. Used instead of the average because reaction times have a long tail of distracted outliers.
Spread
Median absolute deviation. A large spread means inconsistent attention more often than inconsistent reflexes.
Measured system floor
Latency the measuring chain adds that can actually be computed. Your own contribution is at most the median minus this.
Too early
Clicking before the cue. The wait is randomised so it cannot be anticipated, and anticipated clicks would beat nerve conduction.

Common problems and fixes

My time is much worse than sites I used years ago
Those sites usually reported the raw number with none of the chain subtracted, and often on a 60 Hz CRT with lower latency than a modern LCD. The figures are not comparable.
I keep clicking too early
The wait is deliberately random between 1.5 and 5 seconds. Watch rather than count, and let the colour trigger the click.
My results are wildly inconsistent
Look at the spread rather than the median. A large spread usually means attention rather than reflexes, and doing ten attempts in a quiet room narrows it considerably.

Frequently asked questions

What is a normal reaction time?

Simple visual reaction is usually quoted around 200 to 250 ms, but those figures come from laboratory equipment with no browser, display buffer or USB polling in the path. A browser measurement of 250 ms is consistent with a laboratory measurement well under it.

Does my monitor affect my score?

Yes, measurably. At 60 Hz the display alone holds each frame for 16.7 ms and adds about 8 ms on average before you can see anything, plus panel transition time. At 144 Hz that drops to under 4 ms. This is why the refresh rate is measured and reported.

Why is the wait randomised?

So it cannot be anticipated. With a fixed delay people time the click rather than react to it and produce numbers faster than nerve conduction allows, which measures rhythm rather than reaction.

More in Device